Formation of perforated tunnels in subterranean formations

Abstract

A downhole tool includes a housing configured to be coupled to a downhole delivery device; a laser tool located within the housing and configured to transmit a laser beam sufficient to form a tunnel in the subterranean formation; a chamber within the housing and configured to surround a shaped member including at least two laser reflecting surfaces; and a perforation head coupled with the housing. The perforating head includes: an optical path formed to receive a laser beam from a laser tool and output the laser beam toward a subterranean formation through an outlet of the perforating head; and at least one conduit separate from the optical path and configured to receive the shaped member from the chamber and output the shaped member through an outlet of the perforating head.

Description

Technical Field

[0001] The present disclosure describes apparatus, systems, and methods for forming perforation tunnels in a subterranean formation, and more particularly, describes apparatus, systems, and methods for forming perforation tunnels in a subterranean formation using a downhole laser. Background Art

[0002] Downhole laser tools are sometimes used as an alternative to conventional perforating guns for creating perforation tunnels in subterranean formations containing hydrocarbon reserves. Downhole laser tools can have greater accuracy, reliability, control, and cost than conventional perforating tools. In some cases, downhole laser tools can penetrate all types of rock formations, regardless of the hardness and stress orientation of the rock. In addition, downhole laser tools have advantages, including the ability to drill into and penetrate different types of rock, drill different hole sizes, precisely direct the laser beam to form the hole, and this is independent of stress and structure. Summary of the invention

[0003] In an example implementation, a downhole tool includes: a housing configured to be coupled to a downhole conveyance device that can extend from the surface through a wellbore and to a subsurface formation; a laser tool located within the housing and configured to transmit a laser beam sufficient to form a tunnel in the subsurface formation; a chamber located within the housing and configured to enclose a plurality of shaping members, each of the plurality of shaping members including at least two laser reflecting surfaces; and a perforating head coupled to the housing. The perforating head includes: an optical path formed to receive the laser beam from the laser tool and output the laser beam toward the subsurface formation through an outlet of the perforating head; and at least one conduit separate from the optical path and configured to receive at least a portion of the plurality of shaping members from the chamber and output the portion of the plurality of shaping members through an outlet of the perforating head.

[0004] In one aspect that may be combined with the example implementations, the plurality of shaping members includes a plurality of polyhedrons, each of the plurality of polyhedrons including at least two laser reflecting surfaces.

[0005] In another aspect that may be combined with any of the preceding aspects, the plurality of polyhedrons include a first portion that is a first polyhedron having a first number of laser reflecting surfaces and a second portion that is a second polyhedron having a second number of laser reflecting surfaces different from the first number.

[0006] In another aspect that may be combined with any of the preceding aspects, each of the plurality of polyhedrons includes a number of reflective surfaces equal to a number of faces of the polyhedron.

[0007] In another aspect that may be combined with any of the preceding aspects, each of the reflective surfaces comprises a unique angle of incidence and a unique angle of reflection relative to the other reflective surfaces.

[0008] In another aspect that may be combined with any of the preceding aspects, at least one of the plurality of polyhedrons comprises a tetrahedron, a cube, a decahedron, an octahedron, a dodecahedron, or an icosahedron.

[0009] In another aspect that may be combined with any of the preceding aspects, each of the at least two laser reflecting surfaces comprises a mirror surface or a coated surface.

[0010] In another aspect which may be combined with any of the preceding aspects, the laser tool is configured to be coupled to the laser generator via a fiber optic cable.

[0011] In another aspect that may be combined with any of the preceding aspects, the laser generator is configured to generate a laser beam and transmit the generated laser beam to the laser tool via a fiber optic cable.

[0012] In another aspect that may be combined with any of the preceding aspects, the perforating head further comprises: at least one focusing lens located in the optical path and configured to shape the laser beam toward the outlet; and a cover glass located between the at least one focusing lens and the outlet and configured to protect the at least one focusing lens.

[0013] In another aspect that may be combined with any of the preceding aspects, at least one of the plurality of shaping members is hollow.

[0014] In another example implementation, a method for laser perforating a subterranean formation includes running a downhole tool on a downhole conveyor into a wellbore formed from the surface into the subterranean formation. The downhole tool includes a housing coupled to the downhole conveyor, a laser tool located within the housing, a chamber located within the housing, the chamber enclosing a plurality of shaping members, each of the plurality of shaping members including at least two laser reflecting surfaces, and a perforating head coupled to the housing. The method also includes: operating a laser tool to transmit a laser beam through an optical path formed in the perforating head and through an outlet of the perforating head to form a tunnel in the underground formation; after forming the tunnel in the underground formation with the laser beam, releasing at least a portion of the plurality of forming members from the chamber into the tunnel in the underground formation through the outlet of the perforating head; after releasing the portion of the plurality of forming members into the tunnel, operating the laser tool to generate another laser beam to reflect from at least some of the laser reflecting surfaces of the portion of the plurality of forming members; and forming at least one sub-tunnel from the tunnel into the underground formation using the another laser beam reflected from at least some of the laser reflecting surfaces of the portion of the plurality of forming members.

[0015] In one aspect that may be combined with the example implementations, the plurality of shaping members includes a plurality of polyhedrons, each of the plurality of polyhedrons including at least two laser reflecting surfaces.

[0016] In another aspect which may be combined with any of the preceding aspects, the method further comprises: forming a plurality of sub-tunnels from the tunnel into the underground formation using another laser beam reflected from at least two laser reflecting surfaces of the plurality of polyhedrons.

[0017] In another aspect that may be combined with any of the preceding aspects, the plurality of polyhedrons include a first portion that is a first polyhedron having a first number of laser reflecting surfaces and a second portion that is a second polyhedron having a second number of laser reflecting surfaces different from the first number.

[0018] In another aspect that may be combined with any of the preceding aspects, each of the plurality of polyhedrons includes a number of reflective surfaces equal to a number of faces of the polyhedron.

[0019] In another aspect that may be combined with any of the preceding aspects, each of the reflective surfaces comprises a unique angle of incidence and a unique angle of reflection relative to the other reflective surfaces.

[0020] In another aspect that may be combined with any of the preceding aspects, at least one of the plurality of polyhedrons comprises a tetrahedron, a cube, an octahedron, a dodecahedron, or an icosahedron.

[0021] In another aspect that may be combined with any of the preceding aspects, forming at least one sub-tunnel from the tunnel into the underground formation using another laser beam reflected from at least some of the laser reflecting surfaces of that portion of the plurality of forming members includes: forming at least one sub-tunnel from the tunnel into the underground formation using another laser beam reflected from mirror surfaces or coating surfaces of at least some of the laser reflecting surfaces of that portion of the plurality of forming members.

[0022] In another aspect that may be combined with any of the preceding aspects, the method further comprises: generating the laser beam using a laser generator; and transmitting the generated laser beam from the laser generator to the laser tool through the fiber optic cable.

[0023] In another aspect which may be combined with any of the preceding aspects, the tunnel is formed substantially perpendicular to the length of the wellbore, and at least one sub-tunnel is formed to enter the underground formation at an angle from the tunnel.

[0024] In another aspect which may be combined with any of the preceding aspects, the tunnel is formed substantially perpendicular to the length of the wellbore.

[0025] In another aspect that may be combined with any of the preceding aspects, a plurality of sub-tunnels are formed to enter underground strata from the tunnel at a certain angle, at least one of the plurality of sub-tunnels is formed to form a first angle with the tunnel, and at least another one of the plurality of sub-tunnels is formed to form a second angle with the tunnel that is different from the first angle.

[0026] In another aspect that may be combined with any of the preceding aspects, the method further comprises producing fluid from the underground formation into the at least one sub-tunnel and from the at least one sub-tunnel through the tunnel into the wellbore.

[0027] In another aspect that may be combined with any of the preceding aspects, the fluid comprises a hydrocarbon fluid.

[0028] Implementations of systems and methods for forming perforation tunnels using downhole laser tools according to the present disclosure may include one or more of the following features. For example, an example implementation according to the present disclosure may create a network of perforation tunnels by applying a laser beam to improve fluid flow from a hydrocarbon-bearing formation to a wellbore for production by using a forming member. As another example, an example implementation according to the present disclosure may create multiple laser perforation tunnels by applying a laser beam to a subsurface formation once and using the reflected laser beam to increase the production of the wellbore. As another example, a multi-directional laser perforation sub-tunnel may be created from a single laser perforation tunnel in a subsurface formation according to an example implementation of the present disclosure.

[0029] The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter described will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of an example implementation of a wellbore system including a downhole tool for laser perforating a subterranean formation according to the present disclosure.

[0031] Figure 2 is a schematic diagram of another example implementation of a wellbore system according to the present disclosure, the wellbore system including a downhole tool for laser perforating a subterranean formation.

[0032] Figure 3 is a schematic diagram of another example implementation of a downhole tool for laser perforating a subterranean formation according to the present disclosure.

[0033] Figure 4 Included are schematic diagrams of example implementations of shaping members for use in a downhole tool for laser perforating a subterranean formation according to the present disclosure.

[0034] Figure 5Included is a schematic diagram of an example implementation of a shaping member receiving and reflecting a laser beam from a downhole tool for laser perforating a subterranean formation according to the present disclosure.

[0035] Figure 6 is a schematic diagram of a perforating head of a downhole tool for laser perforating a subterranean formation according to the present disclosure.

[0036] Figure 7 A schematic diagram of a laser perforating operation including utilizing a downhole tool for laser perforating a subterranean formation in accordance with the present disclosure.

[0037] Figure 8 is a graph showing penetration rates of a laser beam through different rock types in accordance with the present disclosure.

[0038] Figure 9A-9B Shown are photographs and CT scans of rock samples that have been laser perforated.

[0039] Figure 10A-10B Shown are photographs and CT scans of rock samples that have been laser perforated. DETAILED DESCRIPTION

[0040] Figure 1 is a schematic diagram of a wellbore system 10 including a downhole tool 100 for laser perforating a subterranean formation (ie, a rock formation) from a wellbore according to the present disclosure. Figure 1 A portion of one embodiment of a wellbore system 10 according to the present disclosure is generally shown, wherein a downhole tool 100 can be run into a wellbore 20 and activated to laser perforate a formation with a laser beam 105 to form one or more tunnels 55, and as described in more detail herein, to form one or more sub-tunnels from the tunnel 55 with a laser beam reflected from one or more shaping members inserted into the tunnel 55 by the downhole tool 100. In this example, the downhole tool 100 is connected to a downhole conveyance device 45 during operations of running into and out of the wellbore 20. The downhole conveyance device 45 can be, for example, a cable or wireline or other conductor. In an alternative example, the downhole conveyance device 45 can be a tubing string (e.g., a drill string composed of drill pipe sections, a tubing string, or a coiled tubing). In some aspects, the downhole conveyance device 45 can include two or more conveyance devices, such as a conveyance device for running in and out operations, and a conveyance device (e.g., a fiber optic cable) that supplies a generated laser beam to the downhole tool 100 (which is then transmitted as a laser beam 105).

[0041] According to the present disclosure, a downhole tool 100 may be run into a wellbore 20 to laser perforate a subsurface formation 40 to form tunnel(s) 55 and sub-tunnels for fluid production, such as hydrocarbon fluid production, from the wellbore 20. The dimensions (e.g., diameter and length) of the perforation tunnels and tunnels 55 may be controlled by the beam size of the laser beam 105. For example, a relatively small beam size may create a smaller tunnel 55, while a relatively large beam size may create a larger tunnel 55. In some aspects, the laser beam 105 may create tunnels 55 regardless of rock type (or in most rock types from which hydrocarbon fluids may be produced). Briefly referring to Figure 8 , which shows a graph 800 of the penetration rate of a laser beam relative to rock type. In graph 800, the x-axis 802 represents the rock type, showing limestone, shale, different sandstones, and different granites. In graph 800, the y-axis 804 represents the penetration rate of the laser beam in feet per hour (ft. / hr.). As shown, the laser beam technology can create tunnels in rock formations at speeds ranging from about 70 ft / hr to 120 ft / hr, depending on the rock type.

[0042] Further experiments with the laser technique showed that tunnels could be formed in different rock types. Fig. 9A , which shows an image 900 of a rock sample in which a laser perforated tunnel 902 has been formed. A CT scan 904 of the same rock sample shows a tunnel 906 scanned through the sample. Fig. 9B , which shows an image 910 of a rock sample in which two laser perforated tunnels 912 have been formed. A CT scan 914 of the same rock sample shows the tunnels 912 scanned through the sample. Fig. 10A As further shown, the figure shows an image 1000 of a relatively large laser perforated tunnel formed in a block of sandstone. Fig. 10A Also shown is an image 1010 of a plurality of smaller laser-perforated tunnels precisely formed in a block of sandstone, in contrast. Fig. 10B , which shows an image 1015 of a rock sample before laser perforation, while a CT image 1020 shows the rock sample after laser perforation. As these examples show, laser technology has sufficient precision to control the laser to form a tunnel with a specific size and direction and orientation relative to the rock formation.

[0043] Back to Figure 1, the wellbore system 10 enters a subsurface formation 40 (and other formations) and provides access to hydrocarbons located in such subsurface formation 40. In an example implementation of the system 10, the system 10 may be used in production operations, wherein hydrocarbons may be produced from the subsurface formation 40 within the wellbore tubing (e.g., through the production casing 35 or other production tubing) after laser perforation (and possibly other completion operations) is performed.

[0044] A drilling assembly (not shown) may be used to form a wellbore 20 extending from the surface 12 and through one or more geological formations in the earth. One or more subsurface formations, such as subsurface formation 40, are located below the surface 12. One or more wellbore casings, such as surface casing 30 and production casing 35, may be installed in at least a portion of the wellbore 20. In some embodiments, the drilling assembly used to form the wellbore 20 may be deployed on a body of water rather than the surface 12. For example, in some embodiments, the surface 12 may be an ocean, a bay, a sea, or any other body of water under which hydrocarbon-bearing formations may be found. In short, reference to the surface 12 includes both land and water surfaces, and contemplates the formation and development of one or more wellbore systems 10 from either or both locations.

[0045] In some embodiments of the wellbore system 10, the wellbore 20 may be covered by one or more casings. As shown, the wellbore 20 includes a conductor casing 25 extending from the surface 12 to a shorter distance underground. A portion of the wellbore 20 surrounded by the conductor casing 25 may be a large diameter borehole. In addition, in some embodiments, the wellbore 20 may deviate from a vertical line (e.g., an inclined wellbore). In addition, in some embodiments, the wellbore 20 may be a stepped wellbore, so that a portion is drilled vertically downwards and then bent to a substantially horizontal wellbore portion. Additional substantially vertical and substantially horizontal wellbore portions may be added, depending on, for example, the type of the surface 12, the depth of one or more target underground formations, the depth of one or more productive underground formations, or other criteria.

[0046] Inside the well of the conductor casing 25 may be a surface casing 30. The surface casing 30 may surround a slightly smaller borehole and protect the wellbore 20 from intrusion from, for example, a freshwater aquifer located near the surface 12. The wellbore 20 may then extend vertically downward. This portion of the wellbore 20 may be surrounded by a production casing 35. Any of the casings shown, as well as other casings or tubing that may be present in the wellbore system 10, may comprise a wellbore liner.

[0047] Downhole tool 100 includes a laser tool for creating a fluid flow path through a hydrocarbon-bearing rock formation. The laser tool can be operated downhole to create a fluid flow path (e.g., tunnel 55 and sub-tunnels) through a wellbore casing (e.g., casing 35) and a rock formation (e.g., underground formation 40). The fluid flow path is created by controlling the laser tool to direct a laser beam to rock in the rock formation. In this example, the laser beam has an energy density sufficient to sublimate at least some of the rock in the rock formation. Sublimation includes changing directly from a solid phase to a gas phase without first changing to a liquid phase. In the case of rock, sublimation occurs when the laser beam increases the temperature of the rock to exceed a threshold. This threshold is called the sublimation point and can be different for different types of rock. In this example, the sublimation of the rock creates tunnels or cracks through the rock formation. Fluids can be introduced into these tunnels or cracks to fracture the rock formation, thereby facilitating the flow of production fluids such as oil from the rock formation into the wellbore.

[0048] The example downhole tool 100 may also include one or more sensors to monitor environmental conditions in the wellbore 20 and output signals indicative of the environmental conditions. Examples of sensors may include temperature sensors for measuring downhole temperature, pressure sensors for measuring downhole pressure, and acoustic sensors for measuring downhole noise levels. Other sensors may also be used as described herein. The signals received from the sensors may indicate a problem within the wellbore 20 or a problem with the laser tool of the downhole tool 100. The drilling engineer may take corrective action based on these signals. For example, if the downhole temperature or pressure may cause damage to drilling equipment such as a laser tool, the equipment may be withdrawn from the wellbore.

[0049] Figure 2 Components of a system 200 including an implementation of a laser tool 230 (i.e., a downhole tool including a laser tool) according to the present disclosure are shown. At least a portion of the system 200 is disposed within a wellbore 204. The wellbore 204 passes through a hydrocarbon-bearing formation 202 ("formation 202"). The formation 202 may include a variety of materials, such as limestone, shale, or sandstone. Each of these materials has a different sublimation point. The sublimation point may be affected by material properties, such as the density of the material and the porosity of the material. A casing 208 is cemented 206 in place to strengthen the wellbore against the formation 202. A tubular string 215 containing the laser tool 230 extends downhole through the casing 208.

[0050] The laser tool 230 is configured to output a laser beam 160. In this example, the laser tool is also configured to rotate around an axis in the wellbore 204 (e.g., the central axis of the wellbore 204). In some implementations, the laser tool 230 is mounted on an axis (not shown) for rotation. A motor 232 may be included in the tubular string 215 to enable rotation of the laser tool 230 around the axis. In some implementations, the entire tubular string 215 is connected to a drive 246, which is configured to rotate the tubular string 215, thereby rotating the laser tool 230. The rotation of the laser tool 230 is indicated by the circular arrow 211. During the rotation, the laser beam 160 can sweep across the entire circumference of the wellbore. That is, the laser tool can rotate a full 360°. In some cases, the laser tool can rotate less than 360°.

[0051] The laser tool 230 is configured to direct the laser beam 160 parallel to a surface containing a wellhead or at an angle that is non-parallel to the surface. The laser tool 230 includes a chamber that houses one or more (typically a plurality of) shaping members that may be disposed in a laser perforation tunnel to subsequently create sub-tunnels from the tunnel into the formation 202. As described more fully herein, such sub-tunnels may be created by reflection of the generated laser beam 260 from a reflective surface of a shaping member located in a previously formed perforation tunnel.

[0052] The system 200 includes a laser generating unit, such as a laser generator 210. The laser generator 210 is configured to generate a laser beam and output the laser beam to a laser tool 230. In some implementations, the laser generator 210 is located at the surface near the wellhead. In some implementations, the laser generator 210 is located in whole or in part downhole. The laser beam output by the laser generator 210 is referred to as a raw laser beam because it has not yet been manipulated by the laser tool 230. Examples of the laser generator 210 include ytterbium lasers, erbium lasers, neodymium lasers, dysprosium lasers, praseodymium lasers, and thulium lasers. In an example implementation, the laser generator 210 is a 5.34 kilowatt (kW) ytterbium-doped multi-clad fiber laser.

[0053] In some implementations, the laser generator 210 can be configured to output laser beams with different energy densities. Laser beams with different energy densities can be useful for rock formations composed of different materials with different sublimation points. For example, laser beams with different energy densities can be used to sublimate different types of rocks in a rock formation. In some implementations, the operation of the laser generator 210 is programmable. For example, the laser generator 210 can be programmed to change the optical properties of the laser beam or the energy density of the laser beam.

[0054] In some implementations, the laser beam output by the laser generator 10 has an energy density sufficient to heat at least some rock to its sublimation point. In this regard, the energy density of the laser beam is a function of the average power output of the laser generator during the laser beam output. In some implementations, the average power output of the laser generator 210 is in one or more of the following ranges: between 500 Watts (W) and 1000 W, between 1000 W and 1500 W, between 1500 W and 2000 W, between 2000 W and 2500 W, between 2500 W and 3000 W, between 3000 W and 3500 W, between 3500 W and 4000 W, between 4000 W and 4500 W, between 4500 W and 5000 W, between 5000 W and 5500 W, between 5500 W and 6000 W, between 6000 W and 6500 W, or between 6500 W and 7000 W.

[0055] The laser generator 210 may be part of an optical path that includes a laser tool 230 and one or more optical transmission media. An example of an optical transmission medium that may be used is a fiber optic cable 220. The fiber optic cable 220 may include a single fiber bundle, multiple fiber bundles, or multiple fiber optic cables extending from the laser generator 210 downhole. The fiber optic cable 220 conducts the original laser beam output by the laser generator 210 to the laser tool 230. As described above, the laser tool 230 may manipulate the laser beam to change the geometry of the laser beam, the direction of the laser beam, or both. The laser beam 160 output from the laser tool may penetrate downhole casing and cement to reach the rock formation. In Figure 2 In the example of , this means that the laser beam 260 leaves the tubular string 215 and penetrates the casing 208 and cement 206 to reach the rock formation 202. The system can be configured to minimize or reduce power loss along the optical path. In some implementations, the power density or energy density of each laser beam 160 (at the target of the laser beam) is 70% or more of the power density and energy density of the laser beam output by the laser generator 210.

[0056] The duration that the laser beam 260 is applied to the rock in the formation 202 may affect the extent to which the laser beam sublimates the rock and thus penetrates the rock. For example, the longer the laser beam 260 is applied to a particular location, the greater the extent of rock penetration at that location.

[0057] In some implementations, the laser generator 210 is configured to operate in an operating mode until the target penetration depth is reached. The operating mode may include a cyclic mode, a continuous mode, or both. During the continuous mode, the laser generator 210 continuously, for example, uninterruptedly, generates a laser beam. In the continuous mode, the laser generator 210 generates a laser beam until the target penetration depth is reached. During the cyclic mode, the laser generator 210 cycles between on and off. In some implementations, the laser generator 310 generates a laser beam during the on period. In some implementations, the laser generator 210 does not generate a laser beam during the off period. In some implementations, the laser generator 210 generates a laser beam during the off period, but the laser beam is interrupted before reaching the downhole laser tool 230. For example, the laser beam can be safely diverted, or the laser beam can be blocked and cannot be output. The laser generator 210 can operate in a cyclic mode to reduce the possibility of overheating of one or more components of the system, clear the path of the laser beam, or both.

[0058] In the cycle mode, the duration of the on period can be the same as the duration of the off period. In the cycle mode, the duration of the on period can be greater than the duration of the off period, or the duration of the on period can be less than the duration of the off period. The duration of each on period and each off period can be based on the target penetration depth. Other factors that affect the duration of the on period and the duration of the off period include, for example, rock type, purging method, laser beam diameter, and laser power.

[0059] The duration of each on period and each off period can be determined experimentally. Experiments can be conducted on rock samples in the formation before or after the laser tool is lowered into the wellbore. Such experiments can be conducted to determine the optimal or improved duration of each on period and each off period for the circulation pattern. Alternatively or additionally, the duration of each on period and each off period can be determined by geological methods. For example, seismic data or underground geological maps of the rock formation 202 can be analyzed, and the duration can be based on the results of one or more analyses.

[0060] In some implementations, the on period and the off period may last from 1 to 5 seconds. In one example operation, the on period lasts for 204 seconds and the off period lasts for 204 seconds. Such an operation may allow the laser beam to penetrate a rock formation composed of Berea sandstone to a depth of 230 centimeters (cm).

[0061] In this regard, the selection of the operating mode can be based on the type of rock to be penetrated and the target penetration depth. Rock formations that may require the laser generator to be operated in a cyclic mode include, for example, sandstones with a large quartz content, such as Berea sandstone. Rock formations that may require the laser generator to be operated in a continuous mode include, for example, limestone.

[0062] The target penetration depth can be determined based on a variety of factors, such as the type of material or rock in the formation, the maximum horizontal stress of the material or rock in the formation, the compressive strength of the material or rock in the formation, the desired penetration depth, or a combination of two or more of these characteristics. In some examples, the penetration depth is measured from the inner wall of the wellbore. Examples of penetration depths can be on the order of millimeters, centimeters, or meters. Examples of penetration depths can include a penetration depth between 200 millimeters (mm) and 210 mm, a penetration depth between 200 centimeters (cm) and 100 cm, and a penetration depth between 200 meters (m) and 200 m.

[0063] In this example implementation, the system 200 includes a motion system 240. The motion system may include, for example, a hydraulic system, an electrical system, or a motor operating system to move the laser tool to a target location. In this regard, the motion system is configured to move the laser tool 230 to different locations within the wellbore 204, such as different depths. To this end, the motion system includes at least one component that can move within the wellbore, such as a downhole conveyor. For example, the motion system may include a cable 242 that is configured to move uphole or downhole to enable the laser tool 230 to reach a target height. In an example, the cable 242 may be at least partially wound on a reel. A motor 244 may be connected to the reel. The motor 244 is configured to drive the reel to wind or unwind the cable 242. This allows the cable 242 to move uphole or downhole within the wellbore.

[0064] The cable 242 is physically connected to the tubular string 215 so that movement of the cable 242 translates into corresponding movement of the tubular string 215. As described above, the tubular string 215 may include the laser tool 230. Thus, when the tubular string 215 moves, the laser tool 30 also moves. Thus, the length of the cable 242 within the wellbore may be controlled to position the laser tool.

[0065] In some implementations, the motion system uses a component other than cable 242 to move the laser tool. For example, the motion system can be connected to tubing string 215 using a coiled tubing string. The coiled tubing string can be moved uphole or downhole in the same manner as cable 242 is moved uphole or downhole.

[0066] In some implementations, the motion system can include a rotational drive system to achieve rotation of the tubular string 215, thereby achieving rotation of the laser tool 230 about an axis in the wellbore. In an example implementation, the rotational drive system includes a motor and a transmission system, such as a shaft or a rack and pinion arrangement (not shown) connected to the cable 242 to achieve rotation of the tubular string 215.

[0067] The computing system may be configured (e.g., programmed) to control the positioning and operation of the laser tool 230. Examples of computing systems that may be used are described in this specification. Alternatively or additionally, the laser generator may be configured to control the positioning and operation of the laser tool 230. For example, the laser generator 210 may include circuitry or may include an onboard computing system to enable control of the positioning and operation of the laser tool. In either case, signals may be exchanged with the motion system and the laser tool via a wired or wireless connection. In some implementations, signals may be exchanged with the motion system or the laser tool via an optical fiber medium.

[0068] During operation, the laser tool 230 can relay its angular position to a control system, such as a computing system or a laser generator. In response, the control system can operate the tool to form a tunnel or fracture in the rock formation. In these aspects, the control system is intended to include various forms of digital computing hardware. Generally, the control system can include one or more processors, one or more memory components, and in some aspects, input / output devices. Each component can be interconnected using a system bus. Certain features of the control system can be implemented in digital electronic circuits in a controller, or in computer hardware, firmware, software, or a combination thereof. Features can be implemented in a computer program product tangibly contained in an information carrier (e.g., in a machine-readable storage device) for execution by a programmable processor, and the method steps can be performed by a programmable processor that executes an instruction program to perform the functions of the described implementation by operating on input data and generating output. The described features can be advantageously implemented in one or more computer programs that can be executed on a programmable system that includes at least one programmable processor, at least one input device, and at least one output device, and the programmable processor is coupled to receive data and instructions from a data storage system and send data and instructions to a data storage system. A computer program is a set of instructions that can be used directly or indirectly in a computer to perform a specific activity or produce a specific result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0069] The materials used to implement the downhole components of the system 200 can withstand the temperatures, pressures, and vibrations that may be experienced within the wellbore 204. These materials can protect the system from fluids, dust, and debris. In some implementations, the material includes one or more of iron, nickel, chromium, manganese, molybdenum, niobium, cobalt, copper, titanium, silicon, carbon, sulfur, phosphorus, boron, tungsten, steel, alloy steel, stainless steel, or tungsten carbide.

[0070] Figure 3 is a schematic diagram of another example implementation of a downhole tool 300 for laser perforating a subterranean formation according to the present disclosure. In some aspects, the downhole tool 300 may be used to Figure 1 or Figure 2 , and the like, for laser perforating a wellbore to form tunnels and sub-tunnels (i.e., additional tunnels extending from the laser perforated tunnel due to reflected laser energy) in a subsurface formation. In this example, a downhole tool 300 is shown coupled to a downhole conveyor 45 in the wellbore 20, which facilitates movement of the downhole tool 300 uphole and downhole in the wellbore 20, and in some aspects (as shown in reference Figure 2 As described above), it helps the downhole tool 300 to rotate in the wellbore 20.

[0071] In this example implementation, downhole tool 300 includes a housing 302 coupled to conveyance device 45 (e.g., threadedly or otherwise). A laser perforating tool 306 (or laser tool 306) and chamber 304 are coupled to or located within housing 302. A perforating head 308 is coupled to or located within housing 302 at a downhole end of downhole tool 300.

[0072] Typically, the laser tool 306 (in this example) is connected within an optical path for delivering the laser beam 350 from the outlet of the perforating head 308. In some aspects, the optical path includes a fiber optic cable 50 connected to, for example, a laser generator located in a working string including the downhole tool 300 or at the surface (as shown in reference Figure 2 In some aspects, the fiber optic cable 50 can extend to (or through) the laser tool 306 to deliver the raw (eg, unshaped) laser beam 320 to the perforating head 308 .

[0073] The chamber 304 comprises a volume sized to enclose a plurality of forming members, e.g. Figure 4 An example implementation of a shaping member is shown. Figure 4Examples of forming members 400, 408, 416, 424, and 432 are shown. In these examples, the forming members are polyhedrons (e.g., generally spherical members having a plurality of faces). Examples of polyhedrons may include tetrahedrons, decahedrons, cubes, octahedrons, dodecahedrons, and icosahedrons, among many other examples. As shown in these examples, each forming member 400, 408, 416, 424, and 432 has a plurality of faces 402, 410, 418, 426, and 434, respectively. The number of the plurality of faces 402, 410, 418, 426, and 434 depends on the type of polyhedron (e.g., an octahedron has 8 faces, a dodecahedron has 12 faces, and so on).

[0074] exist Figure 4 In the example implementation of the forming member shown, at least some faces (in some aspects, all faces) of the forming member can include a laser reflective surface (e.g., a mirror surface or a coated surface). Examples of materials or surfaces from which the faces (in some aspects, the entire forming member) can be made include mirror-polished quartz, sapphire, aluminum, bronze, or steel, as well as other examples that can reflect light (or are coated with materials that can reflect light). In some aspects, examples of forming members 400, 408, 416, 424, and 432 are solid. In other examples, forming members 400, 408, 416, 424, and 432 are hollow.

[0075] Back to Figure 3 , a perforating head 308 is connected to the housing 302 at the downhole end and is used to output a focused (eg, shaped) laser beam 350 toward the casing 35 (and the subterranean formation 40). Figure 6 , which shows a more detailed view of the perforating head 308. Figure 6 As shown, the fiber optic cable 50 delivers the raw laser beam 320 to an optical path 314 in the perforating head 308 toward one or more focusing lenses 310. The focusing lenses 310 may shape the raw laser beam 320 into a particular desired shape, for example, depending on the type and focus of these lenses 310. For example, the lenses 310 shape the raw laser beam 320 to produce a desired beam shape and size, which in turn will determine the size of the laser perforation tunnel formed by the focused laser beam 350.

[0076] In some aspects of the downhole tool 300, the lens 310 can be a mono-optic element. An example of a mono-optic element is a unitary optical structure that is configured, for example, constructed, arranged, or both, to manipulate a laser beam. Manipulation includes changing one or more properties of a laser beam. Examples of mono-optic elements include crystals and lenses. Other examples of mono-optic elements are provided in this specification. The mono-optic element can be configured to receive a raw laser beam 320 output from a laser generator via an optical path 314. The optical path can include one or more optical transmission media, such as optical fiber cables, strung downhole. The received laser beam is "raw" because the laser beam has not yet been acted upon by a mono-optic element. The mono-optic element manipulates the raw laser beam by changing the geometry of the raw laser beam, the direction of the raw laser beam, or both the geometry and the direction of the raw laser beam. The laser beam output by the mono-optic element is directed to the rock formation as a laser beam 350. As previously described, the laser beam heats the rock to form a tunnel or crack in the rock formation.

[0077] The shaped laser beam 350 then passes through the cover glass 318 and reaches the outlet 328 of the perforating head 308. The cover glass 318 can prevent the focused laser beam 350 from being reflected back to the perforating head 308 unnecessarily and protect the focusing lens 310 (or lenses 310).

[0078] As shown in this example, one or more conduits 312 (two in this example) extend through the perforating head 308, separate from the optical path 314, and may house a plurality of shaping members 316 (e.g., one or more of shaping members 400, 408, 416, 424, or 432, or a combination thereof). The shaping members 316 may be released from the chamber 304 to travel or fall into the conduits 312, or, alternatively, the conduits 312 may extend to the chamber 304 and be filled with the shaping members 316 during operation of the downhole tool 300. For example, the chamber 304 may be pressurized (e.g., with fluid from the surface or otherwise) to urge the shaping members 316 from the chamber 304 into the conduits 312 (and out of the conduits 312 into the laser perforation tunnel).

[0079] like Figure 6 As further shown, one or more conduits 312 are also coupled to an outlet 328 of the perforating head 308 to allow the one or more shaping members 316 to exit the perforating head 308 through the outlet 328 (eg, when the focused laser beam 350 is not output through the outlet 328).

[0080] like Figure 6As further shown, the perforating head 308 can include one or more lens purge devices 324 (e.g., at least one lens purge device per lens 310). In some aspects, the lens purge device 324 is located on one side (or one on each side) of the lens 310 and can provide a purge gas to clean and cool the lens 310 (e.g., during or after the laser tool is operated to provide the raw laser beam 320) as the lens 310 heats up due to the laser energy.

[0081] The perforating head 308 may also include a tool purge device 322. The tool purge device 322 may be used to clear the path of the focused laser beam 350 and prevent any debris from entering the perforating head 308 through the outlet 328 and damaging the lens 310.

[0082] like Figure 6 As shown, one or more sensors 326 may be mounted or positioned in the perforating head 308, such as at or near the outlet 328. Figure 2 As described, one or more sensors 326 can be used to monitor environmental conditions in the wellbore and output signals indicating the environmental conditions. Examples of sensors may include temperature sensors for measuring downhole temperature, pressure sensors for measuring downhole pressure, and acoustic sensors for measuring downhole noise levels. The signals received from the sensors may indicate that there is a problem in the wellbore or a problem with the laser tool 306 of the downhole tool 300.

[0083] Figure 7 The present invention includes a schematic diagram of a laser perforation operation using a downhole tool 300, and specifically an example sequence of operations of a perforating head 308 of the downhole tool 300. In an example operation, the downhole tool 300 can be run to a specific depth or location in a wellbore (e.g., on a downhole conveyor 45 and coupled to a fiber optic cable 50). Once at a desired location in the wellbore, the laser tool 306 can be operated to transmit a raw laser beam 320 from a laser generator to the perforating head 308 (e.g., via an optical path 314). Figure 7 The original laser beam 320 is shaped and focused by one or more lenses 310 and output through the outlet 328 of the perforating head 308 toward the underground formation (and casing or other tubulars, if present), as shown in FIG. Figure 7 As shown in (A) in Figure 7 As shown in (A), the focused laser beam 350 forms a tunnel 700 in the underground formation.

[0084] After forming the tunnel 700, the laser tool 306 is deactivated, stopping the delivery of the original laser beam 320 to the perforating head 308, as shown in FIG. Figure 7Next, one or more (and possibly many) shaping members 216 are released from the perforating head 308 to move through the (one or more) conduits 312, the outlet 328, and into the tunnel 700. In some aspects, a fluid (e.g., a gas) or other substance (e.g., a gel) may be circulated through the conduit 312 to urge the shaping members 316 through the outlet 328 and into the tunnel 700. This is also Figure 7 In some aspects, the size and / or number of shaping members 316 can be designed according to the size (eg, diameter and / or length) of tunnel 700 .

[0085] Once the forming member 316 has been positioned in the tunnel 700 (as shown in (B) of the figure), the laser tool 306 can be activated again to transmit the original laser beam 320 to the perforating head 308 through the optical path 314, as shown in FIG. Figure 7 Then, as shown in the figure, the focused laser beam 350 can be output through the outlet 328 to contact the forming member 316 and be reflected by it. Figure 5 , which shows a shaped member that receives and reflects a laser beam from a downhole tool such as downhole tool 300. As shown in the figure, Figure 5 Different views (A)-(C) of a forming member 500 are included that have multiple laser reflective surfaces that receive a focused laser beam 504 and reflect the focused laser beam 504 as reflected laser beams 502. As shown, each focused laser beam 504 contacts the forming member at a specific angle of incidence, and each reflected laser beam 502 reflects from the forming member 500 at a specific angle of reflection (e.g., depending on which reflective surface receives the focused laser beam 504 and depending on the angle of incidence). Thus, for a single forming member 500, a single focused laser beam 504 can generate multiple reflected laser beams 502.

[0086] Back to Figure 7 700, and produces a reflected laser beam 702 to subsequently create sub-tunnels 706 in the underground formation. The number of sub-tunnels 706 and the orientation of each sub-tunnel 706 relative to the tunnel 700 from which the sub-tunnel 706 extends can depend on, for example, the incident angle of the focused laser beam 350 on the particular shaping member 316 and the reflection angle of the reflected laser beam 702 reflected from the particular shaping member 316.

[0087] like Figure 7As further shown in (C), tunnel 700 and sub-tunnel 706 can form a fluid path for fluid 704 from the underground formation to the wellbore. Fluid 704 can be a hydrocarbon fluid or other fluid. In some aspects, fluid 704 can be produced to the surface. In some aspects, the flow of fluid 704 can also circulate shaping member 316 from tunnel 700 into the wellbore (for recovery to the surface or not to the surface).

[0088] Once the sub-tunnel 706 has been created, the laser tool 306 may be deactivated. Figure 7 The described example operating steps may be repeated at different depths in the wellbore or at the same depth but at different radial locations within the wellbore. For example, the downhole tool 300 may be rotated on the conveyor 45 (as previously described) and additional tunnels 700 and sub-tunnels 706 may be formed at one or more other radial locations at a particular depth in the wellbore. Furthermore, the downhole tool 300 may be moved (uphole or downhole) and additional tunnels 700 and sub-tunnels 706 may be formed at multiple depths in the wellbore.

[0089] A number of implementations have been described. However, it should be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. For example, the example operations, methods, or processes described herein may include more or fewer steps than those described. In addition, the steps in these example operations, methods, or processes may be performed in an order different from that described or shown in the figures. Therefore, other implementations are within the scope of the appended claims.

Claims

1. A downhole tool comprising: a housing configured to be coupled to a downhole conveyance device extendable from the surface through the wellbore and into a subterranean formation; a laser tool located within the housing and configured to transmit a laser beam sufficient to form a tunnel in the subterranean formation; a chamber located within the housing and configured to enclose a plurality of forming members, each of the plurality of forming members including at least two laser reflective surfaces; as well as A perforating head is coupled to the housing, the perforating head comprising: an optical pathway formed to receive a laser beam from the laser tool and output the laser beam toward the subsurface formation through an outlet of the perforating head; as well as At least one conduit is separate from the optical path and is configured to receive at least a portion of the plurality of shaping members from the chamber and output the portion of the plurality of shaping members through an outlet of the perforating head.

2. The downhole tool according to claim 1, wherein: The plurality of forming members includes a plurality of polyhedrons, each of the plurality of polyhedrons includes the at least two laser reflecting surfaces.

3. The downhole tool according to claim 2, wherein: The plurality of polyhedrons include a first portion that is a first polyhedron having a first number of laser reflecting surfaces and a second portion that is a second polyhedron having a second number of laser reflecting surfaces that is different from the first number.

4. The downhole tool according to claim 2, wherein: Each of the plurality of polyhedrons includes a number of reflective surfaces equal to a number of faces of the polyhedron.

5. The downhole tool according to claim 4, wherein: Each of the reflective surfaces includes a unique angle of incidence and a unique angle of reflection relative to the other reflective surfaces.

6. The downhole tool according to claim 2, wherein: At least one of the plurality of polyhedrons includes a tetrahedron, a cube, a decahedron, an octahedron, a dodecahedron, or an icosahedron.

7. The downhole tool according to claim 1, wherein: Each of the at least two laser reflecting surfaces includes a mirror surface or a coating surface.

8. The downhole tool according to claim 1, wherein: The laser tool is configured to be coupled to a laser generator through a fiber optic cable, and the laser generator is configured to generate a laser beam and transmit the generated laser beam to the laser tool through the fiber optic cable.

9. The downhole tool according to claim 1, wherein: The perforating head further comprises: at least one focusing lens located in the optical path and configured to shape the laser beam toward the outlet; and The cover glass is located between the at least one focusing lens and the outlet and is configured to protect the at least one focusing lens.

10. The downhole tool according to claim 1, wherein: At least one of the plurality of shaping members is hollow.

11. A method for laser perforating a subterranean formation, the method comprising: A downhole tool on a downhole conveying device is run into a wellbore formed from the surface into an underground formation, wherein the downhole tool comprises: a housing coupled to the downhole conveying device, a laser tool, located within the housing, a chamber within the housing, the chamber enclosing a plurality of forming members, each of the plurality of forming members comprising at least two laser reflecting surfaces, and a perforating head coupled to the housing; operating the laser tool to transmit a laser beam through an optical path formed in the perforating head and through an outlet of the perforating head to form a tunnel in the subterranean formation; after forming the tunnel in the subterranean formation with the laser beam, releasing at least a portion of the plurality of shaping members from the chamber into the tunnel in the subterranean formation through an outlet of the perforating head; after releasing the portion of the plurality of forming members into the tunnel, operating the laser tool to generate another laser beam to reflect from at least some of the laser reflective surfaces of the portion of the plurality of forming members; and At least one sub-tunnel is formed from the tunnel into the underground formation using the another laser beam reflected from at least some of the laser reflecting surfaces of the portions of the plurality of forming members.

12. The method according to claim 11, wherein: The plurality of shaping members comprises a plurality of polyhedrons, each of the plurality of polyhedrons comprises the at least two laser reflecting surfaces, the method further comprising: A plurality of sub-tunnels are formed from the tunnel into the underground formation using the another laser beam reflected from the at least two laser reflecting surfaces of the plurality of polyhedrons.

13. The method according to claim 12, wherein: The plurality of polyhedrons include a first portion that is a first polyhedron having a first number of laser reflecting surfaces and a second portion that is a second polyhedron having a second number of laser reflecting surfaces that is different from the first number.

14. The method according to claim 12, wherein: Each of the plurality of polyhedrons includes a number of reflective surfaces equal to a number of faces of the polyhedron.

15. The method according to claim 14, wherein: Each of the reflective surfaces includes a unique angle of incidence and a unique angle of reflection relative to the other reflective surfaces.

16. The method according to claim 12, wherein: At least one of the plurality of polyhedrons includes a tetrahedron, a cube, an octahedron, a dodecahedron, or an icosahedron.

17. The method according to claim 11, wherein: Forming the at least one sub-tunnel from the tunnel into the underground formation using the other laser beam reflected from at least some of the laser reflecting surfaces of the parts of the plurality of forming components includes: forming the at least one sub-tunnel from the tunnel into the underground formation using the other laser beam reflected from the mirror surfaces or coating surfaces of at least some of the laser reflecting surfaces of the parts of the plurality of forming components.

18. The method according to claim 11, further comprising: generating a laser beam using a laser generator; as well as The generated laser beam is transmitted from the laser generator to the laser tool via a fiber optic cable.

19. The method according to claim 11, wherein: The tunnel is formed substantially perpendicular to the length direction of the wellbore, and the at least one sub-tunnel is formed to enter the underground formation at a certain angle from the tunnel.

20. The method according to claim 12, wherein: The tunnel is formed substantially perpendicular to the length of the wellbore, and The multiple sub-tunnels are formed to enter the underground stratum from the tunnel at a certain angle, at least one of the multiple sub-tunnels is formed to form a first angle with the tunnel, and at least another one of the multiple sub-tunnels is formed to form a second angle with the tunnel different from the first angle.

21. The method according to claim 11, further comprising: Fluid is generated from the subsurface formation into the at least one sub-tunnel and from the at least one sub-tunnel through the tunnel into the wellbore.

22. The method according to claim 21, wherein: The fluid comprises a hydrocarbon fluid.

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