A carbonate oil well screen completion string and a method for releasing the stuck

Abstract

The present invention discloses a carbonate oil well screen completion pipe string and a method for releasing the jam, including a rotatable release device, a safety joint, a temporary blocking screen and a flushing head connected from top to bottom; the rotatable release device includes a core shaft, a cylinder sleeve, a piston, an outer cylinder, an open ratchet clamp ring, an upper cone, a lower cone, an expansion sleeve, a clamp block, a valve seat, a lower joint, and a lower end cap; the cylinder sleeve, the piston, the lower cone, and the lower joint are nested in the outer side of the core shaft from top to bottom in sequence; the piston is fixedly connected to the core shaft; the lower joint is fixedly connected to the lower end of the lower cone; the outer cylinder, the open ratchet clamp ring, the upper cone, and the expansion sleeve are all nested in the outer side of the lower cone; a plurality of holes are provided on the lower body of the core shaft, and the position and size of the holes correspond to the groove of the lower cone; the clamp block is located in the groove of the lower cone and the hole of the core shaft, and the lower end cap is fixedly connected to the lower end of the core shaft. The device and method provided by the present invention can effectively deal with the serious problems of encountering obstacles, jamming, and not being able to be lowered into place at one time that are difficult to deal with in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of well completion engineering, in particular to a carbonate oil well screen completion string and a method for releasing the jam. Background Art

[0002] Of the world's proven oil and gas reserves, 60% are marine carbonate reservoirs. my country's carbonate oil and gas reservoirs are also widely distributed, mainly in the Tarim Basin and Sichuan Basin, with huge potential for exploration and development. At present, open hole completion is generally used for carbonate reservoirs. Due to changes in formation stress and rock strength, open hole completion is very prone to wellbore instability, resulting in wellbore collapse and sand burial of reservoirs, affecting the normal production of oil wells. In order to support the open hole well wall and prevent wellbore collapse and sand burial, the existing technology uses screen completion. However, the existing screen completion string is not easy to salvage in the case of sand burial, and the well repair is difficult, which affects the later side drilling, layer modification, deepening and other operations. In order to solve this problem, the existing technology uses easy-to-drill and grind screens to complete wells in carbonate oil wells. In the later stage, there is no need to salvage the screens. The easy-to-drill and grind screens can be directly drilled and ground off, and then the well is re-completed. Chinese patent CN107939358A introduces the easy-to-drill and grind screen completion. At present, this technology has been promoted and applied in the Halahatang Oilfield and Tahe Oilfield in the Tarim Basin. However, in the process of lowering the screen completion string, there are problems such as obstruction, jamming, and the string cannot be lowered into place, especially in highly deviated horizontal wells. In response to this type of problem, large-volume flushing and movable tubing are usually used to unblock, but due to the special structure of the screen and the hand release device, the unblocking fluid passes through the screen holes and cannot be flushed to the position where it encounters obstruction or jamming; at the same time, the existing hand release device cannot drive the lower completion string to rotate. Therefore, once the screen completion encounters obstruction or jamming, it is difficult to effectively unblock, which will lead to complex accidents. Summary of the invention

[0003] In view of the above problems, the present invention provides a carbonate oil well screen completion string and a method for unblocking the string, which has a simple structure and is easy to install and disassemble, and can effectively solve the problems of serious obstruction, jamming, and failure to reach the desired position in one go that are difficult to solve with the prior art.

[0004] The technical solution of the present invention is as follows:

[0005] A carbonate oil well screen completion string, comprising a rotatable hand release device, a safety joint, a temporary plugging screen and a flushing head connected from top to bottom;

[0006] The rotatable hand-dispensing device comprises a core shaft, a cylinder sleeve, a piston, an outer cylinder, an open ratchet collar, an upper cone, a lower cone, an expansion sleeve, a clamping block, a valve seat, a lower joint, and a lower end cap; the cylinder sleeve, the piston, the lower cone, and the lower joint are sequentially nested on the outer side of the core shaft from top to bottom; the piston, the cylinder sleeve, and the core shaft are sealed to form a sealed hollow cavity inside the core shaft; the piston is fixedly connected to the core shaft by a shearable pin; the lower joint is fixedly connected to the lower end of the lower cone; the outer cylinder, the open ratchet collar, the upper cone, and the expansion sleeve are all nested on the outer side of the lower cone; the middle outer wall of the lower cone is provided with an inverted tooth structure, and the lower middle part of the lower cone is provided with a plurality of discontinuous grooves; a plurality of holes are provided on the lower middle body of the core shaft, and the positions and sizes of the holes correspond to the grooves of the lower cone; the clamping block is located in the groove of the lower cone and the hole of the core shaft, and the lower end cap is fixedly connected to the lower end of the core shaft;

[0007] The temporary plugging screen pipe comprises a base pipe, wherein the base pipe adopts a circular pipe column, a plurality of holes are evenly drilled on the pipe column, and temporary plugging sheets are arranged in the holes;

[0008] The safety joint, the flushing head and the temporary plugging screen are all made of easy-to-drill and grind materials.

[0009] Furthermore, the valve seat is fixed inside the core shaft by a shearable pin, and the clamping block is pressed into the groove of the lower cone to achieve the connection of the clamping block to the groove of the lower cone and the eye of the core shaft.

[0010] Furthermore, the inner diameter of the lower head is smaller than the outer diameter of the valve seat.

[0011] Furthermore, the temporary plugging screen pipe includes a base pipe, a coupling, a temporary plugging piece, a sealing ring and a pressure ring.

[0012] Furthermore, the eyelet of the temporary plugging screen pipe includes two parts with different diameters, which are respectively used as the first eyelet and the second eyelet. The first eyelet is located inside the tube body, and the second eyelet is located outside the tube body. The diameter of the second eyelet is larger than the diameter of the first eyelet. There is a step between the first eyelet and the second eyelet for supporting the temporary plugging piece, and a groove is provided on the step. The sealing ring is located in the groove of the step, and then the temporary plugging piece is placed in the second eyelet. The pressure ring is fixed on the upper part of the second eyelet to press the temporary plugging piece against the step.

[0013] Furthermore, in the temporary plugging screen, the temporary plugging sheet is made of a polymer material soluble in formation fluid.

[0014] Furthermore, the temporary plugging sheet material is polyester BA1-28, and the compressive strength is required to be greater than 5MPa;

[0015] Furthermore, in the temporary plugging screen pipe, the base pipe and the pressure ring are made of aluminum alloy material that is easy to drill and grind.

[0016] A method for unblocking a carbonate oil well screen completion string, comprising the following steps:

[0017] S100, assemble the rotatable hand-dropping device and temporary blocking screen pipe separately to meet the connection and sealing standard requirements;

[0018] S200, connecting the rotatable hand release device, the safety joint, the temporary plugging screen and the flushing head from top to bottom to form a screen completion string, using a drill pipe or a tubing as an upper string, connecting the screen completion string to the bottom of the upper string by rotating the hand release device, and lowering the screen completion string into the well bottom using the upper string;

[0019] S300, if there is any obstruction or stuck during the lowering process, a jam-releasing operation is performed. The jam-releasing operation steps are: a large-volume positive or reverse circulation of the unblocking fluid is used for flushing. Since the screen tube holes are in a temporarily blocked state, the unblocking fluid can be circulated to the bottom of the well and sprayed out or entered through the flushing head, thereby ensuring that the flushing fluid effectively flushes the obstruction and stuck points; at the same time, the upper pipe string is rotated at the wellhead to drive the lower pipe string to rotate, flushing and rotating, and slowly lifting and lowering the pipe string until the completion pipe string is unstuck;

[0020] After the S400 and screen completion string are successfully lowered into the well bottom, the well is circulated and flushed to remove the mud on the well wall and impurities in the wellbore;

[0021] S500, after the well is washed, the hand is released, and the upper pipe string is taken out, and the fluid is sprayed out; the temporary plugging piece of the temporary plugging screen pipe left in the well is dissolved, and the screen pipe recovers its flow capacity and supporting function.

[0022] S600, during the later workover process, a special salvage tool is lowered to salvage the rotatable hand release device, and then a drilling and grinding tool is lowered to directly drill and grind off some components of the rotatable hand release device, safety joints, temporary plugging screens and flushing heads remaining in the well, and the wellbore is restored for secondary completion.

[0023] Furthermore, the plugging-removing fluid may be the completion fluid, acid solution, mud cake dissolving fluid, or lubricant of the original well.

[0024] Furthermore, the step of letting go in step S500 is specifically as follows:

[0025] First, the rotatable thrower is used for throwing the ball. After the ball falls into the valve seat, it is pressed. The pressure cuts off the pin on the upper part of the piston. The piston moves downward, driving the outer sleeve and the upper cone downward. Under the squeezing action of the upper cone and the lower cone, the two ends of the slit expansion sleeve expand and make it close to the inner wall of the casing, thereby achieving the function of hanging and supporting the lower pipe column. After the upper cone moves downward, the open ratchet clamp ring is clamped on the inverted teeth in the middle of the lower cone to ensure that the casing suspension will not loosen.

[0026] Then continue to pressurize. Since the pressure of the pin of the valve seat is greater than that of the piston pin, when the pressure is further increased, the pin of the valve seat is sheared off, and the valve seat slides down and is caught by the lower head; the upper pipe column is lifted up, and the block and the ball fall into the valve seat, the mandrel is separated from the lower cone, and the mandrel together with the valve seat, cylinder liner and outer sleeve are lifted out, and the lower cone is stuck in the outer sleeve, realizing the separation of the upper pipe column;

[0027] Furthermore, in the step of releasing the hand in step S500, if no upper suspension support is needed, the upper pressure hole of the mandrel can be blocked, and the ball can be dropped to pressurize the upper part without support, so that only the lower valve seat pin is sheared off, and the bottom of the well is used to support the pipe string.

[0028] The present invention is beneficial in that:

[0029] (1) The screen holes are blocked with temporary plugging pieces, which realizes the circulating flushing of the screen section and is conducive to dealing with the stuck situation of the screen section;

[0030] (2) After the screen completion string is in place, the entire well section can be circulated and flushed, effectively removing the mud cake on the well wall and impurities in the wellbore, which is beneficial to protecting the reservoir;

[0031] (3) The block of the rotatable release device is fixed in multiple discontinuous grooves, which can limit the lower cone to rotate with the core shaft, and can drive the lower pipe string to rotate by rotating the upper pipe string, thereby realizing the release of the bottom hole rotary drill bit;

[0032] (4) The temporary plugging screen and the rotatable hand-dropping device are used together to utilize the dual functions of flushing and rotating the pipe column, which can effectively deal with the serious obstruction, jamming, and inability to reach the correct position in one go that are difficult to deal with with the existing technology;

[0033] (5) The temporary plugging screen and flushing head are made of easy-to-drill and grind materials. In the later well repair, there is no need to salvage the screen and completion string. The screen and flushing head can be directly drilled and ground off, reducing the difficulty and operation cost of well repair and saving time. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of a carbonate oil well screen completion string structure provided in an embodiment;

[0035] Figure 2 A schematic diagram of the structure of a flushing head provided in an embodiment;

[0036] Figure 3 A schematic diagram of a temporary plugging screen tube structure provided in an embodiment;

[0037] Figure 4 A schematic diagram of an enlarged structure of a temporary plugging screen tube hole provided in an embodiment;

[0038] Figure 5 This is a schematic diagram of the structure of a rotatable hand-release device provided in an embodiment.

[0039] Notes in the figure:

[0040] 1 Rotatable hand release device, 2 Safety joint, 3 Temporary blocking screen, 4 Flushing head, 5 Easy-to-drill oil pipe;

[0041] 101 core shaft, 102 cylinder sleeve, 103 piston, 104 outer cylinder, 105 open ratchet clamp ring, 106 upper cone, 107 lower cone, 108 expansion sleeve, 109 clamping block, 110 valve seat, 111 lower joint, 112 lower head;

[0042] 301 base pipe, 302 coupling, 303 temporary plugging piece, 304 sealing ring, 305 pressure ring;

[0043] 401 threaded buckle, 402 eyelet. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0045] like Figure 1 As shown, a carbonate oil well screen completion string includes a rotatable release device 1, a safety joint 2, a temporary plugging screen 3 and a flushing head 4 connected from top to bottom;

[0046] like Figure 5 As shown, the rotatable hand-release device 1 includes a core shaft 101, a cylinder sleeve 102, a piston 103, an outer cylinder 104, an open ratchet collar 105, an upper cone 106, a lower cone 107, an expansion sleeve 108, a block 109, a valve seat 110, a lower joint 111, and a lower head 112; the cylinder sleeve 102, the piston 103, the lower cone 107, and the lower joint 111 are sequentially nested on the outer side of the core shaft 101 from top to bottom; the piston 103, the cylinder sleeve 102 and the core shaft 101 are sealed to form a sealed hollow cavity inside the core shaft 101; the piston 103 is connected to the core shaft 101 through a shearable pin 01 is fixedly connected; the lower joint 111 is fixedly connected to the lower end of the lower cone 107; the outer cylinder 104, the open ratchet collar 105, the upper cone 106, and the expansion sleeve 108 are all nested on the outside of the lower cone 107; the middle outer wall of the lower cone 107 is provided with an inverted tooth structure, and the lower middle part of the lower cone 107 is provided with a plurality of discontinuous grooves; a plurality of holes are provided on the lower body of the mandrel 101, and the position and size of the holes correspond to the grooves of the lower cone 107; the block 109 is located in the groove of the lower cone 107 and the hole of the mandrel 101, and the lower head 112 is fixedly connected to the lower end of the mandrel 101;

[0047] like Figure 3 and 4 As shown, the temporary plugging screen pipe 3 comprises a base pipe 301, a coupling 302, a temporary plugging piece 303, a sealing ring 304 and a pressure ring 305; the base pipe 301 adopts a circular pipe column, holes are evenly drilled on the pipe body, and temporary plugging pieces 303 are arranged in the holes.

[0048] The safety joint 2, the flushing head 4 and the temporary plugging screen pipe 3 are all made of easy-to-drill and grind materials.

[0049] The valve seat 110 is fixed inside the core shaft 101 by a shearable pin, and the clamping block 109 is pressed into the groove of the lower cone 107 to achieve the connection between the clamping block 109 and the groove of the lower cone 107 and the eyelet of the core shaft 101.

[0050] The inner diameter of the lower head 112 is smaller than the outer diameter of the valve seat 110 .

[0051] The eyelet of the temporary plugging screen pipe 3 includes two parts with different diameters, which are respectively used as the first eyelet and the second eyelet. The first eyelet is located inside the pipe body, and the second eyelet is located outside the pipe body. The diameter of the second eyelet is larger than the diameter of the first eyelet. There is a step between the first eyelet and the second eyelet for supporting the temporary plugging piece 303, and a groove is provided on the step. The sealing ring 304 is located in the groove of the step, and then the temporary plugging piece 303 is placed in the second eyelet. The pressure ring 305 is fixed on the upper part of the second eyelet to press the temporary plugging piece 303 against the step.

[0052] In the temporary plugging screen 3, the temporary plugging sheet 303 is made of a polymer material soluble in formation fluid, such as polyester BA1-28, and the compressive strength is required to be greater than 5 MPa; in the temporary plugging screen 3, the base pipe 301 and the pressure ring 305 are made of an aluminum alloy material that is easy to drill and grind.

[0053] The flushing head 4 is a hollow cylinder with an ellipsoidal bottom. A plurality of water holes 402 are provided on the bottom for flushing the formation. A threaded buckle 401 is provided on the upper end thereof so that it can be connected to the temporary plugging screen pipe 3 .

[0054] For the above carbonate oil well screen completion string, the method for unblocking the string is as follows:

[0055] S100, assembling the rotatable hand-dropping device 1 and the temporary blocking screen tube 3 respectively to meet the connection and sealing standard requirements;

[0056] S200, connecting the rotatable hand release device 1, the safety joint 2, the temporary plugging screen 3 and the flushing head 4 from top to bottom to form a screen completion string, using a drill pipe or a tubing as an upper string, connecting the screen completion string to the bottom of the upper string by rotating the hand release device, and lowering the screen completion string into the well bottom using the upper string;

[0057] S300, once there is resistance or jam during the lowering process, the jam-releasing operation is performed, and the jam-releasing operation steps are: use a large-volume positive or reverse circulation to flush with a jam-releasing fluid, and the jam-releasing fluid can be the completion fluid, acid, mud cake dissolving fluid, and lubricant of the original well; because the screen tube holes are in a temporarily blocked state, the jam-releasing fluid can be circulated to the bottom of the well, and sprayed out or entered through the flushing head 4, ensuring that the flushing fluid effectively flushes the resistance and jam points; at the same time, the upper pipe string is rotated at the wellhead to drive the lower pipe string to rotate, flushing and rotating, and slowly lifting and lowering the pipe string until the completion pipe string is unstuck; S400, after the screen tube completion pipe string is successfully lowered to the bottom of the well, the well is circulated and flushed to remove the mud on the well wall and impurities in the wellbore;

[0058] S500, after the well washing is completed, the hand-dropping operation is carried out. First, the rotatable hand-dropping device 1 is thrown into the ball operation, and the pressure is applied after the ball falls into the valve seat 110. The pressure cuts off the pin on the upper part of the piston 103, and the piston 103 moves downward to drive the outer cylinder 104 and the upper cone 106 downward. Under the squeezing action of the upper cone 106106 and the lower cone 107, the two ends of the slit expansion sleeve 108 expand and make it close to the inner wall of the casing, so as to achieve the function of hanging and supporting the lower pipe column; after the upper cone 106 moves downward, the open ratchet clamp ring 105 is stuck on the inverted teeth in the middle of the lower cone 107 to ensure that the casing suspension will not loosen; then continue to press, by Because the pressure on the pin of the valve seat 110 is greater than that on the pin of the piston 103, when the pressure is further increased, the pin of the valve seat 110 is sheared off, and the valve seat 110 slides down and is caught by the lower head 112; the upper pipe string is lifted up, and the block 109 and the ball fall into the valve seat 110, the mandrel 101 is separated from the lower cone 107, and the mandrel 101 together with the valve seat 110, the cylinder sleeve 102, and the outer cylinder 104 are lifted out, and the lower cone 107 is stuck in the outer cylinder 104, so that the upper pipe string is separated by hand; and the upper pipe string is lifted out, and the liquid is sprayed out; the temporary plugging sheet 303 of the temporary plugging screen pipe 3 left in the well is dissolved, and the screen pipe recovers its flow capacity and supporting function.

[0059] S600. During the later workover process, a special salvage tool is lowered to salvage the rotatable hand release device 1, and then a drilling and grinding tool is lowered to directly drill and grind away some components of the rotatable hand release device 1, the safety joint 2, the temporary plugging screen 3 and the flushing head 4 remaining in the well, and the wellbore is restored for secondary completion.

[0060] Furthermore, in the step of releasing the hand in step S500, if no upper suspension support is needed, the upper pressure hole of the mandrel 101 can be blocked, and the ball can be dropped to pressurize it, so that the upper part is not supported, so that only the pin of the lower valve seat 110 is sheared off, and the bottom of the well is used to support the pipe string.

[0061] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A carbonate oil well screen completion string, comprising a rotatable release device, a safety joint, a temporary plugging screen and a flushing head connected from top to bottom; It is characterized in that The rotatable hand-dispensing device comprises a core shaft, a cylinder sleeve, a piston, an outer cylinder, an open ratchet collar, an upper cone, a lower cone, an expansion sleeve, a clamping block, a valve seat, a lower joint, and a lower end cap; the cylinder sleeve, the piston, the lower cone, and the lower joint are sequentially nested on the outer side of the core shaft from top to bottom; the piston, the cylinder sleeve, and the core shaft are sealed to form a sealed hollow cavity inside the core shaft; the piston is fixedly connected to the core shaft by a shearable pin; the lower joint is fixedly connected to the lower end of the lower cone; the outer cylinder, the open ratchet collar, the upper cone, and the expansion sleeve are all nested on the outer side of the lower cone; the middle outer wall of the lower cone is provided with an inverted tooth structure, and the lower middle part of the lower cone is provided with a plurality of discontinuous grooves; a plurality of holes are provided on the lower middle body of the core shaft, and the positions and sizes of the holes correspond to the grooves of the lower cone; the clamping block is located in the groove of the lower cone and the hole of the core shaft, and the lower end cap is fixedly connected to the lower end of the core shaft; The temporary plugging screen pipe comprises a base pipe, a coupling, a temporary plugging piece, a sealing ring and a pressure ring; The base pipe adopts a circular pipe column, a plurality of holes are evenly drilled on the pipe column, and temporary plugging pieces are arranged in the holes; The eyelet of the temporary plugging screen pipe includes two parts with different diameters, which are respectively used as the first eyelet and the second eyelet; the first eyelet is located inside the pipe body, and the second eyelet is located outside the pipe body, and the diameter of the second eyelet is larger than the diameter of the first eyelet; there is a step between the first eyelet and the second eyelet for supporting the temporary plugging piece, and a groove is provided on the step, and the sealing ring is located in the groove of the step, and then the temporary plugging piece is placed in the second eyelet, and the pressure ring is fixed on the upper part of the second eyelet to press the temporary plugging piece against the step; The safety joint, the flushing head and the temporary plugging screen are all made of easy-to-drill and grind materials.

2. A carbonate oil well screen completion string according to claim 1, characterized in that: The valve seat is fixed inside the core shaft by a shearable pin, and the clamping block is pressed into the groove of the lower cone to achieve the connection between the clamping block and the groove of the lower cone and the eye of the core shaft.

3. A carbonate oil well screen completion string according to claim 2, characterized in that: The inner diameter of the lower head is smaller than the outer diameter of the valve seat.

4. A carbonate oil well screen completion string according to claim 3, characterized in that: In the temporary plugging screen, the temporary plugging piece is made of a polymer material soluble in formation fluid; In the temporary plugging screen pipe, the base pipe and the pressure ring are made of aluminum alloy material which is easy to drill and grind.

5. A method for unstuck a carbonate oil well screen completion string as claimed in claim 4, comprising the following steps: S100, assemble the rotatable hand-dropping device and temporary blocking screen pipe separately to meet the connection and sealing standard requirements; S200, connecting the rotatable hand release device, the safety joint, the temporary plugging screen and the flushing head from top to bottom to form a screen completion string, using a drill pipe or a tubing as an upper string, connecting the screen completion string to the bottom of the upper string by rotating the hand release device, and lowering the screen completion string into the well bottom using the upper string; S300, if there is any obstruction or stuck during the lowering process, a jam-releasing operation is performed. The jam-releasing operation steps are: a large-volume positive or reverse circulation of the unblocking fluid is used for flushing. Since the screen tube holes are in a temporarily blocked state, the unblocking fluid can be circulated to the bottom of the well and sprayed out or entered through the flushing head, thereby ensuring that the flushing fluid effectively flushes the obstruction and stuck points; at the same time, the upper pipe string is rotated at the wellhead to drive the lower pipe string to rotate, flushing and rotating, and slowly lifting and lowering the pipe string until the completion pipe string is unstuck; After the S400 and screen completion string are successfully lowered into the well bottom, the well is circulated and flushed to remove the mud on the well wall and impurities in the wellbore; S500, after the well is washed, the hand is released, and the upper pipe string is pulled out, and the fluid is sprayed out; the temporary plugging piece of the temporary plugging screen pipe left in the well is dissolved, and the screen pipe resumes its flow capacity and supporting function; S600, during the later workover process, a special salvage tool is lowered to salvage the rotatable hand release device, and then a drilling and grinding tool is lowered to directly drill and grind off some components of the rotatable hand release device, safety joints, temporary plugging screens and flushing heads remaining in the well, and the wellbore is restored for secondary completion.

6. The method for unstuck the carbonate oil well screen completion string according to claim 5, characterized in that: The plugging-removing fluid can be the completion fluid, acid solution, mud cake dissolving fluid, and lubricant of the original well.

7. The method for unstuck the carbonate oil well screen completion string according to claim 5, characterized in that: The step of releasing the hand in step S500 is specifically as follows: First, the rotatable thrower is used for throwing the ball. After the ball falls into the valve seat, it is pressed. The pressure cuts off the pin on the upper part of the piston. The piston moves downward, driving the outer sleeve and the upper cone downward. Under the squeezing action of the upper cone and the lower cone, the two ends of the slit expansion sleeve expand and make it close to the inner wall of the casing, thereby achieving the function of hanging and supporting the lower pipe column. After the upper cone moves downward, the open ratchet clamp ring is clamped on the inverted teeth in the middle of the lower cone to ensure that the casing suspension will not loosen. Then continue to pressurize. Since the pressure-bearing capacity of the pin of the valve seat is greater than that of the piston pin, when the pressure is further increased, the pin of the valve seat is sheared off, and the valve seat slides down and is caught by the lower head; the upper pipe column is lifted up, and the block and the ball fall into the valve seat, the core shaft is separated from the lower cone, and the core shaft together with the valve seat, cylinder liner and outer sleeve are lifted out, and the lower cone is stuck in the outer sleeve, realizing the separation of the upper pipe column.

8. The method for unstuck the carbonate oil well screen completion string according to claim 7, characterized in that: In the step S500, if the upper suspension support is not needed, the upper pressure hole of the mandrel is blocked, and the ball is dropped to pressurize the upper part, so that only the lower valve seat pin is sheared off, and the bottom of the well is used to support the pipe string.

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