A precise reverse-threading system for oil and gas field downholes and its application method

Abstract

This invention discloses a precise reverse-threading system for oil and gas field downhole wells, comprising, from bottom to top, a hydraulic positioner, a positioning sub, a hydraulic anchor, a reverse-threading compensator, a hydraulic reverse-threading device, and a mechanical anchor. The hydraulic positioner is used for hydraulic initiation and positioning, and is positioned at the gap connecting the upper and lower casing via the casing coupling. The positioning sub connects the hydraulic positioner and the hydraulic anchor. The hydraulic anchor is anchored within the casing. The reverse-threading compensator is used for axial expansion and contraction to compensate for axial displacement of the casing during reverse-threading. The hydraulic reverse-threading device generates a release torque downhole to separate the threaded casing. The mechanical anchor works in conjunction with the hydraulic reverse-threading device to transmit the release torque to the upper casing that needs to be twisted. This invention ensures that the connecting threads are reverse-threaded at a predetermined position downhole, ensuring that all upper casing can be pulled out in one operation, guaranteeing operational safety, and improving operational efficiency.

Description

Technical Field

[0001] This invention relates to the field of downhole tools technology for oil drilling and production, and in particular to a precision reverse-threading system for oil and gas fields and its usage method. Background Technology

[0002] During well workover operations in oil and gas fields, it is often necessary to remove damaged casing from the well and replace it with new casing to restore production. Some older wells, unable to resume production, need to be abandoned. To ensure safety and environmental compliance, regulations stipulate that abandoned wells require the removal of the surface casing before backfilling. A key aspect of abandoned well operations is disconnecting the connecting threads at a predetermined location downhole to remove the casing. Current technology only allows for back-threading from the wellhead using surface equipment. Since the casing downhole has multiple connections, it's impossible to ensure that the connection is disconnected at the designated location, thus requiring multiple back-threading operations. Sometimes, removing the upper casing can cause wellbore collapse, preventing further operations from being completed. Summary of the Invention

[0003] The purpose of this application is to provide a precise downhole reverse connection system for oil and gas fields and its usage method, so as to solve the problems mentioned in the background art.

[0004] The present invention solves its problems through the following technical solution: A precision reverse-clamping system for oil and gas field downhole applications is provided, comprising a first casing, a second casing, and a third casing arranged sequentially from top to bottom. The first and second casings are connected by a first casing coupling, and the second and third casings are connected by a second casing coupling. The system includes, from bottom to top, a hydraulic positioner, a positioning sub, a hydraulic anchor, a reverse-clamping compensator, a hydraulic reverse-clamping device, and a mechanical anchor. The hydraulic positioner is used for hydraulic initiation and positioning, and is positioned at the gap connecting the second and third casings via the second casing coupling. The positioning sub connects the hydraulic positioner and the hydraulic anchor. The hydraulic anchor is anchored within the second casing. The reverse-clamping compensator is used for axial expansion and contraction to compensate for axial displacement of the first casing during reverse-clamping. The hydraulic reverse-clamping device generates a release torque downhole to separate the threaded connection between the first and second casings. The mechanical anchor is anchored within the first casing and works in conjunction with the hydraulic reverse-clamping device to transmit the release torque to the first casing requiring torsion.

[0005] Optionally, the hydraulic positioner includes a body, a sleeve, a positioning block, a first spring, a first piston, a first shear sleeve, a first ball seat, and a first lower connector. The body has multiple grooves around its circumference to accommodate the positioning block. A first spring is provided between the positioning block and the body. The upper and lower ends of the positioning block are respectively restricted by the sleeve and the first piston. The lower end of the body is provided with a first lower connector. The first lower connector contains a first shear sleeve and a first ball seat connected by a first shear pin. The lower end of the first piston is connected to the first lower connector by a second shear pin. When the first piston moves downward along the body, the positioning block is released radially outward.

[0006] Optionally, the hydraulic anchor includes a first upper connector, an upper clutch, a lower clutch, a spindle, a second shear sleeve, a locking ring sleeve, a locking ring, a second piston, a first locking sleeve, a slider, and a limiting sleeve. The spindle is provided with a limiting sleeve and a second piston. The spindle has multiple stepped grooves in its circumferential direction. The slider is located in the stepped grooves. The first locking sleeve is provided outside the slider. The first locking sleeve has a notch corresponding to the slider. The upper and lower ends of the first locking sleeve are respectively connected to the second piston and the limiting sleeve. The upper end of the second piston is connected to the locking ring sleeve through a third shear pin. The locking ring sleeve is provided with a locking ring. The upper end of the locking ring sleeve is provided with a second shear sleeve. The upper end of the second shear sleeve is connected to the lower clutch through a third shear pin. An upper clutch is provided above the lower clutch. The upper clutch is connected to the first upper connector. The first upper connector is located at the upper end of the spindle.

[0007] Optionally, the inverted compensator includes a second upper connector, a disc spring spindle, a disc spring outer cylinder, a disc spring, a washer, a spline outer cylinder, and a spline spindle. The upper end of the spline spindle is provided with a spline groove, the spline outer cylinder is provided with splines, the spline outer cylinder is connected to the spline spindle, the upper end of the spline spindle is provided with a disc spring spindle, the upper end of the spline outer cylinder is provided with a disc spring outer cylinder, a disc spring is provided between the disc spring spindle and the disc spring outer cylinder, the lower end of the disc spring is provided with a washer, and the upper end of the disc spring outer cylinder is provided with a second upper connector.

[0008] Optionally, the hydraulic reversing device includes a third upper connector, an upper piston, an outer piston cylinder, an upper piston mandrel, an intermediate cylinder, a lower piston, a first sealing mandrel, a second ball seat, a ball outer cylinder, a ball torque shaft, a clutch sleeve, an inner clutch, a drive mandrel, an outer clutch, and a second lower connector. The third upper connector, upper piston mandrel, first sealing mandrel, ball torque shaft, drive mandrel, and second lower connector are arranged from top to bottom. A lower piston is provided outside the ball torque shaft. The lower piston and the ball torque shaft form a screw-nut structure. The upper part is provided with a main spring, and an inner clutch is provided at the lower end of the main spring. The inner clutch is located at the upper end of the drive spindle. An outer clutch is provided outside the drive spindle. A clutch spring is provided at the lower end of the outer clutch. A spring retaining ring is provided at the lower end of the clutch spring. The spring retaining ring is located at the upper end of the second lower connector. A clutch sleeve, a ball outer cylinder, an intermediate cylinder and a piston outer cylinder are provided in sequence at the upper end of the outer clutch. The upper end of the piston outer cylinder is connected to the third upper connector. An upper piston and a main spring are provided from top to bottom between the piston outer cylinder and the upper piston spindle. A second ball seat is provided inside the first sealing spindle.

[0009] Optionally, the mechanical anchor includes a fourth upper connector, a second locking sleeve, an adjusting sleeve, a limiting block, a locking nut, an anchoring sleeve, a fixed wing plate, a supporting wing plate, a wing plate bed, a power spindle, a positioning ring, a torque release sleeve, a release shear pin, a power sleeve, a power outer cylinder, a second sealing spindle, a second spring, a drop sleeve, a third piston, and a third lower connector. The power spindle, the second sealing spindle, and the third piston are arranged from top to bottom. The outer side of the power spindle is provided with the second locking sleeve, the limiting block, the adjusting sleeve, and the anchoring sleeve from top to bottom. The system includes a wing plate bed, a positioning ring, and a power outer cylinder. The anchoring sleeve and the wing plate bed are connected by a locking nut. The fixed wing plate and the supporting wing plate are located on the wing plate bed. A torque release sleeve is provided between the wing plate bed and the power outer cylinder. The torque release sleeve and the power outer cylinder are connected by a release shear pin. A power sleeve is provided between the power outer cylinder and the power spindle. A second spring is provided at the upper end of the third piston. The second spring is located outside the second sealing spindle. A drop sleeve and a third lower connector are provided in sequence at the lower end of the power outer cylinder. A fourth upper connector is provided at the upper end of the power spindle.

[0010] A method of using the aforementioned precision reverse-cashing system for oil and gas field downholes includes the following steps: The pitching and striking action begins by activating the hydraulic positioner, which determines the seat position by measuring the resistance of the vertically moving tubing. Increase the pressure to open the hydraulic anchor, giving the tubing a support point against the wellbore. Then press down the tubing to lock the hydraulic anchor, while simultaneously compressing the reverse compensator to provide sufficient locking force to the hydraulic anchor. Increase pressure to knock off the ball seat and keep the tubing clear; Rotating the upper drill pipe in the forward direction activates the mechanical anchor, causing the mechanical anchor support wing plates to open and support the inner wall of the casing. The mechanical anchors and hydraulic anchors at the upper and lower ends are respectively fixed to the two ends of the connecting threads to be loosened; the hydraulic reverser starter ball is inserted into the wellhead, the wellhead is pressurized cyclically, the hydraulic reverser rotates to uncouple, and the downhole loosening state is determined by the change in wellhead pressure; After the uncoupling operation is completed, the tubing string is rotated to the left to release the mechanical anchor, then the hydraulic anchor is lifted to release the hydraulic anchor, and the tubing string is pulled out to complete the downhole uncoupling operation.

[0011] In summary, the technical effects and advantages of this invention are as follows: This invention can ensure that the connecting threads are reversed at a predetermined position downhole, ensure that all upper casings are pulled out at once, ensure operational safety, and improve operational efficiency. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the structure of a precision reverse-drilling system for oil and gas field downholes according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a hydraulic positioner according to an embodiment of the present invention; Figure 3 This is a schematic diagram showing the position of the hydraulic positioner and the sleeve coupling according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a hydraulic anchor according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an inverted compensator according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a hydraulic buckling device according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a mechanical anchor according to an embodiment of the present invention.

[0014] in: 1. Hydraulic positioner; 101. Body; 102. Sleeve; 103. Positioning block; 104. First spring; 105. First piston; 106. Second shear pin; 107. First lower connector; 108. First shear sleeve; 109. First shear pin; 110. First ball seat; 2. Position the short section; 3. Hydraulic anchor; 301. First upper connector; 302. Upper clutch; 303. Lower clutch; 304. Mandrel; 305. Second shear sleeve; 306. Locking ring sleeve; 307. Locking ring; 308. Second piston; 309. First locking sleeve; 310. Third spring; 311. Slider; 312. Limiting sleeve; 313. Third shear pin; 4. Inverted compensator; 401. Second upper connector; 402. Disc spring spindle; 403. Disc spring outer cylinder; 404. Disc spring; 405. Washer ring; 406. Splined outer cylinder; 407. Splined spindle; 5. Hydraulic reverser; 501. Third upper connector; 502. Upper piston; 503. Piston outer cylinder; 504. Upper piston mandrel; 505. Intermediate cylinder; 506. Lower piston; 507. First sealing mandrel; 508. Second ball seat; 509. Ball outer cylinder; 510. Ball torque shaft; 511. Wear-resistant copper sleeve; 512. Clutch sleeve; 513. Inner clutch; 514. Drive mandrel; 515. Outer clutch; 516. Spring retaining ring; 517. Second lower connector; 518. Main spring; 519. Ball seat spring; 520. Clutch spring; 6. Mechanical anchor; 601. Fourth upper connector; 602. Second locking sleeve; 603. Adjusting sleeve; 604. Limiting block; 605. Locking nut; 606. Anchoring sleeve; 607. Fixed wing plate; 608. Supporting wing plate; 609. Wing plate bed; 610. Power spindle; 611. Positioning ring; 612. Torque release sleeve; 613. Release shear pin; 614. Power sleeve; 615. Power outer cylinder; 616. Second sealing spindle; 617. Second spring; 618. Drop sleeve; 619. Third piston; 620. Third lower connector; 621. Assembly tooling pin; 7. Second sleeve; 8. Third sleeve; 9. Second sleeve coupling; 11. Steel ball. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] In oil and gas field well workover operations, it is necessary to back-open the casing threads at a predetermined location downhole to remove damaged casing or pull out surface casing to meet the requirements for well abandonment and backfilling. This system involves a combination of multiple downhole tools that work together to accomplish specific operational requirements.

[0017] This embodiment proposes a precise downhole reverse connection system for oil and gas fields, such as... Figure 1-7As shown, it is applied to a first sleeve, a second sleeve 7, and a third sleeve 8 arranged sequentially from top to bottom. The first sleeve and the second sleeve 7 are connected by a first sleeve coupling, and the second sleeve 7 and the third sleeve 8 are connected by a second sleeve coupling 9. It includes a hydraulic positioner 1, a positioning sub 2, a hydraulic anchor 3, a reverse compensator, a hydraulic reverser 5, and a mechanical anchor 6 arranged sequentially from bottom to top. The hydraulic positioner 1 is used for hydraulic starting and positioning. The hydraulic positioner 1 is positioned at the second sleeve coupling 9 connecting the second sleeve 7 and the third sleeve 8. At the gap of casing 8; the positioning sub 2 is used to connect the hydraulic positioner 1 and the hydraulic anchor 3; the hydraulic anchor 3 is used to anchor in the second casing 7; the backing compensator is used for axial expansion and contraction to compensate for the axial displacement of the first casing during backing; the hydraulic backing device 5 is used to generate uncoupling torque downhole to separate the threaded connection of the first and second casings 7; the mechanical anchor 6 is used to anchor in the first casing, and the mechanical anchor 6 is used to cooperate with the hydraulic backing device 5 to transmit the uncoupling torque to the first casing that needs to be twisted. This embodiment is a specific combination of multiple tools to meet the needs of a dedicated backing system for precise point positioning.

[0018] Specifically, the hydraulic positioner 1 includes a body 101, a sleeve 102, a positioning block 103, a first spring 104, a first piston 105, a first shear sleeve 108, a first ball seat 110, and a first lower connector 107. The body 101 has a plurality of grooves circumferentially arranged to accommodate the positioning block 103. The first spring 104 is provided between the positioning block 103 and the body 101. The upper and lower ends of the positioning block 103 are respectively restricted by the sleeve 102 and the first piston 105. The lower end of the body 101 is provided with a first lower connector 107. The first lower connector 107 is provided with a first shear sleeve 108 and a first ball seat 110 connected by a first shear pin 109. The lower end of the first piston 105 is connected to the first lower connector 107 by a second shear pin 106. When the first piston 105 moves downward along the body 101, the positioning block 103 is released radially outward.

[0019] like Figure 2 As shown, the assembly position relationship of hydraulic positioner 1 from left to right is as follows: 1) Insert the sleeve 102 into the right end of the body 101, thread it in, tighten it, and align it with the mounting holes and slots of the positioning blocks 103, then install the set screws; 2) Install the first springs 104 into the inner holes of the six positioning blocks 103 respectively, and then insert the whole into the corresponding slots of the body 101; 3) Compress the first springs 104 of the six positioning blocks 103, and then insert the first piston 105 into the right end of the body 101, so that the first piston 105 fits into the six positioning blocks 103 and is limited by the right end of the sleeve 102; 4) Insert the first shear sleeve 108 into the left end of the first ball seat 110, and assemble the first shear pin 109, and then insert the whole into the inner hole from the left end of the first lower connector 107; 5) Thread the first lower connector 107 into the body 101 and tighten it, and install the second shear pin 106 and the set screws; the second shear pin 106 is the starting shear pin.

[0020] Working principle of hydraulic positioner 1: After the hydraulic positioner 1 is lowered into the designated position in the wellbore along with the tool string, the ball is dropped into the tubing and the steel ball 11 sits on the first ball seat 110; the tubing is pressurized inside, the first piston 105 moves downward under the internal pressure, shears the second shear pin 106, the outer circle of the positioning block 103 is unrestrained, and under the reset force of the first spring 104, the positioning block 103 is pushed outward to contact the casing; In the free state, the steps at both ends of the positioning block 103 are blocked by the sleeve 102 and the first piston 105; The hydraulic positioner 1 moves up and down with the tubing column at a designated position, and the change in the weight of the tubing column is observed until the positioning block 103 enters the target casing coupling; the inside of the tubing column is pressurized until the hydraulic anchor 3 is completely anchored on the second casing 7 under hydraulic action; the inside of the tubing column is pressurized again to cut the first shear pin 109, and the steel ball 11 is knocked down with the first ball seat 110 and falls into the screen tube at the lower end of the tubing column, thereby realizing the connection between the inner and outer tubing columns, and then proceeding to the next step of casing inversion operation.

[0021] like Figure 3 The diagram shows the position of the hydraulic positioner 1 and the sleeve coupling. The positioning block 103 of the hydraulic positioner 1 is positioned at the gap between the second sleeve coupling 9 and the second sleeve 7 and the third sleeve 8.

[0022] Specifically, the positioning section 2 is connected to the hydraulic positioner 1 and the hydraulic anchor 3 respectively. The positioning section 2 sets the anchoring position of the hydraulic anchor 3 in the undercutting operation according to the sitting position of the hydraulic positioner 1, ensuring that the hydraulic anchor 3 avoids the connecting threads and is accurately fixed on the inner wall of the second sleeve 7 that needs to be undercut, providing torque support for the undercutting operation.

[0023] Specifically, the hydraulic anchor 3 includes a first upper connector 301, an upper clutch 302, a lower clutch 303, a spindle 304, a second shear sleeve 305, a locking ring sleeve 306, a locking ring 307, a second piston 308, a first locking sleeve 309, a slider 311, and a limiting sleeve 312. The spindle 304 is provided with a limiting sleeve 312 and a second piston 308. The spindle 304 has multiple stepped grooves in its circumferential direction. The slider 311 is disposed in the stepped grooves. The first locking sleeve 309 is provided outside the slider 311. The first locking sleeve 309 has a notch corresponding to the slider 311. The upper and lower ends of the first locking sleeve 309 are connected to the second piston 308 and the limiting sleeve 312, respectively. The upper end of the second piston 308 is connected to a locking ring sleeve 306 via a third shear pin 313. A locking ring 307 is provided inside the locking ring sleeve 306. A second shear sleeve 305 is provided at the upper end of the locking ring sleeve 306. The upper end of the second shear sleeve 305 is connected to the lower clutch 303 via the third shear pin 313. An upper clutch 302 is provided above the lower clutch 303. The upper clutch 302 is connected to the first upper connector 301. The first upper connector 301 is located at the upper end of the mandrel 304. By pressurizing at the wellhead, the slider 311 hydraulically moves upward and opens along the inclined support surface of the stepped groove of the mandrel 304, supporting itself on the inner wall of the second casing 7. Anchoring teeth are embedded on the slider 311, which bite into the inner wall of the second casing 7, providing torque support for downhole reverse anchoring operations. After initial hydraulic anchoring, the lower tubing string is pressed to lock the anchoring force.

[0024] like Figure 4 As shown, the assembly position relationship of the hydraulic anchor 3 from right to left is as follows: 1) Fix the mandrel 304, and install the limiting sleeve 312 and the second piston 308 from the left end of the mandrel 304 to the corresponding limiting shoulder in sequence; 2) Install the three sliders 311 to the stepped grooves of the mandrel 304 respectively, install the third spring 310 into the slider spring groove, and then install and fix the three-lobed first locking sleeve 309 in alignment with the slider 311; 3) Install the locking ring 307 into the locking ring sleeve 306, and then install the whole from the left end of the mandrel 304 to the left shoulder of the second piston 308 for limiting, and install the third shear pin 313; 4) Slide the second shear sleeve 305 from the right end of the lower clutch 303, and then install the whole from the left end of the mandrel 304 into the corresponding groove; 5) Slide the upper clutch 302 from the right end of the first upper connector 301, and then install the whole from the left end of the mandrel 304 and tighten the threads to fix it.

[0025] Working principle of hydraulic anchor 3: After the hydraulic anchor 3 is lowered into the designated position in the wellbore along with the tool string, the inside of the tubing is pressurized. The second piston 308 moves upward under the action of internal pressure, cutting off the upper third shear pin 313. At the same time, it drives the first locking sleeve 309 to move upward. Under the bidirectional action of the axial force of the first locking sleeve 309 and the stepped groove of the mandrel 304, the slider 311 moves upward and opens outward to contact and anchor the second casing 7. Under the unidirectional movement restriction of the locking ring sleeve 306 and the locking ring 307, the state of the slider 311 anchoring the casing is locked. When the inverted operation is completed, the lifting column cuts off the lower end of the third shear pin 313, and the second piston 308 and the mandrel 304 lose their position constraints. As the column continues to be lifted, the slider 311 loses the inclined surface support of the stepped groove of the mandrel 304, thus losing its anchoring with the second sleeve 7 and being unsealed.

[0026] Specifically, the inverted compensator 4 includes a second upper connector 401, a disc spring spindle 402, a disc spring outer cylinder 403, a disc spring 404, a washer 405, a splined outer cylinder 406, and a splined spindle 407. The upper end of the splined spindle 407 has a spline groove, and the splined outer cylinder 406 has splines. The splined outer cylinder 406 is connected to the splined spindle 407. The upper end of the splined spindle 407 has the disc spring spindle 402, and the upper end of the splined outer cylinder 406 has the disc spring outer cylinder 403. A disc spring 404 is located between the disc spring spindle 402 and the disc spring outer cylinder 403. The lower end of the disc spring 404 has a washer 405, and the upper end of the disc spring outer cylinder 403 has the second upper connector 401. A spline connection is used between the splined spindle 407 and the splined outer cylinder 406 to allow axial expansion and contraction and to withstand circumferential torque. The axial telescopic distance connects the hydraulic anchor 3 and the hydraulic reverser 5 to compensate for the axial displacement of the sleeve during reverser operation, thus preventing the lower hydraulic anchor 3 from becoming loose.

[0027] like Figure 5 As shown, the assembly position relationship of the inverted compensator 4 from right to left is as follows: 1) Fix the spline mandrel 407 and install the spline outer cylinder 406 from the left end of the spline mandrel 407 into the corresponding spline groove; 2) Install the disc spring mandrel 402 from the left end of the spline mandrel 407 into the connecting thread and tighten it; 3) Install the washer 405 and the corresponding assembly relationship and quantity of disc springs 404 from the left end of the disc spring mandrel 402 in sequence; 4) Install the disc spring outer cylinder 403 from the right end of the second upper connector 401 into the connecting thread and tighten it, and then install the whole from the left end of the disc spring mandrel 402, and tighten the disc spring outer cylinder 403 and the spline outer cylinder 406 into the threaded connection.

[0028] Working principle of the inverted compensator 4: After the reverse-clamp compensator 4 is lowered into the designated position in the wellbore along with the tool string, the casing reverse-clamping operation is a prerequisite for disengagement. The upper tubing string needs to have a certain displacement while ensuring the tubing string is sealed. When the reverse-clamping torque generated by the hydraulic reverse-clamping device 5 drives the mechanical anchor 6 to rotate, the target casing disengages and moves upward, causing the spline mandrel 407 and disc spring mandrel 402 to move upward. The upward force compresses the disc spring 404 to absorb energy, thus not affecting the position of the upper tubing string.

[0029] Specifically, the hydraulic reverser 5 includes a third upper connector 501, an upper piston 502, a piston outer cylinder 503, an upper piston spindle 504, an intermediate cylinder 505, a lower piston 506, a first sealing spindle 507, a second ball seat 508, a ball outer cylinder 509, a ball torque shaft 510, a clutch sleeve 512, an inner clutch 513, a drive spindle 514, an outer clutch 515, and a second lower connector 517. The third upper connector 501, upper piston spindle 504, first sealing spindle 507, ball torque shaft 510, drive spindle 514, and second lower connector 517 are arranged from top to bottom. A lower piston 506 is provided outside the ball torque shaft 510. The lower piston 506 and the ball torque shaft 510 form a screw and nut structure. The drive spindle 514 is equipped with a main spring 518, and an inner clutch 513 is located at the lower end of the main spring 518. The inner clutch 513 is located at the upper end of the drive spindle 514. An outer clutch 515 is located outside the drive spindle 514. A clutch spring 520 is located at the lower end of the outer clutch 515. A spring retainer 516 is located at the lower end of the clutch spring 520. The spring retainer 516 is located at the upper end of the second lower connector 517. A clutch sleeve 512, a ball outer cylinder 509, an intermediate cylinder 505, and a piston outer cylinder 503 are sequentially arranged at the upper end of the outer clutch 515. The upper end of the piston outer cylinder 503 is connected to the third upper connector 501. An upper piston 502 and a main spring 518 are arranged from top to bottom between the piston outer cylinder 503 and the upper piston spindle 504. A second ball seat 508 is located inside the first sealing spindle 507.

[0030] like Figure 6 As shown, the assembly position relationship of the hydraulic buckle 5 from the middle to the left and right sides is as follows ( Figure 6 This refers only to the assembly relationship of a single tool, the hydraulic reversing device (5-piece set). Figure 1 (This is a diagram of a precision inverted tool string) 1) Fix the lower piston 506, insert the ball torque shaft 510 from the right end of the lower piston 506 and align it with the ball groove, install the ball steel balls 11, and then insert the wear-resistant copper sleeve 511 from the right side of the ball torque shaft 510 into the inner stepped hole of the lower piston 506; 2) Insert the second ball seat 508 and ball seat spring 519 from the left end of the first sealing mandrel 507, and then insert the whole assembly from the left side of the lower piston 506 into the inner stepped hole; 3) Insert the upper piston mandrel 504 from the left end of the lower piston 506 and thread it in; 4) Insert the intermediate cylinder 505 and main spring 518 from the left end of the upper piston mandrel 504, and then thread the upper piston 502 to the upper piston mandrel 504 and tighten it; 5) Insert the piston outer cylinder 503 from the upper piston... 502 is inserted from the left end and threadedly connected to the intermediate cylinder 505. Then, the third upper connector 501 is threadedly connected to the piston outer cylinder 503 and tightened. 6) The ball outer cylinder 509 is inserted from the right end of the lower piston 506 and threadedly connected to the intermediate cylinder 505 and tightened. 7) From left to right, the main spring 518, the inner clutch 513, and the drive spindle 514 are inserted from the right side of the ball torque shaft 510. 8) The clutch sleeve 512 is inserted from the right end of the drive spindle 514 and threadedly connected to the ball outer cylinder 509 and tightened. 9) From left to right, the outer clutch 515, the clutch spring 520, and the spring retaining ring 516 are inserted from the right end of the drive spindle 514. 10) The lower connector is threadedly connected to the drive spindle 514 and tightened.

[0031] Working principle of hydraulic reversing device 5: After the hydraulic reversing device 5 is lowered into the designated position in the wellbore along with the tool string, the ball is dropped into the pipe to pressurize it, pushing the lower piston 506 downward. The steel balls in the spiral groove of the lower piston 506 drive the ball torque shaft 510 to rotate to the right, converting the axial downward thrust into right-hand torque. The lower hydraulic anchor 3 is anchored and fixed to the lower tubing string. Therefore, the downward right-hand torque is transmitted in reverse through the outer ball cylinder 509 to the left-hand uncoupling torque of the upper casing, thereby achieving precise uncoupling operation of the upper casing.

[0032] Working process of hydraulic reversing device 5: a. The ball is thrown from the tubular column onto the steel ball, which sits on the second ball seat 508; b. When the inside of the tubing is pressurized, the hydraulic pressure pushes the lower piston 506 downward, compressing the main spring 518. The steel balls in the spiral groove inside the lower piston 506 drive the ball torque shaft 510 to rotate to the right (clockwise), converting the axial downward thrust into right-hand torque. c. The ball torque shaft 510 and the inner clutch 513 are connected by a spline to transmit right-hand torque downwards. The inner clutch 513 and the drive spindle 514 are connected by ratchet meshing to transmit right-hand torque to the lower connector at the lower end in sequence. d. The tubing is depressurized, and under the reset action of the upper and lower main springs 518, the upper piston 502 and the lower piston 506 return to their initial positions; e. The inner clutch 513 and the drive spindle 514 are engaged by ratchet teeth. Clockwise rotation can transmit right-hand torque. When the piston is reset, the teeth can be automatically skipped to complete the reset. The clutch sleeve 512 and the outer clutch 515 are engaged by reverse ratchet teeth. Clockwise rotation can automatically skip the teeth to complete the reset. When the piston is reset, it is automatically locked to ensure that the reverse torque state is maintained. f. Continue applying pressure and repeat the above steps until the inversion is complete.

[0033] Specifically, the mechanical anchor 6 includes a fourth upper connector 601, a second locking sleeve 602, an adjusting sleeve 603, a limiting block 604, a locking nut 605, an anchoring sleeve 606, a fixed wing plate 607, a supporting wing plate 608, a wing plate bed 609, a power spindle 610, a positioning ring 611, a torque release sleeve 612, a release shear pin 613, a power sleeve 614, a power outer cylinder 615, a second sealing spindle 616, a second spring 617, a release sleeve 618, a third piston 619, and a third lower connector 620. The power spindle 610, the second sealing spindle 616, and the third piston 619 are arranged from top to bottom. The outer side of the power spindle 610 is provided with the second locking sleeve 602, the limiting block 604, the adjusting sleeve 603, and the anchoring sleeve 606 from top to bottom. 06. Wing bed 609, positioning ring 611 and power outer cylinder 615, anchor sleeve 606 and wing bed 609 are connected by locking nut 605, fixed wing plate 607 and supporting wing plate 608 are provided on wing bed 609, torque release sleeve 612 is provided between wing bed 609 and power outer cylinder 615, torque release sleeve 612 and power outer cylinder 615 are connected by release shear pin 613, power sleeve 614 is provided between power outer cylinder 615 and power spindle 610, second spring 617 is provided at the upper end of third piston 619, second spring 617 is located outside of second sealing spindle 616, lower end of power outer cylinder 615 is provided with glove release sleeve 618 and third lower connector 620 in sequence, upper end of power spindle 610 is provided with fourth upper connector 601. By rotating the tubing string at the wellhead to activate the anchoring flange, the teeth on the flange engage with the inner wall of the casing, transmitting the uncoupling torque generated by the hydraulic back-coupling to the upper casing, causing the upper and lower casings to rotate relative to each other, loosening the connecting threads, and rotating the tubing string in the opposite direction can release the anchoring.

[0034] The mechanical anchor 6 works in conjunction with the hydraulic reverser 5 to transmit the uncoupling torque to the upper casing that needs to be twisted. By rotating the upper drill string, the drive flange opens and supports the casing. The flange is then locked to the support arm. The reverse torque of the reverser is transmitted to the support arm through the lower connector of the mechanical anchor 6, causing the upper casing to rotate and loosen. After the reverser is completed, the mechanical anchor 6 retracts the flange and support arm by reversing the upper drill string.

[0035] like Figure 7 As shown, the assembly position relationship of the mechanical anchor 6 from the middle to the left and right sides is as follows: 1) Fix the power spindle 610, install the split power sleeve 614 into the stepped groove on the right end of the power spindle 610, and insert the four assembly tool pins 621 into the aligned holes; 2) Install the power outer cylinder 615 into the threaded connection from the right end of the power sleeve 614 and tighten it, then remove the four assembly tool pins 621; 3) Install the second sealing spindle 616 into the empty groove from the left end of the dispensing sleeve 618, and tighten it with the threaded connection of the whole assembly to the power outer cylinder 615; 4) Install the second spring 6 17. Insert the inner hole from the right end of the glove-dropping sleeve 618, then insert the third piston 619 from the right end of the glove-dropping sleeve 618 and thread it into the second sealing mandrel 616 for secure fastening. The third lower connector 620 is threaded into the right end of the glove-dropping sleeve 618 for secure fastening. 5) Insert the torque release sleeve 612 from the left end of the power outer cylinder 615, aligning it with the spline groove, and install the release shear pin 613, aligning it with the shear pin hole. 6) After connecting the fixed wing plate 607 and the support wing plate 608 with the pin, insert the wing... The wing bed 609 corresponds to the slot; the positioning ring 611 is inserted from the right end of the wing bed 609 and engages with the protruding pin on the right end of the fixed wing plate 607; the anchoring sleeve 606 is inserted from the left end of the wing bed 609 and engages with the protruding pin on the left end of the fixed wing plate 607; then the locking nut 605 is inserted from the left end of the wing bed 609 and threaded to tighten; 7) Align the entire assembly of the wing bed 609, etc., from the left end of the power spindle 610 with the left end of the wing bed 609. 8) Insert the spline and torque release sleeve 612 into the inner spline groove position as a whole; 9) Insert the adjusting sleeve 603 from the left end of the power spindle 610 and thread it into the anchor sleeve 606; 10) Insert the second locking sleeve 602 from the left end of the power spindle 610 into the rightmost end, aligning it with the spline groove; 11) Thread the fourth upper connector 601 into the power spindle 610 and tighten it. Align the end face spline and retract the second locking sleeve 602. Then insert the limit block 604 into the corresponding empty position of the adjusting sleeve 603.

[0036] Working principle of mechanical anchor 6: After the mechanical anchor 6 is lowered into the designated position in the wellbore along with the tool string, it directly rotates the tubing string clockwise. The clockwise torque is transmitted to the anchoring sleeve 606 through the fourth upper connector 601, the second locking sleeve 602, and the adjusting sleeve 603. The wing plate bed 609 is connected to the power outer cylinder 615 and the lower part of the anchor 606 through splines, shear pins, etc., and is relatively fixed. Under the action of rotational torque, the anchoring sleeve 606 drives the fixed wing plate 607 to rotate, thereby anchoring the support wing plate 608 to the casing. The torque transmitted upward by the hydraulic reverser 5 to the mechanical anchor 6 makes the anchoring more secure. Therefore, the downward clockwise torque is transmitted in reverse through the ball outer cylinder 509 of the hydraulic reverser 5 to the left-hand uncoupling torque of the upper casing, thereby realizing the precise uncoupling operation of the upper casing.

[0037] 4. Working process of the mechanical rewinding device: a. Overall right-handed tubular column; b. The right-hand torque is transmitted to the anchoring sleeve 606 via the fourth upper connector 601, the second locking sleeve 602, and the adjusting sleeve 603: c. The wing bed 609 is fixed relative to the power outer cylinder 615 and the lower part of the anchor through splines, shear pins and other connections; d. Therefore, the right-hand torque acts on the anchoring sleeve 606, causing the fixed wing plate 607 to rotate, thereby anchoring the supporting wing plate 608 to the sleeve; e. The right-hand torque transmitted upward by the lower hydraulic reverser 5 to the mechanical anchor 6 will make the support wing plate 608 more firmly anchored to the sleeve.

[0038] This embodiment also proposes a method for using the aforementioned precision reverse-cashing system for oil and gas field downhole wells, including the following steps: The pitching and striking action first activates the hydraulic positioner 1, and determines the seat position by measuring the resistance of the vertically moving tube column. Increase the pressure to open the hydraulic anchor 3, so that the tubing string has a support point with the well wall. Then press down the tubing string to lock the hydraulic anchor 3, and at the same time compress the reverse compensator to give the hydraulic anchor 3 sufficient locking force. Increase pressure to knock off the ball seat and keep the tubing clear; Rotating the upper drill pipe in the forward direction activates the mechanical anchor 6, causing the flanges of the mechanical anchor 6 to open and support the inner wall of the casing. The mechanical anchors 6 and hydraulic anchors 3 at the upper and lower ends are respectively fixed to the two ends of the connecting threads to be loosened; the hydraulic reverser 5 is put into the wellhead to start the ball, the wellhead is circulated and pressurized, the hydraulic reverser 5 is rotated to uncoupling, and the loosening state of the wellhead is determined by the change of wellhead pressure; After the uncoupling operation is completed, the tubing string is rotated to the left to release the mechanical anchor 6, and then the hydraulic anchor 3 is lifted to release the tubing string, thus completing the downhole uncoupling operation.

[0039] The precision uncoupling system is characterized by its innovative tool combination and innovative operating process. The specific tool combination enables accurate location of the uncoupling point downhole.

[0040] In summary, this embodiment can ensure that the connecting threads are reversed at a predetermined position downhole, ensure that all upper casings are pulled out at once, ensure operational safety, and improve operational efficiency.

[0041] Finally, it should be noted that: the accompanying drawings of the embodiments disclosed in this invention only involve structures related to the embodiments disclosed in this invention, and other structures can refer to general designs. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0042] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A precision reverse-threading system for oil and gas field downholes, applied to a first casing, a second casing, and a third casing arranged sequentially from top to bottom, wherein the first casing and the second casing are connected by a first casing coupling, and the second casing and the third casing are connected by a second casing coupling, characterized in that, The system comprises, from bottom to top, a hydraulic positioner, a positioning sub, a hydraulic anchor, a backlash compensator, a hydraulic backlash device, and a mechanical anchor. The hydraulic positioner is used for hydraulic initiation and positioning, and is positioned at the gap connecting the second and third casings via the second casing coupling. The positioning sub connects the hydraulic positioner and the hydraulic anchor. The hydraulic anchor is anchored within the second casing. The backlash compensator is used for axial expansion and contraction to compensate for the axial displacement of the first casing during backlash. The hydraulic backlash device generates a backlash torque downhole to separate the threaded connection between the first and second casings. The mechanical anchor is anchored within the first casing and works in conjunction with the hydraulic backlash device to transmit the backlash torque to the first casing that needs to be twisted.

2. The precision reverse-threading system for oil and gas field downhole wells according to claim 1, characterized in that, The hydraulic positioner includes a body, a sleeve, a positioning block, a first spring, a first piston, a first shear sleeve, a first ball seat, and a first lower connector. The body has multiple grooves around its circumference to accommodate the positioning block. A first spring is provided between the positioning block and the body. The upper and lower ends of the positioning block are respectively restricted by the sleeve and the first piston. The lower end of the body has a first lower connector. The first lower connector contains a first shear sleeve and a first ball seat connected by a first shear pin. The lower end of the first piston is connected to the first lower connector by a second shear pin. When the first piston moves downward along the body, the positioning block is released radially outward.

3. The precision reverse-threading system for oil and gas field downhole wells according to claim 1, characterized in that, The hydraulic anchor includes a first upper connector, an upper clutch, a lower clutch, a spindle, a second shear sleeve, a locking ring sleeve, a locking ring, a second piston, a first locking sleeve, a slider, and a limiting sleeve. The spindle is provided with a limiting sleeve and a second piston. The spindle has multiple stepped grooves around its circumference. The slider is located in the stepped grooves. The first locking sleeve is located outside the slider. The first locking sleeve has a notch corresponding to the slider. The upper and lower ends of the first locking sleeve are connected to the second piston and the limiting sleeve, respectively. The upper end of the second piston is connected to the locking ring sleeve through a third shear pin. The locking ring sleeve contains a locking ring. The upper end of the locking ring sleeve is provided with a second shear sleeve. The upper end of the second shear sleeve is connected to the lower clutch through a third shear pin. The upper clutch is located above the lower clutch and is connected to the first upper connector. The first upper connector is located at the upper end of the spindle.

4. The precision reverse-threading system for oil and gas field downhole wells according to claim 1, characterized in that, The inverted compensator includes a second upper connector, a disc spring spindle, a disc spring outer cylinder, a disc spring, a washer, a spline outer cylinder, and a spline spindle. The upper end of the spline spindle is provided with a spline groove, the spline outer cylinder is provided with splines, the spline outer cylinder is connected to the spline spindle, the upper end of the spline spindle is provided with a disc spring spindle, the upper end of the spline outer cylinder is provided with a disc spring outer cylinder, a disc spring is provided between the disc spring spindle and the disc spring outer cylinder, the lower end of the disc spring is provided with a washer, and the upper end of the disc spring outer cylinder is provided with a second upper connector.

5. The precision reverse-threading system for oil and gas field downhole wells according to claim 1, characterized in that, The hydraulic reverser includes a third upper connector, an upper piston, an outer piston cylinder, an upper piston mandrel, an intermediate cylinder, a lower piston, a first sealing mandrel, a second ball seat, a ball outer cylinder, a ball torque shaft, a clutch sleeve, an inner clutch, a drive mandrel, an outer clutch, and a second lower connector. The third upper connector, upper piston mandrel, first sealing mandrel, ball torque shaft, drive mandrel, and second lower connector are arranged from top to bottom. A lower piston is located outside the ball torque shaft. The lower piston and the ball torque shaft form a screw-nut structure. A main spring is located below the lower piston. An inner clutch is located at the lower end of the main spring. The inner clutch is located at the upper end of the drive mandrel. An outer clutch is located outside the drive mandrel. A clutch spring is located at the lower end of the outer clutch. A spring retainer is located at the lower end of the clutch spring. The spring retainer is located at the upper end of the second lower connector. A clutch sleeve, a ball outer cylinder, an intermediate cylinder, and an outer piston cylinder are arranged sequentially at the upper end of the outer clutch. The upper end of the outer piston cylinder is connected to the third upper connector. The upper piston and the main spring are arranged from top to bottom between the outer piston cylinder and the upper piston mandrel. A second ball seat is located inside the first sealing mandrel.

6. The precision reverse-threading system for oil and gas field downhole wells according to claim 1, characterized in that, The mechanical anchor includes a fourth upper connector, a second locking sleeve, an adjusting sleeve, a limiting block, a locking nut, an anchoring sleeve, a fixed wing plate, a supporting wing plate, a wing plate bed, a power spindle, a positioning ring, a torque release sleeve, a release shear pin, a power sleeve, a power outer cylinder, a second sealing spindle, a second spring, a drop sleeve, a third piston, and a third lower connector. The power spindle, the second sealing spindle, and the third piston are arranged from top to bottom. The outer side of the power spindle is provided with the second locking sleeve, the limiting block, the adjusting sleeve, the anchoring sleeve, and the wing plate from top to bottom. The plate bed, positioning ring, and power outer cylinder, the anchoring sleeve and the wing plate bed are connected by locking nuts. The fixed wing plate and the supporting wing plate are set on the wing plate bed. A torque release sleeve is provided between the wing plate bed and the power outer cylinder. The torque release sleeve and the power outer cylinder are connected by a release shear pin. A power sleeve is provided between the power outer cylinder and the power spindle. A second spring is provided at the upper end of the third piston. The second spring is located outside the second sealing spindle. A drop sleeve and a third lower connector are provided in sequence at the lower end of the power outer cylinder. A fourth upper connector is provided at the upper end of the power spindle.

7. A method of using the precision reverse-threading system for oil and gas field downholes as described in any one of claims 1-6, characterized in that, Includes the following steps: The pitching and striking action begins by activating the hydraulic positioner, which determines the seat position by measuring the resistance of the vertically moving tubing. Increase the pressure to open the hydraulic anchor, giving the tubing a support point against the wellbore. Then press down the tubing to lock the hydraulic anchor, while simultaneously compressing the reverse compensator to provide sufficient locking force to the hydraulic anchor. Increase pressure to knock off the ball seat and keep the tubing clear; Rotating the upper drill pipe in the forward direction activates the mechanical anchor, causing the mechanical anchor support wing plates to open and support the inner wall of the casing. The mechanical anchors and hydraulic anchors at the upper and lower ends are respectively fixed to the two ends of the connecting threads to be loosened; the hydraulic reverser starter ball is inserted into the wellhead, the wellhead is pressurized cyclically, the hydraulic reverser rotates to uncouple, and the downhole loosening state is determined by the change in wellhead pressure; After the uncoupling operation is completed, the tubing string is rotated to the left to release the mechanical anchor, then the hydraulic anchor is lifted to release the hydraulic anchor, and the tubing string is pulled out to complete the downhole uncoupling operation.

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