[0001] This application: (i) claims, under 35 U.S.C. §1 19(e)(1 ), the benefit of the filing date of February 24, 201 1 of US provisional application serial number

61/446,041 ; (ii) claims, under 35 U.S.C. §1 19(e)(1 ), the benefit of the filing date of February 24, 201 1 of US provisional application serial number 61/446,312; (iii) claims, under 35 U.S.C. §1 19(e)(1 ), the benefit of the filing date of February 24, 201 1 of US provisional application serial number 61/446,040; (iv) claims, under 35 U.S.C.

§1 19(e)(1 ), the benefit of the filing date of February 24, 2011 of US provisional application serial number 61/446,043; and (v) claims, under 35 U.S.C. §1 19(e)(1 ), the benefit of the filing date of February 24, 201 1 of US provisional application serial number 61/446,042, the entire disclosures of each of which are incorporated herein by reference.

[0002] This invention was made with Government support under Award DE-

AR0000044 awarded by the Office of ARPA-E U.S. Department of Energy. The Government has certain rights in this invention.

BACKGROUND OF THE INVENTION

Field of the Invention

[0003] The present inventions relate to high power laser energy tools and systems and methods.

[0004] As used herein, unless specified otherwise, "high power laser energy" means a laser beam having at least about 1 kW (kilowatt) of power. As used herein, unless specified otherwise "great distances" means at least about 500 m (meter). As used herein the term "substantial loss of power," "substantial power loss" and similar such phrases, mean a loss of power of more than about 3.0 dB/km (decibel/kilometer) for a selected wavelength. As used herein the term "substantial power transmission" means at least about 50% transmittance.

[0005] As used herein, unless specified otherwise, the term "earth" should be given its broadest possible meaning, and includes, the ground, all natural materials, such as rocks, and artificial materials, such as concrete, that are or may be found in the ground, including without limitation rock layer formations, such as, granite, basalt, sandstone, dolomite, sand, salt, limestone, rhyolite, quartzite and shale rock.

[0006] As used herein, unless specified otherwise, the term "borehole" should be given it broadest possible meaning and includes any opening that is created in a material, a work piece, a surface, the earth, a structure (e.g., building, protected military installation, nuclear plant, offshore platform, or ship), or in a structure in the ground, (e.g., foundation, roadway, airstrip, cave or subterranean structure) that is substantially longer than it is wide, such as a well, a well bore, a well hole, a micro hole, slimhole, a perforation and other terms commonly used or known in the arts to define these types of narrow long passages. Wells would further include exploratory, production, abandoned, reentered, reworked, and injection wells. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a vertical line, based upon a level as a reference point, a borehole can have orientations ranging from 0° i.e., vertical, to 90°, i.e., horizontal and greater than 90° e.g., such as a heel and toe and combinations of these such as for example "U" and Ύ" shapes. Boreholes may further have segments or sections that have different orientations, they may have straight sections and arcuate sections and combinations thereof; and for example may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the "bottom" of a borehole, the "bottom surface" of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole furthest along the path of the borehole from the borehole's opening, the surface of the earth, or the borehole's beginning. As used herein unless specified otherwise, the terms "side" and "wall" of a borehole should to be given their broadest possible meaning and include the longitudinal surfaces of the borehole, whether or not casing or a liner is present, as such, these terms would include the sides of an open borehole or the sides of the casing that has been positioned within a borehole. Boreholes may be made up of a single passage, multiple passages, connected passages and combinations thereof, in a situation where multiple boreholes are connected or interconnected each borehole would have a borehole bottom. Boreholes may be formed in the sea floor, under bodies of water, on land, in ice formations, or in other locations and settings. [0007] Boreholes are generally formed and advanced by using mechanical drilling equipment having a rotating drilling tool, e.g., a bit. For example and in general, when creating a borehole in the earth, a drilling bit is extending to and into the earth and rotated to create a hole in the earth. In general, to perform the drilling operation the bit must be forced against the material to be removed with a sufficient force to exceed the shear strength, compressive strength or combinations thereof, of that material. Thus, in conventional drilling activity mechanical forces exceeding these strengths of the rock or earth must be applied. The material that is cut from the earth is generally known as cuttings, e.g., waste, which may be chips of rock, dust, rock fibers and other types of materials and structures that may be created by the bit's interactions with the earth.

These cuttings are typically removed from the borehole by the use of fluids, which fluids can be liquids, foams or gases, or other materials know to the art.

[0008] As used herein, unless specified otherwise, the term "advancing" a borehole should be given its broadest possible meaning and includes increasing the length of the borehole. Thus, by advancing a borehole, provided the orientation is not horizontal, e.g., less than 90° the depth of the borehole may also be increased. The true vertical depth ("TVD") of a borehole is the distance from the top or surface of the borehole to the depth at which the bottom of the borehole is located, measured along a straight vertical line. The measured depth ("MD") of a borehole is the distance as measured along the actual path of the borehole from the top or surface to the bottom. As used herein unless specified otherwise the term depth of a borehole will refer to MD. In general, a point of reference may be used for the top of the borehole, such as the rotary table, drill floor, well head or initial opening or surface of the structure in which the borehole is placed.

[0009] As used herein, unless specified otherwise, the terms "ream",

"reaming", a borehole, or similar such terms, should be given their broadest possible meaning and includes any activity performed on the sides of a borehole, such as, e.g., smoothing, increasing the diameter of the borehole, removing materials from the sides of the borehole, such as e.g., waxes or filter cakes, and under-reaming.

[0010] As used herein, unless specified otherwise, the terms "drill bit", "bit",

"drilling bit" or similar such terms, should be given their broadest possible meaning and include all tools designed or intended to create a borehole in an object, a material, a work piece, a surface, the earth or a structure including structures within the earth, and would include bits used in the oil, gas and geothermal arts, such as fixed cutter and roller cone bits, as well as, other types of bits, such as, rotary shoe, drag-type, fishtail, adamantine, single and multi-toothed, cone, reaming cone, reaming, self-cleaning, disc, three cone, rolling cutter, crossroller, jet, core, impreg and hammer bits, and

combinations and variations of the these.

[0011] Mechanical bits cut rock with shear stresses created by rotating a cutting surface against the rock and placing a large amount of weight-on-bit ("WOB"). Mechanical bits cut rock by applying crushing (compressive) and/or shear stresses created by rotating a cutting surface against the rock and placing a large amount of WOB. In the case of a bit made of the material polycrystalline diamond compact ("PDC"), e.g., a PDC bit, this action is primarily by shear stresses and in the case of roller cone bits this action is primarily by crushing (compression) and shearing stresses. For example, the WOB applied to an 8 3/4" PDC bit may be up to 15,000 lbs, and the WOB applied to an 8 3/4" roller cone bit may be up to 60,000 lbs. When mechanical bits are used for drilling hard and ultra-hard rock excessive WOB, rapid bit wear, and long tripping times result in an effective drilling rate that is essentially economically unviable. The effective drilling rate is based upon the total time necessary to complete the borehole and, for example, would include time spent tripping in and out of the borehole, as well as, the time for repairing or replacing damaged and worn bits.

[0012] As used herein, unless specified otherwise, the term "drill pipe" should be given its broadest possible meaning and includes all forms of pipe used for drilling activities; and refers to a single section or piece of pipe. As used herein the terms "stand of drill pipe," "drill pipe stand," "stand of pipe," "stand" and similar type terms are to be given their broadest possible meaning and include two, three or four sections of drill pipe that have been connected, e.g., joined together, typically by joints having threaded connections. As used herein the terms "drill string," "string," "string of drill pipe," string of pipe" and similar type terms are to be given their broadest definition and would include a stand or stands joined together for the purpose of being employed in a borehole. Thus, a drill string could include many stands and many hundreds of sections of drill pipe.

[0013] As used herein, unless specified otherwise, the term "tubular" should be given its broadest possible meaning and includes drill pipe, casing, riser, coiled tube, composite tube, vacuum insulated tubing ("VIT), production tubing and any similar structures having at least one channel therein that are, or could be used, in the drilling industry. As used herein the term "joint" is to be given its broadest possible meaning and includes all types of devices, systems, methods, structures and components used to connect tubulars together, such as for example, threaded pipe joints and bolted flanges. For drill pipe joints, the joint section typically has a thicker wall than the rest of the drill pipe. As used herein the thickness of the wall of tubular is the thickness of the material between the internal diameter of the tubular and the external diameter of the tubular. SUMMARY

[0014] There has been a long-standing need for rapidly and efficiently drilling boreholes into hard and very hard materials, and to do so with minimal damage to the drilling bit. The present inventions, among other things, solve these and other needs by providing the articles of manufacture, devices and processes taught herein.

[0015] Thus, there is provided herein a method of directed energy mechanical drilling having the steps of: providing directed energy to a surface of a material;

providing mechanical energy to that surface; so that the ratio of directed energy to mechanical energy is greater than about 5; and, in this manner a borehole is advance through the surface of the material.

[0016] Further, there is provided a method directed energy mechanical drilling having steps including: providing directed energy to a surface of a material; providing mechanical energy to the surface; so that the ratio of directed energy to mechanical energy is greater than about 10; and, in this manner a borehole is advance through the surface of the material.

[0017] Moreover, there is provided a method of directed energy mechanical drilling including the following: providing directed energy to a surface of a material; providing mechanical energy to the surface; so that the ratio of directed energy to mechanical energy is greater than about 20; and, in this manner a borehole is advance through the surface of the material.

[0018] Still further, there is provided a method of providing directed energy to a surface of a material and providing mechanical energy to the surface; in a manner where the ratio of directed energy to mechanical energy is greater than about 40; and, in this manner a borehole is advance through the surface of the material.

[0019] Further still, there is provided directed energy mechanical drilling by directing directed energy to a surface of a material and directing mechanical energy to the surface in a ratio of directed energy to mechanical energy that is greater than about 2 and this manner a borehole is advance through the surface of the material.

[0020] Additionally, there is provided a method of directed energy mechanical drilling having the steps of: providing high power laser directed energy to a surface of a material; providing mechanical energy to the surface; and, so that the ratio of high power laser directed energy to mechanical energy is greater than about 5; and, in this manner a borehole is advance through the surface of the material.

[0021] Yet still additionally, there is provided a directed energy mechanical drilling method of providing high power laser directed energy to a surface of a material; providing mechanical energy to the surface; in the ratio of high power laser directed energy to mechanical energy that is greater than about 10; and, thus advancing a borehole through the surface of the material.

[0022] Additionally, there is provided a method of directed energy mechanical drilling by providing high power laser directed energy to a surface of a material, providing mechanical energy to the surface, so that the ratio of high power laser directed energy to mechanical energy is greater than about 20; and, in this manner a borehole is advance through the surface of the material.

[0023] Still further, there is provided a method of directed energy mechanical drilling having steps including: providing high power laser directed energy to a surface of a material; providing mechanical energy to the surface; and, so that the ratio of high power laser directed energy to mechanical energy is greater than about 40; and, in this manner a borehole is advance through the surface of the material. [0024] Yet additionally, there is provided a directed energy mechanical drilling method by providing high power laser directed energy to a surface; providing

mechanical energy to the surface; in a ratio of directed energy to mechanical energy that is greater than about 2 and, thus advancing a borehole through the surface of the material are utilized.

[0025] Still further, the methods may also include steps, conditions and parameters in which: the directed energy is high power laser energy and in which the high power laser directed energy has a power of at least about 40 kW; the surface is not substantially melted by the laser energy; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds; the mechanical energy is provided by a bit having a weight-on-bit less than about 1000 pounds; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 10 feet per hour; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 10 feet per hour; the high power laser directed energy has a power of at least about 20 kW and the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour; the high power laser directed energy has a power of at least about 20 kW and the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour; the high power laser directed energy has a power of at least about 20 kW and the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour; the high power laser directed energy has a power of at least about 50 kW and the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds so that the borehole is advanced at a rate of penetration the rate of penetration of at least about 20 feet per hour through material having an average hardness of about 20 ksi (kilopound per square inch) or greater; the borehole is advanced for greater than about 500 feet; and the borehole is advanced for greater than about 5,000 feet.

[0026] Moreover, there is provided a method of advancing borehole in the earth using high power laser mechanical drilling techniques, the method involving:

directing laser energy, in a moving pattern, to a bottom surface of a borehole in the earth; heating the earth with the directed laser energy to a point below the melting point; providing mechanical energy to the heated earth; so that the ratio of laser energy to mechanical energy is greater than about 2; and, in this manner the borehole is advanced

[0027] Furthermore, the methods may also include steps, conditions and parameters in which: the laser energy has a power of about 20 kW or greater; the power/area of the laser energy on the surface of the bottom of the borehole is about 50 W/cm ² or greater; the power/area of the laser energy on the surface of the bottom of the borehole is about 75 W/cm ² or greater; the power/area of the laser energy on the surface of the bottom of the borehole is about 100 W/cm ² or greater; the laser energy on the surface of the bottom of the borehole is about 200 W/cm ² or greater; the power/area of the laser energy on the surface of the bottom of the borehole is about 300 W/cm ² or greater; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds; the mechanical energy is provided by a bit having a weight- on-bit less than about 1000 pounds; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds and so that the borehole is advanced at a rate of penetration of at least about 10 feet per hour; the mechanical energy is provided by a bit having a weight-on-bit, so that the weight-on-bit is less than about 2000 pounds and so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds and so that borehole is advances at a rate of penetration of at least about 10 feet per hour through material having an average hardness of about 20 ksi or greater; the mechanical energy is provided by a bit having a weight-on-bit less than about 2000 pounds and so that the borehole is advanced at a rate of penetration of at least about 20 feet per hour through material having an average hardness of about 20 ksi or greater; and the borehole is advanced for greater than about 1 ,000 feet, greater than about 2,000 feet, and greater than then about 5,000 feet and greater than about 10,000 feet.

[0028] Moreover, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of material having a hardness greater than about 30 ksi by: providing a laser-mechanical bit into a borehole, the laser- mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole while propagating a laser beam against the borehole surface; with an RPM of from about 240 to about 720, a WOB of less than about 2,000 lbs, a DE Power/Area of about 90 W/cm ² to about 560 W/cm ² , and an ME Power/Area of about 4 W/cm ² to about 250 W/cm ² ; and in this manner the borehole is advanced at an ROP of at least about 10ft/hr.

[0029] Further, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of material having a hardness greater than about 30 ksi by: providing a laser-mechanical bit into a borehole, the laser- mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole while propagating a laser beam against the borehole surface; with an RPM of from about 600 to about 800, a WOB of less than about 5,000 lbs, a DE Power/Area of about 40 W/cm ² to about 250 W/cm ² , and an ME Power/Area of about 200 W/cm ² to about 3000 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 15 ft/hr.

[0030] Additionally, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of material having a hardness greater than about 20 ksi by: providing a laser-mechanical bit into a borehole, the laser- mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole while propagating a laser beam against the borehole surface; with an RPM of from about 600 to about 1250, a WOB of from about 500 to about 5,000 lbs, a DE Power/Area of about 90 W/cm ² to about 570 W/cm ² , and an ME Power/Area of about 40 W/cm ² to about 270 W/cm ² ; and in this manner the borehole is advanced at an ROP of at least about 10.

[0031] Yet additionally, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi by: providing a laser-mechanical bit into a borehole, the laser-mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole with an RPM of about 250, a WOB of from about 1 ,000 lbs, a DE Power/Area of about 370 W/cm ² , and an ME Power/Area of about 40 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 20 ft/hr.

[0032] Yet still further, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi, the method having the steps of: providing a laser- mechanical bit into a borehole, the laser-mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole with an RPM of from about 720, a WOB of from about 2,000 lbs, a DE

Power/Area of about 190 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 50 ft/hr.

[0033] Further still, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi by: providing a laser-mechanical bit into a borehole, the laser- mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole with an RPM of from about 720, a WOB of from about 2,000 lbs, a DE Power/Area of about 370 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 50 ft/hr.

[0034] Still further, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi by: providing a laser-mechanical bit into a borehole, the laser- mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole with an RPM of from about 720, a WOB of from about 5,000 lbs, a DE Power/Area of about 290 W/cm ² , and an ME Power/Area of about 240 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 20 ft/hr. [0035] Moreover, there is provided a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi, this method includes: providing a laser-mechanical bit into a borehole, the laser-mechanical bit in optical communication with a high power laser beam source; rotating the laser-mechanical bit against a surface of the borehole with an RPM of from about 1 ,200, a WOB of from about 500 lbs, a DE Power/Area of about 470 W/cm ² , and an ME Power/Area of about 100 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 30 ft/hr.

[0036] Still further, a method of laser-mechanical drilling a borehole in a formation having at least 500 feet of hard rock material, having a hardness greater than about 20 ksi, by: providing a laser-mechanical bit into a borehole, the laser-mechanical bit in optical communication with a high power laser beam source; rotating the laser- mechanical bit against a surface of the borehole with an RPM of from about 720, a WOB of from about 2,000 lbs, a DE Power/Area of about 470 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; and, in this manner the borehole is advanced at an ROP of at least about 30 ft/hr.

[0037] Furthermore, there is also provided a method of laser-mechanical drilling a borehole in a formation by: providing a laser-mechanical bit into a borehole, the laser-mechanical bit in optical communication with a high power laser beam source; applying from the high power laser beam source a high power laser beam to a surface of the borehole, so that the high power laser beam generates an intensity ranging from about 150 to about 250 W/cm ² on a surface of the borehole for an elapsed time sufficient to cause a surface temperature rise in the range from about 400 degrees C to about 1 ,000 degrees C and thus forming a laser applied surface; and applying a mechanical force to the laser applied surface, so that the mechanical force generates an intensity ranging from about 30 to about 250 W/cm ² to remove the laser applied surface of the borehole. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 A is a perspective view of an embodiment of a fixed cutter laser- mechanical bit in accordance with the present invention.

[0039] FIG. 1 B is a bottom view of the bit of FIG. 1 A.

[0040] FIG. 1 C is a cross section view of the bit of FIGS 1 A and 1 B taken along line 1 C-1 C.

[0041] FIG. 2 is a schematic of an embodiment of a high power laser drilling, workover and completion unit in accordance with the present invention.

[0042] FIG. 3 is a chart showing various directed energy regimes.

[0043] FIG. 4 is schematic of chips of basalt.

[0044] FIG. 5 is a schematic of chips of dolomite.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] The present inventions relate to directed energy mechanical drilling methods that utilize high power directed energy in conjunction with mechanical forces. These methods may find uses in many different types of materials and structures, such as metal, stone, composites, concrete, the earth, and structures in the earth. In particular, these methods may find preferable uses in situations and environments where advancing a borehole with conventional, e.g., non-directed energy technology, was difficult or impossible, because, for example, the remoteness of the area where the borehole was to be advanced, difficult environmental conditions or other factors that placed great, and at times insurmountable burdens on conventional drilling or boring technologies. These methods also find preferable uses in situations where reduced noise and vibrations, compared to conventional technologies, are desirable or a requisite.

[0046] In general, the present methods involve the application of directed energy and mechanical forces to a surface, e.g., the bottom of a borehole, to remove material and advance the borehole. The directed energy and mechanical forces are preferably applied in a rotating or revolving manner, so that they are so moved about or on the surface to be drilled {i.e., the drilling surface), e.g., the bottom of a borehole. "Directed energy" would include, for example, optical laser energy, non-optical laser energy, microwaves, sound waves, plasma, electric arcs, flame, flame jets, steam and combinations of the foregoing, as well as, water jets (although a water jet may be viewed as having a mechanical interaction with the drilling surface, for the purpose of this specification it will be characterized amongst the group of directed energies, based upon the following specific definition of mechanical energy), and other forms of energy that are not "mechanical energy" as defined in these specifications. "Mechanical energy," as used herein, is limited to energy that is transferred to the drilling surface by the interaction or contact of a solid object, e.g., a drill bit cutter, roller cone, or a saw blade, with the drilling surface.

[0047] These methods provide for the application of unique combinations of directed energy and mechanical force to obtain a synergism. This synergism enables these methods to advance boreholes through very hard materials, such as hard rocks and ultra hard rocks, with very low WOB, e.g., less than about 5,000 lbs, less than about 2000 lbs and preferably about 1000 lbs or less. This reduction in WOB has the potential benefit of providing for substantially longer drilling bit life, longer drilling times where the bit can remain in the borehole, and reduced tripping, which in turn has the potential to greatly reduce the cost of drilling a borehole. In addition to reducing WOB, in other processes, such as in a cutting application, the associated mechanical forces that are needed may similarly be greatly reduced.

[0048] In general, and using drilling a borehole in the earth as an illustrative example, as the bit is rotated in the bottom of the borehole, the directed energy is propagated at the bottom surface (and potentially side and gauge surfaces). The directed energy weakens (and may also partially remove, and remove) the material so contacted, i.e., directed energy affected material. The mechanical devices, e.g., cutters, then rotate in the borehole, contacting and removing the directed energy affected material (and potentially some additional material). However, it is preferable, as shown by the examples below, that the mechanical cutter, and the mechanical energy that it delivers, is only sufficient to remove the directed energy affected material. In this way the life of the cutters is preserved, damage is minimized, and the amount of heat built up from friction is controlled and preferably in some embodiments kept to a minimum.

[0049] Preferably, in these methods the source of directed energy is a high power laser beam. Thus, and more preferably the laser beam, or beams, may have 10 kW, 20 kW, 40 kW, 80 kW or more power; and have a wavelength in the range of from about 445 nm (nanometers) to about 2100 nm, preferably in the range of from about 800 to 1900 nm, and more preferably in the ranges of from about 1530 nm to 1600 nm, from about 1060 nm to 1080 nm, and from about 1800 nm to 1900 nm. Further, the types of laser beams and sources for providing a high power laser beam may be the devices, systems, optical fibers and beam shaping and delivery optics that are disclosed and taught in the following US Patent Applications and US Patent Application

Publications: Publication No. US 2010/0044106, Publication No. US 2010/0044105, Publication No. US 2010/0044103, Publication No. US 2010/0044102, Publication No. US 2010/0215326, Publication No. 2012/0020631 , Serial No. 13/210,581 , and Serial No. 61/493,174, the entire disclosures of each of which are incorporated herein by reference. The source for providing rotational movement may be a string of drill pipe rotated by a top drive or rotary table, a down hole mud motor, a down hole turbine, a down hole electric motor, and, in particular, may be the systems and devices disclosed in the following US Patent Applications and US Patent Application Publications:

Publication No. US 2010/0044106, Publication No. US 2010/0044104, Publication No. US 2010/0044103, Serial No. 12/896,021 , Serial No. 61/446,042 and Serial No.

13/21 1 ,729, the entire disclosures of each of which are incorporated herein by reference. The high power lasers for example may be fiber lasers or semiconductor lasers having 10 kW, 20 kW, 50 kW or more power and, which emit laser beams with wavelengths preferably in about the 1064 nm range, about the 1070 nm range, about the 1360 nm range, about the 1455 nm range, about the 1550 nm range, about the 1070 nm range, about the 1083 nm range, or about the 1900 nm range (wavelengths in the range of 1900 nm may be provided by Thulium lasers). Thus, by way of example, there is contemplated the use of four, five, or six, 20 kW lasers to provide a laser beam in a bit having a power greater than about 60 kW, greater than about 70 kW, greater than about 80 kW, greater than about 90 kW and greater than about 100 kW. One laser may also be envisioned to provide these higher laser powers.

[0050] Preferably, the source of mechanical energy is a fixed cutter drill bit or roller cone used as part of a laser-mechanical bit. In general, the components of a laser mechanical bit may be made from materials that are known to those of skill in the art for such applications or components, or that are later developed for such

applications. For example, the bit body may be made from steel, preferably a high- strength, weldable steel, such as SAE 9310, or cemented carbide matrix material. The blades may be made from similar types of material. The blades and the bit body may be made, for example by milling, from a single piece of metal, or they may be separately made and affixed together. The cutters may be made from for example, materials such as polycrystalline diamond compact ("PDC"), grit hotpressed inserts ("GHI"), and other materials known to the art or later developed by the art. Cutters are commercially available from for example US Synthetic, MegaDiamond, and Element 6. The roller cone arms may be made from steel, such as SAE 9310. Like the blades, the arms and the bit body may be made from a single piece of metal, or they may be made from separate pieces of metal and affixed together. Roller cone inserts, for example, may be made from sintered tungsten carbide insert ("TCI") or the roller cones may be made with milled teeth ("MTs"). Roller cones, roller cone inserts, and roller cones and leg assemblies, may be obtained commercially from Varel International, while TCI may be obtained from for example Kennametal or ATI Firth Sterling. It is preferred that the inner surface of the beam path be made of material that does not absorb the laser energy, and thus, it is preferable that such surfaces be reflective or polished surfaces. It is also preferred that any surfaces of the bit that may be exposed to reflected laser energy, reflections, also be non-absorptive, minimally absorptive, and preferably be polished or made reflective of the laser beam.

[0051] An example of such a bit and system to provide the high power laser energy and mechanical energy are set forth in FIGS. 1 A to C, and in FIG. 2.

[0052] In FIGS. 1 A, 1 B and 1 C there is shown views of an embodiment of a fixed cutter type laser-mechanical bit. Thus, there is provided a laser-mechanical bit 100 having a body section 101 and a bottom section 102. The bottom section 102 has mechanical blades 103, 104, 105, 106, 107, 108, 109, and 110.

[0053] The bit body 101 may have a receiving slot for each mechanical blade. For example, in FIG. 1A receiving slots, 1 1 1 , 1 12, 1 13, are 1 14 are identified. Note that with respect to blades, of the type shown as blades 108, 109 and 1 10, the receiving slots may be joined or partially joined, into a unitary opening. The bit body 101 has side surfaces or areas, e.g., 1 15a, 1 15b, 1 17 in which the blade receiving slots are formed. The bit body 101 has surfaces or areas, e.g., 1 16a, 1 16b for supporting gauge pads, e.g., 141. The bit body 101 further has surfaces 1 19a, 1 19b, 1 19c, 119d, that in this embodiment are substantially normal to the surfaces 1 15a, 1 15b, 1 16a, 1 16b, which surfaces 115a, 115b, have part of the blade receiving slots formed therein. The surface 1 19 a, 119b, 119c, 1 19d are connected to surfaces 1 15a, 1 15b, 1 16a, 1 16b by angled surfaces or areas 1 18a, 1 18b, 1 18c, 1 18d.

[0054] The bit is further provided with beam blades, 120, 121 , 122, 123. In this embodiment the beam blades are positioned along essentially the entirely of the width of the bit 100 and merge at the end 126 of beam path slot 125 into a unitary structure. The inner surfaces or sides of the beam blades form, in part, slot 125. The outer surfaces or sides of the beam blades also form a sidewall for the junk slots, e.g., 170. Thus, the beam blades are positioned in both the bit body section 101 and the bottom section 102. Other positions and configurations of the beam blades are contemplated. In the embodiment of FIGS. 1 A and 1 B the bottom of the beam blades is located at about the same level as the depth of cut limiters, e.g., 146, that are located on blades 103, 107, i.e. depth of cut blades, and slightly below the bottom of the cutters, e.g., 134. As used herein "bottom" refers to the section of the bit that is intended to engage or be closest to the bottom of a borehole, and top of the bit refers to the section furthers away from the bottom. The distance between the top and the bottom of the bit would be the bit length, or longitudinal dimension; and the width would be the dimension transverse to the length, e.g., the outside diameter of the bit, as used herein unless specified otherwise.

[0055] The longitudinal position of the bottom of the beam blades with respect to the cutters and any depth of cut limiters, e.g., the beam blades relative proximity to the bottom of the borehole, may be varied in each bit design and configuration and will depend upon factors such as the power of the laser beam, the type of rock or earth being drilled, the flow of and type of fluid used to keep the beam path clear of cuttings and debris. In general it is preferable that the longitudinal positioning of the bottoms of the beam blades, any depth of cut limiter blades and the cutter blades all be relatively close, as shown in FIG. 1A, although other positions and configurations are envisioned.

[0056] A beam path 124 is formed in the bit, and is bordered, in part, by the inner surfaces or sides of the beam blades 120, 121 , 122, 123 and the inner ends of blades 103, 105, 107 and 109. In this embodiment the beam path extends through the center axis 161 of the bit and divides the bit into two separate sections, as more clearly seen in FIG. 1 B. Thus, it is preferable that the structures and their configuration on one side of the beam path 124, be similar, and more preferably the same, as the structures on the other side of the beam path 124, which is the case for this embodiment. This positioning and configuration is preferred, although other positions and configurations are contemplated. The beam path 124 should be close to, but preferably not touch the beam blades or the beam blade inner surfaces. When using high power laser energy, and in particular laser energy greater than 5 kW, 10 kW, 20 kW, 40 kW, 80 kW and greater, if the beam path, and, in particular, the laser beam 160, which is propagated along the beam path, contacts a blade it will melt or otherwise remove that section of the blade in the beam path, and potentially damage the remaining section of the blade, bit, or other bit structure or component that is struck.

[0057] The beam path in this embodiment also serves as a fluid path for a fluid, such as air, nitrogen, or a transmissive, or substantially transmissive liquid to the laser beam. This fluid is used to keep the laser beam path clear and also to remove or help remove cuttings from the borehole. Configurations, systems and methods for providing and removing such fluids in laser drilling, and for keeping the beam path clear, as well as, the removal of cuttings from the borehole, during laser drilling are provided in the following US Patent Applications and US Patent Application Publications:

Publication No. US 2010/0044102, Publication No. US 2010/0044103, Publication No. US 2010/0044104, Serial No. 12/896,021 , Serial No. 13/211 ,729, Serial No. 13/210,581 and Serial No. 13/222,931 , the entire disclosures of each of which are incorporated herein by reference.

[0058] The beam blades 120, 121 , 122 and 123 form a beam path slot 125, which slot has ends, e.g., 126a, 126b. In this embodiment, although other

configurations and positions are contemplated, the beam path slot 125 extends from the bottom section 102 partially into the bit body section 101 . The beam path slot 125 may also have end sections 126a, 126b, these end sections 126a, 126b, are angled, such that they do not extend into the beam path. The beam pattern, e.g., the shape of the area of illumination by the laser upon the bottom of the borehole, or at any cross section of the beam as it is traveling toward the area to be cut, e.g., a borehole surface, when the bit is not in rotation, in this embodiment is preferably a narrow ellipse or rectangular type of pattern, and more preferably may be such a generally elliptical rectangular pattern where less energy or on laser energy is provided to center of pattern. (In FIG. 1 B the laser beam 160 is shown as having a beam pattern that is substantially rectangular.) The beam path for this pattern expands from the optics, not shown, until it strikes the bottom of the borehole (see and compare, FIG. 1 C showing a cross section of the laser beam 160 and the beam path 161 , with FIG. 1 B showing the bottom view of the laser beam pattern, and thus, the shape of the area of illumination of the bottom surface of the borehole by the laser beam when the beam is not rotating). It should additionally be noted that in this embodiment the beam path is such that the area of illumination of the bottom of the borehole surface is wider, i.e., a larger diameter, than the diameter of the bit, put about the same as the outer diameter of the gauge cutters. It is contemplated that the area of illumination may be equal to the bit diameter

(excluding or including gauge cutters and/or gauge reamers as forming the outer diameter of the bit), substantially the same as the bit diameter (excluding or including gauge cutters and/or gauge reamers as forming the outer diameter of the bit), greater than the bit diameter (excluding or including gauge cutters and/or gauge reamers as forming the outer diameter of the bit). The bottom of the end section 126 also defines the end of the slot 125 with respect to the outer surface of the bit body. In this embodiment the end of the slot 125 is at about the same longitudinal position as the end of the blades, e.g., 127. [0059] The slot, beam slot or beam path slot refers to the opening or openings, e.g., a slot, in the sides, or side walls, of the bit that permit the beam path and the laser beam to extend out of, or from the side of the bit, as illustrated, by way of example, in FIG. 1 C.

[0060] In the embodiment of FIGS 1A-C there are provided gauge cutters,

128, 129, 130, 131. The gauge cutters are located on blades 105, 106, 109 and 110. Blades 106 and 1 10 only support gauge cutters 128, 130. Blades 105, 109 support gauge cutters 131 , 129, as well as, bottom cutters 132, 133, 134, 138, 139, 140, which cutters remove material from the bottom of the borehole, after it has been softened, or otherwise weakened, e.g., laser-affected material, by the laser beam 160. Depending upon the configuration and shape of the laser beam, the gauge cutters may also be removing laser-affected rock or material. Gauge pads, e.g., 141 are positioned in surfaces of the bit body, e.g., 1 16a. In this embodiment gauge reamers 142, 143, 144, 145 are positioned in blades 104, 105 (and also similarly positioned in blades 108, 109 although not seen in FIG. 1A). Blades 103 and 107 have depth of cut limiters, e.g., 146. The blades, and in particular the blades having cutters, may have internal passages for cooling, e.g., vents or ports, such as, e.g., 147, 148, 149 (it being noted that the actual openings for vents 148, 149, are not seen in the view of FIG. 1A).

[0061] As best illustrated in FIG. 1 B, the cutters are positioned with respect to each other, such that they each take a slightly different path along the bottom of the borehole, in this way each cutter is assisting in the removal of laser-affected rock, and preferably does not encounter any rock that has not first been affected by the laser. In this embodiment the distance of travel by a cutter before it contacts laser-affected rock is shown by arc 162. Arc 162 defines an angle between the laser beam path, and in this embodiment the laser beam, and the plane of the blade supporting the cutters. This angle, which may be referred to as the "beam path angle," can be from about 90 degrees to about 140 degrees, about 100 degrees to about 130 degrees, and about 110 degrees to about 120 degrees. Beam path angles of less than 90 degrees may be employed, but are not preferred, as they tend to not give enough time for the heat deposited by the laser to affect the rock before the cutter reaches the area of laser affected rock. (Greater angles than 140 degrees may be employed, however, at greater angles space and strength of component issues can become significant, as the blades have very little space in which to be positioned.) Additionally, when multiple blades are used, each blade could have the same, substantially the same, or a different angle (although care should be taken when using different angles to make certain that the cutters and overall engagement with the borehole surface is properly balanced.) In the embodiment of FIG. 1 B this angle, defined by arc 162, is 135 degrees.

[0062] This angle between the laser beam (and the beam path, since generally in a properly functioning bit they are coincident) and the cutter position has a relationship to, and can be varied and selected to, address and maximize, efficiency based upon several factors, including for example, the laser power that is delivered to the rock, the reflectivity and absorptivity of the rock to the laser beam, the rate and depth to which the laser beam's energy is transmitted into the rock, the thermal properties of the rock, the porosity of the rock, and the speed, i.e., RPM at which the bit is rotated. Thus, as the laser is fired, e.g., a laser beam is propagated, along its beam path from optics to the surface of the borehole, a certain amount of time will pass from when the laser first contacts a particular area of the surface of the borehole until the cutter revolves around and reaches that point. This time can be referred to as soak time. Depending upon the above factors, the soak time can be adjusted, and optimized to a certain extent by the selection of the cutter-laser beam angle.

[0063] The bit 100 has channels, e.g., junk slots, 170, 171 that provide a space between the bit 100 and the wall or side surface 150 of the borehole, for the passage of cuttings up the borehole. The relationship of the gauge cutters 129, 128, 131 , 130 as well as other components of the bit 100 to the wall of the borehole 150 can been seen in FIG. 1 B.

[0064] The blades that support the cutters, 104, 105, 106, 108, 109, 1 10, i.e., the cutter blades, in the embodiment of FIGS. 1A-C, are essentially right angle shaped. Thus, the bottom section of the blades, i.e., the lower end holding the cutters that engage the bottom and/or gauge of the borehole, and also the associated bottom of the cutters positioned in that end {e.g., cutters 134, 133, 132,129), are along an essentially straight line that forms a right angle with the side section of the blades, i.e., the side end holding the cutters that engage the side and/or gauge of the borehole, and also the associated side of the cutters positioned in that end {e.g., cutters 142, 144, 129) form a right angle. This right angle configuration of all of the cutter blades, as shown in the embodiment of FIGS. 1 , is referred to as a flat bottom configuration, or a flat bottom laser-mechanical bit. Thus, the lower ends of the blades, as well as their associated cutters, are essentially co-planar and thus provided the flat bottom of the bottom section 102 of the bit 100. Accordingly, in laser mechanical-bits, having fixed cutters, it is preferable that the bottom of the bit, as primarily defined by the end of the cutter blades, and the position of the cutters in those ends, is essentially flat and more preferably flat, and as such will engage the borehole in an essentially even manner, and more preferably an even manner, and will in general provide a borehole with an essentially flat bottom and more preferably a flat bottom.

[0065] In the bit of FIGS. 1 the cutters, e.g., 134, 133, 132, gauge cutters, e.g., 129, and gauge reamers, e.g., 144, 142, may be PDC; and the gauge pads, e.g., 141 , may be carbide inserts, which provides for impact resistance, enhanced wear, as well as bit stability.

[0066] Further examples of laser-mechanical bits, beam paths, beam patterns including split beam patterns, hybrid-laser-mechanical bits, beam path angles and related processes and systems are disclosed and taught in the following US Patent Applications: Serial No. 61/446,043 and co-filed patent application having attorney docket no. 13938/79 (Foro s13a), the entire disclosures of each of which are

incorporated herein by reference.

[0067] Thus, in general, and by way of example, there is provided in FIG. 2 a high efficiency laser drilling system 1000 for creating a borehole 1001 in the earth 1002. FIG. 2 provides a cut away perspective view showing the surface of the earth 1030 and a cut away of the earth 1002 below the surface 1030. In general and by way of example, there is provided a source of electrical power 1003, which provides electrical power by cables 1004 and 1005 to a laser 1006 and a chiller 1007 for the laser 1006. The laser provides a laser beam, i.e., laser energy, that can be conveyed by a laser beam transmission means 1008 to a spool of tubing 1009. A source of fluid 1010 is provided. The fluid is conveyed by fluid conveyance means 101 1 to the spool of tubing 1009. [0068] The spool of tubing 1009, e.g., coiled tubing, composite tubing or other conveyance device, is rotated to advance and retract the tubing 1012. Preferred examples of such conveyance means are disclosed and taught in the following US Patent Applications and US Patent Application Publications: Publication No. US

2010/0044106, Publication No. US 2010/0044104, Publication No. US 2010/0044105, Publication No. US 2010/0044103, Publication No. US 2010/0215326, Publication No. 2012/0020631 , Serial No. 13/210,581 , Serial No. 13/366,882 and Serial No.

13/21 1 ,729, the entire disclosures of each of which are incorporated herein by reference. Thus, the laser beam transmission means 1008 and the fluid conveyance means 101 1 are attached to the spool of tubing 1009 by means of rotating coupling means 1013. The tubing 1012 contains a means to transmit the laser beam along the entire length of the tubing, i.e.,"long distance high power laser beam transmission means," to the bottom hole assembly, 1014. The tubing 1012 also contains a means to convey the fluid along the entire length of the tubing 1012 to the bottom hole assembly 1014.

[0069] Additionally, there is provided a support structure 1015, which holds an injector 1016, to facilitate movement of the tubing 1012 in the borehole 1001. Further other support structures may be employed, for example, such structures could be derrick, crane, mast, tripod, or other similar type of structure or hybrid and combinations of these. As the borehole is advance to greater depths from the surface 1030, the use of a diverter 1017, a blow out preventer (BOP) 1018, and a fluid and/or cutting handling system 1019 may become necessary. The tubing 1012 is passed from the injector 1016 through the diverter 1017, the BOP 1018, a wellhead 1020 and into the borehole 1001.

[0070] The fluid is conveyed to the bottom 1021 of the borehole 1001 . At that point the fluid exits at or near the bottom hole assembly 1014 and is used, among other things, to carry the cuttings, which are created from advancing a borehole, back up and out of the borehole. Thus, the diverter 1017 directs the fluid as it returns carrying the cuttings to the fluid and/or cuttings handling system 1019 through connector 1022. This handling system 1019 is intended to prevent waste products from escaping into the environment and separates and cleans waste products and either vents the cleaned fluid to the air, if permissible environmentally and economically, as would be the case if the fluid was nitrogen, or returns the cleaned fluid to the source of fluid 1010, or otherwise contains the used fluid for later treatment and/or disposal.

[0071] The BOP 1018 serves to provide multiple levels of emergency shut off and/or containment of the borehole should a high-pressure event occur in the borehole, such as a potential blow-out of the well. The BOP is affixed to the wellhead 1020. The wellhead in turn may be attached to casing. For the purposes of simplification the structural components of a borehole such as casing, hangers, and cement are not shown. It is understood that these components may be used and will vary based upon the depth, type, and geology of the borehole, as well as, other factors.

[0072] The downhole end 1023 of the tubing 1012 is connected to the bottom hole assembly 1014. The bottom hole assembly 1014 contains optics for delivering the laser beam 1024 to its intended target, in the case of FIG. 1 , the bottom 1021 of the borehole 1001. The bottom hole assembly 1014, for example, also contains means for delivering the fluid.

[0073] Thus, in general this system operates to create and/or advance a borehole by having the laser create laser energy in the form of a laser beam. The laser beam is then transmitted from the laser through the spool and into the tubing. At which point, the laser beam is then transmitted to the bottom hole assembly where it is directed toward the surfaces of the earth and/or borehole.

[0074] Without being bound by the following theory providing an explanation for the synergistic effects the present method obtains, and without being bound by the following theory of energy-rock interaction, physics and thermodynamics, the following theory is offered by way of illustration and to assist in the understanding of, and explanation for, the surprising and never before obtained results of these methods.

[0075] Thus, this process can be viewed as a hybrid thermal/mechanical process in which thermally-induced compressive stresses are generated in a thin skin of rock at the drilling surface. These thermally induced stresses create fractures parallel to the surface of the rock and give rise to rock removal from the borehole via chips of material. Mechanical cutter action is present primarily to ensure continuous removal of the fractured material, which in the presence of laser energy only might not be completely expelled from the surface. The physics of the process and experimental and theoretical results indicate that higher rates of penetration can be achieved by increases in laser power delivered to the drilling surface.

[0076] When laser power is absorbed by a rock, the response depends on both the intensity of the impinging laser power, as well as, the illumination time. As shown in the chart of FIG. 3, the material response can generally include several regimes, which may be generally classified as: an ultrafast regime 310, a heating regime 320, a melting regime 330, and a vaporization regime 340. Various processes may occur along these regimes, such as shock hardening 341 , drilling 342, glazing 331 , cutting 332, welding 333, cladding 334, stereo lithography 321 , and transformation hardening 322. At laser intensities and times below the melting of rock, regime 340, lies the regime in which spallation or rock fragmentation occur, as shown in regime area 350. The spallation regime 350 is the preferred area in which it is presently believed that the greatest synergistic benefit for the tailored directed energy mechanical energy process may occur.

[0077] When laser power is absorbed by the rock, a thin layer of rock near the surface of the sample is rapidly heated. The thickness of the layer is determined both by the quantity of absorbed laser power, and the thermal properties of the rock. Rock is a naturally insulating material, which means that the propagation of heat into the rock is slow, and the heated region may by necessity be very near the surface. In an unconstrained rock sample, laser absorption would cause the heated region to expand in volume. However, in a drilling environment, the heated rock is constrained on all sides by the surrounding rock mass, and the result is a thermally induced stress state in the heated section that is compressive in nature.

[0078] When the magnitude of the thermally induced stress reaches a level comparable to the compressive strength of the rock, it induces fracture in the direction of the maximum compressive stress (i.e., parallel to the heated surface). Under sufficiently large stress, these fractures can extend to very long distances until they intersect with the surface, resulting in the formation of chips, in a process known as "spallation". Turning to FIG. 4, these chips 401 , 402, 403, 404 are characterized by a high aspect ratio, e.g., the lateral dimensions 1.48" arrow 41 1 , and 1 .87" arrow 412 are much greater than the thickness 0.140" of chip 404. These chips, e.g., 401 of FIG. 4 are basalt. Similar characteristics of dolomite chips are shown in FIG. 5. Thus, chips 501 , 502, 503, 504, 505, 506, 507, 508, 509, 510, and 51 1 are characterized by a high aspect ratio, e.g., the lateral dimensions 1 .06" arrow 521 , and 1.52" arrow 522, are much greater than the thickness 0.182" of chip 51 1.

[0079] However, spallation without a mechanical removal mechanism may be and at time has been shown to be an unreliable drilling solution. Not every rock type spalls (e.g., a spallable limestone is believed to have never been identified, for example), and macroscopic fractures in the rock mass can inhibit the spallation process. Although the generation of thermal stress and stress-induced fracture is likely a universal rock response, the explosive release of spalled chips is presently believed to be material specific.

[0080] The introduction of mechanical action to a primarily thermal process, then, can increase robustness in a synergistic manner by removing the thermally fractured and damaged material without relying on explosive spallation for rock removal. For a combined thermal/mechanical process, a laser represents an ideal directed energy source, as a high flux of energy can be delivered to the rock over a precisely controlled area designed to minimize heat loads on the mechanical cutters. In the preferred method of operation the role of the mechanical cutters is to provide a minimum amount of pressure sufficient to remove the damaged material; and so that they do not otherwise contribute substantially to the rate of material removal.

[0081] The surface temperature of the rock during the process may generally be around 250-650 ^° C, which is the temperature rise sufficient to generate compressive stresses comparable to the strength of the rock; broader ranges are provide in the table of examples and may prove advantageous for various tailored drilling conditions and parameters, Under intense laser power, the surface temperature rise may be sufficient to melt rock directly under the laser beam. This melting would reduce or eliminate the thermal stresses responsible for laser processing, and is therefore preferably a condition to be avoided for this method of processing. Processes whereby the rock surface is melted allowed to cool and then scraped off are contemplated. Such processes do not rely upon a spallation regime and thus may have a broader application to different materials and in particular materials that do not exhibit spallation. Thus, this directed energy mechanical energy process is not material specific.

[0082] The methods provided herein can further be understood by the exemplary conditions and parameters set forth in the examples of Table 1 . As used in the Table 1 , the headings have the following meanings:

WOB: Weight on bit. Force applied by the bit. Units of pounds.

ROP: Rate of penetration. This is the speed of advancement of the drilling surface. Units of feet per hour.

RPM: Rotation speed of the bit in revolutions per minute.

Torque: the degree of twist applied by the bit. Units of foot-pounds.

Mechanical power: The power transmitted to the rock by the bit, given by the equation torque ^* RPM. Units of kilowatts.

Ratio of DE/ME: The ratio of directed energy or directed laser energy to mechanical energy is the delivered directed laser energy (DE) divided by the delivered mechanical energy (ME). Dimensionless number.

DE Power/Area: The directed energy laser power per unit of drilling surface area. Units are Watts per square centimeter.

ME Power/Area: The delivered mechanical energy power per unit of drilling surface area. Units are Watts per square centimeter.

[0083] Table 1

[0084] In these examples of drilling conditions and parameters, the laser power is to be delivered to the rock surface. The examples are for use with air as the fluid for drilling, and may be utilized with, by way of example, the bits and systems that are described in FIGS. 1A-C and 2 of this specification and with the bits and systems 5 disclosed and taught in US Patent Applications: Serial No. 61/446,043 and co-filed patent application having attorney docket no. 13938/79 (Foro s13a).

[0085] Thus, from the forgoing examples, which provide various illustrative laser-mechanical drilling conditions and parameters, there is contemplated generally, and by way of further example, a method of laser-mechanical drilling a borehole in a 0 formation having at least 500 feet, at least about 1 ,000 ft, at least about 5,000 and at least about 10,000 feet of material having a hardness greater than about 15 ksi, greater than about 20 ksi, greater than about 30 ksi, and greater than about 40 ksi and at drilling rates, e.g., ROP, of at least about 10 ft/hr, at least about 20 ft/hr, at least about 30 ft/hr and at least about 40 ft/hr. Such methods in generally would include, by way of example, drilling under the following conditions and parameters: (i) an RPM of from about 240 to about 720, a WOB of less than about 2,000 lbs, a DE Power/Area of about 90 W/cm ² to about 560 W/cm ² , and an ME Power/Area of about 4 W/cm ² to about 250 W/cm ² ; (ii) an RPM of from about 600 to about 800, a WOB of less than about 5,000 lbs, a DE Power/Area of about 40 W/cm ² to about 250 W/cm ² , and an ME Power/Area of about 200 W/cm ² to about 3000 W/cm ² ; (iii) an RPM of from about 600 to about 1250, a WOB of from about 500 to about 5,000 lbs, a DE Power/Area of about 90 W/cm ² to about 570 W/cm ² , and an ME Power/Area of about 40 W/cm ² to about 270 W/cm ² ; (iv) an RPM of about 250, a WOB of from about 1 ,000 lbs, a DE Power/Area of about 370 W/cm2, and an ME Power/Area of about 40 W/cm ² ; (v) an RPM of from about 720, a WOB of from about 2,000 lbs, a DE Power/Area of about 190 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; (vi) an RPM of from about 720, a WOB of from about 2,000 lbs, a DE Power/Area of about 370 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; (vii) an RPM of from about 720, a WOB of from about 5,000 lbs, a DE

Power/Area of about 290 W/cm ² , and an ME Power/Area of about 240 W/cm ² ; (viii) an RPM of from about 1 ,200, a WOB of from about 500 lbs, a DE Power/Area of about 470 W/cm ² , and an ME Power/Area of about 100 W/cm ² ; (ix) an RPM of from about 720, a WOB of from about 2,000 lbs, a DE Power/Area of about 470 W/cm ² , and an ME Power/Area of about 250 W/cm ² ; and, combinations and variations of these.

[0086] Many other uses for the present inventions may be developed or realized and thus, the scope of the present inventions is not limited to the foregoing examples, uses conditions, and applications. For example, in addition to the forgoing examples and embodiments, the implementation of these directed/mechanical energy processes may find applications in down hole tools, and may also be utilized in holes openers, perforators, reamers, whipstocks, and other types of boring tools.

[0087] The present inventions may be embodied in other forms than those specifically disclosed herein without departing from their spirit or essential

characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.