RELATED APPLICATION DATA

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application Serial No. 63/188,556, filed May 14, 2021, and titled “SYSTEM AND METHOD FOR BACKFILLING VOIDS FROM CARBONACEOUS EXTRACTION”. This application also claims the benefit of priority to International Patent Application PCT/US22/25921, filed on April 22, 2022, and titled “LASER-BASED GASIFICATION OF CARBONACEOUS MATERIALS, AND RELATED SYSTEM AND METHODS”. Each of these applications is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

[0002] The present invention generally relates to material deposition. In particular, the present invention is directed to depositing materials in a gaseous state using a laser-based applicator, and related methods, apparatuses, and systems.

BACKGROUND

[0003] Fossil fuels can provide an answer to the growing energy demand of developed and developing countries. The larger availability and lower cost of coal relative to other fossil fuels make it the leading energy resource for electricity generation across the world. On the other hand, coal is a source of environmental concern, not only for its greenhouse impact in terms to carbon dioxide. In addition, the health and safety impact of conventional coal extraction methods on workers and local environments is also a major consideration.

[0004] Common problems with mining and other extraction techniques are the ecological and geological concerns with the remaining voids. Voids left by mining operations can result in ground collapse, groundwater contamination, and other ecological disasters. With multiple lower seams, this can result in subsidence and breakage occurring under the self-weight of the strata. The effects of overburden pressure constantly develop, causing surface subsidence, thus resulting in problems such as soil and water loss, land subsidence, vegetation dieback, and building collapse.

[0005] Existing techniques for mitigating problems resulting from mining and extraction include backfilling using three different types of material. The first type of material is a solid waste material, such as a fly ash. Backfilling a void using solid waste material requires a conveyor system

1 to physically deliver the solid waste material, as well as manpower and effort to properly place the material into the void. This technique is costly both in time and manpower, as well as lacking in effectiveness for voids in submerged and/or deep seams. The requirements to convey the solid waste material and then effectively pack or place it underground has limited value.

[0006] A second type of material is a cementitious backfill material. Similar to the solid waste material, the backfill technique for cementitious material requires a large crew to feed the material into the underground void. Thus, backfilling with solid waste material or cementitious material is a costly endeavor, working to negate the cost-effectiveness and value of coal extraction that generates the void.

[0007] A third type of material is a liquid material. The technique using liquid material requires manually pumping the material into the void(s). This technique does not always work well, because water can leak, has a different weight and density relative to the liquid material, can be environmentally unsound, etc. For example, the liquid material can cause contamination of underground water tables, simply replacing one ecological disaster for another. Additionally, this technique can be cost-prohibitive, requiring installation of multiple slurry preparation systems, slurry conveying and mixing systems, as well as labor, electricity, materials, and other costs.

SUMMARY OF THE DISCLOSURE

[0008] In one implementation, the present disclosure is directed to a method of depositing a material to a deposition region, wherein the material contains two or more components. The method includes providing a precursor material comprising the two or more components in a homogeneous mixture with one or more substances that make the precursor material flowable; flowing the precursor material to a laser-irradiation region; irradiating the precursor material with laser energy in the laser-irradiation region so as to create a gaseous material; and flowing the gaseous material to the deposition region and allowing the gaseous material to solidify in the deposition region.

[0009] In another implementation, the present disclosure is directed to a method of processing a deposit of carbonaceous material to extract calorific material from the deposit. The method includes (a) processing portions of the carbonaceous material within the deposit so as to extract the calorific material and form a void within the deposit; (b) irradiating a precursor material with laser energy so as to create a gaseous material; and (c) directing the gaseous material to one or more deposition regions within the void and allowing the gaseous material to solidify so as to stabilize portions of the carbonaceous material that define the void.

2 [0010] In yet another implementation, the present disclosure is directed to a method of processing a deposit of carbonaceous material to remove calorific material from the deposit. The method includes sinking an access well into the deposit, wherein the access well has a length; forming a plurality of lateral bores along the length of the access well so as to create a plurality of removal levels, wherein all of the lateral bores extend away from the access well in a common direction; on each removal level: (a) processing portions of the carbonaceous material within the deposit so as to remove the calorific material and form a void within the deposit; (b) heating a precursor filler material with laser energy so as to create a gaseous material; and (c) directing the gaseous material into the void and allowing the gaseous material to solidify so as to stabilize portions of the carbonaceous material that define the void.

[0011] In still another implementation, the present disclosure is directed to an applicator for applying a stabilizing material to a deposition region. The applicator includes a body that includes: a laser-irradiation region designed and configured to receive a precursor material to the stabilizing material, the laser-irradiation region including one or more laser outputs for, when the precursor material is present in the laser-irradiation region, irradiating the precursor material with sufficient energy to transform the precursor material into a gaseous material; a passageway designed and configured to deliver the precursor material to the heating region; and an outlet region for directing the gaseous material toward the deposition region so as to form the stabilizing material.

[0012] In a further implementation, the present disclosure is directed to a combination head assembly for performing pyrolysis and stabilization within a pyrolysis chamber within a carbonaceous material. The combination head includes a laser head designed and configured to controllably heat portions of the carbonaceous material so as pyrolyze the portions of the carbonaceous material and thereby create the pyrolysis chamber; and an applicator head coupled to the laser head, the applicator head designed and configured to deposit a stabilizing material into the pyrolysis chamber after pyrolyzing the portions of the carbonaceous material using the laser head.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0014] FIG. 1 is an isometric diagram illustrating a conventional underground coal gasification (UCG) system and process for producing a product gas from a coal seam;

3 [0015] FIG. 2 is a elevational view of a section of a coal seam illustrating physical aspects that occur within the coal seam during UCG;

[0016] FIG. 3 is a flow diagram illustrating an example product-gas-production method of the present disclosure, wherein laser-energy is used to heat a carbonaceous material so as to cause the carbonaceous material to pyrolyze and form a product gas;

[0017] FIG. 4 is a high-level block diagram illustrating an example laser-based gasification system that can be used to perform a product-gas-production method of the present disclosure, such as the example product-gas-production method of FIG. 3;

[0018] FIG. 5A is a flattened view of a portion of the inner wall of a pyrolysis chamber in a carbonaceous material, illustrating an example pattern for heating the inner wall so as to cause the carbonaceous material to pyrolyze, wherein the irradiation regions abut one another;

[0019] FIG. 5B is a flattened view of a portion of the inner wall of a pyrolysis chamber in a carbonaceous material, illustrating an example pattern for heating the inner wall so as to cause the carbonaceous material to pyrolyze, wherein the irradiation regions overlap one another;

[0020] FIG. 5C is a flattened view of a portion of the inner wall of a pyrolysis chamber in a carbonaceous material, illustrating an example pattern for heating the inner wall so as to cause the carbonaceous material to pyrolyze, wherein the irradiation regions are spaced from one another;

[0021] FIG. 6A is a transverse cross-sectional view of a pyrolysis chamber and surrounding portions of a carbonaceous material, illustrating the formation of a generally circular pyrolysis chamber as pyrolysis is performed on the carbonaceous material, wherein the laser head remains at the bottom (relative to FIG. 6 A) of the pyrolysis chamber;

[0022] FIG. 6B is a transverse cross-sectional view of a pyrolysis chamber and surrounding portions of a carbonaceous material, illustrating the formation of a generally rectangular pyrolysis chamber as pyrolysis is performed on the carbonaceous material, wherein the laser head remains at the bottom (relative to FIG. 6B) of the pyrolysis chamber;

[0023] FIG. 6C is a transverse cross-sectional view of a pyrolysis chamber and surrounding portions of a carbonaceous material, illustrating the formation of a generally circular pyrolysis chamber as pyrolysis is performed on the carbonaceous material, wherein the laser head remains at the geometric center of the transverse cross-sectional area of the pyrolysis chamber;

4 [0024] FIG. 6D is a transverse cross-sectional view of a pyrolysis chamber and surrounding portions of a carbonaceous material, illustrating the formation of a generally rectangular pyrolysis chamber as pyrolysis is performed on the carbonaceous material, wherein the laser head remains at the geometric center of the transverse cross-sectional area of the pyrolysis chamber;

[0025] FIG. 7 A is cross-sectional view of a portion of a deposit of carbonaceous material containing an access well and a lateral pyrolysis chamber joined to the access well, showing a flexible laser-head assembly being inserted into the lateral pyrolysis chamber via the access well;

[0026] FIG. 7B is a cross-sectional view similar to the cross-sectional view of FIG. 7A, but with the laser-head assembly located in a first gasification location and pyrolysis having been fully performed at this location;

[0027] FIG. 7C is a cross-sectional view similar to the cross-sectional view of FIG. 7B but with the laser-head assembly located in a second gasification location and pyrolysis having been partially performed at this location;

[0028] FIGS. 8A to 8C are cross-sectional views along the longitudinal axis of a portion of a bore-type pyrolysis chamber, showing a timelapse progression of pyrolysis within the pyrolysis chamber and three snapshots in time;

[0029] FIG. 9 is a cross-sectional view along the longitudinal axis of a portion of a bore-type pyrolysis chamber, illustrating progression of pyrolysis within the pyrolysis chamber as a laser head is moved along the pyrolysis chamber;

[0030] FIG. 10A is a side view of an example laser head having gas-delivery outlets and gas- collection inlets located on opposite ends of the laser head for, respectively, delivering one or more gases (e.g., oxidant(s), heating gas(es), etc.) to a pyrolysis chamber and removing one or more gases (e.g., product gas) from the pyrolysis chamber;

[0031] FIG. 10B is an enlarged cross-sectional view of the tether attached to the laser head of FIG. 10 A, showing internal components of the tether;

[0032] FIG. 11 A is an isometric diagram illustrating an example UCG system and arrangement of the present disclosure, showing the initial arrangement of a first access well, a second access well, and a pyrolysis chamber extending between the first access well and the second access well;

5 [0033] FIG. 1 IB is an isometric diagram corresponding to the example UCG system and arrangement of FIG. 11 A, illustrating the pyrolysis chamber at the beginning of heating the carbonaceous material with laser head;

[0034] FIG. 11C is an isometric diagram corresponding to the example UCG system and arrangement of FIGS. 11 A and 1 IB, illustrating the injection of an oxidant flow and the pyrolysis chamber after pyrolysis has continued for a period of time;

[0035] FIG. 12 is a flow diagram illustrating an example method of depositing a material via a gaseous material created by irradiating a fluid precursor material with laser energy;

[0036] FIG. 13 A is a high-level schematic diagram of an example laser-based applicator of the present disclosure;

[0037] FIG. 13B is a partial cross-sectional view of the applicator of FIG. 13 A, showing an example laser-irradiation region that is fed a precursor material via one or more nozzles;

[0038] FIG. 13C is a partial cross-sectional view of the applicator of FIG. 13A, showing an example laser-irradiation region provided in a chamber having one or more outlet nozzles for expelling the gaseous material from the chamber;

[0039] FIG. 14 is a flow diagram illustrating an example method of processing a deposit of carbonaceous material to remove calorific material in accordance with aspects of the present disclosure;

[0040] FIGS. 15A-15C are schematic diagrams illustrating the filling of a void using laser- based material deposition techniques of the present disclose;

[0041] FIG. 16 is an elevational view of a laser-based applicator head of the present disclosure, showing the applicator head depositing a stabilizing material in a void;

[0042] FIG. 17 is a high-level block diagram illustrating an example laser-based deposition system that can be used to perform a laser-based-deposition method of the present disclosure, such as the example methods of FIGS. 12 and 14;

[0043] FIG. 18 is an elevational view of a combination head assembly that couples together a pyrolysis laser head and laser-based applicator, showing the assembly processing carbonaceous material to first pyrolyze portions of the carbonaceous material and then stabilize remaining portions of the carbonaceous material; and

6 [0044] FIG. 19 is a cross-sectional view of a deposit of carbonaceous material being processed to extract calorific material from the deposit in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

[0045] 1. LASER-BASED DEPOSITION

[0046] In some aspects, the present disclosure is directed to methods of depositing materials using laser energy to irradiate a fluid (e.g., a liquid, colloid, suspension, solution, etc.) precursor material so as to cause the precursor material to transform to a gaseous material, which then deposits in a deposition region and becomes a solid deposited material in the deposition region. The depositing of material in accordance with the present disclosure can be deployed for any of a wide variety of purposes, including filling voids (manmade or natural), stabilizing structures, and covering surfaces, among others, for any of a variety of reasons, such as inhibiting collapse, blocking flow of liquid (e.g., groundwater), providing a wear surface, providing a protective lining, etc. Fundamentally, there are no limitations on the purpose(s) and/or reasons(s) for utilizing a deposition method of the present disclosure and a corresponding deposited material. It is noted that the final form of the deposited material, and hence, its properties, can be tailored to the particular application at issue by modifying the components and chemistry of the precursor material and the deposition parameters, such as irradiation level, secondary heating (if any), and inclusion of one or more additional components (e.g., foaming agent, catalyst, binder, etc.), among others.

[0047] In some embodiments, the precursor material may be a mixture, e.g., a heterogeneous colloid, suspension, solution, etc., of two or more material components that will form the final deposited material, dispersed in a suitable substance that allows the precursor material to be flowable. Examples of material components include silicon, carbon, and geopolymers, to name just a few. Examples of substances that make the precursor material flowable include liquids, gels, solvents, gases, etc. In some embodiments, the chemistry(ies) involved with the irradiation of the precursor material and subsequent formation of the deposited material can be the same as or similar to sol-gel chemistry(ies) used to make gels, aerogels, foams, solids, etc., composed of inorganic and/or organic components. It is noted that the material that results from the laser irradiation is referred to herein and in the appended claims as a “gaseous material”. Those skilled in the art should understand that this gaseous state can include a combination of gas and liquid phases. In some embodiments, the laser-irradiation does not require complete vaporization or converting of the precursor material into a wholly gas phase, but rather can include a combination of liquid and gas. For example, in some embodiments, the gaseous state of the laser-irradiated material can be akin to a

7 foam having properties of both gas and liquid. The precursor material can have any suitable viscosity, but it is typically in a fluid (e.g., liquid) state so as to be flowable from a source to a deposition location located remotely from the source. In some embodiments, one or more additional materials, such as, for example, air, oxygen, gas, and/or other gaseous material, and/or providing of heat apart from the laser irradiation, may need to be provided to cause the deposited material to form properly. In some embodiments, provisions may be required for venting any excess heat, steam, and/or other byproduct(s) resulting from the deposition process.

[0048] In some aspects, the present disclosure is directed to applicators and systems for depositing materials using laser energy. For example, an applicator of the present disclosure may include a laser-irradiation region wherein a precursor material is irradiated so as to cause the precursor material to transform into a gaseous material. When the precursor material is present, one or more laser outputs direct laser energy to the precursor material within the laser-irradiation region to transform the precursor material into the gaseous material. In some embodiments, the irradiating laser beam(s) and/or other laser beam(s) may provide a motive force for moving the gaseous material toward a deposition region. As discussed below, in some embodiments, the applicator may take the form of a body having one or more passageways for directing the precursor material to the laser-irradiation region. In some embodiments, the precursor material may be forcefully moved through the passageway and through one or more nozzles or other outlet(s) into the laser-irradiation region to provide momentum for forcing the gaseous material toward a deposition region. In some embodiments, the laser-irradiation region may be located upstream of one or more nozzles or other outlet(s), wherein the heating of the precursor material (e.g., in liquid / colloid / suspension form) causes expansion of the gaseous material that forces the gaseous material out of the outlet(s) to provide momentum for forcing the gaseous material toward a deposition region. In some embodiments, forces caused by the irradiating laser beam(s) and/or by one or more supplemental motive laser beams may be used to cause or increase momentum of the gaseous material in a direction toward the deposition region.

[0049] The foregoing and other aspects are described below with respect to a number of detailed examples.

[0050] Example General Laser-Based Deposition Methods and Systems

[0051] Turning now to the drawings, FIG. 12 illustrates an example method 1200 of depositing a material to a deposition region in accordance with aspects of the present disclosure. As mentioned

8 above, the deposition region will depend on the application to which the method 1200 is applied.

For example, the deposition region can be a region overlaying a surface that is being coated with the material for any one or more of a variety of reasons, such as to provide a wear surface, to stabilize the surface, to protect the surface, to waterproof the surface, etc. As another example, in the context of filling or otherwise deploying the material into a void, the deposition region may be a portion of the void or the entirety of the void. Detailed examples of filling or otherwise depositing a material into manmade voids in accordance with the present disclosure are discussed below. The void need not be manmade; rather it can be a naturally occurring void. Typically, the material deposited includes two or more components, for example, chemical elements, oxides of chemical elements, and/or polymers (inorganic or organic), etc., that chemically bond or otherwise chemically interact with one another to form a rigid stable material in any suitable form, such as amorphous solid, crystalline solid, rigid gel, aerogel, etc., or any combination thereof.

[0052] At block 1205, a precursor material to the material to be deposited is provided. As discussed above, the precursor material may be flowable mixture of the two or more components of the material deposited mixed with a substance (which includes a plural of substances) that make(s) the precursor material flowable. The flowable precursor material may be, for example, in colloidal form, gel form, liquid form, suspension form, solution form, etc., as the particular chemistry of the desired material deposited requires. Some example components of the material deposited are noted above. Those skilled in the art will readily appreciate the type and nature of the precursor material needed for the particular material to be deposited.

[0053] At block 1210, the precursor material is flowed to a laser-irradiation region. The laser- irradiation region is any region in which the precursor material is irradiated with energy from one or more laser beams. In some embodiments, the laser-irradiation region may be a chamber within an applicator designed and configured to deposit the material in the deposition region. In some embodiments, the laser-irradiation region may be a region of free space, such as a region outside and/or within a void desired to be filled or a region above a surface to be coated, among others. Fundamentally, there are no limitations on the nature and character of a laser-irradiation region other than that it is located and/or configured to properly effect deposition of the material in the desired deposition region.

[0054] The precursor material may be provided to the laser-irradiation region in any suitable manner. In some embodiments, the precursor material may be delivered to the laser-irradiation

9 region via one or more fluid-carrying conduits and/or one or more fluid passageways formed in a one or more bodies, such as may be present in an applicator, for example. In some embodiments, the precursor material may be provided to the laser-irradiation region by expelling the precursor material through one or more nozzles. In some embodiments, forceful expulsion of the precursor material from one or more nozzles can assist with deposition by providing a motive force to the precursor material. In some embodiments, the precursor material may not be provided as a single homogeneous mixture. Rather, multiple separate flowable components may be flowed simultaneously toward the laser-irradiation region and only mixed together in and/or near the laser- irradiation region.

[0055] At block 1215, the precursor material is irradiated with laser energy in the laser- irradiation region so as to create a gaseous material. The irradiation of block 1215 may be accomplished using one or more laser beams trained and/or scanned onto the precursor material in the laser-irradiation region. In some embodiments, one or more laser beams may each have an optical axis substantially parallel to the flow direction of the precursor material, one or more laser beams may each have an optical axis substantially perpendicular to the flow direction of the precursor material, and/or one or more laser beams may each have an optical axis that forms an oblique angle relative to the flow direction of the precursor material, or any combination or subcombination thereof. If scanning is used, the angular relationships just noted may be nominal in nature. In some embodiments, each laser beam may be provided by a laser-output having suitable optics for forming the laser beam. In some embodiments each laser-output may be optically connected to one or more lasers, which may be any suitable type of laser, such as any of the laser types mentioned hereinafter. In some embodiments, the laser energy (power, wavelength(s), power density, etc.) hitting the precursor material can be tuned so as to cause heating and/or chemical reactions to occur within the precursor material so as to transform the precursor material into a gaseous material. Those skilled in the art will readily understand how to select and/or design parameters for producing the desired material to be deposited based on knowledge in the art and routine testing.

[0056] At block 1220, the gaseous material is flowed to the deposition region and allowed to solidify in the deposition region so as to form the deposited material. Depending on the type of material deposited, solidification may involve a chemical reaction, formation of chemical bonds, drying, hydration, polymerization, crystallization, among other processes, or any suitable combination thereof. Depending on the nature of the formation of the deposited material from the

10 gaseous material, additional laser energy may be provided to assist with the formation. An example of formation that can require additional energy is photo-crosslinking. The same laser beams used to form the gaseous material may be used to assist with material formation, and/or other laser beams may be used.

[0057] In some embodiments, the flow of the gaseous material to the deposition region can be assisted in any one or more of a variety of ways. For example, the laser beam(s) that irradiate the precursor material in the laser-irradiation region, if suitably directed, may apply a motive force to the gaseous material in the general direction of the deposition region. As another example, if one or more nozzles, or other opening(s), are used to expel the precursor material into the laser-irradiation zone as mentioned above, then momentum of the precursor material may carry through to the gaseous material so as to assist the flow of the gaseous material to the deposition region. As a further example, in embodiments in which the laser-irradiation region is located in a restricted chamber, one or more nozzles, or other opening(s), can be used to expel the gaseous material from the nozzle(s) / opening(s), thereby imparting motive forces to the gaseous material to assist with flowing the gaseous material to the deposition region. For example, the laser irradiation within the laser-irradiation region (here, chamber) may increase the pressure within the chamber as the irradiation transforms the liquid precursor material into a gaseous material, and this pressure may cause the gaseous material to be forcibly expelled through the nozzle(s) / opening(s).

[0058] FIG. 13A illustrates an example laser-based applicator 1300 that can be used to deposit a material into a deposition region in accordance with the present disclosure, such as in accordance with the method 1200 of FIG. 12. Referring to FIG. 13A, in this example the laser-based applicator 1300 includes a laser-irradiation region 1304, wherein a precursor material 1308 is irradiated with laser energy 1312 so as to create a gaseous material 1316, which then flows to a deposition region (not shown). When the gaseous material 1316 solidifies, the deposition region contains a rigid material (not shown) formed from the gaseous material. The precursor material 1308 may be any suitable precursor material, such as any of the precursor material discussed above. In the example shown, the precursor material 1308 is shown as entering the laser- based applicator 1300 as a single flow stream. However, in other embodiments, the precursor material 1308 may enter the laser-based applicator 1300 in multiple flow streams. In other embodiments, the precursor material 1308 may be provided in two or more parts (not shown) and mixed within the laser-based applicator 1300 before entering the laser-irradiation region 1304.

11 [0059] The laser energy 1312 may be provided from any one or more suitable lasers (not shown), such as one or more lasers located onboard the laser-based applicator 1300 and/or one or more lasers located offboard the laser-based applicator. Each laser may be any suitable type of laser, such as any of the lasers mentioned in this disclosure. Those skilled in the art will readily understand how to select the type(s) of laser(s) and the irradiation par based on the material to be deposited and the corresponding precursor material and chemistry involved.

[0060] In this example, the laser-irradiation region 1304 is illustrated as being an open-ended chamber 1304C within the laser-based applicator 1300, and the precursor material 1308 is flowed into the laser-irradiation region generally without restriction. However, in other embodiments, the laser-irradiation region 1304 may be embodied in another form, and/or the precursor material 1308 may be delivered to the laser-irradiation region in a different manner.

[0061] For example, FIG. 13B illustrates a laser-irradiation region 1304' that is an open-ended chamber 1304C similar to the open-ended chamber 1304C of FIG. 13 A, but the precursor material 1308 is provided to the laser-irradiation region via one or more nozzles 1320 (only one shown). As discussed above, the use of one or more nozzles 1320 can have one or more benefits, such as controlling the size, shape, and/or location of the stream(s) 1308S (only one shown) of the precursor material 1308 within the laser-irradiation region 1304' to suit a desired irradiation scheme. Another benefit can be that forceful expulsion of the precursor material 1308 from the nozzle(s) 1320 can provide motive force to the gaseous material 1316 for assisting in flowing the gaseous material to the deposition region (not shown).

[0062] FIG. 13B also shows an example arrangement of laser outputs 1324 (only a few labeled to avoid clutter), which, in this example output corresponding respective laser beams 1328 that irradiate the stream(s) 1308S of the precursor material 1308 within the laser-irradiation region 1304' to create the gaseous material 1316. In this example, the laser outputs 1324 are located and oriented so as to direct their laser beams 1328 at oblique angles 1332 (only a few labeled to avoid clutter) relative to the longitudinal axis 1308LA of the stream 1308S of the precursor material 1308. Thusly, there is a vector component (not shown) of each laser beam 1328 that is directed in a direction parallel to the longitudinal axis 1308LA. This vector component can contribute motive force to the gaseous material 1316 in the direction of the deposition region (not shown, but taken to be in the direction of the arrow depicting the gaseous material).

12 [0063] FIG. 13C shows another example laser-irradiation region 1304" / chamber 1304C". As seen in FIG. 13C, in this example the laser-irradiation chamber 1304C" is a closed chamber having one or more nozzles 1304N (only one shown) at an outlet end of the laser-irradiation chamber. The nozzle(s) 1304N" can be designed so that the irradiation of the precursor material 1308 in the laser- irradiation chamber 1304C", which creates the gaseous material 1316, causes expansion of the materials within the laser-irradiation chamber. This expansion, in turn, causes the newly formed gaseous material 1316 within the laser-irradiation chamber 1304C" to be forcefully expelled from the laser-irradiation chamber 1304C" through the nozzle(s) 1304N in the direction of the deposition region (not shown, but taken to be in the direction of the arrow depicting the gaseous material 1316).

[0064] FIG. 13C also shows an example arrangement of laser outputs 1324' (only a few labeled to avoid clutter), which, in this example output corresponding respective laser beams 1328' that irradiate the stream(s) 1308S' of the precursor material 1308 within the laser-irradiation region 1304" to create the gaseous material 1316. In this example, the laser outputs 1324' are located and oriented so as to direct their laser beams 1328' perpendicularly to the longitudinal axis 1308LA' of the stream 1308S' of the precursor material 1308. In this example, due to the exploitation of pressure within the laser-irradiation chamber 1304C" from the laser irradiation for providing motive force to the gaseous material 1316 being expelled from the nozzle(s) 1304N, there is no need to obliquely angle the laser beams 1328' relative to the direction of the deposition region (not shown). It is noted that features of the two embodiments of, respectively, FIGS. 13B and 13C can be combined in any suitable way. Those skilled in the art will readily appreciate that the embodiments, features, and arrangements for a laser-based applicator of the present disclosure are merely exemplary, and that many other embodiments, features, and arrangements are possible using this disclosure as a guide and common knowledge in the art. It is noted that while the laser-irradiation regions 1304, 1304', and 1304" shown in FIGS. 13A, 13B, and 13C, respectively, are internal to the laser-based applicator 1300 (FIG. 13 A), in other embodiments, a laser-irradiation region may be located externally to any deposition equipment.

[0065] Laser-Based Deposition For Calorific-Material Extraction

[0066] In some embodiments, laser-based deposition methods of the present disclosure can be useful for processing a deposit of carbonaceous material to extract calorific material from the deposit. Examples of carbonaceous materials include, but are not limited to, coal of any suitable rank, oil shales, and sapropel fuels, generally, among others. Examples of calorific materials that can be removed from deposits of carbonaceous material include, but are not limited to, methane,

13 hydrogen, short and medium chain hydrocarbons, syngas, coal, coal gas, shale oil, and shale gas, among others, in any logical combination based on the extraction process. Laser-based deposition methods of the present disclosure can be used to backfill or otherwise stabilize voids resulting from the calorific-material extraction. As discussed above in the Background section, the backfilling or other stabilization of voids created during the extraction of calorific materials is a vital part of the overall processing of a carbonaceous-material deposit. Laser-based deposition methods of the present disclosure can be particularly suited to processing carbonaceous-material deposits for a number of reasons, including, but not limited to, the facts that an entire backfilling or other stabilizing operation can be performed using relatively few personnel, the personnel involved can work entirely above ground, precursor materials to the deposited material are typically readily available, relatively inexpensive, and relatively easy to handle, the instantaneous and binary (i.e., on- off) nature of laser energy makes the deposition process highly controllable, and the use of laser energy makes the deposition process clean (e.g., no on-site hydrocarbon fuel is needed for supplying energy) and efficient, among others.

[0067] FIG. 14 illustrates an example method 1400 of processing a deposit of carbonaceous material to remove calorific material from the deposit. At block 1405, portions of the carbonaceous material within the deposit are processed to extract calorific material from the deposit and form a void within the deposit. The processing that occurs at block 1405 may be any processing required to extract the form(s) of calorific material desired to be extracted from the carbonaceous material. For example, if it is desired to gasify the carbonaceous material, then pyrolysis processing may be performed. For example, the pyrolysis processing may proceed in accordance with any one or more of the techniques discussed below in section _ of this disclosure. Alternatively, other pyrolysis techniques can be performed as desired. As another example, if it is desired to remove portions of the deposit in solid form, various fracturing and material-removal techniques, such as conventional fracturing and material-removal techniques can be used. Fundamentally, there is no limitation on the type of processing of the natural deposits that can be used for the extraction of calorific material, other than the processing leaves a void that does not collapse prior to filling or otherwise stabilizing the void using laser-based deposition in accordance with features of the present disclosure. It is noted that a void can have any shape or configuration and is often in the form of a single chamber left by the extraction processing or two or more such chambers interconnected by one or more smaller passageways that connect the multiple chambers with one another and allow a gaseous material to flow from one chamber to another, among other void configurations.

14 [0068] At block 1410, a precursor material is irradiated with laser energy so as to create a gaseous material. The precursor material may be any suitable precursor material to the material that is ultimately deposited within the void. Examples of precursor materials and deposited materials suitable for use in the method 1400 are discussed above. Also discussed above and below are techniques for irradiating the precursor material with laser energy that can be used in the method 1400.

[0069] At block 1415, the gaseous material is directed to one or more deposition regions within the void, and the gaseous material is allowed to solidify so as to stabilize portions of the carbonaceous material that define the void. As discussed above and below, there are a variety of passive and active ways in which the gaseous material can be directed to the deposition region(s), including, but not limited to, using laser energy, using motive forces imparted by expulsion from one or more nozzles, and via motive forces from the flowing of the precursor material to the void, among others. As also discussed above, the solidification of the gaseous material into a stabilizing deposited material may involve any one or more processes that transform the gaseous material into a load-bearing material.

[0070] The stabilization that the deposited material provides may range, for example, from providing a partial lining layer (e.g., on the roof and/or side walls of the void) to providing a full lining layer (i.e., 360° circumferentially around the transverse cross-sectional shape of the void) to completing filling the void to providing a combination of a partial lining layer and/or a full lining layer with intermittent bulkheads spaced from one another within the void, among others. Fundamentally, there are no limitations on the configuration(s) and the deposited material within the void so long as it / they provide the requisite stabilization.

[0071] FIGS. 15A-15C illustrate a simplified example of filling a void 1500, such as a void that remains after processing performed at block 1405 of FIG. 14. That said, the void 1500 can be of any origin, including a natural void, such as a cave or fissure, among others. FIG. 15A shows the void 1500 prior to filling. As seen in FIG. 15 A, a precursor material 1504 is flowed toward the void 1500 via a conduit 1508, and laser energy 1512 is directed to a location 1516 proximate to the outlet 15080 of the conduit. In this arrangement, a laser-irradiation region 1520 is formed at the location 1516.

[0072] FIG. 15B illustrates the state of filling the void 1500 after the void has been partially filled with the gaseous material 1524 created by irradiating the precursor material 1504 in the laser-

15 irradiation region 1520. As noted above, the filling process may require venting, which in this example is illustrated by an optional vent 1528. As further noted above, the reaction that occurs to the precursor material 1504 may require one or more additional materials (e.g., air, oxygen, catalyst, steam, etc.). Consequently, the example of FIG. 15B includes an optional input conduit 1532 for providing any additional material 1532M.

[0073] FIG. 15C shows the void 1500 after the gaseous material 1524 (FIG. 15B) has completely filled the void and has solidified into the final deposited material 1536. In this example, the deposited material 1536 has been selected and engineered to provide sufficient strength and rigidity to prevent the material 1540 (e.g., carbonaceous material) above the void from degrading and/or collapsing.

[0074] FIGS. 15A-15C illustrate a basic method of filling a void 1500 using a laser-based deposition scheme of the present disclosure, wherein the precursor material 1504 (FIGS. 15 A, 15B) and laser energy 1512 (FIGS. 15A, 15B) are provided at a single location for the entire void. However, many other laser-based deposition schemes are possible.

[0075] For example, FIG. 16 illustrates an example applicator head 1600 that can be removably deployed into a void, here, a void 1604 that is located down-hole relative to an access well 1608. In one example, the void 1604 is the result of extracting calorific material from a deposit 1612 of carbonaceous material as discussed above. In this example, the applicator head 1600 includes a plurality of laser-based applicators 1616A (only a few labeled to avoid clutter), each of which may be the same as or similar to the laser-based applicator 1300 illustrated in FIGS. 13A-13C and described above. The laser-based applicators 1616A may be part of an overall laser-based applicator system 1616 that will typically include equipment 1616E, such as storage vessels for precursor material and/or components of the precursor material, mixing equipment, pumps, lasers, controllers, etc., located remotely from the applicator head 1600, such as on the surface 1618 proximate to the access well 1608.

[0076] In the example of FIG. 16, the applicator head 1600 is configured so that it can deposit material, such as material 1620 within the void 1604360° in a radial direction around the circumference of the applicator head (see material region 1620R) in a plane normal to the plane of the sheet containing FIG. 16 as well as deposit the material longitudinally beyond the applicator head (see material region 1620L). It is noted that while the example applicator head 1600 provides 360° circumferential coverage, other embodiments can be configured for other circumferential

16 coverages. For example, if an alternative applicator head is configured to rest on the bottom of a void, the laser-based applicators may be configured and arranged to provide less than 360° circumferential coverage in a pure radial direction relative to the applicator head. In other embodiments, the applicator head may be configured to deposit material beyond the applicator head, for example, only include the laser-based applicators in the longitudinal region 1616L of the applicator head 1600 of FIG. 16.

[0077] In this example, the laser-based applicators 1616A are generally grouped into two groups, namely a radially directed group in zone 1616R and a generally longitudinally directed group in zone 1616L. In some embodiments, this or similar arrangement of the laser-based applicators can provide for efficient filling of the entirety of the void 1604 and/or selectivity in determining whether to completely fill the void or provide a stabilizing layer on the walls of the void. For example, if complete filling of the void 1604 is desired, that may be accomplished either by depositing the material 1620 only longitudinally beyond the applicator head 1600, i.e., in the material region 1620L, using only the laser-based applicators 1616A in the longitudinal-application zone 1616L or by using a combination of the laser-based applicators in the longitudinal-application zone and the laser-based applicators in the radial-application zone 1616R. Alternatively, if it is desired to provide only a stabilizing layer of material 1620, such as appears in material region 1620R, throughout a portion or the entirety of the void 1604, then the deposition process may involve only the laser-based applicators 1616A in the radial-application zone.

[0078] In this example, the applicator head 1600 may be designed to move, or be moved, along the length of the void 1604 as the material 1620 is deposited and/or between depositing the material in differing regions of the void. In this connection, the applicator head 1600 may include a traction system (not shown, but see the traction system 712 of the laser head assembly 700 of FIG. 7B). The size, including the length, of the applicator head 1600 may be any size needed / desired to suit a particular application and deposition plan.

[0079] In this example, the applicator head 1600 of FIG. 16 includes additional features, which can be optional in some embodiments. A first optional additional feature is the provision of one or more venting ports 1624P (only one shown) that allow for venting of gases that may build up within the void 1604 during the deposition process, such as from the irradiation process and/or solidifying process. The venting port(s) 1624P may be part of an overall ventilation system 1624 that may have equipment 1624E, such as one or more fans, pumps, collection components, controllers, etc., located

17 remotely from the applicator head 1600, such as on the surface 1618 proximate to the access well 1608.

[0080] Another optional additional feature is the provision of one or more material outlets 16280 (only one shown) for delivering one or more additional materials to the void 1604, for example, to assist with any chemical reaction(s) and/or other process(es) (such a drying) occurring in connection with the laser irradiation to create the gaseous material 1632 and/or the solidifying of the gaseous material into the deposited material 1620. Similar to the venting port(s) 1624P, the material outlet(s) 16280 may be part of an overall additional -material -handling system 1628, which may have equipment 1628E, such as one or more pumps, fans, storage vessels, controllers, etc., located remotely from the applicator head 1600, such as on the surface 1618 proximate to the access well 1608.

[0081] A further optional additional feature is the provision of one or more sensors 1636S for sensing the extent of deposition of the deposited material 1620. In embodiments wherein the applicator head 1600 is deployed out of the line of sight from an operator, the sensor(s) 1636S can be provided to provide an operator with information that allows them to know the extent of the deposition and/or quality of the deposition to ensure that the material 1620 deposited is deposited properly. Sensors that can be deployed as the sensor(s) 1636S include, but are not limited to, visual sensors, distance sensors, materials sensors, thermal sensors, among others, and any combination thereof. The sensor(s) may be part of an overall sensing system 1636, which may have equipment 1636E, such as one or more processors, controllers, video displays, readouts, etc., located remotely from the applicator head 1600, such as on the surface 1618 proximate to the access well 1608. Some or all of the equipment, such as equipment 1616E, 1624E, 1628E, and 1636E, located remotely from the laser head 1600 may be connected to the laser head via a multipurpose tether 1640.

[0082] FIG. 17 illustrates an example laser-based deposition system 1700 (“deposition system”, for short) that is configured to perform a deposition method of the present disclosure, including the method 1400 of FIG. 14, among others, and any method derivable from the descriptions of deposition methods in this disclosure. In the example shown, the deposition system 1700 includes one or more applicator heads 1704 (collectively shown as a single applicator head), each of which is deployed to a corresponding void (not shown) during use. At a high level, each applicator head 1704 includes a plurality of laser-based applicators 1704A (only a few labeled to avoid clutter)

18 that each output a corresponding stream of gaseous material (not illustrated) to deposit a desired material within the void. The laser-based applicator(s) 1704A can be the same as or similar to the laser-based applicators 1616A of FIG. 16 and/or the laser-based applicator 1300 illustrated in FIGS. 13A-13C, among others. In some embodiments, the one or more applicator heads 1704 may be operatively connected to a laser system 1708 that includes one or more lasers 1708 A and may include a tether 1708B. In some embodiments, the tether 1708B may include any needed fiber-optic cabling (not shown) and/or any needed control, sensing cabling (not shown), precursor-material-feed conduit(s), and/or any additional conduit(s) for effecting deposition.

[0083] Each applicator head 1704 may further include a plurality of sensing elements 1704B (only a few labeled to avoid clutter) that are used to sense the state of deposition within a void (not shown) in which the applicator head is deployed. Examples of states that can be sensed, as desired, include, but are not limited to, distances (e.g., to measure void size / extent of deposition) and conditions of deposition as may be discernable in any of a variety of ways, such as visual appearance, temperature, material composition of the deposited material, and makeup of byproducts, among others. Depending on the configuration and needs, the sensing elements 1704B may be of the same type or differing types, with the type of each sensing element 1704B corresponding to the state it is deployed to measure. Depending on its type, each sensing element 1704B may be or comprise, for example, an imaging sensor, lensing for light-based sensing (including visible and infrared), ultrasound transducer(s) for ultrasound-based sensing, or radar component(s) for radar- based sensing, among others. Depending on various factors, such as the type of each sensing element 1704B, the directionality of each condition-sensing element, and the coverage area for each sensing element, one, some, or all of the condition-sensing elements may be pivotable so as to allow the sensing element to be directed to the desired region(s) of interested. In some examples, one, some, or all of the condition-sensing elements may be of the scanning type so as to be able to conduct areal scans. Fundamentally, there are no limitations on the nature or type(s) of the sensing elements 1704B.

[0084] Depending on the configuration of the deposition system 1700, the applicator head 1704 may include either one or more gas-delivery ports 1704C or one or more gas-collection ports 1704D, or both. The gas-delivery port(s) 1704C, if provided, may deliver one, some or all of flow of one or more gases for assisting the irradiation and/or deposition process, such as oxygen, steam, catalyst, heated air, etc. The gas-collection port(s) 1704D, if provided, may collect any byproduct gas and/or any remnants of the gas(es) provided via the gas-delivery port(s) 1704C.

19 [0085] Referring still to FIG. 17, the example deposition system 1700 may also include, among other systems, 1) a sensing system 1712 that includes all of the physical equipment, physical components, and/or software needed for sensing and/or measuring conditions within a void, including the sensing elements 1704B aboard the applicator head(s) 1704, 2) an applicator-head- movement system 1716 that includes all of the physical equipment, physical components, and/or software needed for moving the laser head, including for deployment and/or for moving one or more laser heads between discrete pyrolysis sessions and/or during one or more continuous pyrolysis session(s), 3) a precursor-material-delivery system 1720 that includes all of the physical equipment, physical components, and/or software needed for storing, supplying, and delivering a precursor material to one or more voids, including storage vessel(s), delivery system(s), and control system(s), 4) an additional-gas-delivery system 1724 that includes all of the physical equipment, physical components, and/or software needed for providing one or more gases to one or more voids to assist with deposition, and 5) a gas-collection system 1726 that includes all of the physical equipment, physical components, and/or software needed for removing one or more gases from one or more voids as part of the deposition process. Each of these systems may be composed of conventional elements to the extent that any specialized element(s) are not needed to practice a gasification system of the present disclosure, such as the deposition system 1700 of FIG. 17. Those skilled in the art will readily appreciate the many ways that each of the systems 1712, 1716, 1720, 1724, and 1726 can be embodied, including the wide variety of equipment, components, and software configurations for executing these systems and that skilled artisans will be able to make and use these ways for the relevant gasification-system designs using only knowledge in the art and this disclosure as a guide.

[0086] In some embodiments, non-laser heating may be needed in each void to assist with the deposition process, and such heating may be provided by a heating source other than one or more heating gases. For example, each applicator head 1704 may include an onboard heat source 1704E or a component of an offboard heat source (not shown). Examples of such other heat sources can be found, for example, in U.S. Patent No. 7,225,866, titled “IN SITU THERMAL PROCESSING OF AN OIL SHALE FORMATION USING A PATTERN OF HEAT SOURCES” and issued on June 5, 2007, to Berchenko et ak, which is incorporated herein by reference for its teachings of heat sources.

[0087] In this example, the deposition system 1700 includes a control system 1728 that controls all operations of the deposition system either automatically or manually, or a combination of automatically and manually. As those skilled in the art will readily appreciate, while the control system 1728 is illustrated as a single block in FIG. 17, all of the control functions that the control

20 system performs need not be centralized. Rather, embodiments of the deposition system 1700 may have any one or more control subsystems, such as one or more deposition-control subsystems 1728 A, one or more sensing control subsystems 1728B, one or more applicator-head- movement control subsystems 1728C, one or more applicator-head stabilization control subsystems 1728D, one or more precursor-material-delivery control subsystems 1728E, one or more addition-gas-delivery control subsystems 1728F and one or more gas-collection subsystems 1728G, among others. In some examples one or more of the control subsystems can be a standalone control subsystem and/or one or more of the control subsystems may be networked with one another and/or to a master controller 1728H, among other architectures. Those skilled in the art will readily appreciate the many ways that the control system 1728 can be embodied, including the wide variety of hardware and software configurations for implementing the control system and that skilled artisans will be able to make and use these ways for the relevant gasification-system designs using only knowledge in the art and this disclosure as a guide.

[0088] As those skilled in the art will readily appreciate, the control system 1728 can include many algorithms for performing a wide variety of tasks that the deposition system 1700 must perform during deployment for depositing a material into one or more voids. Some of these algorithms include deposition-control algorithms 1732 that control the deposition that occurs in any one or more voids in which one or more applicator head(s) 1704 are deployed. Depending on the configuration of the deposition system 1700 and the manner(s) in which deposition can be controlled and the state(s) of the deposition can be determined, the functionalities that the deposition-control algorithms 1732 need to perform can vary. Examples of functionalities that the deposition-control algorithms 1732 may provide include, but are not limited to:

• controlling laser-power density provided to the laser-irradiation region for irradiating the precursor material, in some cases as a function of the deposition conditions inside the void(s) and/or the deposition rate and/or deposition quality, among other variables;

• controlling the flow of precursor material to the laser-irradiation region, in some cases as a function of the deposition conditions inside the void(s) and/or the deposition rate and/or deposition quality, among other variables;

• controlling the flow of one or more additional gases to the void(s), in some cases as a function of the deposition conditions inside the void(s) and/or the deposition rate and/or deposition quality, among other variables;

21 • controlling the collection of byproduct and/or other gas(es), in some cases as a function of the deposition conditions inside the void(s) and/or the deposition rate and/or deposition quality, among other variables;

• controlling the movement of the application head(s), in some embodiments as a function of state and/or rate of deposition;

• controlling sequencing of use of the laser-based applicators, for example, as a function of the sequencing and/or manner of depositing the material;

• controlling the amount of non-laser heating, in some embodiments including controlling the flow of one or more heating gases (e.g., steam) to the pyrolysis chamber;

• controlling the sensing of one or more states and/or conditions within each active void; and

• controlling collection of sensor data, and any combination thereof, among others.

[0089] Those skilled in the art will readily understand that the deposition-control algorithms 1732 and the associated computing hardware 1736 that executes the machine-executable instruction 1740 that embody the deposition-control algorithms will be in operative communication with the necessary systems, such as, for example, the laser system 1708, the sensing system 1712, the applicator-head-movement system 1716, the precursor-material-delivery system 1720, the additional-gas-delivery system 1724, and/or the gas-collection system 1726, among others, as needed to receive the necessary data (e.g., condition measurements, location information, component statuses, etc.) from these systems and to provide the necessary information, such as control signals, status information, operating parameters, etc.) to these systems. The computing hardware 1736 includes memory 1736 A, which can be any type of physical storage memory, including, but not limited to non-volatile memory (e.g., solid-state, optical, magnetic, etc. hard-drive memory, and/or other type of long-term storage memory) and volatile memory (e.g., RAM and/or cache memory, among other types). Fundamentally, there is no limitation on the type(s) of the memory 1736A, the number of memory devices that compose the memory 1736A, and the physical location(s) of the memory device(s) that compose the memory 1736A, other than that the memory is not in the form of any transitory signal. Many types of computing systems, computing architectures, and programming styles are ubiquitous and well-known in the art and are usable to implement the deposition-control algorithms 1732, such that it is not necessary to describe these in detail for those skilled in the art to implement them for any application and design that may be devised using the present disclosure as a guide.

22 [0090] FIG. 18 illustrates an example combination head assembly 1800 that can be deployed for pyrolyzing (e.g., to gasify) a carbonaceous material 1804, especially carbonaceous material in natural deposits, such as coal deposits and oil-shale deposits, among others, and subsequently stabilizes the void created by the pyrolyzation process. The example combination head assembly 1800 in this example is designed for downhole pyrolysis, such as described below in connection with FIG. 9. That said, those skilled in the art will readily understand that the combination head assembly 1800 of FIG. 18 can be modified for using in other pyrolysis scenarios, such as the scenarios depicted in, and described in connection with, FIGS. 7 A through 8C, among others.

[0091] As seen in FIG. 18, the example combination head assembly 1800 includes a laser head 1808 for pyrolyzing the carbonaceous material 1804, for example, as described below in section 2, and an applicator head 1812 for depositing a stabilizing material 1816, for example, as described above. The pyrolysis laser head 1808 may be made in accordance with the present disclosure and be embodied in any suitable form, such as any suitable laser head of the present disclosure, including, but not limited to the laser head 900 of FIG. 9 and the laser head 404 of FIG. 4, among others. In addition, the pyrolysis laser head 1808 may be part of an overall pyrolysis/ gasification system, such as the gasification system 400 of FIG. 4. In a similar manner, the deposition applicator head 1812 may be made in accordance with the present disclosure and be embodied in any suitable form, such as any suitable laser head of the present disclosure, including, but not limited to the applicator head 1600 of FIG. 16 and the laser head 1704 of FIG. 17, among others. In addition, the applicator head 1812 may be part of an overall deposition system, such as the deposition system 1700 of FIG. 17.

[0092] FIG. 18 depicts the combination assembly head 1800 as performing both pyrolysis and deposition in continuous manners. That is, as the combination assembly head 1800 moves from right to left in FIG. 18, the pyrolysis laser head 1808 continuously pyrolyzes the carbonaceous material 1804 to increasingly expand the transverse cross-sectional size of the pyrolysis chamber / void 1820, while at the same time the deposition applicator head 1812 continuously deposits the stabilizing material 1816 within the pyrolysis chamber / void. It is noted that the pyrolysis and/or the deposition need not be continuous as per FIG. 18. For example, pyrolyzation may be completed throughout an entire pyrolysis chamber or section thereof before deposition is started. In some embodiments, this may be accomplished by repositioning the combination assembly head 1800 between pyrolysis and deposition.

23 [0093] The example of embodiment of the combination assembly head 1800 of FIG. 18 shows the deposition applicator head 1812 as being located at the distal end of the pyrolysis laser head 1808. In other embodiments, the deposition applicator head 1812 may be made retractable into the pyrolysis laser head 1808. In yet other embodiments, the deposition applicator head 1812 and the pyrolysis laser head 1808 may be fully integrated with one another, meaning that individual ones of the laser-based applicators 1812A (only a few labeled for convenience) of the deposition applicator head can be interdigitated with, or otherwise dispersed among the laser outlets 18080 (only a few labeled for convenience) of the pyrolysis laser head. Those skilled in the art will readily understand how to embody a suitable combination assembly head for a particular application at issue using the present disclosure as a guide and knowledge in the art.

[0094] Referring back to FIG. 14, the method 1400 shown there is a process for extracting calorific material from a single void within a deposit of carbonaceous material. However, the various components of the method 1400, for example, as expressed in blocks 1405, 1410, and 1415, may be repeated serially and/or in parallel multiple times within a target deposit. This can allow for maximizing of the amount of calorific material that can be extracted from the deposit. FIG. 19 illustrates an example of processing a deposit 1900, for example, a coal seam, to extract a maximal amount of calorific material (not shown) from the deposit.

[0095] FIG. 19 shows a portion of a deposit 1900 during the extraction of calorific material using the method 1400 of FIG. 14. In this example, the deposit 1900 is located beneath the ground’s surface 1904 and several layers of overburden 1908. To access the deposit 1900 and perform the extraction, an access well 1912 is utilized. The access well 1912 may be, for example, a preexisting well, a new well, or a preexisting well modified for performing the method 1400. In this example, a plurality of lateral bores, here, five lateral bores 1916(1) to 1916(5), but could be any number, are provided using, for example, conventional lateral boring techniques known in the art. The present example focuses on using laser-based pyrolysis techniques that utilize one or more laser heads (not shown, but may be any laser head disclosed herein, for example) to pyrolyze and gasify the carbonaceous material that makes up the deposit. Details of suitable laser-based pyrolysis techniques are disclosed below in detail in section 2. It is noted that FIG. 19 depicts the five lateral bores 1916(1) to 1916(5) existing at the same time. However, this need not be so. For example,

FIG. 19 shows an example of generally top-down processing of the deposit 1900 in which the lateral bores 1916(1) and 1916(3) are currently active and the lateral bore 1916(2) was already used, whereas the lateral bores 1916(4) and 1916(5) have not yet been used. In this example, one or both

24 of the currently unused lateral bores 1916(4) and 1916(5) need not exist in the snapshot in time depicted in FIG. 19. Rather, they may be formed later on according to any suitable later-boring plan.

[0096] The five lateral bores 1916(1) to 1916(5) correspond, respectively, to five extraction levels 1920(1) to 1920(5) on which calorific material will be extracted. Since FIG. 19 illustrates the deposit 1900 being gasified using pyrolysis using techniques of the present disclosure, each of these extraction levels 1920(1) to 1920(5) had, has, or will have an associated pyrolysis chamber (only three pyrolysis chambers 1924(1) to 1924(3) currently exist (1924(1) and 1924(3) or existed (1924(2)). In this example, each level delineator 1916D located between any adjacent pair of lateral bores 1916(1) to 1916(5) is located at the midway point between the relevant lateral bores, and each level has a level height, LH. In this example, the deposit 1900 is maximally pyrolyzed to the extent that the post-pyrolyzation height, PCH, of each pyrolysis chamber (see pyrolysis chambers 1924(1) to 1924(3) is equal to the level height LH of the extraction levels. As will be readily appreciated, this means that once each pyrolysis chamber, such as pyrolysis chambers 1924(1) to 1924(3) has been fully pyrolyzed and filled using laser-based deposition techniques disclosed herein, 1) pyrolysis on a level immediately adjacent to an already filled level occurs all the way to the deposited material 1928 (see, e.g., regions 1932(1) and 1932(2)), and 2) after filling, the deposited material on one level immediately abuts the deposited material on an immediately adjacent level (see region 1936). The precisely controllable nature of laser-based pyrolysis of section 2, below, can readily allow for such precision processing / pyrolysis. That said, in other embodiments, the post-pyrolyzation heights PCH of the pyrolysis chambers 1924(1) to 1924(3) can be less than the height H of the processing levels 1920(1) to 1920(5) so as to leave carbonaceous material remaining on each processing level between the pyrolysis chambers and subsequent levels of deposited material 1928.

[0097] In the example shown, the deposited material 1928 on each level completely fills, or will completely fill, the corresponding pyrolysis chamber, here pyrolysis chambers 1924(1) to 1924(3), and this filling may be accomplished using any suitable deposition technique, such as any laser- based deposition techniques disclosed herein. In other embodiments, post-pyrolyzation stabilization on each level may not involve complete filling, but rather another configuration of the deposited material 1928, such as wall-stabilization layers, perhaps with spaced bulkheads made of the deposited material, among other configurations that will suitably stabilize the deposit 1900.

25 [0098] As noted above, the example of FIG. 19 shows a generally top-down approach to processing the deposit 1900. Other embodiments may deploy a generally bottom-up processing approach, or a middle-out approach, among others. In some embodiments, the approach to processing may depend on site-specific conditions, such as presence of fissures, presence of groundwater, etc. In addition, it is noted that the scenario depicted in FIG. 19 shows the processing of the deposit 1900 in a single vertical plane and to only one side of the access well 1912. In an actual processing situation, the scenario, or similar scenario, can be replicated at multiple vertical planes parallel to the plane depicted in FIG. 19 either spaced apart in a direction perpendicular to the plane of the sheet of FIG. 19 and/or in a direction parallel to the plane of the sheet of FIG. 19, as the situation demands. In addition, or alternatively, a scenario the same as or similar to the scenario depicted in FIG. 19 may be replicated on the opposite side of the access well 1912 in the same plane or in multiple vertical planes that radiate out from the access well in multiple locations around the circumference of the access well. In addition, it is noted that FIG. 19 depicts a scenario of a vertical access well 1912 and horizontal lateral bores 1916(1) to 1916(5). However, these components may be at other orientations as needed to conform to site-specific conditions.

[0099] If needed, one or more additional wells, such as optional well 1940, can be provided to satisfy a needed function, such as for calorific material extraction, venting, providing of additional gas(es), etc. While FIG. 19 depicts laser-based pyrolysis as the calorific-material extraction technique, any other suitable extraction technique(s) can be used.

[0100] 2. LASER-BASED PYROLYSIS

[0101] INTRODUCTION

[0102] In some aspects, the present disclosure is directed to methods of producing a product gas from one or more carbonaceous materials, including, but not limited to, any of a variety of ranks of coals and any of a variety of oil shales, among other, by heating the carbonaceous material using laser energy in a controlled manner so as to produce the product gas in a desired composition. In some embodiments, the laser-based heating is accompanied by heating via an additional heat source, such as one or more heated gases, such as steam.

[0103] As will become apparent from reading and understanding this entire disclosure, a feature of this disclosure is the use of laser energy to heat the carbonaceous material in a highly controlled manner so as to control the state of pyrolysis in order to produce a product gas having a desired composition. Methodologies disclosed herein leverages the property of laser heating that heating

26 occurs only when the target material, here, carbonaceous material, is being irradiated with laser energy. Generally, solid carbonaceous materials, such as coal and oil shale, have relatively low thermal conductivities that result in heating be contained to or within each laser spot on the carbonaceous material being irradiated. Consequently, when the target material is not being irradiated, heating does not occur. This binary and instantaneous application of heat or no heat allows for relatively precise control of the heating of the target material and, consequently, relatively precise control of the product gas. As described below in detail, this unique way of controllably heating carbonaceous material can be enhanced by implementing a feedback mechanism that constantly or continually monitors the heating and/or other condition(s) of the state of pyrolysis so as to provide even more accuracy and precision to the heating / pyrolysis.

[0104] As those skilled in the art will readily appreciate, a product gas produced by pyrolyzing a carbonaceous material contains one or more calorific gases, such as methane and hydrogen, and one or more other gases, such as carbon monoxide and carbon dioxide, among others. The composition of product gas in terms of its constituent gas species varies as a function of, for example, the temperature and other conditions (e.g., presence of an oxidant, presence of contaminants, etc.) at which the carbonaceous material is devolatilized. To produce a product gas of a desired composition, the conditions of devolatilization need to be controlled to the conditions required for the desired composition. As discussed below in detail, laser-based gasification methods of the present disclosure provide the necessary level of control.

[0105] Typically, the carbonaceous material will be present in a mass of material, such as in a natural underground deposit, either undisturbed or disturbed by prior extraction operations.

However, in some cases, the carbonaceous material may be present in another form, such as in a surface mass, such as a pile, formed from already extracted carbonaceous material. Fundamentally, there is no limitation on the form of the mass of the carbonaceous material, although underground deposits are particularly suited to many of the methodologies disclosed herein.

[0106] In embodiments involving natural underground deposits, gasification methods of the present disclosure can be more cost efficient, more environmentally sound, and more effective at producing high-quality product gas than conventional gasification methods. Other aspects of the present disclosure are directed to laser-based pyrolysis systems for enabling gasification of carbonaceous materials to produce product gas of a desired composition. In some embodiments, a laser-based heating system of the present disclosure is particularly configured for gasifying portions

27 of natural underground deposits of carbonaceous materials using one or more pyrolysis bores within the carbonaceous materials.

[0107] In further aspects, the present disclosure is directed to laser-based gasification systems for performing any one or more of the laser-based gasification methods disclosed herein, or portion(s) thereof. In additional aspects, the present disclosure is directed to laser heads specially configured to effect gasification methodologies of the present disclosure in pyrolysis chambers within a carbonaceous material, such as may be formed or otherwise present in natural underground deposits of the carbonaceous materials. In yet further aspects, the present disclosure is directed to product gas compositions that can result from the proper tuning of a laser-based gasification process of the present disclosure. These and other aspects are described in detail below. However, prior to describing the various aspects in detail, general information that may assist the reader in understanding and appreciating some example applications of the inventions disclosed herein is presented first.

[0108] It is noted that throughout the present disclosure and the appended claims, the term “about” when used with a corresponding numeric value refers to ±20% of the numeric value, typically ±10% of the numeric value, often ±5% of the numeric value, and most often ±2% of the numeric value. In some embodiments, the term “about” can mean the numeric value itself.

[0109] GENERAL

[0110] The economics of adding new coal power capacity in the United States using existing technologies and mining practices has become increasingly difficult to justify, given rising prices, greater scrutiny of the health, climate, and other environmental hazards associated with coal power and the emergence of a collection of alternatives, mainly wind, solar, with the baseload provision being provided by newly available natural gas and nuclear power plants. Direct replacement of old, dirty coal plants with cleaner, cheaper, less risky alternatives would be a far better solution. Clean coal could indeed be part of the energy mix and could offer this potential.

[0111] Underground Coal Gasification

[0112] Underground coal gasification (UCG) is a technique for realizing benefits of cleaner and environmentally friendlier energy production. UCG is a technique for acquiring the energy from unworked coal, i.e., coal still in the ground, by converting it into a calorific gas that can be used, for example, for industrial heating, power generation, and manufacturing hydrogen, synthetic natural gas, or diesel fuel. UCG technology allows countries that are endowed with coal to fully utilize their

28 resource from otherwise unrecoverable coal deposits in an economically viable and environmentally safe way. In UCG, the gasification reactor is a cavity within the coal deposit itself so that the gasification takes place underground instead of at the surface.

[0113] FIG. 1 illustrates a basic UCG process 100 that involves drilling three wells into a coal seam 104, a first well 108(1) for injection of a feed gas (oxidants) flow 104 (water/air or water/oxygen mixtures), a second well 108(2) some distance away to bring the product gas 116 to the surface 120, and a third well 108(3) at an end of the coal seam that acts as an ignition well, through which an ignition source 124 is provided. The coal at the base of the first well 108(1) is then heated to temperatures that would normally cause the coal to burn. However, through careful regulation of the flow of the oxidants 112, the coal does not burn but rather separates into a product gas 116.

[0114] Various chemical reactions, temperatures, pressures, and gas compositions exist at different locations within a UCG gasifier 128 that is forced to form within the seam 112 under proper conditions. The gasification channel within a UCG gasifier, such as UCG gasifier 128 of FIG. 1, is normally divided into three zones: an oxidization zone, a reduction zone, and a dry distillation and pyrolysis zone. In the oxidization zone, multiphase chemical reactions occur involving the oxygen in the gasification agents and the carbon in the coal. The highest temperatures in the gasifier occur in the oxidation zone due to the large release of energy during the initial reactions. The following reactions occur in the oxidation zone:

[0115] 393 .8 Kj

[0116] 2 C+ 0 ₂ - 2CO + 231 .4 kJ

[0117] 571 .2 kj

[0118] In the reduction zone, the main reactions involve the reduction of H ₂ 0(g) and C0 ₂ into H ₂ and CO at high temperatures within the oxidation zone. The following endothermic reactions occur in the reduction zone:

[0119] C + C0 ₂ -> 2CO - 162.4 kj

[0120] 131.5 kJ

[0121] Under the catalytic action of coal ash and metallic oxides, the following methanation reaction occurs:

[0122] C + 2H ₂ -> CH ₄ +74.9 kj

29 [0123] Following ignition and the delivery of the feed gas (air or oxygen) and steam via the feed gas flow 112 injected into the first well 108(1), product gas 116 is then drawn out of the second well 108(2).

[0124] In one method of UCG, vertical wells are combined with methods for opening a pathway between the wells. In another method of UCG, inseam boreholes use technology adapted from oil and product gas that can move the injection point during the process. Generally, the main criteria used for identifying the resource areas with potential for UCG can be summarized as seams of 5m thickness or greater, seams at depths between 200m and 600m from the surface, greater than 100m vertical separation from major aquifers, greater than 100m vertical separation from major overlying unconformities, and less than 60% ash content. Other factors that generally need to be considered include impermeable layers of strata surrounding the target coal seam, absence of any major faults in the area, low values for sulfur content and ash content, environmental and hydro geological conditions, and license conditions that might be imposed by regulatory and planning authorities.

[0125] For example, another UCG process 200 performed within a coal seam 204 is depicted in FIG. 2. In this example, an injection well 208(1) provides a feed gas flow 212, and a combustion front 216 within the coal seam 204 is initially ignited at the root 208(1)A of the injection well. Combustion then occurs along the coal seam 204 until it reaches one or more production wells 208(2), thereby forming a cavity 220. The rate of propagation of the combustion front 216 is determined by many factors, such as gas flow kinetics, and variations in temperature, spoliation levels, etc. The cavity 220 formed during gasification is generally tear-drop shaped, and the passage(s) 224 to the production well(s) 208(2) is/are narrowed and can be obstructed, thereby yielding low combustion levels and restricted outflow and yield of combustible products 228, for example, calorific gas such as syngas.

[0126] There are a number of risks associated with UCG practices, including, but not limited to: heavy faulting; overburden composition; potential leakage of produced gases/byproducts into aquifers; maintenance of the ignition reaction (e.g., ground water or flow instabilities quenching the reaction); subsidence due to cavity collapse; seam thickness variability; coal conditions inductive to lateral combustion and uncontrolled growth; emissions or migration of potentially harmful combustion products; and potential for contamination.

30 [0127] Coal Pyrolysis and Devolatilization

[0128] Coal pyrolysis and gasification are complex processes that involve many interactions of chemical and physical phenomena. In coal conversion processes, such as combustion or high temperature gasification, the extent of pyrolysis is an important parameter. Increasing amounts of coal converted directly to gaseous species would reduce the remaining material, i.e., char, that can be converted by relatively slow char-gas reactions. Coal pyrolysis and devolatilization is always the first step and plays a fundamental role. Coal rank and properties significantly influence heat and mass transfer, as do reaction rates. Therefore, conversion times, yields, and gaseous emissions depend on the original source material. However, there are general findings that can be considered. A key to understanding the phenomena occurring thus lies first in the characterization of the initial coal and then in describing the primacy devolatilization phase and the released products. Thermochemical conversion of coal in practical systems results from a strong interaction between chemical and physical processes at the micro level and also at the reactor level, i.e., the level of the surrounding environment, such as within an in-situ natural carbonaceous material deposit.

[0129] It is well known that coal devolatilization is a process in which coal is transformed at elevated temperatures to produce gases, tar, and char. Functional groups of the original coal are mainly released as gases and can be reasonably predicted by first-order reaction models. Tar, defined as condensable species formed during coal devolatilization, is a major volatile product, composing up to 50% of coal weight for bituminous coals.

[0130] At low temperatures (or low heating rates), coals initially form char and volatile species (tar and gas) that are still in the condensed phase. The tar in the condensed phase can be released with a proper kinetic rate and can interact with char in cross-linking reactions to increase the residual char and produce further gas. At high temperatures (or high heating rates), coals directly decompose to gas and tar and form more aromatic char structures. Lignitic coals first move through an activated state in the condensed phase and then undergo a real decomposition reaction. The transition temperature, where gradually high temperature decomposition prevails, is between 800K for 1200K depending on the aromatic structure of the coal.

[0131] For ease of describing main characteristics, the description of gas species is simplified herein. However, those skilled in the art will readily understand the additional complexities in real- world applications and instantiations. Light gases typically produced are ¾, C¾, and a mixture of C2-C5 hydrocarbons. The main oxygenated products are typically CO, CO2, and H2O. Other

31 oxygenated species are typically present at lower concentrations. As an example, formaldehyde, methanol, ketene, and acetic acid can form from primary pyrolysis.

[0132] Upon heating, bituminous coals undergo molting and pyrolytic decomposition, with a significant part forming an unstable liquid that can escape from the coal by evaporation. The transient liquid within the pyrolyzing coal causes softening or plastic behavior that can influence the chemistry and physics of the process. The extent of pyrolysis is known to be influenced, directly or indirectly, by temperature, heating rate, and exposure time. In standard methods, the amount of coal converted to volatile matter is determined at low temperatures, slow heating rates, and long exposure times. As a result, relatively low volatile yields are obtained, and also the resulting char is much less reactive. These effects have been recognized, and some studies have been reported on this aspect. The extent of pyrolysis increases significantly with temperature, with an apparent plateau or a peak in the weight loss curve at 900°C - 1100°C. Effective pyrolysis therefore occurs in the region of 500°C - 800°C, with greater yield at higher temperatures.

[0133] EXAMPLE EMBODIMENTS

[0134] Before presenting example embodiments, it is noted that the example embodiments are primarily directed to UCG. However, UCG is not the only application of the disclosed technology. Consequently, the term “carbonaceous material” as used herein and in the appended claims, refers to any solid, liquid, or gaseous carbon-containing material suitable for use as a fuel, i.e., a material that can be consumed to produce energy. Included within the scope of this term are fossil fuels, including coal, oil, natural gas, and oil shale, biomass (e.g., plant materials and animal wastes used as fuel), coke, char, tars, wood waste, methanol, ethanol, propanol, propane, butane, ethane, etc. Those skilled in the art will readily understand how to adapt the overall methodologies of the present disclosure to the carbonaceous material at issue.

[0135] As noted above, aspects of the present disclosure utilize laser energy to heat a carbonaceous material in a controlled manner, sometimes in the presence of a non-laser heat source, so as to produce a product gas of a desired composition. Such laser energy may be generated by any suitable laser and does not necessarily require any particular wavelength or spectral band to be effective. Therefore, the term “laser” as used herein has a broad meaning and refers generally to a category of optical devices that emit a spatially and temporally coherent beam of light otherwise known as a “laser beam”. In some embodiments, the term “laser” refers to “conventional” lasers (such as CO2 lasers, YAG lasers, and fiber lasers, among others), as well as solid-state lasers (such

32 as double heterostructure laser diodes, quantum well laser diodes, quantum cascade laser diodes, etc.). Fundamentally, there is no limitation on the type(s) of laser(s) that can be used in a method, system, or apparatus of the present disclosure as long as it can effect the desired heating.

[0136] Example Laser-Based Gasification Method

[0137] Referring to FIG. 3, an embodiment of the present disclosure is directed to a method 300 of producing a product gas from a mass of carbonaceous material having a pyrolysis chamber defined by surrounding portions of the carbonaceous material. While the carbonaceous material and the mass of such material may be any that are suitable for producing a product gas, a common example combination is coal as the carbonaceous material and a natural underground coal deposit, or coal seam, as the corresponding mass of the carbonaceous material. The pyrolysis chamber may be any suitable passageway within the mass of carbonaceous material that is sized and shaped to allow product gas production according to the method 300. In some instantiations, the pyrolysis chamber may be formed using a boring process, such as a lateral boring process. In some instantiations, the pyrolysis chamber may be formed for the specific purpose of performing the method 300, while in some instantiations the pyrolysis chamber may be an artifact of prior boring for another purpose, such as during past extraction operations for extracting one or more portions of the mass of carbonaceous material or exploration, among others. In some instantiations, the pyrolysis chamber may be a fissure or other natural void within the mass, among others. Fundamentally, there is no limitation on the nature of the pyrolysis chamber as long as it can be used to perform the method 300. It is also noted that while the method 300 is described relative to a single pyrolysis chamber, it may involve two or more pyrolysis chambers, each of which may be utilized according to the method. Further, and as noted above, the mass of the carbonaceous material is not constrained to an underground deposit. Rather, the mass can be located aboveground, such as in a freestanding pile or other form of previously extracted carbonaceous material.

[0138] In some embodiments, the pyrolysis chamber may be connected to a surface above and/or adjacent to the mass of carbonaceous material, depending on the location of the mass, via a first access well. The first access well may be a preexisting well, for example, from a prior extraction process, or a new access well specifically sunk for performing gasification to produce a desired product gas according to the method 300. In either case, if the pyrolysis chamber is not already present, the first access well may be used in forming the pyrolysis chamber, for example, using lateral boring techniques, such as known lateral boring techniques. In some embodiments, the first access well itself may be used as the pyrolysis chamber.

33 [0139] In some embodiments, the first access well may function as an injection well for providing a heating flow (e.g., of steam) to the pyrolysis chamber to assist laser-based heating, for providing an oxidant flow to the pyrolysis chamber for participating in pyrolysis, and/or for providing an extraction flow for causing any produced product gas to flow out of the pyrolysis chamber, for example, to a product-gas-collection system. In some embodiments, the first access well may also or alternatively provide a pathway for inserting a laser head into the pyrolysis chamber (see, e.g., block 305, described below). In some embodiments, the first access well may provide production functionality, in addition to heating flow, oxidant flow, extraction flow, and/or laser-head insertion functionality, to carry the product gas produced by the method 300 to the surface. To provide multiple functionalities, the first access well may include two or more separate passageways for providing the differing functions. Such passageways may or may not be concentrically located relative to one another and/or may have differing lengths depending on the functions involved and the configuration of the pyrolysis chamber. Alternatively, such passageways may be containing in a tether that connects to a laser head (see, e.g., FIGS. 10A and 10B).

[0140] In some embodiments, a second access well may optionally be used to connect the pyrolysis chamber to equipment, such as a product-gas collection system, located on the surface. As with the first access well, the second access well may be a preexisting well or a new well sunk to perform the method 300. The second access well, when provided, will typically be spaced, for example, horizontally, from the first access well. In some embodiments, the first and second access wells may be spaced from one another on opposite ends of the pyrolysis chamber. In some embodiments wherein a second access well is present, the second access well may function as a production well for removing the product gas produced by the method 300 and/or may function to provide a passageway for engaging the laser head with the pyrolysis chamber, among others. Additional access wells beyond the first and second access wells can be provided as needed to suit any particular need for a desired application.

[0141] At block 305, a laser head is inserted into the pyrolysis chamber in any suitable manner, such as via either the first or second access well, if present, as mentioned above. The laser head may have any suitable structure and configuration for effecting the heating of a target portion of carbonaceous material surrounding the pyrolysis chamber so as to perform the method and commensurate with the type(s) of laser(s) used to effect the heating. In some embodiments, one or more lasers may be integrated into the laser head, with the laser head further including a lens system for appropriately configuring and directing, for example, by scanning, one or more laser beams

34 generated by the integrated laser(s). Each integrated laser may be of any suitable type, such as a solid-state type or a non-solid-state type. In some embodiments, laser energy may be provided to the laser head from one or more lasers located remotely from the laser head, such as on the surface of a geological formation in an underground gasification embodiment. In such embodiments, the laser energy may be provided to the laser head via one or more fiber optic cables, such as may be provided in a tether that tethers the laser head to a surface-based laser system.

[0142] The laser head may be tethered, wirelessly and/or wiredly, to one or more systems that may be present on the surface. Examples of systems to which the laser head can be tethered include, but are not limited to, a laser system, a laser-head movement system, a laser-beam control system, a pyrolysis-state-detection system, and a product-gas collection system, among others. In some embodiments, when any of these systems is present, each may be under the control of a human operator and/or a master controller. The master controller, if present, may be operated under human and/or automated control. A detailed example of a laser-based gasification system 400 having at least one laser head and various types of systems for operating each laser head and the gasification system generally is described below in connection with FIG. 4.

[0143] As alluded to above, in some embodiments it is important to precisely control the extent of pyrolysis that the laser energy causes to occur in the adjacent carbonaceous material so as to produce a product gas having a desired composition. In such embodiments, it can be desirable to control the extent of pyrolysis by controlling the amount of heating that the laser energy causes at multiple irradiated regions of the carbonaceous material exposed within the pyrolysis chamber. In some examples, the laser beams that the laser head outputs are scanned over these irradiated regions in a highly controlled manner, such as by controlling one or more of the irradiation residency time that each laser beam remains at any given irradiation site with each irradiated region, the frequency that each irradiation site is irradiated, the power density of each laser beam, and the duty cycle of each laser beam, or any combination thereof. In some examples, the irradiated regions are configured to be as continuous with one another as possible and/or to minimize gaps and/or overlaps between the irradiated regions. Some example configurations of irradiated regions are presented in FIGS. 5A to 5C and discussed below.

[0144] Referring to FIG. 5A, this figure illustrates an example heating pattern 500 for heating the carbonaceous material with a plurality of laser-beams (not shown) emanating from a laser head (not shown) made in accordance with the present disclosure. In some embodiments, laser beams can

35 be scanned to create the pattern 500. In some embodiments, the pattern 500 can be created using fixed outputs, such as by using beam expanders and/or other optics known in the art. In this example there are 20 irradiated regions 504(1) to 504(20) that are each irradiated by one or more laser beams. It is noted that FIG. 5A illustrates a flattened view of the illustrated region of a cylindrical-bore-type pyrolysis chamber having a curved irradiated wall 508, which has been flattened for illustrative purposes. As seen in FIG. 5A, the 20 irradiated regions 504(1) to 504(20) are generally rectangular regions that abut one another so as to completely cover the entirety of the illustrated portion of the irradiated wall 508. When the irradiation is performed uniformly across all of the irradiated regions 504(1) to 504(20), the induced pyrolysis will likewise be uniform, assuming uniformity of the carbonaceous material forming the irradiated wall 508.

[0145] FIG. 5B illustrates another example heating pattern 520, showing 10 irradiated regions 524(1) to 524(10) that may be similar to the irradiation regions 504(1) to 504(20) shown in FIG. 5A. As seen in FIG. 5B, however, each irradiation region 524(1) to 524(10) is oval in shape and overlaps with other ones of the irradiated regions. In this case, the overlap regions may experience higher temperature increases than non-overlap regions when the scanning is uniform. However, if the sizes of the overlap regions are minimized, then the impact on the heating and resulting product gas will be negligible.

[0146] It is noted that while FIG. 5A illustrates abutting irradiated regions 504(1) to 504(20) and FIG. 5B illustrates overlapping irradiated regions 524(1) to 524(10), in other embodiments the irradiation regions may be spaced from one another such that gaps are present between adjacent ones of the irradiated regions. For example, the carbonaceous material being heated by the irradiation is thermally conductive to one extent or another, such that the portions of the carbonaceous material in the gaps will be heated by conduction from the irradiated regions, and this conductive heating may be sufficient to achieve the desired pyrolysis.

[0147] FIG. 5C illustrates an example heating pattern 540 that may be suited for embodiments in which heating is accomplished while moving the corresponding laser head (not shown, but see FIG. 9 and its accompanying description below). In this example, there are 15 irradiated regions 544(1) to 544(15) arranged into three groups 548(1) to 548(3), each having a corresponding width Wl, W2, W3, with adjacent ones of the groups spaced apart at corresponding spacings SI and S2 that define corresponding non-irradiated regions 552(1) and 552(2). As with the irradiation regions 504(1) to 504(20) of FIG. 5A and the irradiation regions 524(1) to 524(10) of FIG. 5B, each

36 of the irradiation regions 544(1) to 544(15) of FIG. 5C may be irradiated by one or more laser beams (not shown), such as by scanning or fixed output as mentioned above. When the laser head (not shown) is moved along the pyrolysis chamber, the grouped irradiation regions 544(1) to 544(15) will typically move in unison with the laser head. Thus, FIG. 5C may be considered to illustrate a snapshot in time. Consequently and assuming the movement of the laser head and grouped irradiated regions 544(1) to 544(15) is toward the left relative to FIG. 5C, at a later instant in time, all or a portion of non-irradiated region 552(1) will be irradiated by the group 548(2) and all or a portion of the non-irradiated region 552(2) will be irradiated by the group 548(3). Those skilled in the art will readily appreciated that the size of each width W1 through W3 and the size of each spacing SI and S2 can be determined as a function of variables, such as the speed at which the laser head is moved, the residence time for the laser beams utilized, and the progress of the pyrolysis induced by the heating, among others. Those skilled in the art will readily appreciate that only three groups 548(1) to 548(3) are shown for convenience and that more or fewer groups can be used.

Also, as with other examples, the number and shape(s) of the irradiated regions 544(1) to 544(15) can be any suitable number and shape(s) desired to suit a particular application. In addition, the areas of the irradiated regions can vary depending on variables such as laser power, number of laser outputs, the type of the carbonaceous material, etc. Fundamentally and generally, the only limits on the areas of the irradiated regions are imposed by physical limitations of the components of the laser system.

[0148] To effect irradiation and heating of the irradiated regions of the surrounding carbonaceous material, the laser head may include a beam-scanning system that scans the laser beams in a suitable manner for ensuring coverage of the corresponding one(s) of the irradiated regions. In some embodiments, the beam-scanning system may include any sort of scanning mechanism for each laser beam or group of laser beams, as a particular design warrants. Examples of scanning mechanisms or components thereof include, but are not limited to, moveable reflective and/or refractive elements (similar to, e.g., a digital light processor (DLP)), controllably moveable gimballed lensing system, controllably moveable gimballed laser-diode support, and/or a rotatable lensing system that rotates around a longitudinal central axis of the laser head, among others, or any combination thereof. In addition, differing laser beams can be directed with differing angular coverages, for example, as measured relative to a longitudinal central axis of the laser head. Fundamentally, there is no limitation on the beam-scanning system and arrangement of laser-beam outputs that can be provided to a laser head of the present disclosure. It is noted that in other

37 embodiments the laser outputs may be fixed. The laser power provided for irradiation may be continuous or intermittent as needed to suit the particular application at issue.

[0149] In some embodiments, the laser-beam outputs may be partitioned into sets so that differing sets emit their laser beams at differing times, such as in a predetermined sequence. The partitions may be made longitudinally along the length of the laser head and/or circumferentially around the circumference, or portion thereof, of the laser head. Such partitioning may be particularly useful when available laser energy is limited and it is desired to gasify the longest length of a pyrolysis chamber as possible while the laser head remains stationary. As a simple example, say that the laser head includes 30 sets of laser-beam outputs spaced from one another along the length of the laser head, with each set including 8 laser-beam outputs distributed 360° around the laser-head’s circumference and with a single laser providing the laser energy for the entire heating process. The eight laser-beam outputs in each set are scanning-type outputs that provide full 360° heating coverage, and the laser-beam outputs in adjacent ones of the sets provide contiguous heating regions. Assuming that heating parameters allow for both scan-style heating in combination with a duty cycle that allows the laser energy from the single laser to be continually sequenced among the 30 sets, the full laser power from the single laser can be provided to each of the 30 sets to effect heating. Such sequencing can be effected in any suitable manner, such as providing a rotating optic (lens(es) and/or mirror(s)), DLP (or the like), or other optical switch. The sequencing can be any suitable sequencing among the sets. As noted above, the partitioning of the laser-beam outputs may additionally or alternatively be in the circumferential direction of the laser head. It is noted that the example with 30 sets is merely exemplary and that more or fewer sets may be used. In addition, more than one laser can be provided. Those skilled in the art will readily understand how to devise and implement a laser-energy-sequenced configuration by working out a suitable irradiation plan using this disclosure as an enabling guide and knowledge in the art.

[0150] In some embodiments, the laser head may be configured to direct laser energy 360° radially about the longitudinal axis of the pyrolysis chamber, either continuously or intermittently. This may be accomplished in any one or more of a variety of ways, including having multiple fixed or rotating (e.g., about a longitudinal central axis of the laser head) laser-beam outputs distributed circumferentially around an exterior of the laser head or one or more movable laser beam outputs that rotate about the longitudinal axis of the pyrolysis chamber, and any combination thereof. In some embodiments, the laser head may be configured to direct one or more laser beam at an angle less than 360° radially about the longitudinal axis of the pyrolysis chamber, such as 270° 180°, 120°,

38 90°, among others, either continuously or intermittently, and in any one or more directions, such as upward, downward, laterally, etc. Fundamentally, the laser head can be configured relative to the manner in which the laser beam(s) is/are emitted in any way suitable for the application at issue.

[0151] Due to the use of laser energy for causing and driving the pyrolysis, either alone or in combination with a non-laser heat source, the shape of the pyrolysis chamber can be highly controlled by suitably controlling heating parameters, such as beam power density, beam residence time, beam cycle duty, and scanning pattern, among others. FIGS. 6A through 6D illustrate some example pyrolysis chamber transverse cross-sectional shapes that are possible using suitably controlled heating and pyrolysis. FIG. 6A illustrates a generally circular pyrolysis chamber 600 that is formed after some amount of pyrolysis has been achieved in a carbonaceous material 604 using a laser head 608. In this example, the original pyrolysis chamber is a cylindrical-bore-type pyrolysis chamber 600', with the laser head 608 being located at the bottom (relative to FIG. 6 A) of both the original pyrolysis chamber 600' and the larger pyrolysis chamber 600 formed after pyrolysis of the carbonaceous material 604. In this example, the heating and pyrolysis is performed via five scanning zones 612(1) to 612(5) scanned by one or more laser beams (not shown) emanating from the laser head 608. In this connection, it is noted that the number of laser heads used to scan each scanning zone 612(1) to 612(5) may increase as the pyrolysis chamber 600', 600 becomes larger and larger as pyrolysis progresses. For example, the area that each laser-beam can scan may be a fixed size such that, as the pyrolysis chamber 600', 600 gets larger and the area of the carbonaceous material that must be scanned in each scanning zone 612(1) to 612(5) increases, that area becomes larger than an individual laser beam can scan such that another laser beam needs to be activated to cover the larger area.

[0152] FIG. 6B illustrates a generally rectangular pyrolysis chamber 620 formed in a carbonaceous material 624 using six scanning zones 628(1) to 628(6), with a laser head 632 present in the original cylindrical -bore-type pyrolysis chamber 620' and still present at the bottom (relative to FIG. 6B) of the pyrolysis chamber 620. As noted above, the rectangular shape can be easily formed by suitably controlling the heating and corresponding pyrolysis precisely with the corresponding laser beams (not shown) in scanning zones 628(1) to 628(6). Aspects of the scanning zones 628(1) to 628(6) not specifically described can be the same as or similar to the scanning zones 612(1) to 612(5) described above relative to FIG. 6A. An advantage of a rectangular or other shape (e.g., polygonal) is that it is more efficient in the usage of as much of the carbonaceous material as possible for gasification.

39 [0153] Each of FIGS. 6C and 6D illustrate, respectively, a circular pyrolysis cavity 640 and a rectangular pyrolysis cavity 660 similar, respectively, to pyrolysis chambers 600 and 620 of FIGS. 6A and 6B. However, in the examples of FIGS. 6C and 6D, the corresponding laser heads 644 and 664 are located at the geometric center 640A, 660A of the respective pyrolysis chamber 640 and 660, with each of the laser head being initially located within a corresponding original cylindrical -bore-type pyrolysis chamber 640', 660'. FIGS. 7 A to 7C illustrate a laser-head assembly 700 that could be used to create each of the pyrolysis cavities 640 and 660 of FIGS. 6C and 6D.

[0154] In FIG. 6C, the circular shape of the pyrolysis chamber 640 is formed using 8 scanning zones 648(1) to 648(8) that each scan a 45° arc so as to provide 360° continuous circumferential coverage of the entire wall 652A of the carbonaceous material 652. In FIG. 6D, the circular shape of the pyrolysis chamber is formed using 8 scanning zones 668(1) to 668(8) that each scan a 45° arc so as to provide 360° continuous circumferential coverage of the entire wall 672 A of the carbonaceous material 672. Those skilled in the art will readily understand that the number of scanning zones, the configurations of the scanning zone, and the shape of the pyrolysis chambers of the examples in FIGS. 6 A to 6D are merely examples and that each may be different as needed to suit a particular design and application. Those skilled in the art will also readily understand that the scanning zones in FIGS. 6 A to 6D are illustrated in two dimensions and that the actual scanning zones will typically be three-dimensional, extending into and/or out of the plane of the page containing each of FIGS. 6A to 6D.

[0155] Because the laser energy from the laser head can be precisely controlled in a heating - no heating binary manner at any location within the pyrolysis chamber, the gasification system can be designed to detect non-carbonaceous material, such as bedrock, that abuts or is present in an underground deposit of the carbonaceous material, and, upon detection, stop irradiating. In this manner, laser energy is not wasted and any negative consequences of heating non-carbonaceous material, such as inducing cracking within a barrier layer abutting a natural deposit of the carbonaceous material, can be avoided. In addition, gasification of as much of the carbonaceous material as possible can be performed without being concerned with encountering non-carbonaceous material. Detection of non-carbonaceous material can be performed by measuring one or more conditions of the pyrolysis (see block 315 of FIG. 3 and corresponding description below) and determining whether or not the measured condition(s) is/are anomalous and/or meet one or more

40 conditions expected of another material, among other determinations that can be made to detect the encountering of a non-carbonaceous material.

[0156] In some embodiments, the laser head may include a positioning structure for properly positioning the laser head within the transverse cross-sectional shape of the pyrolysis chamber. For example, the pyrolysis chamber may have a circular transverse cross-sectional shape and the laser head may be designed to be centered within the circular transverse cross-sectional shape. In this example, the positioning structure may include one or more sets of arms (e.g., three or more arms per set) that engage the walls of the pyrolysis chamber and maintain the laser head centrally within the transverse cross-sectional shape of the pyrolysis chamber. Such arms may be spring-loaded and/or controlled using one or more actuators, among other things.

[0157] In some embodiments, the laser head may be rigid in a direction along its length so as to be supported in a cantilevered manner from a laser-head support that holds the rigid laser head in a desired position within the pyrolysis chamber. When the pyrolysis chamber is of the linear-bore type that extends to a surface of a geological formation containing the carbonaceous material, the laser head can be rigid even when present on the surface (i.e., be permanently rigid), since a laser head need only be inserted into a linear bore that opens to the surface. However, when the pyrolysis chamber is not immediately accessed from the surface, such as in a lateral-bore-type pyrolysis chamber formed down an access well, an entire long laser head cannot be permanently rigid, as it would not be possible to insert it into the lateral-bore-type pyrolysis chamber. To accommodate such a situation, the laser head may be provided, for example, with pivoting joints that can pivot about one or more axes to allow the laser head to snake through non-linear passageways and/or non linear transitions between passageways. The pivoting joints may be located between rigid links that each contain one or more laser outputs. The laser head would include one or more locking mechanisms that releasably lock the pivoting joint to make the entire laser head rigid. The locking mechanism(s) can be any suitable mechanism(s) that provide the locking feature. For example, adjacent links may become electromagnetically attracted to one another via electromagnetic mechanisms or one or more tensioning cables can be used to firmly draw the rigid links into locking engagement with one another, among many other locking mechanisms.

[0158] The laser-head support may be suitably sized to substantially fill the transverse cross- sectional area of the pyrolysis chamber and provide adequate support for the cantilevered rigid laser head. If needed, the laser-head support may be similarly segmented with pivotable joints and

41 include one or more locking mechanisms for locking the segments together once the laser-head support is in the pyrolysis chamber. The laser-head support may further include stabilizing features for fixedly stabilizing the laser-head support and corresponding cantilevered laser head within the pyrolysis chamber. The laser-support head may further include a traction system for moving the laser-head support and laser head along the pyrolysis chamber, and the stabilizing features can be integrated with the traction system, as needed. FIGS. 7A to 7C illustrate an example laser-head assembly 700 comprising flexible-rigid laser head 700A and flexible-rigid laser-head support 700B.

[0159] FIG. 7A illustrates the laser-head assembly 700 partially inserted into a lateral-bore-type pyrolysis chamber 704 from an access well 708. The pyrolysis chamber 704 is where the laser head 700A will be deployed for use to create a product gas 712 (FIG. 7C). As can be seen in FIG. 7A, the flexible laser head 700A is shown snaking around the transition from the access well 708 into the pyrolysis chamber 704. Once the laser-head assembly 700 is in proper position, the locking mechanisms of each of the laser head 700A and the laser-head support 700B are activated so as to make both of these components rigid. The result of making the laser head 700A and the laser-head support 700B rigid is shown in FIG. 7B. As also seen in FIG. 7B, this embodiment of the laser-head support 700B also includes a traction system 712 that both effects movement of the laser-head assembly 700 along the pyrolysis chamber 704 and centers the laser- head assembly within the transverse cross-section of the pyrolysis chamber. Further, FIG. 7B shows the state of the pyrolysis chamber 704 after the laser head 700A has fully pyrolyzed the carbonaceous material 716 that was originally surrounding pyrolysis chamber 704 and just before the laser-head assembly 700 is advanced to its next location for a next round of pyrolysis as shown in FIG. 7C. As can be seen in FIG. 7B, the laser-head support 700B maintains the laser head 700A in a fixed position as heating and pyrolysis is performed 360° around the circumference of the laser head. FIG. 7C shows the laser-head assembly 700 after being moved from its initial position (FIG. 7B) and after the laser head 700A has been operated to pyrolyze a portion of the carbonaceous material 716 desired to by pyrolyzed at this new position. Not shown are the laser-beam outputs, sensing elements, and other features of a laser head as described above.

[0160] Referring again to FIG. 3, at block 310, when the laser head is engaged with the pyrolysis chamber, the target portion of the carbonaceous material defining the pyrolysis chamber is heated with energy from the laser head so as to sustain a desired pyrolysis state that produced the product gas from the carbonaceous material. Generally, the product gas is produced from pyrolysis and other thermally initiated reactions induced in the carbonaceous material by the heating that the

42 laser head causes. In some embodiments, the surrounding portions of the carbonaceous materials are irradiated with one or more laser beams output by the laser head in a continuous or intermitted pattern to any desired extent circumstantially around a longitudinal axis of the pyrolysis chamber, such as 360°, 270°, 180°, 120°, 90°, among others, and in any desired direction(s), e.g., upward, downward, laterally, etc. The laser head may be controlled to heat the surrounding carbonaceous material defining the pyrolysis chamber while the laser head is moving, is stationary, or is intermittently moving and stationary, as desired for a particular application.

[0161] As discussed above, a benefit of heating the surrounding portions of the carbonaceous material using laser energy is that heating temperature(s), and therefore the state of pyrolysis, can be highly controlled by controlling one or more heating parameters, such as laser-beam power density, laser-beam duty cycle, and irradiation residency time, and irradiation site frequency, among others. Providing such high levels of control allows the gasification reactions to proceed in highly predictable manners such that the composition of the generated product gas can be tuned to a desired compositional makeup of differing gases in desired mole ratios.

[0162] For example, laser-based gasification and pyrolysis described herein may produce variable heating rates, e.g., from 25°C/s (slow pyrolysis) to 10,000°C/s (flash pyrolysis) simply by adjusting the relevant heating parameter(s). In contrast with conventional heating mechanisms and without limiting to any one particular theory, advantages achieved by laser-based pyrolysis of the present disclosure, such as the product gas production method 300 of FIG. 3, include, but are not limited to, greater levels of pyrolysis, greater control of pyrolysis, greater pyrolysis rates, higher efficiencies, tunability of the composition of the product gas, and less waste, among others.

[0163] In some embodiments, pyrolysis is aided by supplying one or more oxidants (e.g., air or oxygen) and/or non-laser-based heat (e.g., via a heating gas, such as steam) to the pyrolysis chamber. In some embodiments, the oxidant(s) and/or heating gas (or other heat source) may be provided via the first access well. The flow of the oxidant(s) can be carefully controlled as a function of the extent and advancement of the pyrolysis to keep the pyrolysis conditions (e.g., temperature and rate) within design parameters so as to control the advancement of the pyrolysis and resulting composition of the product gas that the pyrolysis produces.

[0164] The heating at block 310 is performed so as to sustain the desired pyrolysis state. However, those skilled in the art will readily understand that, in practice, this mean that the heating is performed to achieve as close to a desired pyrolysis state as practicable. This is so because skilled

43 artisans will appreciate that the conditions of pyrolysis, especially in natural underground deposits, are subject to sometimes not insignificant variations caused by varying conditions that can occur. Such varying conditions can include, but are not limited to, variations in the composition of the carbonaceous material, variations in presence of voids, variations in moisture content, and variations in delivery of oxidant flow (e.g., due to encountering an unknown fissure), among others. Consequently, those skilled in the art will readily understand that in practice, it may be the case that the desired pyrolysis state is neither always precise from one location to another within the pyrolysis chamber nor is its maintenance always possible to maintain. Thus, those skilled in the art will understand that “to sustain the desired pyrolysis state” is to be understood to account for any unavoidable variabilities while at the same time requiring a sense of intent of the implementer of method 300 to control the heating in a manner that sustains, within limits of practicalities, the state of pyrolysis linked to a desired product gas composition.

[0165] In some embodiments, the heating of the target region of the carbonaceous material surrounding the laser head may be performed while the laser head is stationary within the pyrolysis chamber. For example, the laser head can continue to scan each laser beam with the same directionality so as to continually and incrementally cause the carbonaceous material at that location to continually pyrolyze and produce the desired product gas. An example time-sequenced view of one location within the carbonaceous material is shown in FIGS. 8A to 8C, which are in scale relative to one another, showing the progressive pyrolysis at three snapshots in time within a bore- type pyrolysis chamber 800. In this example, the laser head 804 remains stationary while a set of laser beams 808 (only some labeled for convenience) are scanned over the same target region 812A of the carbonaceous material 812 to cause pyrolysis to continue at increasing depths into the carbonaceous material. As time progresses from FIG. 8 A through to FIG. 8C, the effective diameter DE of the pyrolysis chamber 800 increases as pyrolysis continues.

[0166] In some embodiments, the heating of the target region of the carbonaceous material surrounding the laser head may be performed while the laser head is moved within the pyrolysis chamber. For example, the laser head may be provided with multiple laser-beam outputs along its length, with the leading (in the direction of laser head movement) laser beams from those laser-beam outputs causing the initial pyrolysis of the carbonaceous material, with one or more successive sets laser beams continuing pyrolysis at increasing depths into the carbonaceous material. In some embodiments, the laser head may be moved in a continuous manner or an intermittent manner, or a

44 combination of the two. An example of pyrolysis created while a laser head 900 is being moved within a pyrolysis chamber 904 is illustrated in FIG. 9.

[0167] As seen in FIG. 9, the laser head 900, which provides four laser-beam-output zones 908(1) to 908(4) along its length, is moved from right to left (as indicated by arrow 912) during the pyrolysis of a moving target region 916A of a carbonaceous material 916 surrounding the pyrolysis chamber 904. In this example, for each of the laser-beam-output zones 908(1) to 908(4) the laser head 900 outputs a corresponding plurality of laser beams 900(1) to 900(4). The laser- beam-output zone 908(1) is the leading laser-beam output relative to the direction of movement 912 of the laser head 900, and the laser-beam-output zone 908(4) is the trailing output relative to the direction of movement of the laser head. At the instant in time shown in FIG. 9, the effects of the corresponding laser beams 900(1) to 900(4) output by the laser head 900 on the carbonaceous material 916 are shown at the four corresponding respective laser-beam-output zones 908(1) to 908(4). Here, the regions of the carbonaceous material 916 in the laser-beam-output zone 908(1) is being pyrolyzed by the laser beams 900(1), the regions of the carbonaceous material in laser-beam- output zone 908(2) is being pyrolyzed by the laser beams 900(2) and has been pyrolyzed by the laser beams 900(1), the regions of the carbonaceous material in the laser-beam-output zone 908(3) is being pyrolyzed by the laser beams 900(3) and has been pyrolyzed by the laser beams 900(1) and 900(2), and the regions of the carbonaceous material in the laser-beam-output zone 908(4) is being pyrolyzed by the laser beams 900(4) and has been pyrolyzed by the laser beams 900(1) to 900(3), with the effective diameter of the pyrolysis chamber 904 increasing as the laser head 900 is moved 912 and as additional ones of the laser beams heat and pyrolyze the regions. Those skilled in the art will readily appreciate that the four laser-beam-output zones 908(1) to 908(4) are used in the example for convenience and that the number of laser beams along length of the laser head 900 can range from two to tens or hundreds, among others.

[0168] Referring back to FIG. 3, at block 315 measurements of at least one condition of the target portion being heated that has a known correlation to the desired pyrolysis state are obtained. Generally, the measurements at block 315 are obtained concurrently with the heating of the target region. The measurements do not necessarily need to be obtained simultaneously with the heating, for example, if simultaneous heating would interfere with the accuracy of the measurements. Examples of conditions that may be suitably correlated to the state of pyrolysis include, but are not limited to temperature of the surface of the target portion of the carbonaceous material, the physical composition of the target portion, and the composition of one or more products of the target portion

45 already pyrolyzed, such as the product gas, tar, char, etc., among others. In this connection, the laser head may be outfitted with one or more suitable sensing element types that participate in obtaining measurements. For example, for temperature measurements, the laser head may include sensing elements for infrared-based thermal sensing. As another example, for physical composition of the target portion, the laser head may include sensing elements based on laser technology, such as disclosed in U S. Patent No. 10,928,317, titled “FIBER-OPTIC BASED THERMAL REFLECTANCE MATERIAL PROPERTY MEASUREMENT SYSTEM AND RELATED METHODS”, and issued on February 23, 2021, to Foley et al., which is incorporated herein by reference for its teachings on relevant techniques.

[0169] As a further example, for pyrolysis product detection, the laser head may include “electronic nose” sensing elements for sensing presence and/or relevant amounts of individual components of the product gas. These are simply a few examples of sensing elements, and those skilled in the art will readily appreciate that other sensing elements can be used depending on the condition(s) being measured. It is noted that in some cases, a single sensing element may be used for the target region, while in some cases multiple sensing elements may be used for differing regions with the target region. It is further noted that some types of sensing elements, such as infrared and laser-based sensing elements can be moveable, for example scannable to take measurements at differing locations. Each type of sensing element may be part of an overall pyrolysis monitoring system that can be continuously or continually used to determine the state of pyrolysis for comparing to the desired pyrolysis state to effect heating control.

[0170] At block 320, the heating of the target portion of the carbonaceous material is controlled as a function of the measurements of the at least one condition of target portion at block 315. For example, the pyrolysis monitoring system, and/or other part(s) of an overall laser-based gasification system, may use suitable algorithms for comparing condition measurements to corresponding parameters of the desired pyrolysis state and, based on the comparisons, for determining one or more control signals for controlling the heating of the target region in a manner that maintains or attempts to maintain, as much as practicable, the pyrolysis occurring at the target zone as close as possible to the desired pyrolysis state. In some embodiments, the parameters of the desired pyrolysis state may be determined based on a-priori testing of the carbonaceous material that is the subject of gasification. Such testing may be performed either in-situ or ex-situ , or both, depending on the testing methodologies performed.

46 [0171] If in-situ testing is performed, then the laser-based gasification system may be deployed for a testing phase, wherein the laser head is placed, sequentially, in one or more pyrolysis chambers, with the laser-based gasification system being operated so as to create a range of differing pyrolysis states, with the resulting product gas for each pyrolysis state being assayed to determine its composition. Once all of the testing data have been reviewed and a desired product-gas composition has been selected, operating parameters for the desired pyrolysis state can be determined. Then, the laser-based gasification system can be deployed for product-gas production using the operating parameters corresponding to the desired pyrolysis state. In some embodiments, in-situ testing may be performed at multiple differing locations as needed depending on the composition of the natural carbonaceous deposit at issue. In some examples, all multi -location testing may be performed prior to stating any product-gas production, while in some embodiments, multi -location testing may be performed intermittently with product-gas production. For example, testing may be performed in any one pyrolysis chamber or related set of pyrolysis chambers prior to initiating product gas production.

[0172] If ex-situ testing is performed to determine parameters of the pyrolysis state and the corresponding operating parameters for the laser-based gasification system, then one or more samples may be taken from one or more locations within the mass of material targeted for gasification and tested in a suitable testing laboratory. Once the parameters of the desired pyrolysis state is determined, the operating parameters for the laser-based gasification system that will cause the desired pyrolysis state in situ may be determined for the product-gas production phase.

[0173] At block 325, the product gas resulting from the pyrolysis caused by heating using the laser head is extracted from the mass of carbonaceous material. The extraction of the product gas can proceed in any suitable way, such as using conventional product gas extraction equipment or any other suitable extraction technique. For example, extracting the product gas resulting from the pyrolysis may include providing an extraction flow from the pyrolysis chamber to cause the product gas to flow to a suitable collection system, which may include one or more storage tanks (e.g., surface-mounted tanks) and/or processing equipment to process the product gas in one or more of a variety of ways. The extraction flow may be a positive-pressure flow induced by flowing an extraction gas into the pyrolysis chamber. The extraction gas may be separate from or combined with any oxidant flow provided for pyrolysis, as mentioned above. The extraction flow may be a negative-pressure flow induced, for example, by a vacuum system. For example, the vacuum system may include one or more fans that draw the product gas from the pyrolysis chamber. In some

47 embodiments, a positive-pressure flow on an inlet end of the pyrolysis chamber may be used in combination with a negative-pressure flow on an outlet end of the pyrolysis chamber. If provided, product-gas processing equipment may include, but not be limited to, constituent gas separation equipment, pressurizing equipment, liquification equipment, and flow-gas removal equipment,, among others, singly or in any suitable combination. Fundamentally, there are no limitations on the type(s) of processing equipment that can be used.

[0174] In some embodiments, some or all of the activities of the foregoing blocks 305 through 325 may be repeated at differing locations within one or more pyrolysis chambers. For example, a first pass through method 300 may proceed with the laser head stationary at a first location within a pyrolysis chamber, such as at a first position along the length of a bore-type pyrolysis chamber. Then, the laser head may be moved to a second position within the bore-type pyrolysis chamber along the length of the pyrolysis chamber and the activities at block 310 through block 325 repeated at the second position. This type of repetition may continue until a desired amount of the carbonaceous material along a desired length of the bore-type pyrolysis chamber is pyrolyzed. As another example, once the method 300 has been performed in a first pyrolysis chamber, the laser head may be moved to a second pyrolysis chamber, wherein activities at blocks 305 through 325 may be repeated. Similar to the same-chamber example, the repeating of moving the laser head from one pyrolysis chamber to another may be repeated until a desired pyrolysis has been performed in a desired number of pyrolysis chambers. Those skilled in the art will readily appreciate the variety of ways in which various activities in blocks 305 through 325 can be executed and repeated as desired.

[0175] Example Laser-Based Gasification System

[0176] FIG. 4 illustrates an example laser-based gasification system 400 (“gasification system”, for short) that is configured to perform a gasification method of the present disclosure, including the method 300 of FIG. 3 and any method derivable from the above-detailed description of the method 300. In the example shown, the gasification system 400 includes one or more laser heads 404 (collectively shown as a single laser head), each of which is deployed to a corresponding pyrolysis chamber (not shown) during use. At a high level, each laser head 404 includes a plurality of laser-beam outputs 404A (only a few labeled to avoid clutter) that outputs a corresponding laser beam (not illustrated) to irradiate the carbonaceous material (not show) with energy sufficient to heat the carbonaceous material to a desired temperature to cause the carbonaceous material to pyrolyze

48 and produce a product gas. The laser-beam outputs 404A output laser beams generated by a laser system 408, which can take any one or more of a variety of forms.

[0177] For example, in some embodiments each laser-beam output 404A may include a scanning means, such as scanning optics, gimballed mount, etc. In some embodiments, each laser- beam output 404A may be a fixed output. Examples of fixed outputs include suitable optics, such as beam-expanding optics, fiber bundles, etc. In some embodiments implementing fixed outputs, the fixed outputs may be configured and/or utilized to increase the size of the irradiated regions as the pyrolysis chamber grows in size due to continuing pyrolysis. For example, a beam expander may be a variable beam expander. In some embodiments, each laser-beam output 404A may include both scanning features and beam expanding features, among other variations.

[0178] For example, the laser system 408 may include one or more lasers 408A (collectively shown as a single laser) that provide laser energy to the laser-beam outputs 404A via optic fibers (e.g., in one or more optic-fiber cables), collectively shown as optic-fiber cable 408B. At a high level, multiple laser heads are provided so as to be able to heat relatively large areas of the carbonaceous material exposed to the laser head 404 within a pyrolysis chamber. In this connection, it is desired to cause relatively large areas of the exposed carbonaceous material to pyrolyze at any given time so as to produce relatively large volumes of product gas in an effective and efficient manner. As those skilled in the art will readily appreciate, the number of laser-beam outputs 404A and the number of lasers 408 A providing laser energy to those laser-beam outputs will depend on, for example, physical limitations of the relevant current laser technology (e.g., output power, efficiency, optic-fiber-cable capacity, etc.) and associated monetary costs. While it is desirable to make the laser head 404 as long as possible (e.g., tens of feet or hundreds of feet or more in length) and provide as many laser-beam outputs 404A as needed to suit such long lengths, it is recognized that for practical applications that tradeoffs in laser-head length and number of laser-beam output may need to be made in order to deploy a gasification system of the present disclosure, such as the gasification system 400, in an economically and commercially successful manner.

[0179] Each laser may be based on any suitable technology, such as CO2 lasing technology, YAG lasing technology, optic-fiber lasing technology, solid-state lasing technology, etc. In some embodiments, the output wavelength(s) of the lasers need not necessarily be selected and/or tuned to specific absorption spectra of the target carbonaceous material, although in some cases the lasers can be so selected or tuned. In some embodiments, each laser 408A may be located remotely from the

49 laser head 404, while in some embodiments, each laser may be located onboard the laser head, depending on the technology at issue. In some embodiments, one or more lasers 408A may be located remotely from laser head 404 and one or more lasers 408A may be located onboard the laser head.

[0180] Each laser head 404 may further include a plurality of condition-sensing elements 404B (only a few labeled to avoid clutter) that are used to sense one or more conditions within a pyrolysis chamber (not shown) in which the laser head is deployed. Examples of conditions that can be sensed, as desired, include, but are not limited to, distances (e.g., to measure pyrolysis-chamber size / extend of pyrolysis) and conditions of pyrolysis as may be discernable in any of a variety of ways, such as temperature, material composition of irradiated face, and makeup of product gas, among others. Depending on the configuration and needs, the condition-sensing elements 404B may be of the same type or differing types, with the type of each condition-sensing element 404B corresponding to the condition it is deployed to measure. Depending on its type, each condition sensing element 404B may be or comprise, for example, lensing for light-based sensing (including infrared), ultrasound transducer(s) for ultrasound-based sensing, or radar component(s) for radar- based sensing, among others. Depending on various factors, such as the type of each condition sensing element 404B, the directionality of each condition-sensing element, and the coverage area for each sensing element, one, some, or all of the condition-sensing elements may be pivotable so as to allow the sensing element to be directed to the desired region(s) of interested. In some examples, one, some, or all of the condition-sensing elements may be of the scanning type so as to be able to conduct areal scans, such as in a manner discussed above relative to scanning the laser beams to effect areal heating. Fundamentally, there are no limitations on the nature or type(s) of condition sensing elements 404B.

[0181] Depending on the configuration of the gasification system 400, the laser head 404 may include either one or more gas-delivery ports 404C or one or more gas-collection ports 404D, or both. The gas-delivery port(s) 404C, if provided, may deliver one, some or all of an oxidant flow, a heating flow, and a extraction flow for, respectively, assisting the pyrolysis, heating the pyrolysis zone, and assisting with removing the product gas. The gas-collection port(s) 404D, if provided, may collect the product gas and any remnants of the oxidant flow that may be present and any extraction flow that may be present. Providing the laser head 404 with both gas-delivery and gas- collection ports 404C and 404D allows many aspects of the laser-based gasification process to be performed locally within the pyrolysis chamber. If one or both types of gas-delivery and gas

50 collection ports 404C and 404D is/are not provided, then other type(s) of execution methods may be provided, such as conventional surface-based methods of delivering one or more gases downhole and conventional surface-based method of collecting one or more gases from underground, among others. FIG. 10A illustrates an example laser head 1000 that includes both gas-delivery ports 1004 and gas-collection ports 1008.

[0182] Referring to FIG. 10A, which illustrates the laser head 1000 deployed in a pyrolysis chamber 1012 located within a carbonaceous material, in this example, the laser head 1000 is tethered to surface equipment (not shown) such as a laser system, an oxidant-flow system, a heating flow system, and a gas-collection system via a tether 1016. The laser head 1000 has a length, L, with the gas-delivery ports 1004 being present at one end of the length L and the gas-collection ports 1008 being present at the opposite end of length L. This arrangement allows for creating a generally uniform and laminar flow of gases in the space surrounding the laser head 1000, as illustrated by arrows 1020. Not shown to avoid clutter are other components of the laser head 1000, such as laser-beam outputs and any condition-sensing elements that may be present. It is noted that the locations of the gas-delivery ports 1004 and the gas-collection ports 1008 can be reversed. In other embodiments, the gas-delivery ports 1004 and the gas-collection ports 1008 can be located elsewhere, such as at locations distributed along the length L of the laser head. Those skilled in the art will readily appreciate how to organize any gas-delivery ports and gas-collection ports for any particular design and application of a laser head.

[0183] FIG. 10B shows an example configuration of the tether 1016. In this example, the tether includes an outer sheath 1016A that contains 1) an optic-fiber cable 1016B that delivers laser energy to the laser outputs (not shown) from one or more lasers (not shown) and, optionally carries optical signals to and/or from any condition-sensing element that may be aboard the laser head 1000 (FIG. 10 A), 2) a gas-delivery conduit 1016C for delivering one or more gases to the gas-delivery ports 1004, 3) a gas-collection conduit 1016D for collecting gas via the gas-collection ports 1008, and 4) electrical cabling 1016E needed for operating and/or controlling any electronic equipment (not shown) that may be aboard the laser head and/or laser-head support and/or to carry any electrical signals that may be generated onboard the laser head, among others. Examples of electronic equipment include, but are not limited to, a traction system, scanning motors, digital-light- processors, and onboard sensors, among others. Examples of electrical signals generated onboard the laser head 1000 include, but are not limited to, signals from onboard pyrolysis-chamber sensors and signals from other onboard electronics and/or onboard equipment. Those skilled in the art will

51 readily understand the wide variety of electronic equipment that can be placed aboard a laser head and/or laser-head support of the present disclosure.

[0184] Referring back to FIG. 4, the example gasification system 400 may also include, among other systems, 1) a measurement system 412 that includes all of the physical equipment, physical components, and/or software needed for sensing and measuring conditions within a pyrolysis chamber, including the condition-sensing elements 404B aboard the laser head(s) 404, 2) a laser- head-movement system 416 that includes all of the physical equipment, physical components, and/or software needed for moving the laser head, including for deployment and/or for moving one or more laser heads between discrete pyrolysis sessions and/or during one or more continuous pyrolysis session(s), 3) a gas-delivery system 420 that includes all of the physical equipment, physical components, and/or software needed for storing, supplying, and delivering one or more gases, such as one or more oxidants, one or more heating gases, and/or one or more extraction gases, to one or more pyrolysis chambers, including storage vessel(s) and delivery system(s), and 4) a gas-collection system 424 that includes all of the physical equipment, physical components and/or software needed for collecting, processing, and/or storing one or more gases, such product gas, excess oxidant(s), and/or extraction gas(es), from one or more pyrolysis chambers, among others. Each of these systems may be composed of conventional elements to the extent that any specialized element(s) are not needed to practice a gasification system of the present disclosure, such as the gasification system 400 of FIG. 4. Those skilled in the art will readily appreciate the many ways that each of the systems 412, 416, 420, and 424 can be embodied, including the wide variety of equipment, components, and software configurations for executing these systems and that skilled artisans will be able to make and use these ways for the relevant gasification-system designs using only knowledge in the art and this disclosure as a guide.

[0185] In some embodiments, non-laser heating of the carbonaceous material in the pyrolysis chamber may be provided by a heating source other than one or more heating gases. For example, each laser head 404 may include an onboard heat source 404E or a component of an offboard heat source (not shown). Examples of such other heat sources can be found, for example, in U.S. Patent No. 7,225,866, titled “IN SITU THERMAL PROCESSING OF AN OIL SHALE FORMATION USING A PATTERN OF HEAT SOURCES” and issued on June 5, 2007, to Berchenko et ak, which is incorporated herein by reference for its teachings of heat sources.

52 [0186] In this example, the gasification system 400 includes a control system 428 that controls all operations of the gasification system either automatically or manually, or a combination of automatically and manually. As those skilled in the art will readily appreciate, while the control system 428 is illustrated as a single block in FIG. 4, all of the control functions that the control system performs need not be centralized. Rather, embodiments of the gasification system 400 may have any one or more control subsystems, such as one or more laser-control subsystems 428A, one or more measurement control subsystems 428B, one or more laser-head-movement control subsystems 428C, one or more laser-head stabilization control subsystems 428D, one or more gas- delivery control subsystems 428E, and one or more gas-collection subsystems 428F, among others.

In some examples one or more of the control subsystems can be a standalone control subsystem and/or one or more of the control subsystems may be networked with one another and/or to a master controller 428G, among other architectures. Those skilled in the art will readily appreciate the many ways that the control system 428 can be embodied, including the wide variety of hardware and software configurations for implementing the control system and that skilled artisans will be able to make and use these ways for the relevant gasification-system designs using only knowledge in the art and this disclosure as a guide.

[0187] As those skilled in the art will readily appreciate, the control system 428 can include many algorithms for performing a wide variety of tasks that the gasification system 400 must perform during deployment for gasifying a mass of carbonaceous material. Some of these algorithms include pyrolysis-control algorithms 432 that control the pyrolysis that occurs in any one or more pyrolysis chambers in which one or more laser heads 404 are deployed. Depending on the configuration of the gasification system 400 and the manner(s) in which pyrolysis can be controlled and the state(s) of the pyrolysis can be determined, the functionalities that the pyrolysis-control algorithms 432 need to perform can vary. Examples of functionalities that the pyrolysis-control algorithms 432 can provide include, but are not limited to:

• controlling laser-power density provided to the carbonaceous material, in some embodiments as a function of measurements of the state of pyrolysis and/or the size and/or shape of the region(s) of the carbonaceous material being pyrolyzed and/or movement of the laser head(s) 404;

• controlling laser-beam scanning of the carbonaceous material, for example via the laser-beam outlets 404B of the laser head(s), in some embodiments as a function of measurements of the

53 state of pyrolysis and/or the size and/or shape of the region(s) of the carbonaceous material being pyrolyzed and/or movement of the laser head(s);

• controlling the movement of the laser head(s), in some embodiments as a function of measurements of the state of pyrolysis and/or the size and/or shape of the region(s) of the carbonaceous material being pyrolyzed;

• controlling sequencing of providing laser energy to various ones of the laser-beam outputs, in some embodiments as a function of measurements of the state of pyrolysis and/or the size and/or shape of the region(s) of the carbonaceous material being pyrolyzed and/or movement of the laser head(s);

• controlling the amount of oxidant gas(es) provided to the pyrolysis chamber;

• controlling the amount of non-laser heating, in some embodiments including controlling the flow of one or more heating gases (e.g., steam) to the pyrolysis chamber;

• controlling the sensing of one or more conditions within each active pyrolysis chamber;

• controlling collection of sensor data;

• comparing condition measurements to one or more predetermined parameters for a desired pyrolysis state that produced a desired product gas; and

• conducting in-situ pyrolysis testing to determine one or more parameters of a desired pyrolysis state, in some embodiments as a function of the constituency of the product gas, and any combination thereof, among others.

[0188] Those skilled in the art will readily understand that the pyrolysis-control algorithms 432 and the associated computing hardware 436 that executes the machine-executable instruction 440 that embody the pyrolysis-control algorithms 432 will be in operative communication with the necessary systems, such as, for example, the laser system 408, the measurement system 412, the laser-head-movement system 416, the gas-delivery system 420, and/or the gas-collection system 424, among others, as needed to receive the necessary data (e.g., condition measurements, location information, component statuses, etc.) from these systems and to provide the necessary information, such as control signals, status information, operating parameters, etc.) to these systems. The computing hardware 436 includes memory 436A, which can be any type of physical storage memory, including, but not limited to non-volatile memory (e.g., solid-state, optical, magnetic, etc. hard-drive memory, and/or other type of long-term storage memory) and volatile memory (e.g.,

RAM and/or cache memory, among other types). Fundamentally, there is no limitation on the type(s) of the memory 436 A, the number of memory devices that compose the memory 436 A, and

54 the physical location(s) of the memory device(s) that compose the memory 436 A, other than that the memory is not in the form of any transitory signal. Many types of computing systems, computing architectures, and programming styles are ubiquitous and well-known in the art and are usable to implement the pyrolysis-control algorithms 432, such that it is not necessary to describe these in detail for those skilled in the art to implement them for any application and design that may be devised using the present disclosure as a guide.

[0189] EXAMPLE INSTANTIATIONS - Laser-based UCG

[0190] FIGS. 11 A through 11C illustrate an example instantiation of a laser-based UCG system 1100 (hereinafter, “UCG system” for short) as deployed in accordance with aspects of the present disclosure. Referring first to FIG. 11 A, in this example, the UCG system 1100 is deployed to perform gasification on a portion of a natural underground coal seam 1104 that lies beneath the earth’s surface 1108, an aquifer 1112, and overburden 1116 that includes a sedimentary rock layer 1116A that seals the coal seam from the aquifer. In this example, the UCG system 1100 includes a first access well 1120 and associated surface equipment 1120A (e.g., a laser system, an oxidant-supply system, etc.; see, e.g., FIG. 4), a second access well 1124 and associated surface equipment 1124A (e.g., a gas-collection system, etc.; see, e.g., FIG. 4), and a pyrolysis chamber 1128 that extends from the first access well to the second access well and contains a laser head 1132 located within the pyrolysis chamber 1128 for delivering laser energy to the coal seam in which the pyrolysis chamber is formed. Depending on the particular history of the portion of the coal seam 1104 selected for UCG, one, the other, or each of the first access well 1120 and the second access well 1124 may be a preexisting well or one, the other, or each of the first and second access wells may be a new well sunk for the specific purpose of performing the UCG. Correspondingly, the pyrolysis chamber 1128 may be a preexisting bore or other void or may be a newly formed bore or other void formed specifically for performing the UCG. In some embodiments well-known boring techniques can be used for forming the first and second access wells 1120 and 1124 and the pyrolysis chamber 1128 as needed.

[0191] As illustrated in FIG. 1 IB, laser energy from the laser head 1132 is then used to raise the temperature of the coal walls of the pyrolysis chamber 1128 to a pyrolysis temperature along the entire length, Lc, of the pyrolysis chamber. Depending on the length Lc of the pyrolysis chamber 1128 and the length, LH, of the laser head 1132, the laser head may need to be moved to perform pyrolysis along the entire length Lc of the pyrolysis chamber 1128. The surface equipment 1120A of the first access well 1120 is used to feed one or more gases, for example,

55 oxidant gas(es), into the pyrolysis chamber 1128 to support the pyrolysis reaction within the pyrolysis chamber. In this example, the coal surrounding and defining the pyrolysis chamber 1128 is heated to 360° around the circumference of the pyrolysis chamber, and the resulting pyrolysis reaction proceeds in the coal seam 1104 radially outwardly from the initial bore of the pyrolysis chamber until an optimum pyrolysis radius, Rp, is reached, as illustrated in FIG. 11C. In some embodiments, the optimum pyrolysis radius Rp can depend on any of a number of factors, such as the thickness, Tcs, of the coal seam 1104, the stability of the coal seam, and any limitations of the laser head 1132 (FIGS. 11 A and 1 IB) in delivering the laser energy to create the necessary heating, among others. In this connection it is noted that while the pyrolysis chamber 1128 is shown as being horizontal, for example, to conform to the stratification geometry of the coal seam 1104 and other geological layers, such as the sedimentary rock layer 1116A (FIG. 11 A), the pyrolysis chamber, or any other pyrolysis chamber disclosed herein, does not need to be horizontal. For example, the angle of the pyrolysis chamber 1128 or other pyrolysis chamber may form any suitable non-zero angle relative to geological horizontal. Furthermore, any pyrolysis chamber of the present disclosure may alternatively not be straight. For example, a pyrolysis chamber of this disclosure, such as pyrolysis chamber 1128 may be curved. It is noted that while FIGS. 11 A to 11C illustrate pyrolyzation of the coal seam 1104 in a single pyrolysis chamber 1128, any number of additional pyrolysis chambers (not shown) can be created and utilized to gasify a larger extent of the coal seam.

[0192] While not limited to one particular theory, the laser-based-heating approach to gasification of the present disclosure can achieve any one or more of a number of advantages over conventional gasification techniques. These advantages include, but are not limited to: 1) direct delivery of optical power through long fiber-optic cables made possible, for example, through the provision of high transmission communication SiCh fibers; 2) the ability to condition specific high- energy intensities required for heating coal and/or other carbonaceous material to a desired pyrolysis state; 3) the ability to heat an entire length of a pyrolysis chamber, thereby creating greater area for pyrolysis; 4) the ability to provide direct primary heating of secondary heat sources, such as steam injection; 5) the ability to precisely control the constituency of the product gas from the pyrolysis; and 6) high levels of reliability (e.g., approaching 1,000,000 hours or more) necessary for long service life and performing multiple ignition programs with the same equipment, among others.

[0193] In some embodiments, implementing systems and methods of the present disclosure result in significant energy gains compared to conventional methods. For example, FIG. 11C depicts a scenario in which a volume of coal having a diameter, D (generally 2 x Rp), and the length Lc is

56 heated using via laser to produce a product gas. The following Table I describes physical properties of an example illustrative, but not limiting, underground coal deposit:

Table

Physical Property Value

Specific Heat Capacity (J/kg K) ¹ 1.38

Density (kg/m ³ ) ¹ 1.35 x 10 ³

Calorific Value of Volatiles (kJ/m ³ ) ² 9 x 10 ³

Pyrolysis Temperature (K) ³ 1100

Length (m) 600

Diameter (m) 20

¹ Typical for bituminous coals

² Known values for conventional UCG (9 kJ/m ³ to 11 kJ/m ³ )

³ Optimum temperature for pyrolysis

[0194] The total energy, Q, required to raise a body of mass, m, from a starting temperature, Ti, to a final temperature, T2, is given by:

Q=mCp(T _{2 -} Ti) wherein Cp is the specific heat capacity of coal. Results of this calculation for a range of operating volumes are given in the following Table II:

TABLE

Energy Value

Required to raise volume to ignition 3xl0 ⁸ J (D = 0.3m; L = 600m)

Yield from combustion of seam 2xl0 ¹³ J

(D = 20m; L = 600m)

Gain 7xl0 ⁴ J

[0195] Without being bound to one particular theory, the energy gain according to some embodiments can result, for example, in some 70,000 times the energy used to heat the seam to ignition. Additionally, 3xl0 ⁸ Joules of energy are required to raise 180 m ³ of coal to the ignition temperature of 800°C. In some embodiments, usable lasers include, but are not limited to, lasers capable of delivering continuous power outputs 1 lpW to lOOkW, which can provide the total required energy in a matter of minutes.

[0196] In some embodiments, systems and methods disclosed herein include providing one or more gases, e.g., oxidant gas(es), heating gas(es), extraction gas(es), etc., into the linkage bore from

57 an injection well in a controlled manner. Without being bound to one particular theory, the one or more gases facilitate the production of a product gas. The composition and rate of the one or more gases introduced into the linkage bore can vary depending on the size of pyrolysis chamber, amount of carbonaceous material surrounding the pyrolysis chamber, the temperature required to produce the product gas and other variables. In some embodiments, these systems and methods can include controlling the one or more gases provided to the linkage bore to increase the product gas- producing conditions.

[0197] In some embodiments, these systems and methods produce a product gas comprising from 1 percent to 10 percent, by mole, carbon dioxide, from 1 percent to 10 percent, by mole, carbon monoxide, from 20 percent to 30 percent, by mole, methane, and from 40 percent to 50 percent, by mole, hydrogen. The methods of producing a product gas described herein offer several advantages to conventional methods including a high ratio of hydrogen gas to carbon monoxide due to the highly controlled pyrolysis that can be performed. For example, in some embodiments, the mole ratio of hydrogen gas to carbon monoxide of the product gas produced is from 4: 1 to 50: 1. In some embodiments, the mole ratio of hydrogen gas to carbon monoxide of the product gas is from 10: 1 to 20:1. In some embodiments, the mole ratio of hydrogen gas to carbon monoxide of the product gas produced is about 15:1. In some applications, producing significant amount of hydrogen is highly desirable. For example, as a carbon-free fuel it can be combusted as a fuel gas in combined-cycle gas turbines (CCTGs) without CO2 emissions. Going forward, it is also a fuel of choice for fuel cells, both for stationary power generation and electric vehicles. In addition, hydrogen is a valuable chemical feedstock used, for example, in hydrocrackers in the refining sector.

[0198] In some embodiments, a ruggedized fiber laser beam delivery system is used within any of the above-described methods. In some embodiments, the laser beam delivery system includes laser injection head technology or optical assemblies capable of achieving desired pyrolysis parameters in an underground setting.

[0199] In some embodiments, these methods include further processing or refining the product gas. Refining techniques include removal of impurities, carbon capture and other gas processing steps. In some embodiments, the product gas is further refined to produce a clean product gas. The clean product gas can be used, for example, to generate power, provide feedstocks for chemical products, provide feedstocks for fuel products, and other similar uses.

58 [0200] Without being bound to one particular theory, these systems and methods can achieve significant cost efficiencies over conventional coal energy extraction technology. For example, some embodiments can significantly reduce the number of personnel required to operate the production operation, thereby reducing the resources and human capital needed to produce the product gas.

[0201] In some embodiments, a method of laser-assisted drilling of wells or bores in underground carbonaceous materials, such as oil shale, includes using a laser that emits at wavelength and illumination conditions to meet the absorption bands of water present in the carbonaceous material. For example, granite and shale deposits contain about 5 wt.% water to 7 wt.% water, which allows for laser-scabbing techniques that rely on the explosive response of the superheated water in the body of the shale or rock, to effect large scale tracking effects and/or removal of material and production of hydrocarbons. In some embodiments, methods of extracting hydrocarbons from shale oil include deploying an ultraviolet laser down a bore hole, wherein the ultraviolet laser volatilizes hydrocarbons present in shale oil, the volatilized compounds are then collected, refined and used to create energy, chemical feedstocks, or fuel feedstocks according to methods known to those of skill in the art.

[0202] EXPERIMENTAL EXAMPLE

[0203] A system used to perform experiments included a steel containment vessel containing a block of dry bituminous coal of unknown origin, predrilled with a 6mm bore throughout its length.

A high power CO2 laser was focused into the bore with a ZnSe lens of focal length 100mm, and air assist was blown coaxially through a flat-tipped Cu nozzle at a flow rate of 2 l/min. A continuous- wave CO2 laser (Rofin Sinar DCOIO) gave an energy output of around 40 W/cm ² at a wavelength of 10.6 pm. The general procedure was to seal the coal sample chamber into which the laser beam was fired. Gas flowed through the borehole, and then progressed through to a Dreschel bottle filled with 60mm of water. Gas exiting the Dreschel bottle was fed to a nozzle. Gas samples for various exposure conditions as shown in Table III below were extracted for subsequent analysis by mass spectrometry. The gas exit temperature was measured with a K-type thermocouple.

[0204] Pyrolysis was conducted at various incident laser power levels. All laser powers generated a pyrolytic reaction that occurred rapidly on laser exposure. Both gaseous products and some particulates escaped from the reaction vessel, and the particulates were caught in the liquid volume of the Dreschel bottle. Pyrolysis of the samples was a continuous process that could be

59 observed for as long as the air and laser energy was allowed to flow through the system. High levels of ignitable gas were observed for power levels above 150W, as shown in Table III. On termination of the laser beam above the ignition threshold of 100W, the gas mixture composition changed such that it could no longer maintain ignition of the burn-off flame.

Table III

Power (W) Air flow rate fl/min) Note

50 2 No gas

50 6 No gas

50 8 No gas

50 10 No gas

50 12 No gas

100 2 Gas / no ignition

100 6 Gas / no ignition

100 8 Gas / no ignition

100 10 Gas / no ignition

100 12 Gas / no ignition

100 2 Gas / no ignition

150 2 Gas / ignition

150 6 Gas / ignition

150 8 Gas / ignition

150 10 Gas / ignition

150 12 Gas / ignition

200 2 Gas / ignition

200 6 Gas / ignition

200 8 Gas / ignition

200 10 Gas / ignition

200 12 Gas / ignition

[0205] Gaseous products produced above the ignition level of 150W are summarized in the following Table IV:

Table IV

Product/Temp Laser-ignited UCG Conventional UCG Estimated Temp. 900°C 1600°C H2 45 54 CH4 22 10 C02 3 14 CO 7 16 S <1 <1

Other hydrocarbons 12 6

60 [0206] Table IV illustrates the average gas composition of laser-ignited UCG (LUCG) pyrolysis, in mole %, at 150W power level compared to conventional UCG processes, such as those described at the Central Mining Institute, Katowice, Poland, Reported May 2015, UK Energy symposium, Kegworth, UK, which is incorporated by reference herein.

[0207] These gases represent a typical hydrocarbon product mix from low temperature coal carbonization process. Refinement of these products in subsequent catalytic steps, such as hydrogenation, could significantly increase their calorific value.

[0208] The above results demonstrate the feasibility of delivering an LUCG process for the production of product gas from coal beds. Results have shown that low levels of laser irradiation in a narrow bore bitumen coal deposit of < 150W/cm ² , whilst capable of generating a product gas, appears to be insufficient to convert sufficient levels of hydrocarbons for ignition at standard temperature and pressure (STP). Higher levels of laser illumination at > 150W/cm ² appear to be required for the generation of ignitable product gas which contain product gas similar to those found in low temperature carbonization processes. At this power density, removal of the laser illumination reduced the product gas composition such that a sustainable combustion process was terminated. It is worth noting that the power levels used in these experiments are similar to those found in domestic lighting systems. As such, the process offers the opportunity to use industrial scale laser energy to control product gas production levels and the possibility to control product yield, since the product gas composition is heavily dependent on reaction temperature. Moreover, the use of methanation reactions such as catalysts of steam, could significantly enhance the calorific value of the product gas, converting the hydrogen component into greater levels of C¾, C ₂ H ₅ , and other alkanes and higher molecular weight hydrocarbons.

[0209] The accompanying figures contain illustrations allowing for an explanation of aspects of the present invention. Notably, the figures and examples above are not meant to limit the scope of the present disclosure to a single embodiment, as other embodiments are possible by way of interchanging some or all of the described and/or illustrated elements. Moreover, where certain elements of any example or illustration can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present disclosure are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure any inventive aspect. In the present specification, an embodiment showing a singular component should not necessarily be limited to other embodiments

61 including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, the present disclosure encompasses present and future known equivalents to the known components referred to herein by way of illustration.

[0210] The foregoing description of the specific embodiments so fully reveals the general nature of the invention that others can, by applying knowledge within the skill of the relevant art(s) (including the contents of the documents cited and incorporated by reference herein), readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Such adaptations and modifications are therefore intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0211] Various modifications and additions can be made without departing from the spirit and scope of this invention. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present invention. Additionally, although particular methods herein may be illustrated and/or described as being performed in a specific order, the ordering is highly variable within ordinary skill to achieve aspects of the present disclosure. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.

[0212] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention.

62