Downhole torque-controllable horizontal well coring tool and method

Abstract

The application discloses a downhole torque-controllable horizontal well coring tool and method, which comprises a torque control structure, a second end of the torque control structure is sequentially connected with a measurement-while-drilling structure, a screw drill structure, an automatic ball launching structure and a coring structure; the torque control structure can be connected with an upper pipe column and the measurement-while-drilling structure to transmit the torque of the upper pipe column, or the torque control structure can be separated from the upper pipe column and the measurement-while-drilling structure to disconnect the torque transmission of the upper pipe column; the automatic ball launching structure can release a steel ball according to a pressure wave signal sent from the ground, and the steel ball can block a first end of a coring inner cylinder to make the coring inner cylinder extend outward to complete directional coring operation after the pump pressure is increased. The application applies the coring tool combination of the torque control structure, the measurement-while-drilling structure, the screw drill structure, the automatic ball launching structure and the coring structure, realizes the continuous rotation of the upper pipe column above the torque control structure, and realizes the directional coring operation of the horizontal section by combining the screw drill structure and the coring structure.

Description

Technical Field

[0001] This invention relates to the field of drilling and coring technology in the oil and gas industry, particularly to horizontal well coring technology, and especially to a downhole torque-controlled horizontal well coring tool and method. Background Technology

[0002] As major oilfields in China enter their mid-to-late stages of development, the application of horizontal wells is becoming increasingly widespread. However, due to the strong heterogeneity of reservoirs, the analysis and research of formation properties in horizontal sections are particularly important. Previous conventional vertical well coring data has insufficient guidance for tapping remaining oil potential. There is an urgent need in the field to conduct horizontal well coring and subsequent analysis of horizontal sections to accurately grasp the reservoir distribution patterns and provide theoretical basis and technical support for the overall effective development of the reservoir in the later stages. Furthermore, thin layers of 0.5-1 meter remain a no-go zone for horizontal coring, necessitating the acquisition of new horizontal core samples in the field.

[0003] Horizontal well construction, due to its high difficulty, technical requirements, and numerous uncertainties, is often described as "threading a needle a thousand meters underground." Controlling the horizontal wellbore trajectory is crucial for core extraction. Currently, various drill string combinations are employed in the field, with optimized technical parameters and precise software calculations to achieve accurate landing of the build-up section, improving single-tube core extraction footage and stable recovery rates in ultra-deep horizontal wells. Horizontal well core extraction often utilizes a composite drive (screw + top drive rotary table) method. Unlike conventional core extraction in vertical wells, the stress conditions in composite drilling are more complex, and the uncertainty in drill string trajectory control significantly impacts the effective core recovery rate. Furthermore, due to high frictional torque and common pressure issues in horizontal well core extraction, drilling pressure cannot be effectively transmitted to the drill bit, resulting in unstable mechanical drilling rates, which is detrimental to core insertion and affects core integrity.

[0004] Therefore, based on years of experience and practice in related industries, the inventor proposes a downhole torque-controllable horizontal well coring tool and method to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a downhole torque-controlled horizontal well coring tool and method, overcoming the problems of trajectory control difficulties, low mechanical drilling speed, and low coring recovery rate in existing horizontal well coring. It applies a coring tool combination of torque control structure + measurement while drilling structure + screw drill string structure + automatic ball dropping structure + coring structure, realizing continuous rotation of the upper tubing string above the torque control structure, and the combination of screw drill string structure and coring structure to realize directional coring operations in the horizontal section.

[0006] The objective of this invention is achieved as follows: a downhole torque-controllable horizontal well coring tool includes a torque control structure. A first end of the torque control structure is connected to the upper tubing string, and a second end of the torque control structure is sequentially connected to a measurement-while-drilling (MWD) structure, a screw drill string structure, an automatic ball dropping structure, and a coring structure. The torque control structure can connect the upper tubing string and the MWD structure to transmit the torque of the upper tubing string, or it can separate the upper tubing string and the MWD structure to disconnect the torque transmission from the upper tubing string. When the upper tubing and the measurement-while-drilling (MWD) structure are separated, the screw drill string structure can drive the MWD structure, the automatic ball-dropping structure, and the coring structure to rotate synchronously. The coring structure includes a coaxially arranged outer coring cylinder and an inner coring cylinder. The first end of the outer coring cylinder is connected to the automatic ball-dropping structure, and the second end of the outer coring cylinder is connected to the coring bit. The automatic ball-dropping structure can release steel balls according to the pressure wave signal sent from the ground. The steel balls can block the first end of the inner coring cylinder so that the inner coring cylinder extends outward after the pump pressure increases to complete the directional coring operation.

[0007] In a preferred embodiment of the present invention, the torque control structure includes a first housing, within which a torque controller, a torque control actuator, an upper clutch, and a lower clutch are disposed. The torque controller is fixedly connected to the first housing. The torque control actuator is circumferentially fixedly connected to the torque controller. The upper clutch is circumferentially fixedly connected to the torque control actuator, and the torque control actuator can drive the upper clutch to move axially. The lower clutch and the first housing are circumferentially rotatable relative to each other, and the lower clutch is connected to the measurement-while-drilling (MSD) structure. The torque controller controls the torque control actuator to move so that the upper clutch engages the lower clutch to transmit torque or disengages the upper clutch to disconnect the lower clutch from torque transmission.

[0008] In a preferred embodiment of the present invention, a first pressure sensor is disposed inside the first housing, and a first battery compartment and a torque control circuit are disposed inside the torque controller. The first battery compartment is used to supply electrical energy, and the torque control circuit is electrically connected to the first pressure sensor. The first pressure sensor receives the pressure wave signal transmitted from the ground and transmits it to the torque control circuit. The torque control circuit controls the torque control actuator to drive the upper clutch to move axially according to the pressure wave signal.

[0009] In a preferred embodiment of the present invention, the measurement while drilling structure includes a non-magnetic drill collar, and a measurement while drilling instrument is disposed inside the non-magnetic drill collar; the end of the lower clutch away from the upper clutch is connected to the central shaft, the central shaft is connected to the first end of the non-magnetic drill collar through a lower connector, and the second end of the non-magnetic drill collar is connected to the screw drill tool structure.

[0010] In a preferred embodiment of the present invention, the screw drill structure is a single-bend screw drill.

[0011] In a preferred embodiment of the present invention, the automatic ball-throwing structure includes a second housing, and a ball-throwing controller is disposed inside the second housing. The ball-throwing controller is connected to a variable ball seat that can slide axially and extend radially. The variable ball seat can retract to fix the steel ball or expand radially to release the steel ball.

[0012] In a preferred embodiment of the present invention, a second pressure sensor is provided inside the second housing. The second pressure sensor receives the pressure wave signal transmitted from the ground and transmits it to the ball-throwing controller. The ball-throwing controller includes a telescopic rod, one end of which is connected to the variable ball seat. The ball-throwing controller can control the telescopic rod to extend and push the variable ball seat to open radially to release the steel ball.

[0013] In a preferred embodiment of the present invention, a core-cutting ball seat is provided at the first end of the core-taking inner cylinder, and the core-cutting ball seat is connected to the core-taking outer cylinder by a shear pin; the steel ball can block the core-cutting ball seat, and the pump pressure increases at the end of the core-cutting ball seat near the automatic ball-throwing structure. After the pump pressure increases to a level greater than the shearing force of the shear pin, the core-taking inner cylinder moves outward along the axial direction under the action of the pump pressure.

[0014] In a preferred embodiment of the present invention, the second end of the core-taking inner cylinder is connected to a core claw and a clamp. The core claw moves outward and tightens to complete the core cutting operation, and the clamp is used to hold the core in place.

[0015] The objective of this invention can also be achieved as follows: a downhole torque-controlled horizontal well coring method includes: lowering the aforementioned downhole torque-controlled horizontal well coring tool into the well via an upper tubing string; under normal operating conditions, a torque control structure connects the upper tubing string and the measurement-while-drilling (MWD) structure to transmit torque, and the MWD structure, screw drill string structure, automatic ball dropping structure, and coring structure rotate synchronously with the upper tubing string;

[0016] Based on the pressure monitoring results, a pressure wave signal is sent from the surface to the downhole. The torque control structure separates the upper tubing string and the measurement-while-drilling (MSWD) structure. The upper tubing string continues to rotate continuously. The MSWD structure, the automatic ball dropping structure, and the core sampling structure rotate under the drive of the screw drill string structure. The core sampling bit drills the footage. After drilling is completed, another pressure wave signal is sent from the surface to the downhole. The automatic ball dropping structure releases a steel ball, which blocks the first end of the core sampling inner cylinder. The core sampling inner cylinder moves outward after the pump pressure increases. The core claw contracts to cut the core, the clamp holds the core, and the entire core sampling string is lifted to the drilling platform to complete the core extraction.

[0017] As described above, the downhole torque-controlled horizontal well coring tool and method of the present invention have the following beneficial effects:

[0018] This invention utilizes a core drilling tool combination that integrates a torque control structure, a measurement-while-drilling (MWD) structure, a screw drill string structure, an automatic ball dropping structure, and a core sampling structure. This combination solves problems such as trajectory control difficulties, low mechanical drilling speed, and low core recovery rate in horizontal well core sampling. It enables continuous rotation of the upper tubing string above the torque control structure, achieving friction reduction and effective transmission of drilling pressure. The automatic ball dropping structure ensures controllable core sampling operations, while the combination of the screw drill string structure and the core sampling structure enables directional core sampling in the horizontal section. The core sampling structure can precisely directionally sample cores under the drive of the screw drill string structure. Attached Figure Description

[0019] The accompanying drawings are intended only to illustrate and explain the present invention and do not limit the scope of the invention.

[0020] in:

[0021] Figure 1 : This is a schematic diagram of the downhole torque-controllable horizontal well coring tool of the present invention.

[0022] Figure 2a : This is a schematic diagram of the torque control structure of the present invention in a separated state.

[0023] Figure 2b : This is a schematic diagram of the torque control structure of the present invention in the engaged state.

[0024] Figure 3a This is a schematic diagram of the initial state of the automatic ball-throwing structure of the present invention.

[0025] Figure 3b : This is a schematic diagram of the automatic ball-throwing structure of the present invention in the ball-throwing state.

[0026] In the picture:

[0027] 1. First housing; 2. Torque controller; 3. First pressure sensor; 4. First battery compartment; 5. Torque control circuit; 6. Torque control actuator; 7. Upper clutch; 8. Lower clutch; 9. Central shaft; 10. Lower connector; 11. Non-magnetic drill collar; 12. Measurement while drilling instrument; 13. Screw drill string structure; 14. Second housing; 15. Second pressure sensor; 16. Ball drop controller; 17. Variable ball seat; 18. Steel ball; 19. Core cutting ball seat; 20. Shear pin; 21. Core outer cylinder; 22. Core inner cylinder; 23. Clamp; 24. Core claw; 25. Core drill bit. Detailed Implementation

[0028] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0029] The specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "linked" should be interpreted broadly; for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] like Figure 1 As shown, the present invention provides a downhole torque controllable horizontal well coring tool, including a torque control structure. The first end of the torque control structure is used to connect to the upper tubing string, and the second end of the torque control structure is sequentially connected to the measurement while drilling structure, the screw drill string structure 13, the automatic ball dropping structure and the coring structure.

[0032] The torque control structure can connect the top string and the measurement while drilling (MWD / LWD) structure to transmit the torque of the top string, or the torque control structure can separate the top string and the measurement while drilling (MWD / LWD) structure to disconnect the torque transmission of the top string.

[0033] When the torque control structure separates the upper tubing string and the measurement while drilling (MSD) structure, the screw drill string structure 13 can drive the MSD structure, the automatic ball dropping structure, and the core sampling structure to rotate synchronously. At this time, the upper tubing string (existing technology) can be rotated continuously in the forward direction through the rotary table (existing technology), which can reduce friction and effectively transmit drilling pressure.

[0034] The coring structure includes a coaxially arranged outer coring cylinder 21 and an inner coring cylinder 22. The first end of the outer coring cylinder 21 is connected to an automatic ball-dropping mechanism, and the second end is connected to the coring drill bit 25. The automatic ball-dropping mechanism releases steel balls 18 based on pressure wave signals transmitted from the ground. The steel balls 18 seal the first end of the inner coring cylinder 22, allowing it to extend outwards after the pump pressure increases to complete the directional coring operation. The screw drill bit structure 13, combined with the coring structure, enables directional coring operations in the horizontal section.

[0035] This invention solves the problems of poor wellbore quality and difficulty in cleaning cuttings in horizontal wells: In existing technologies, during drilling in inclined and horizontal sections, the drill string tends to slip and rotate along the high or low edge of the wellbore, easily forming keyways and irregular wellbore shapes, resulting in poor wellbore quality. During drilling circulation, due to gravity, cuttings deposit at the bottom of the wellbore and accumulate to form a cuttings bed. Because the bottom cuttings bed can only be moved a certain distance before re-accumulating, the cuttings bed thickness thins and then forms a new cuttings bed height, making wellbore cuttings cleaning very difficult. The torque control structure can effectively control torque transmission. When the torque control structure is disconnected, the upper tubing string can rotate continuously in the forward direction, avoiding cuttings deposition in the wellbore and solving the problems of poor wellbore quality and difficulty in cleaning cuttings in horizontal wells.

[0036] This invention solves the problem of difficult coring trajectory control: In existing technologies, coring in directional and horizontal wells (in tight formations) often employs a composite drive (screw + top drive / rotary table) method. Therefore, the stress conditions differ from those of conventional power-driven coring. Composite drilling coring tools experience complex stresses, and the build-up capability of the drill string is uncertain. When the torque control structure is disconnected, the screw drill string structure 13 can drive the measurement-while-drilling (MWD) structure, automatic ball dropping structure, and coring structure to rotate synchronously. This simplifies the stress on the coring tool and effectively controls the coring trajectory.

[0037] This invention addresses the problem of low drilling speed in coring machinery: In existing technologies, during coring in directional and horizontal wells, the friction between the drill string and the wellbore is significant. When using a rotary table / top drive, the drilling pressure and torque cannot be effectively applied to the drill bit, resulting in large losses of drilling pressure and torque, thus causing a low coring machine speed. When the torque control structure is disconnected, the screw drill string structure 13 can drive the measurement-while-drilling structure, the automatic ball dropping structure, and the coring structure to rotate synchronously, ensuring a stable and controllable drilling speed for the coring machinery.

[0038] The downhole torque-controlled horizontal well coring tool of this invention utilizes a coring tool combination of torque control structure + measurement while drilling (MWD / LWD instrument) structure + screw drill string structure (low-speed screw) + automatic ball dropping structure + coring structure. This solves the problems of trajectory control difficulties, low mechanical drilling speed, and low coring recovery rate in horizontal well coring. It enables continuous rotation of the upper tubing string above the torque control structure, achieving the effects of reducing friction and resistance and effectively transmitting drilling pressure. The automatic ball dropping structure enables controllable coring operations, and the combination of screw drill string structure and coring structure enables directional coring operations in the horizontal section. The coring structure can accurately directionally core under the drive of the screw drill string structure.

[0039] Furthermore, such as Figure 1 As shown, the torque control structure includes a first housing 1, within which a torque controller 2, a torque control actuator 6, an upper clutch 7, and a lower clutch 8 are disposed. The torque controller 2 is fixedly connected to the first housing 1; the torque control actuator 6 is circumferentially fixedly connected to the torque controller 2; the upper clutch 7 is circumferentially fixedly connected to the torque control actuator 6, and the torque control actuator 6 can drive the upper clutch 7 to move axially; the lower clutch 8 and the first housing 1 are arranged in a circumferentially rotatable relative configuration, and the lower clutch 8 is connected to a drilling measurement-while-drilling (DWD) structure; the torque controller 2 controls the movement of the torque control actuator 6 to engage the upper clutch 7 with the lower clutch 8 to transmit torque or to disengage the upper clutch 7 with the lower clutch 8 to disconnect torque transmission.

[0040] Furthermore, such as Figure 1 As shown, a first pressure sensor 3 is installed inside the first housing 1, and a first battery compartment 4 and a torque control circuit 5 are installed inside the torque controller 2. The first battery compartment 4 is used to supply electrical energy. The torque control circuit 5 is electrically connected to the first pressure sensor 3. The first pressure sensor 3 receives the pressure wave signal transmitted from the ground and transmits it to the torque control circuit 5. The torque control circuit 5 controls the torque control actuator 6 to drive the upper clutch 7 to move axially according to the pressure wave signal.

[0041] Furthermore, such as Figure 1 As shown, the measurement-while-drilling (MWD / LWD) structure includes a non-magnetic drill collar 11, which houses a measurement-while-drilling instrument 12 (MWD / LWD instrument). The lower clutch 8 is connected to a central shaft 9 at the end furthest from the upper clutch 7. The central shaft 9 is connected to the first end of the non-magnetic drill collar 11 via a lower connector 10. The second end of the non-magnetic drill collar 11 is connected to a screw drill tool structure 13.

[0042] Furthermore, the screw drill structure 13 is a single-bend screw drill.

[0043] The surface sends a set of signals via mud pressure waves. The first pressure sensor 3 inside the first housing 1 receives the pressure wave signals transmitted from the surface. The downhole electro-hydraulic system is powered by the first battery compartment 4. The system drives the torque control actuator 6 through the torque control circuit 5 to engage the upper and lower clutches. Figure 2b As shown, and separated as Figure 2a As shown, torque is transmitted / disconnected from the upper tubing string to the measurement-while-drilling (MWD) structure, screw drill string structure 13, automatic ball dropping structure, and core sampling structure (lower tubing string). When the torque is disconnected, the upper tubing string can rotate forward via a rotary table (existing technology), which reduces friction and effectively transmits drilling pressure. The MWD structure, automatic ball dropping structure, and core sampling structure perform horizontal section core sampling under the drive of the low-speed single-bend screw drill string (screw drill string structure 13).

[0044] Furthermore, such as Figure 1 As shown, the automatic ball-throwing structure includes a second housing 14, and a ball-throwing controller 16 is installed inside the second housing 14. The ball-throwing controller 16 is connected to a variable ball seat 17 that can slide axially and extend radially. The variable ball seat 17 can retract to fix the steel ball 18 or expand radially to release the steel ball 18.

[0045] Furthermore, such as Figure 1 As shown, a second pressure sensor 15 is installed inside the second housing 14. The second pressure sensor 15 receives the pressure wave signal transmitted from the ground and transmits it to the ball throwing controller 16. The ball throwing controller 16 includes a telescopic rod, one end of which is connected to a variable ball seat 17. The ball throwing controller 16 can control the telescopic rod to extend and push the variable ball seat to open radially to release the steel ball.

[0046] The variable ball seat 17 is initially in the state of an unreleased ball, such as... Figure 3a As shown, the steel ball 18 is pre-positioned within the variable ball seat 17. When the steel ball 18 needs to be released, the ground sends a set of mud pressure wave commands. The second pressure sensor 15 inside the second housing 14 receives the pressure wave signal transmitted from the ground. The telescopic rod of the ball-throwing controller 16 extends, and the front end of the telescopic rod is connected to the variable ball seat 17. The telescopic rod pushes the variable ball seat 17 to move axially. The second housing 14 has an inner diameter expansion zone, and the variable ball seat 17 opens radially, releasing the steel ball 18. The steel ball 18 moves down into the core-taking inner cylinder 22, as shown. Figure 3b As shown.

[0047] Furthermore, such as Figure 1 As shown, a core-cutting ball seat 19 is provided at the first end of the core-taking inner cylinder 22. The core-cutting ball seat 19 is connected to the core-taking outer cylinder 21 through a shear pin 20. The steel ball 18 can block the core-cutting ball seat 19. The pump pressure increases at the end of the core-cutting ball seat 19 near the automatic ball-throwing structure. After the pump pressure increases to a level greater than the shearing force of the shear pin 20, the core-taking inner cylinder 22 moves outward along the axial direction under the action of the pump pressure.

[0048] Furthermore, such as Figure 1 As shown, the second end of the core-taking inner cylinder 22 is connected to the core claw 24 and the clamp 23. The core claw 24 moves outward and tightens to complete the core cutting operation, and the clamp 23 is used to hold the core.

[0049] With the torque control structure in the disengaged state, normal coring operations are performed. After the coring bit 25 has advanced the required depth, the steel ball 18 is released into the core cutting ball seat 19. The pump pressure increases, causing the shear pin 20 to be cut off. The core claw 24 moves outward and tightens, completing the core cutting operation. The clamp 23 holds the core in place, and the entire coring string is lifted to the drilling platform to complete the core extraction. This completes the entire torque-controlled horizontal well coring operation.

[0050] This invention also provides a downhole torque-controllable horizontal well coring method, comprising,

[0051] The aforementioned downhole torque-controlled horizontal well coring tool is lowered into the well via the upper tubing string. Under normal operating conditions, the torque control structure connects the upper tubing string and the measurement-while-drilling (MWD) structure to transmit torque. The MWD structure, screw drill string structure 13, automatic ball dropping structure, and coring structure rotate synchronously with the upper tubing string.

[0052] As the pressure problem worsens and directional drilling becomes increasingly difficult, a pressure wave signal (mud pressure wave pulse signal) is sent from the surface to the wellbore based on the pressure monitoring results. The torque control structure separates the upper tubing string and the measurement while drilling (MSW) structure. The upper tubing string continues to rotate continuously, while the MSW, automatic ball dropping, and core sampling structures rotate under the action of the screw drill string structure 13. The core sampling bit 25 drills the footage. After drilling is completed, another pressure wave signal (mud pressure wave pulse signal) is sent from the surface to the wellbore. The automatic ball dropping structure releases the steel ball 18, which blocks the first end of the core sampling inner cylinder 22. The core sampling inner cylinder 22 moves outward after the pump pressure increases. The core claw 24 retracts to cut the core, and the clamp 23 holds the core. The entire core sampling string is then lifted to the drilling platform to complete the core extraction.

[0053] In one specific embodiment of the present invention,

[0054] For long horizontal wells, extended reach wells, and five-section directional wells, conventional coring operations involve installing a downhole torque-controlled horizontal well coring tool throughout the coring string (the upper part of the tool forms the upper string). As pressure issues worsen and directional drilling becomes increasingly difficult, a mud pressure wave pulse signal is sent from the surface to the downhole. This activates the torque control structure, causing torque separation between the upper and lower parts of the structure. The rotary table rotates the upper string continuously at 30 rpm, and the screw drill string applies low drilling pressure for coring. After the drilling footage is completed, another mud pressure wave pulse signal is sent from the surface to the downhole. The automatic ball dropping mechanism pushes the variable ball seat 17 to release the steel ball 18. The steel ball 18 falls into the core cutting ball seat 19, applying 8 MPa pressure to shear the shear pin 20. The inner core cylinder 22 moves outward, the core claw 24 retracts to cut the core, and the core is lifted by 10 tons to complete the core cutting operation. The entire coring string is then retrieved, and the core is extracted to the surface.

[0055] As described above, the downhole torque-controlled horizontal well coring tool and method of the present invention have the following beneficial effects:

[0056] This invention utilizes a core drilling tool combination that integrates a torque control structure, a measurement-while-drilling (MWD) structure, a screw drill string structure, an automatic ball dropping structure, and a core sampling structure. This combination solves problems such as trajectory control difficulties, low mechanical drilling speed, and low core recovery rate in horizontal well core sampling. It enables continuous rotation of the upper tubing string above the torque control structure, achieving friction reduction and effective transmission of drilling pressure. The automatic ball dropping structure ensures controllable core sampling operations, while the combination of the screw drill string structure and the core sampling structure enables directional core sampling in the horizontal section. The core sampling structure can precisely directionally sample cores under the drive of the screw drill string structure.

[0057] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A downhole torque-controllable horizontal well coring tool, characterized in that, The system includes a torque control structure, the first end of which is connected to the upper tubing string, and the second end of which is sequentially connected to a measurement-while-drilling (MWD) structure, a screw drill string structure, an automatic ball dropping structure, and a core sampling structure. The torque control structure can connect the upper tubing string and the MWD structure to transmit the torque of the upper tubing string, or it can separate the upper tubing string and the MWD structure to disconnect the torque transmission of the upper tubing string. When the torque control structure separates the upper tubing string and the measurement-while-drilling (MWD) structure, the screw drill string structure can drive the MWD structure, the automatic ball-dropping structure, and the coring structure to rotate synchronously. The coring structure includes a coaxially arranged outer coring cylinder and an inner coring cylinder. The first end of the outer coring cylinder is connected to the automatic ball-dropping structure, and the second end of the outer coring cylinder is connected to the coring bit. The automatic ball-dropping structure can release steel balls according to the pressure wave signal sent from the ground. The steel balls can block the first end of the inner coring cylinder so that the inner coring cylinder extends outward after the pump pressure increases to complete the directional coring operation. The torque control structure includes a first housing, within which a torque controller, a torque control actuator, an upper clutch, and a lower clutch are disposed. The torque controller is fixedly connected to the first housing. The torque control actuator is circumferentially fixedly connected to the torque controller. The upper clutch is circumferentially fixedly connected to the torque control actuator, and the torque control actuator can drive the upper clutch to move axially. The lower clutch and the first housing are circumferentially rotatable relative to each other, and the lower clutch is connected to the measurement-while-drilling (MWD) structure. The torque controller controls the torque control actuator to move so that the upper clutch engages the lower clutch to transmit torque, or to disengage the upper clutch and disconnect the lower clutch from torque transmission; The automatic ball-throwing structure includes a second housing, inside which a ball-throwing controller is installed. The ball-throwing controller is connected to a variable ball seat that can slide axially and extend radially. The variable ball seat can retract to fix the steel ball or expand radially to release the steel ball.

2. The downhole torque-controllable horizontal well coring tool as described in claim 1, characterized in that, A first pressure sensor is installed inside the first housing, and a first battery compartment and a torque control circuit are installed inside the torque controller. The first battery compartment is used to supply electrical energy, and the torque control circuit is electrically connected to the first pressure sensor. The first pressure sensor receives the pressure wave signal transmitted from the ground and transmits it to the torque control circuit. The torque control circuit controls the torque control actuator to drive the upper clutch to move axially according to the pressure wave signal.

3. The downhole torque-controllable horizontal well coring tool as described in claim 1, characterized in that, The measurement-while-drilling (MSD) structure includes a non-magnetic drill collar, and an MSD instrument is installed inside the non-magnetic drill collar; the end of the lower clutch away from the upper clutch is connected to the central shaft, the central shaft is connected to the first end of the non-magnetic drill collar through a lower connector, and the second end of the non-magnetic drill collar is connected to the screw drill tool structure.

4. The downhole torque-controllable horizontal well coring tool as described in claim 1, characterized in that, The screw drill bit structure is a single-bend screw drill bit.

5. The downhole torque-controllable horizontal well coring tool as described in claim 1, characterized in that, A second pressure sensor is installed inside the second housing. The second pressure sensor receives the pressure wave signal transmitted from the ground and transmits it to the ball-throwing controller. The ball-throwing controller includes a telescopic rod. One end of the telescopic rod is connected to the variable ball seat. The ball-throwing controller can control the telescopic rod to extend and push the variable ball seat to open radially to release the steel ball.

6. The downhole torque-controllable horizontal well coring tool as described in claim 1, characterized in that, The first end of the core-taking inner cylinder is provided with a core-cutting ball seat, which is connected to the core-taking outer cylinder by a shear pin. The steel ball can block the core-cutting ball seat. The pump pressure increases at the end of the core-cutting ball seat near the automatic ball-throwing structure. After the pump pressure increases to a level greater than the shearing force of the shear pin, the core-taking inner cylinder moves outward along the axial direction under the action of the pump pressure.

7. The downhole torque-controllable horizontal well coring tool as described in claim 6, characterized in that, The second end of the core-taking inner cylinder is connected to a core claw and a clamp. The core claw moves outward and tightens to complete the core cutting operation, and the clamp is used to hold the core in place.

8. A downhole torque-controllable horizontal well coring method, characterized in that, include: The downhole torque-controlled horizontal well coring tool as described in any one of claims 1-7 is lowered into the well using the upper tubing string; Under normal operating conditions, the torque control structure connects the upper tubing and the measurement-while-drilling (MWD) structure to transmit torque. The MWD structure, screw drill string structure, automatic ball dropping structure, and core sampling structure rotate synchronously with the upper tubing. Based on the pressure monitoring results, a pressure wave signal is sent from the surface to the downhole. The torque control structure separates the upper tubing string and the measurement-while-drilling (MSWD) structure. The upper tubing string continues to rotate continuously. The MSWD structure, the automatic ball dropping structure, and the core sampling structure rotate under the drive of the screw drill string structure. The core sampling bit drills the footage. After drilling is completed, another pressure wave signal is sent from the surface to the downhole. The automatic ball dropping structure releases a steel ball, which blocks the first end of the core sampling inner cylinder. The core sampling inner cylinder moves outward after the pump pressure increases. The core claw contracts to cut the core, the clamp holds the core, and the entire core sampling string is lifted to the drilling platform to complete the core extraction.

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