CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefits of priority to United States Provisional Patent Application No. 63/400,635, filed August 24, 2022, titled DOWNHOLE TOOL ASSEMBLY FOR MULTILATERAL WELLBORE RE-ENTRY, the contents of which are hereby expressly incorporated into the present application by reference in their entirety.

FIELD

[0001] The present disclosure relates to tools for downhole well intervention and drilling, and in particular, to devices, methods and systems for determining a subsurface position of a bottom hole assembly within a multilateral wellbore during a well re-entry.

BACKGROUND

[0002] A multilateral wellbore is a single access parent wellbore containing multiple wellbore branches or laterals extending off the parent wellbore at various junctions. In some cases, a parent wellbore may be a vertical wellbore or a parent wellbore may be a horizontal or deviated wellbore. Multilateral wellbores may include one or more vertical laterals running parallel to the parent wellbore, or may include one or more horizontal or deviated laterals branching in various directions from the parent wellbore.

[0003] When drilling multilateral wellbores, well interventions such as well reentry may be performed to provide a magnetic ranging source downhole to the borehole being drilled. However, a common problem when performing re-entries into multilateral wells, whether with a coil tubing unit or a rig based set up with either drilling tubulars or production tubulars, is determining what lateral of the multilateral wellbore (i.e. child well) has been entered. It can be particularly problematic determining the in-situ position of a bottom hole assembly (BHA) when parent and/or child wells are in close proximity to each other.

[0004] A common method of determining what lateral a BHA has entered during a well intervention is to run the coil/tubular string to the end of the lateral and compare the measured depth of the string against the known depth of the lateral as recorded during drilling of the lateral. However, this process can be time consuming and error prone, while also increasing the risk of a tool string being stuck in hole.

[0005] Accordingly, it would be useful to provide improved techniques for effectively determining a downhole position of a BHA in a multilateral well during well re-entry or drilling operations.

SUMMARY

[0006] According to a first example aspect, a system is disclosed for determining a subsurface position of a bottom hole assembly (BHA) within a multilateral well, the multilateral well comprising a tubing string extending within a casing from a surface level to a subsurface zone of interest, the tubing string conveying the bottom hole assembly towards a multilateral junction in the multilateral well. The system includes: one or more sensors integrated with a multilateral well intervention assembly of the BHA; one or more processor devices; and one or more memories storing machine-executable instructions. The machineexecutable instructions, when executed by the one or more processor devices, cause the system to: obtain, using the one or more sensors, a plurality of well data samples corresponding to one or more properties the multilateral well; and determine, based on the plurality of well data samples, the subsurface position of the BHA within the multilateral well.

[0007] According to a further example aspect, a multilateral well intervention assembly of a bottom hole assembly (BHA) is disclosed. The multilateral well intervention assembly includes: a well conveyance mechanism; a toolstring attached to the well conveyance mechanism, the toolstring including one or more sensors for obtaining a plurality of well data samples; an electromagnetic field source attached to the well conveyance mechanism, the electromagnetic field source for generating a magnetic field; an axial rotating arm connected to the well conveyance mechanism, the axial rotating arm for rotating the BHA along its longitudinal axis; a radially rotating kicker arm connected to the axial rotating arm; a power source for powering the multilateral well intervention assembly; and a telemetry system for providing communication between the toolstring, the electromagnetic field source, the axial rotating arm and the radially rotating kicker arm and the surface.

[0008] According to a further example aspect, a computer implemented method is disclosed for determining a subsurface position of a bottom hole assembly (BHA) within a multilateral well, the multilateral well comprising a tubing string extending within a casing from a surface level to a subsurface zone of interest. The method includes: obtaining a plurality of historical well data samples corresponding to the multilateral well; conveying, on the tubing string, the BHA into the multilateral well, the BHA including a multilateral well intervention assembly; obtaining, using the multilateral well intervention assembly, a plurality of well data samples corresponding to one or more properties the multilateral well at a current position of the BHA in the multilateral well; and correlating the plurality of well data samples corresponding to the one or more properties of the multilateral well at the current position in the multilateral well with the plurality of historical well data samples corresponding to the multilateral well, to determine the subsurface position of the BHA within the multilateral well.

[0009] In some embodiments, the systems, methods and devices described herein can be used to monitor a multilateral well intervention, for example, a well re-entry operation, to determine a subsurface position of a bottom hole assembly (BHA) in relation to one or more laterals of a multilateral well. Advantageously, the methods and devices described herein combine multiple existing technologies into a single multilateral well intervention assembly, allowing for efficient and cost- effective re-entries into multilateral boreholes. A depth correlation is performed in- situ using easily available logging data in order to increase confidence in the subsurface position of the multilateral well intervention assembly, prior to executing a well action such as a well re-entry.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Reference will now be made, by way of example, to the accompanying drawings which show example implementations of the present application, and in which:

[0011] FIG. 1A is a schematic block diagram of a solution mining system suitable for implementation of examples described herein.

[0012] FIG. IB is a schematic block diagram showing a multilateral solution mining system suitable for implementation of examples described herein.

[0013] FIG. 2 is a block diagram of an example computing system suitable for implementation of examples described herein.

[0014] FIG. 3 is a block diagram of an example subsurface position correlation system, in accordance with example implementations described herein.

[0015] FIG. 4A is a schematic block diagram showing an example embodiment of a multilateral well intervention assembly of the multilateral solution mining system of FIG. IB, in accordance with example implementations described herein.

[0016] FIG. 4B is a schematic block diagram showing an example embodiment of a multilateral well intervention assembly navigating a multilateral well junction, in accordance with example implementations described herein.

[0017] FIG. 4C is a is a schematic block diagram showing an example embodiment of a multilateral well intervention assembly providing magnetic well ranging to a drilling assembly while drilling, in accordance with example implementations described herein. [0018] FIG. 4D is a is a schematic block diagram showing a cross-section of an example embodiment of a multilateral well intervention assembly in conjunction with a flow through tool carrier, in accordance with example implementations described herein.

[0019] FIG. 4E is a is a schematic block diagram showing a cross-section of an example embodiment of a multilateral well intervention assembly in conjunction with a flow through probe style tool carrier, in accordance with example implementations described herein.

[0020] FIG. 5 is a flowchart showing operations of a method for determining a position of a multilateral well intervention assembly in a multilateral well, in accordance with example implementations described herein.

[0021] Similar reference numerals have been used in different figures to denote similar components.

DESCRIPTION OF EXAMPLE IMPLEMENTATIONS

[0022] As used herein, the terms, "comprises" and "comprising" are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms, "comprises" and "comprising" and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.

[0023] As used herein, the term "exemplary" or "example" means "serving as an example, instance, or illustration," and should not be construed as preferred or advantageous over other configurations disclosed herein.

[0024] As used herein, the terms "about", "approximately", and "substantially" are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dimensions. [0025] As used herein, statements that a second item (e.g., a signal, value, scalar, vector, matrix, calculation, or bit sequence) is "based on" a first item can mean that characteristics of the second item are affected or determined at least in part by characteristics of the first item. The first item can be considered an input to an operation or calculation, or a series of operations or calculations that produces the second item as an output that is not independent from the first item.

[0026] The present disclosure describes systems, methods, devices and processor-readable media for monitoring a multilateral well intervention, for example, a well re-entry operation, to determine a subsurface position of a bottom hole assembly (BHA) in relation to one or more laterals of a multilateral well. In examples, the systems, methods, devices and processor-readable media may be applied to a multilateral wellbore system that is configured produce an element of interest by solution mining. According to examples, a multilateral well intervention assembly of a BHA may measure a plurality of well data samples representative of physical, geological, geophysical or petrophysical properties of a multilateral well, and in conjunction with a subsurface position correlation system, correlate the plurality of well data samples with historical well data samples obtained during drilling of the multilateral well, to estimate a position of the BHA in the multilateral well. Upon determining that a target depth in the multilateral well has been reached, a well action may be executed, for example, navigating a multilateral junction during a well re-entry.

[0027] During well intervention operations, such as well re-entry, current methods to determine which lateral of a multilateral well has been entered rely on the measured depth of each lateral. However, in applications where laterals may be designed to have the length, for example, when employing downhole fluid circulation-loops for various production operations, identifying which wellbore a bottom hole assembly (BHA) has re-entered cannot be accomplished by comparing the measured depth of the well to measured depths of wells obtained during drilling, as the laterals will have the same measured depth. [0028] In some embodiments, the present disclosure describes examples that address some or all of the above drawbacks of existing techniques for determining a subsurface position of a BHA during well re-entry or well drilling operations.

[0029] To assist in understanding the present disclosure, the following describes some concepts relevant to drilling and/or re-entering multilateral wellbores, along with some relevant terminology that may be related to examples disclosed herein.

[0030] In the present disclosure, a "multilateral wellbore" can mean: a single access parent wellbore containing two or more wellbore branches or laterals drilled off of the parent wellbore from at least one junction. In some cases, a parent wellbore may be a vertical wellbore or a parent wellbore may be a horizontal or deviated wellbore. Multilateral wellbores may include one or more vertical laterals that deviate from the parent wellbore before running in a parallel direction to the parent wellbore. Multilateral wellbores may also include one or more horizontal or deviated laterals branching in various directions from the parent wellbore.

[0031] In the present disclosure, a "parent well" can mean: an initial well to be drilled into a target subsurface formation, for example, before any other wells are drilled. In examples, parent wells may include parent well pairs, in which one well of the well pair is a parent injection well and the other well of the well pair is a parent production well.

[0032] In the present disclosure, a "child well" can mean: a well that is drilled after an initial parent well has been drilled into a subsurface formation, and possibly after a parent well has been on production. Child wells may also be called infill wells, and may be designed to target a region of a subsurface formation that cannot be accessed by a parent well. In some examples, a child well may be a multilateral branch of a multilateral well, where the child well is drilled off of the parent well or off of another child well at a multilateral junction. In examples, child wells may include child well pairs, in which one child well of the child well pair is in fluid connection to a parent injection well and the other child well of the child well pair is in fluid connection to the parent production well. [0033] In the present disclosure, a "fluid circulation-loop" can mean: a well configuration in which fluid can be circulated at a subsurface depth, where the fluid has an entry point in fluid communication with an injection well and an exit point in fluid communication with a production well. In some embodiments, for example, an injection well and a production well may be connected to form a primary fluid circulation-loop. In other embodiments, a child well pair extending off of a primary fluid circulation-loop may be connected to form a secondary fluid circulation-loop.

In some embodiments, for example, a secondary fluid circulation-loop may have an entry point at a multilateral junction and an exit point at another multilateral junction. In examples, a fluid circulation-loop may be a well pair that has been connected toe-to-toe, or a circulation loop may be another well configuration that enables fluid flow at a subsurface depth.

[0034] In the present disclosure, a "bottom hole assembly (BHA)" can mean: the collection of components fixed to the end of a tubing string that has been conveyed down a well. For example, a bottom hole assembly for a drilling string could be considered to include all components extending from the drill bit to the drill pipe, including collars, stabilizers, the drill bit, etc.

[0035] In the present disclosure, a "survey tool" can mean: an instrument or sensor used to measure positional information required to calculate and plot a 3D well path of a wellbore, for example, to obtain a directional survey of a well. In some examples, a survey tool may include a gyroscope, or other sensors, for measuring the inclination and azimuth of a well.

[0036] In the present disclosure, a "well property" or a "well parameter" can mean: a physical, geological, geophysical, petrophysical or other characteristic of either a wellbore or the surrounding rock that can be measured by one or more sensors and stored as a well data sample. Examples of well properties include gamma radiation, porosity, resistivity, density, inclination, azimuth or permeability, among others.

[0037] In the present disclosure, "solution mining" can mean: a mineral extraction method where an element of interest is dissolved in a fluid to form a solution, and the solution is produced, for example, by pumping to the surface, where the element of interest can be recovered. Example minerals which are commonly extracted by solution mining include salts, such as halite, potash or trona, as well as phosphorus, uranium and lithium.

[0038] In the present disclosure, "wellbore" can mean: solution mining wells, oil wells, gas wells and geothermal wells, among others.

[0039] FIG. 1A shows a solution mining system 100a for extracting an element of interest from a subsurface deposit using fluid circulation-loop solution mining methods. The solution mining system 100a is an illustrative example of a system to which the systems, methods, and processor-readable media described herein can be applied, in accordance with examples of the present disclosure.

[0040] In some embodiments, for example, the solution mining system 100a represents a fluid circulation-loop solution mining operation. A parent injection well 102 and a parent production well 104 may be drilled as a well pair, for example, a horizontal well pair or a deviated well pair. In some embodiments, for example, the parent injection well 102 and the parent production well 104 may each comprise a tubing string 132 (e.g. a coiled tubing or a production tubing, see FIG. IB) extending within a wellbore string from a surface level 106 and to subsurface depth corresponding to a zone of interest 108. In some embodiments, for example, the wellbore string may comprise a casing and optionally, a liner having fluid flow openings (e.g. slots in a slotted liner, or another fluid flow communication structure) through which fluid may be exchanged between the wellbore string and the zone of interest 108. In some examples, a casing shoe 116 may be fixed to the end of the casing. At the surface level 106, a wellhead 112 may be fixed to the parent injection well 102 and a wellhead 114 may be fixed to the parent production well 104.

[0041] In some embodiments, for example, the parent injection well 102 and the parent production well 104 may extend vertically from the surface 106 to a target depth corresponding to the zone of interest 108. In some examples, the parent injection well 102 and the parent production well 104 may change direction and extend laterally, for example, horizontally or in a deviated direction to access the zone of interest 108. In some embodiments, for example, the lateral extents of the parent injection well 102 and parent production well 104 may be substantially parallel. In some embodiments, for example, the lateral extents of the parent injection well 102 and parent production well 104 may both access the zone of interest 108 or in other embodiments, one of the parent injection well 102 and parent production well 104 may be positioned outside of the zone of interest 108.

[0042] In some embodiments, for example, the parent injection well 102 and the parent production well 104 may each include a vertical well section and a lateral well section, the lateral well section having a heel region and a toe region, and where the parent injection well 102 and the parent production well 104 may be connected toe-to-toe at a toe region connection point 110 to form a parent well fluid circulation-loop 122.

[0043] In some embodiments, for example, the zone of interest 108 may be a bedded formation defined by a top 118 and a bottom 120 of the formation. In some examples, the zone of interest may include a minable deposit of an element of interest, for example, a salt deposit containing potassium (K) salts such as potash (e.g. potassium chloride or KCI) or other elements of interest. In some examples, the element of interest may be recovered by a solution mining method, for example, where a salt deposit containing KCI is in contact with a fluid in order to sufficiently dissolve the element of interest. In some examples, the fluid in contact with the element of interest may be a brine, for example, a saturated brine or a super saturated brine, for example, comprising sodium chloride (NaCI), or the fluid may be another solvent. In some examples, the fluid may be injected into the parent injection well 102 and may circulate through the primary fluid circulationloop 122, where the fluid may be in contact with the element of interest for a period of time to sufficiently dissolve the element of interest to form a solution. Production tubing may transport the solution containing the dissolved element of interest from the region of interest 108 to the surface level 106, where the element of interest may then be recovered. In some examples, the fluid may be produced by artificial lift, for example, using an electrical submersible pump (ESP) assembly (not shown) disposed at a subsurface intake location near the heel of the parent production well 104.

[0044] While the example embodiments describe a solution mining operation, it should be noted that the systems and methods described herein can apply to other operations utilizing multilateral wellbores, for example, steam assisted gravity drainage (SAGD) operations or geothermal operations, among others.

[0045] FIG. IB shows a multilateral solution mining system 100b for extracting an element of interest from a subsurface deposit using fluid circulationloop solution mining methods. The multilateral solution mining system 100b is an illustrative example of a system to which the systems, methods, and processor- readable media described herein can be applied, in accordance with examples of the present disclosure.

[0046] In the example embodiment of multilateral solution mining system 100b, the solution mining system 100a is extended to include at least one secondary fluid circulation-loop 124 branching off of the primary fluid circulationloop 122. In some examples, a first child well 125a may be drilled off of the parent injection well 102 at a first multilateral junction 126a and a second child well 125b may be drilled off of the parent production well 104 at a multilateral junction 126b to form a child well pair. In some examples, each child well in the child well pair may comprise a lateral section having at least a toe region, where the child well pair may be connected toe-to-toe at a toe region connection point 128 to form the secondary fluid circulation-loop 124.

[0047] In some embodiments, for example, it may be necessary to re-enter a drilled well, for example, the parent injection well 102 or the parent production well 104 or any corresponding child well branches. For example, well re-entries may be required for placement of magnetic ranging tools when drilling new multilateral branches, or when performing well interventions such as well clean-outs, caliper gauge runs, milling operations, cementing, downhole tool installation, etc. A multilateral well intervention assembly 130 may be disposed in a well coupled to a tubing string, for example a coiled tubing 132. Further details of various embodiments of the multilateral well intervention assembly 130 may be described with respect to FIG.s 4A-4E below.

[0048] FIG. 2 is a block diagram of an example computing system 200 including computing hardware suitable for determining a position of a multilateral well intervention assembly 130 in a multilateral well according to example embodiments described herein. In some implementations, computing system 200 can be an electronic computing device, such as a networked server. In other implementations, the computing system 200 can be a distributed computing system including multiple devices (such as a cloud computing platform) or a virtual machine running on one or more devices in mutual communication over a network. Other examples suitable for implementing implementations described in the present disclosure can be used, which can include components different from those discussed below. Although FIG. 2 shows a single instance of each component, there can be multiple instances of each component in the computing system 200.

[0049] The computing system 200 can include one or more processor devices (collectively referred to as processor device 202). The processor device 202 can include one or more processor devices such as a processor, a microprocessor, a digital signal processor, an application-specific integrated circuit (ASIC), a field- programmable gate array (FPGA), a dedicated logic circuitry, a dedicated artificial intelligence processor unit, or combinations thereof.

[0050] The computing system 200 can include one or more network interfaces (collectively referred to as network interface 206) for wired or wireless communication over a network. The network interface 206 can include wired links (e.g., Ethernet cable) and/or wireless links (e.g., one or more antennas). The computing system 200 can communicate with one or more user devices (such as user workstation computers) via the network interface 206. The computing system 200 can also communicate with various sensors or other data sources to obtain data used in determining a position of a multilateral well intervention assembly 130 in a multilateral well, such as sensors 208. In some embodiments, the sensors 208 can include sensors located within, or otherwise integrated with, the multilateral well intervention assembly 130, for example, sensors to measure the inclination and azimuth of the multilateral well intervention assembly 130 or other sensors to measure wellbore or formation properties.

[0051] The computing system 200 can include one or more non-transitory memories (referred to collectively as a memory 204), which can include a volatile or non-volatile memory (e.g., a flash memory, a random access memory (RAM), and/or a read-only memory (ROM)). The memory 204 can also include one or more mass storage units, such as a solid state drive, a hard disk drive, a magnetic disk drive and/or an optical disk drive.

[0052] The memory 204 can store instructions for execution by the processor device 202 to carry out examples described in the present disclosure. The instructions can include instructions 300-1 for implementing and operating the subsurface position correlation system 300 described below with reference to FIG 3. The memory 204 can include other software instructions, such as for implementing an operating system and other applications/functions. In some examples, the computing system 200 can additionally or alternatively execute instructions from an external memory (e.g., an external drive in wired or wireless communication with the computing system 200) or can be provided executable instructions by a transitory or non-transitory computer-readable medium. Examples of non-transitory computer readable media include a RAM, a ROM, an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a CD-ROM, or other portable memory storage. The memory 204 can also store information or data used in executing the depth correlation system 300, for example, historical well data samples 320.

[0053] The computing system 200 can also include a bus 212 providing communication among components of the computing system 200, including those components discussed above. The bus 212 can be any suitable bus architecture including, for example, a memory bus, a peripheral bus or a video bus, or the bus 212 can be another communication link such as a network interface 206. [0054] FIG. 3 is a block diagram of an example subsurface position correlation system 300 of the present disclosure. The subsurface position correlation system 300 may be a software based module that is implemented in the computing system 200 of FIG. 2, in which the processor device 202 is configured to execute instructions 300-1 of the subsurface position correlation system 300 stored in the memory 204. The subsurface position correlation system 300 includes a well position correlator 320.

[0055] In some embodiments, for example, the subsurface position correlation system 300 receives as an input, a plurality of real-time well data samples 310 obtained by the multilateral well intervention assembly 130 disposed in a multilateral well and outputs a predicted position 340 of the multilateral well intervention assembly 130. In some embodiments, for example, the real-time well data samples 310 may be measured by sensors 208, for example, a gyroscope for measuring physical well properties such as inclination and azimuth, or other sensors for taking measurements along the depth of the wellbore, for example, measurements of geological, geophysical or petrophysical properties. In some embodiments, for example, sensors 208 may measure gamma radiation, porosity, resistivity, density and permeability, among other commonly logged properties of a wellbore. In some embodiments, a well position correlator 320 may receive the plurality of real-time well data samples 310 and may correlate the plurality of realtime well data samples 310 with historical well data samples 330 that may have been obtained for the multilateral well during drilling to generate the predicted position 340. In some embodiments, for example, the predicted position 340 may be evaluated to gauge whether the multilateral well intervention assembly 130 has reached a target depth or position in the multilateral well, for example, at a desired multilateral well junction 126a or 126b.

[0056] In some examples, the well position correlator 320 may output the predicted position 340 as a probability that one or more parameters of the real-time data samples correspond to a specific depth or position within the multilateral well. In some embodiments, for example, the well position correlator 320 may perform a cross-correlation between real-time well data samples 310 and historical well data samples 330 as a function of depth, for example, using a maximum likelihood estimation (MLE) methodology. For example, an amplitude of a cross-correlation peak may be evaluated with respect to a pre-determined threshold. In some embodiments, for example, the well position correlator 320 may correlate the realtime well data samples 310 and historical well data samples 330 using one or more windows, the windows having different lengths, for example, larger windows for coarse estimation of a depth or position within the multilateral well or smaller windows for fine estimation of a depth or position. In examples, a well position correlator 320 may first apply a large cross-correlation window to the real-time well data samples 310 and historical well data samples 330 to narrow down on a range of estimated depth or position in the multilateral well. In examples, the well position correlator 320 may then apply a smaller cross-correlation window, such as a medium or a small cross-correlation window to estimate the depth or position within the multilateral well with finer resolution. In examples, when more than one cross-correlation window is applied to the real-time well data samples 310 and historical well data samples 330 by the well position correlator 320, a threshold value may be determined using a weighted vector. In other embodiments, for example, the well position correlator 320 may be a machine learning model, or a rule-based statistical model, or another method may be used. Depending on the predicted position 340, and whether the a well action may be executed, for example, extending a kicker arm 410 of the multilateral well intervention assembly 130 in preparation for navigating a multilateral junction 126a.

[0057] Example embodiments of the multilateral well intervention assembly 130 are now provided with respect to FIG.s 4A-4E.

[0058] FIG. 4A is a schematic block diagram of an example embodiment of a multilateral well intervention assembly 130 of the multilateral solution mining system of FIG. IB, according to example embodiments described herein. The multilateral well intervention assembly 130 may be conveyed down a subsurface well on a tubing string, for example a coiled tubing 132 as part of a bottom hole assembly (BHA). For illustrative purposes, the multilateral well intervention assembly 130 is shown to be disposed in a parent injection well 102, however the multilateral well intervention assembly 130 may be disposed in the parent production well 104 or any other lateral of a multilateral well. In other embodiments, for example, the coil tubing 132 used to convey the BHA including the multilateral well intervention assembly 130 into a wellbore is replaced with a piece of drill string or production tubulars and conveyed by a rig. In still other embodiments, for example, the BHA including the multilateral well intervention assembly 130 may be conveyed into a wellbore from the surface 106 using a tractor device connected to a wireline spool.

[0059] In some embodiments, for example, the multilateral well intervention assembly 130 may include wiring 402, for example, telemetry or power wiring. In some examples, telemetry between the multilateral well intervention assembly 130 and computing system 200 may be provided via a wired connection to the surface (e.g. wireline) or in other embodiments communication may be provided by a wireless connection, for example, using a wireless transceiver to transmit data by conventional electromagnetic, acoustic or mud pulse signaling techniques. In some examples, power to the multilateral well intervention assembly 130 may be provided by wiring from the surface or in other embodiments the multilateral well intervention assembly 130 may have an onboard power source, for example, powered by batteries or a generator (e.g. a turbine device that generates power from flow). In some embodiments, for example, the multilateral well intervention assembly 130 may be powered by an "E-Coil" that also provides real time telemetry to the multilateral well intervention assembly 130.

[0060] In some embodiments, for example, the multilateral well intervention assembly 130 may include a toolstring 404 comprising one or more modules (e.g. 404a, 404b... 404n) for obtaining real-time well data samples 310 corresponding to the physical, geological, geophysical or petrophysical characteristics of the multilateral wellbore or formation. In some embodiments, for example, each module of the toolstring 404 may include one or more sensors 208, for example, a gyroscope for measuring physical properties such as inclination and azimuth, or other sensors for taking measurements along the depth of the wellbore, for example, measurements of gamma rays, porosity, resistivity, density and permeability, among other commonly logged properties of a wellbore. In some embodiments, for example, measurements obtained along the depth of the wellbore may be obtained in real-time, and transmitted to a processor on the surface 106 along wiring 402. In some embodiments, for example, historical well data samples that were recorded along the depth of a wellbore during drilling may be correlated with real-time data samples wellbore properties obtained by the multilateral well intervention assembly 130 as it is conveyed down a multilateral well to determine the current position of the multilateral well intervention assembly 130 in the well.

[0061] In some embodiments, for example, the multilateral well intervention assembly 130 may also include an electromagnetic field source 406, such as an electromagnet, or a rotating permanent magnet, for providing a static or alternating magnetic signal, for example, for providing magnetic ranging to a drilling assembly drilling a lateral in the multilateral well, for example, drilling a child well or a child well pair.

[0062] In some embodiments, for example, the multilateral well intervention assembly 130 may also include at least one axially rotating arm 408 and at least one radially rotating kicker arm 410. In some embodiments, for example, the kicker arm 410 may be positioned at the distal end of the multilateral well intervention assembly 130, or in other embodiments, for example, a series of axially rotating arms 408 and radially rotating kicker arms 410 may alternate in a sequence and be positioned at the distal end of the multilateral well intervention assembly 130. In some examples, the axial rotating arm 408 may enable the BHA including the multilateral well intervention assembly 130 to be rotated along its longitudinal axis. The axial rotating arm 408 may be controlled by motors using an electronic signal or the axial rotating arm 408 may be controlled using a mechanical logic, for example, by mud pressure or flow signals to change the state of the axial rotating arm 408. [0063] In some embodiments, for example, the kicker arm 410 may rotate around its radial axis, where a kicker arm angle 412 describes the position of the rotating joint of the kicker arm 410. In some embodiments the kicker arm 410 may be rotated such that the kicker arm angle 412 is decreased and in other embodiments the kicker arm 410 may be rotated such that the kicker arm angle 412 increases. In some examples, in preparation for navigating a multilateral junction 126a during a well re-entry operation, the axially rotating arm 408 may be used to position the kicker arm 410 in the direction of the desired lateral. For example, prior to re-entering a desired lateral of a multilateral well, the kicker arm 410 may be extended into a straight position (for example, with a kicker arm angle 412 of approximately 180°) with respect to the axis of the multilateral well intervention assembly 130, in order to decrease drag in the well bore. The kicker arm 410 may be controlled by motors using an electronic signal or the kicker arm 410 may be controlled using a mechanical logic, for example, by mud pressure or flow signals to change the state of the kicker arm 410.

[0064] Although example elements of the multilateral well intervention assembly 130 are shown in FIG. 4A in a specific order, elements may be positioned in a different order. In some embodiments, for example, the axial rotating arm 408 can be fitted as the first element in the multilateral well intervention assembly 130 and where the toolstring 404 may be fitted to a rotating section of the tubing 132 such that the toolstring 404 can measure the amount of rotation along the longitudinal axis. In other embodiments an inclination sensor may be fitted onto the end of the kicker arm 410 to measure and provide feedback on the kicker arm angle 412 with respect to the axis of the multilateral well intervention assembly 130. In still other embodiments, a telemetry tool, for example, an electromagnetic telemetry or acoustic tool (not shown) may be installed onto the end of the kicker arm 410 to enable telemetry between the kicker arm 410 and wiring 402 to transmit data to the surface.

[0065] FIG. 4B is a schematic block diagram of an example embodiment of the multilateral well intervention assembly 130 navigating a multilateral well junction 126a, in accordance with example implementations described herein. In the example embodiment, the multilateral well intervention assembly 130 may be conveyed down a subsurface well on a drill string 133 or a production tubular as part of a BHA. In examples, a gap sub 414 may be included in the multilateral well intervention assembly 130 for providing electromagnetic telemetry between multilateral well intervention assembly 130 and computing system 200 while navigating a multilateral borehole junction 126a, for example, while navigating from a parent injection well 102 into a first child well 125a. In some embodiments, the orientation of the parent injection well 102 and child well 125a on either side of the multilateral junction 126a may be vertical, horizontal or deviated, and where a junction angle exists between the two wells.

[0066] In some embodiments, for example, the multilateral well intervention assembly 130 may obtain real-time well data samples 310 from one or more modules of toolstring 404, for example module 404a and module 404b, to use as inputs to the subsurface position correlation system 300. As an illustrative example, module 404a may be a survey tool and module 404b may be a gamma detection sensor, however other combinations of modules may be used. In some embodiments, for example, the subsurface position correlation system 300 generates a predicted position 340 for the multilateral well intervention assembly 130 using the real-time well data samples 310 and historical well data samples 330. Based on the predicted position 340, for example, when the predicted position 340 indicates that the multilateral well intervention assembly 130 has reached a desired multilateral well junction 126a, the multilateral well intervention assembly 130 may then rotate the axial rotating arm 408 and extend the kicker arm 410 in the direction of the child well 125a to be re-entered. Alternately, if the predicted position 340 indicates that the multilateral well intervention assembly 130 has not reached a desired multilateral well junction 126a, the multilateral well intervention assembly 130 may continue to obtain real-time well data samples 310 and compute corresponding predicted positions 340 in an iterative manner as it travels along the multilateral well, until it reaches a target position. [0067] In some embodiments, for example, once the multilateral well intervention assembly 130 has successfully navigated the multilateral well junction 126a and traveled into the child well 125a, the multilateral well intervention assembly 130 may obtain real-time well data samples 310 from the one or more modules of the toolstring 404, (for example, obtaining the inclination and azimuth from module 404a and obtaining gamma readings from module 404b) to use as inputs to the subsurface position correlation system 300. In some embodiments, for example, the subsurface position correlation system 300 uses the real-time well data samples 310 and historical well data samples 330 to generate a predicted position 340 to confirm that the multilateral well intervention assembly 130 has navigated into the correct child well 125a of the multilateral well. In some embodiments, for example, once the position of the multilateral well intervention assembly 130 is confirmed to be correct, the kicker arm 410 may return to a position where the a kicker arm angle 412 is approximately 180° with respect to the axis of the multilateral well intervention assembly 130, to reduce drag while moving along the lateral.

[0068] In some embodiments, the multilateral well intervention assembly 130 may continue to navigate additional multilateral well junctions and travel along additional child wells to reach a desired end position, for example, a desirable position for providing magnetic ranging to a drilling assembly, to facilitate the drilling of child wells or child well pairs. For example, upon reaching the desired end position, the electromagnetic field source 406 may generate a static or alternating magnetic field which may be sensed by a receiver within an adjacent borehole being drilled.

[0069] FIG. 4C is a is a schematic block diagram showing an example embodiment of a multilateral well intervention assembly 130 providing magnetic well ranging to a drilling assembly while drilling, in accordance with example implementations described herein. In the present embodiment, the multilateral well intervention assembly 130 may be conveyed in an existing lateral, for example, parent injection well 102 or another lateral in a multilateral well, on coiled tubing 132 as part of a BHA. In examples, an electromagnetic field source 406 may be activated to provide a static or varying magnetic field 418 to an adjacent lateral that may be in the process of being drilled. In some embodiments, for example, while the electromagnetic field source 406 is active, the kicker arm 410 on the multilateral well intervention assembly 130 may be fully extended to minimize the tool profile (e.g. with a kicker arm angle 412 of approximately 180°).

[0070] In some embodiments, for example, a drilling BHA is shown in child well 125b conveyed on a drill string 133. In examples, the drilling BHA may include a drill bit 420, a mud motor 422 and a measurement while drilling (MWD) tool string 424 comprising a survey tool, among other components. In some embodiments, for example, a drilling BHA may also include other downhole tools for use while drilling, for example, logging tools or telemetry tools. In some examples, the MWD tool string 424 comprising a survey tool may also include a magnetometer or a 3C magnetometer, for measuring the magnetic field 418 and determining a distance between the existing wellbore (e.g. parent injection well 102) and the lateral currently being drilled (e.g. child well 125b). In some examples, it may be advantageous to maintain a constant distance between a well being drilled and existing lateral, therefore providing a magnetic signal 418 to the MWD tool string 424 may help to steer a drilling BHA to ensure that well trajectories maintain a constant separation.

[0071] FIG. 4D is a is a schematic block diagram showing a cross-section of an example embodiment of a multilateral well intervention assembly 130 in conjunction with a flow through tool carrier 430, in accordance with example implementations described herein. In the present embodiment, the multilateral well intervention assembly 130 may be conveyed down a subsurface well (e.g. parent injection well 102) on coiled tubing 132 or using another conveyance method, as part of a BHA. In some embodiments, for example, the multilateral well intervention assembly 130 may include wiring 402, for example, telemetry or power wiring. In the present embodiment, electronics of the multilateral well intervention assembly 130 may be enclosed within a through bore tool carrier 430, for example, a pressure barrel. In examples, the through bore tool carrier 430 may comprise an inner flow tube 432, enabling fluid to flow downhole along a tubing string and through the tool carrier, for example, during well interventions such as well cleanouts, caliper gauge runs, milling operations, cementing, downhole tool installation or during injection operations. In some embodiments, for example, a cavity 431 may be formed between the inner flow tube 432 and an outer wall of the through bore tool carrier 430. In some embodiments, for example, electronics enclosed within the cavity 431, may include a survey tool 434, a wireline telemetry modem 436 or an electromagnetic field source 438. Optionally, another electronic device 439 such as a battery pack, control electronics or additional sensors may be enclosed within the cavity 431. In some embodiments, for example, the through bore tool carrier 430 may be attached to the conveyance method, for example, coiled tubing 132 or rig based conveyance method via threads (not shown) on the through bore tool carrier 430. In some embodiments, the axial rotation arm 408 and the kicker arm 410 may also be attached to the through bore tool carrier 430 via threads (not shown) on the through bore tool carrier 430.

[0072] FIG. 4E is a is a schematic block diagram showing a cross-section of an example embodiment of a multilateral well intervention assembly 130 in conjunction with a flow through probe style tool carrier 440, in accordance with example implementations described herein. In the present embodiment, the multilateral well intervention assembly 130 may be conveyed down a subsurface well (e.g. parent injection well 102) on a coiled tubing 132 or using another conveyance method, as part of a BHA. In some embodiments, for example, the multilateral well intervention assembly 130 may include wiring 402, for example, telemetry or power wiring. In the present embodiment, electronics of the multilateral well intervention assembly 130 may be enclosed within a probe style tool carrier 440 that is held in place by a flow ring or matching profile. In some embodiments, for example, matching profiles may be secured in place by bolts or other fasteners applied from the outside of the probe style tool carrier 440. In examples, a probe style tool carrier 440 may be a flow through tool, for example, where fluid may flow downhole along a tubing string and through the tool carrier, for example, during well interventions such as well clean-outs, caliper gauge runs, milling operations, cementing, downhole tool installation or during injection operations. In some embodiments, for example, electronics enclosed within the probe style tool carrier 430, for example, a survey tool 434, a wireline telemetry modem 436 or an electromagnetic field source 438, among others. In some embodiments, for example, the probe style tool carrier 440 may be attached to the conveyance method, for example, coiled tubing 132 or rig based conveyance method via threads (not shown) on the probe style tool carrier 440. In some embodiments, the axial rotation arm 408 and the kicker arm 410 may also be attached to the probe style tool carrier 440 via threads (not shown) on the probe style tool carrier 440.

[0073] Example implementations of methods for determining a subsurface position of a bottom hole assembly (BHA) in a multilateral well will now be described, with reference to the subsurface position correlation system 300 executed by the example computing system 200 in co-operation with the multilateral solution mining system 100b.

[0074] FIG. 5 is a flowchart showing operations of a method 500 for determining a subsurface position of a BHA, in accordance with examples of the present disclosure. The method 500 can be performed in the context of the components of the multilateral solution mining system 100b shown in FIG. IB in some embodiments.

[0075] Method 500 begins at step 502 in which a plurality of historical well data samples 330 corresponding to the multilateral well are obtained. For example, a plurality of historical well data samples 330 may include logged data samples that were measured and recorded during drilling of the multilateral well.

[0076] At step 504, the BHA may be conveyed down a multilateral well using a conveyance mechanism, such as a tubing string 132. In embodiments, the BHA includes a multilateral well intervention assembly 130 as part of the BHA. [0077] At step 506, a plurality of real-time well data samples 310 corresponding to one or more properties of the multilateral well are obtained using the multilateral well intervention assembly 130. In examples, one or more properties of the multilateral well may include physical, geological, geophysical or petrophysical properties of the multilateral well, among others.

[0078] At step 508, the plurality of real-time well data samples 310 corresponding to the one or more properties of the multilateral well are correlated with the plurality of historical well data samples 330 corresponding to the multilateral well, to determine a subsurface position of the BHA within the multilateral well.

[0079] Optionally, at step 510, based on the subsurface position of the BHA within the multilateral well, one or more well actions may be executed, for example the BHA may re-enter a lateral by navigating across a multilateral junction 126a, or an electromagnetic field source 406 in the multilateral well intervention assembly 130 may be activated for providing magnetic ranging to a child well currently being drilled, or a drilling operation may be initiated, among others. In some embodiments, for example, if the position of the BHA within the multilateral well is determined to match a target position corresponding to a suspected multilateral junction 126a, the multilateral well intervention assembly 130 may use the axially rotating arm 408 to position the kicker arm 410 in the direction of the desired wellbore, before extending the kicker arm 410 in preparation for navigating through the multilateral junction 126a. In some embodiments, for example, the BHA may then receive a command to proceed into a suspected lateral (e.g. child well 125a) via the multilateral junction 126a and may receive a command to stop once the BHA has fully entered the lateral, for example, representing a post-entry position of the BHA in the multilateral well. In some embodiments, for example, the multilateral well intervention assembly 130 may obtain a second plurality of realtime well data samples 310 corresponding to one or more properties of the multilateral well at the post-entry location and may correlate the second plurality of real-time well data samples 310 with the historical well data samples 330 in order to confirm that the post-entry position of the BHA in the multilateral well corresponds to a desired child well 125a of the multilateral well. In some embodiments, for example, once the subsurface position of the BHA in the multilateral well has been confirmed to match a desired child well 125a, the multilateral well intervention assembly 130 may activate the electromagnetic field source 406 to provide magnetic ranging for another wellbore currently being drilled or a BHA including a multilateral well intervention assembly 130 conveyed on a drill string as part of a drilling BHA may initiate drilling operations.

General

[0080] Although the present disclosure describes functions performed by certain components and physical entities, it should be understood that, in a distributed system, some or all of the processes can be distributed among multiple components and entities, and multiple instances of the processes can be carried out over the distributed system.

[0081] Although the present disclosure describes methods and processes with steps in a certain order, one or more steps of the methods and processes can be omitted or altered as appropriate. One or more steps can take place in an order other than that in which they are described, as appropriate.

[0082] Although the present disclosure is described, at least in part, in terms of methods, a person of ordinary skill in the art will understand that the present disclosure is also directed to the various components for performing at least some of the aspects and features of the described methods, either by way of hardware components, software or any combination of the two. Accordingly, the technical solution of the present disclosure can be embodied in the form of a software product. A suitable software product can be stored in a pre-recorded storage device or other similar non-volatile or non-transitory computer readable medium, including DVDs, CD-ROMs, USB flash disk, a removable hard disk, or other storage media, for example. The software product includes instructions tangibly stored thereon that enable a processing device (e.g., a personal computer, a server, or a network device) to execute examples of the methods disclosed herein. In general, the software improves the operation of the hardware in one or more ways.

[0083] The present disclosure can be embodied in other specific forms without departing from the subject matter of the claims. The described example implementations are to be considered in all respects as being only illustrative and not restrictive. Selected features from one or more of the above-described implementations can be combined to create alternative implementations not explicitly described, features suitable for such combinations being understood within the scope of this disclosure. [0084] All values and sub-ranges within disclosed ranges are also disclosed.

Also, although the systems, devices and processes disclosed and shown herein can include a specific number of elements/components, the systems, devices and assemblies could be modified to include additional or fewer of such elements/components. For example, although any of the elements/components disclosed can be referenced as being singular, the implementations disclosed herein could be modified to include a plurality of such elements/components. The subject matter described herein intends to cover and embrace all suitable changes in technology.