Deep well and vertical well ball seat falling object fishing tool and using method
By combining the ultra-thin milling module, the variable diameter mother cone grabbing module, and the fish-falling detection module, the problem of difficult removal of deep well ball seats was solved, enabling rapid and safe ball seat retrieval and reducing construction complexity and operation time.
Patent Information
- Application Number
- CN202411086799.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-08
- Publication Date
- 2026-02-10
AI Technical Summary
In existing technologies, it is difficult to effectively remove ball seats that have detached from deep well casings, especially in downhole return production wells. Conventional retrieval methods are time-consuming and easily damage the casing. In addition, the ball seats are large in size and contain balls that cannot be retrieved from inside the well, making downhole operations complicated.
The deep well vertical well ball seat retrieval tool, composed of an ultra-thin milling module, a variable diameter mother cone grabbing module, and a falling fish detection module, achieves fast and safe ball seat retrieval by milling the ash plug, grabbing the top of the fish, and detecting whether it has been retrieved.
This technology enables the rapid and efficient retrieval of large-sized ball seats in deep wells, reducing construction complexity and operation time, improving operational efficiency, and preventing accidents inside the well.
Smart Images
Figure CN121497253A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of oil exploitation, and is a deep straight well ball seat fish falling tool and use method. BACKGROUND
[0002] Oil and gas well downhole packers are generally divided into retrievable packers and permanent packers. Domestic and foreign permanent packers are used in deep wells and gas wells to prevent long-term production packers from loosening and causing sealing failure, affecting the safety of the wellbore. The permanent packer usually places a set of one-way slips on both sides of the rubber tube, and through axial extrusion, the permanent packer rubber tube is expanded and the slips on both sides are anchored on the casing. Therefore, when the permanent packer bears alternating pressure difference, the load is always acting on the casing, and there is no loosening, and the sealing reliability is greatly improved.
[0003] However, due to the structural characteristics of the permanent packer, the ball seat needs to be driven by ball pressure to anchor the slip during the setting and sealing completion, and the production channel is left after the ball seat is drilled out. After the ball seat is drilled out, the subsequent wellbore operation is carried out. Especially for the downhole return well, the ball seat must be removed before the secondary completion operation can be carried out. The ball seat is usually buried by impurities such as mortar on the surface of the bridge plug, and the ball seat is large in size and contains a ball, which cannot be fished out. The clearance of the casing milling method is narrow, and the current ball seat processing usually adopts the drilling and grinding method, which is time-consuming and easy to wear the casing, causing downhole complexity.
[0004] Therefore, it is urgent to develop a deep straight well ball seat fish falling tool to quickly remove the influence of the ball seat. SUMMARY
[0005] The present application provides a deep straight well ball seat fish falling tool and use method, which overcomes the shortcomings of the prior art and effectively solves the problems of great difficulty, complex process and easy sticking of conventional fishing.
[0006] One of the technical solutions of the present application is realized by the following measures: a deep straight well ball seat fish falling tool, comprising an ultra-thin casing milling module, a variable-diameter female cone grabbing module and a fish falling detection module; The ultra-thin casing milling module is used for fish top introduction and casing milling mortar, and reduces impurity pressure coverage. The variable-diameter female cone grabbing module is used for grabbing the round or oval fish top. The fish falling detection module is used for blocking the pressure relief hole through relative displacement after the fish top is introduced, and then pumping and measuring pressure to detect whether the fish top is grabbed.
[0007] The following is a further optimization or / and improvement of the above-mentioned one of the technical solutions of the present application: The above-mentioned ultra-thin sleeve milling module can be a cylindrical barrel, the upper part of which is fixedly connected with the variable-diameter female cone grabbing module, and the lower part is a circular opening structure, the inner diameter of the ultra-thin sleeve milling module is greater than the maximum outer diameter of the ball seat, and the top of the sleeve milling is embedded with an alloy.
[0008] The above-mentioned variable-diameter female cone grabbing module can be a cylindrical barrel, the upper part of which is fixedly connected with the fish falling detection module, and the inside of which is a variable-diameter female cone, the inner diameter of which gradually decreases from bottom to top.
[0009] The above-mentioned fish falling detection module can be a cylindrical barrel, the upper part of which is connected with the pipe column, and the inside of which is provided with a pressure relief hole.
[0010] Specifically, it can include an upper joint, an outer cylinder, a spring, an upper sealing snap ring, a lower sealing snap ring, a central pipe, a variable-diameter female cone, an ultra-thin sleeve milling barrel and an alloy sleeve milling tooth; wherein the upper joint is connected with the upper fishing pipe column and connected with the outer cylinder; the upper end of the outer cylinder is connected with the upper joint, and the lower end is connected with the variable-diameter female cone; the upper sealing snap ring and the lower sealing snap ring cooperate with each other; the central pipe is a circulating liquid flow channel, supporting and protecting the spring; the alloy sleeve milling tooth is embedded in the top end of the ultra-thin sleeve milling barrel.
[0011] The second technical solution of the present application is realized by the following measures: a use method of a deep well straight well ball seat fish falling tool, comprising the following steps: Step one: connect the deep well straight well ball seat fish falling tool with the pipe column, and lower it into the well one by one; Step two: after reaching the top of the ball seat, test the position of the top of the ball seat, and pump circulating test fluid from the pipe column to test the friction; Step three: introduce the ball seat, pressurize and rotate the pipe column at the same time; Step four: pump from the pipe column, test the pump pressure, and detect whether it is caught; Step five: if it is detected that it is not caught, repeat steps three to four until it is detected that it is caught; Step six: take out the pipe column and the deep well straight well ball seat fish falling tool from the wellbore.
[0012] The following is a further optimization or / and improvement of the above-mentioned second technical solution of the application: In the above-mentioned step two, after reaching the top of the ball seat, the test lifting suspension weight can be slowly lifted first and recorded, and then the position of the ball seat is tested, and when testing, the observation of the suspension weight drop is not greater than 2t.
[0013] In the above-mentioned step two, the circulating test friction can be tested from the pipe column, the displacement is not greater than 0.2m 3 / min, the test time is not less than 10min, and the inlet and outlet densities are less than 0.02g / cm 3 .
[0014] The pressure range in the above-mentioned step three can be 2-5 t, and the pressure and rotation are simultaneously performed, and the rotation number is not less than 15 or the torque is greater than 2500 N·m.
[0015] In the above-mentioned step four, when pumping in the pipe column, whether the pressure continuously rises can be observed; when the pressure is greater than the friction resistance tested in step two by 5 MPa or more, it is determined that the fishing is successful; when the pressure is less than the friction resistance tested in step two by 5 MPa and greater than the tested friction resistance, steps three to four are repeated; when the pressure is equal to the friction resistance tested in step two, it is determined that the fishing is unsuccessful.
[0016] The ultra-thin sleeve milling module of the present application has the functions of fish top introduction and sleeve milling of impurities, can reduce the influence of impurity pressure coverage, and at the same time, the inner cutting angle of the upper and lower parts is designed to maximize the influence of the stuck drill pipe. The variable-diameter female cone grabbing module can realize the grabbing of circular or elliptical fish tops, has wide fishing range and strong adaptability, and improves the grabbing capacity. The fish falling detection module has a simple structure, and after the fish top is introduced, the pressure relief hole is blocked through relative displacement, and then pumping and pressure testing can effectively detect whether the fish top is grabbed, the detection signal is obvious, the invalid fishing caused by the inability to judge is avoided, the operation efficiency is improved, and the construction period is reduced. The pipe string structure of the present application can realize the release of the hand when the complex occurs, avoid the secondary complexity, realize the positive circulation after grabbing, prevent the well kick and blowout accidents caused by the insufficient liquid column height in the well, and prevent the stuck drill pipe accidents caused by the liquid circulation of the debris in the well. The present application can fish the large-size ball seat in the 5 1 inch or more than 2 inch casing in the deep well, solve the problems of large fishing difficulty, complex process and easy sticking of the drill pipe, realize the purpose of one-trip wellbore dredging and clean completion, can quickly fish the dropped ball seat, reduce the construction operation time, improve the operation efficiency, and reduce the influence of complex construction. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is a schematic diagram of the overall structure of the deep well straight well ball seat fishing tool of the embodiment of the present application.
[0018] Figure 2 It is a schematic diagram of the structure of the upper joint of the embodiment of the present application.
[0019] Figure 3 It is a schematic diagram of the structure of the outer cylinder of the embodiment of the present application.
[0020] Figure 4 It is a schematic diagram of the structure of the center pipe and spring of the embodiment of the present application.
[0021] Figure 5 It is a schematic diagram of the structure of the upper sealing snap ring of the embodiment of the present application.
[0022] Figure 6 It is a schematic diagram of the structure of the lower sealing snap ring of the embodiment of the present application.
[0023] Figure 7 This is a schematic diagram of the variable diameter mother cone according to an embodiment of the present invention.
[0024] Figure 8 This is a schematic diagram of the structure of the ultra-thin milling guide shoe according to an embodiment of the present invention.
[0025] Figure 9 This is a schematic diagram of the structure of the detachable ball seat according to an embodiment of the present invention.
[0026] The codes in the attached diagram are as follows: 1 is the upper connector, 2 is the outer cylinder, 3 is the spring, 4 is the upper sealing ring, 5 is the lower sealing ring, 6 is the center tube, 7 is the sealing ring groove, 8 is the variable diameter female cone, 9 is the ultra-thin sleeve milling cylinder, 10 is the alloy sleeve milling gear, 11 is the ultra-thin sleeve milling guide shoe, and 12 is the detachable ball seat. Detailed Implementation
[0027] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.
[0028] The present invention will be further described below with reference to embodiments: Example 1: As shown in the attached document Figure 1 To be continued Figure 9 As shown, the deep well vertical well ball seat object retrieval tool includes an ultra-thin milling module, a variable diameter mother cone grabbing module, and a fallen fish detection module; The ultra-thin milling sleeve module is used for fish-top introduction and milling of ash plugs to reduce impurity accumulation. In this embodiment, the upper and lower parts of the ultra-thin milling sleeve module are provided with internal chamfers to minimize the impact of drill jamming. In this embodiment, the ultra-thin milling sleeve module is a cylindrical body, with its upper part fixedly connected to the variable-diameter female cone gripping module and its lower part having a circular opening structure. The inner diameter of the ultra-thin milling sleeve module is larger than the maximum outer diameter of the ball seat for ball seat introduction. The top of the milling sleeve is inlaid with alloy to grind away ash plugs and other impurities, reducing the impact of accumulation at the large diameter bottom of the ball seat.
[0029] The variable-diameter female cone gripping module is used to grip round or elliptical fish heads. In this embodiment, the variable-diameter female cone gripping module is a cylindrical body, with its upper part fixedly connected to the fish detection module. The interior is a variable-diameter female cone, with the inner diameter gradually decreasing from bottom to top. When the deep well vertical well ball seat falling object retrieval tool is rotated, the female cone gradually engages with the top of the ball seat, achieving the gripping function. The variable-diameter female cone gripping module can grip round or elliptical fish heads, has a wide retrieval range, strong adaptability, and improves gripping capability.
[0030] The fish-catching detection module is used to detect whether the fish has been caught after it has been introduced by relative displacement to seal the pressure relief hole and then pumping pressure. In this embodiment, the fish-catching detection module is a cylindrical body connected to the tubing at the top, with a pressure relief hole inside. After catching, the pumping pressure indicates whether the fish has been caught. The fish-catching detection module has a simple structure. After the fish has been introduced by relative displacement to seal the pressure relief hole and then pumping pressure, it can effectively detect whether the fish has been caught. The detection signal is clear, avoiding invalid catching caused by inability to judge, improving operation efficiency and reducing construction cycle.
[0031] The ultra-thin milling module of this embodiment has the functions of introducing fish-shaped objects and milling impurities such as ash plugs, which can reduce the impact of impurities covering the surface. At the same time, the upper and lower parts are designed with internal chamfers to minimize the impact of stuck drill bits. The variable diameter mother cone grabbing module can grab round or elliptical fish-shaped objects, with a wide retrieval range and strong adaptability, improving the grabbing ability. The fish-fall detection module has a simple structure. After the fish-shaped object is introduced, the pressure relief hole is sealed by relative displacement, and then the pump injection pressure test can effectively detect whether the fish-shaped object has been grabbed. The detection signal is obvious, avoiding invalid retrieval caused by inability to judge, improving operation efficiency and reducing construction cycle. The pipe string structure of this embodiment can release the object when complex, avoiding secondary complexity. At the same time, positive circulation can be achieved after grabbing to prevent well kicks and blowouts caused by insufficient fluid column height in the well, and to prevent stuck drill bits caused by debris in the well through fluid circulation. This embodiment addresses the difficulty of retrieving objects from ball seats and can be used in deep wells. 1 The method of retrieving large-sized ball seats inside casings of 2 inches and above solves the problems of high difficulty, complex procedures, and easy sticking of drill bits in conventional retrieval methods. It achieves the goal of clearing and cleaning the well in one trip, and can quickly retrieve detached ball seats, reducing construction time, improving work efficiency, and reducing the impact of construction complexity.
[0032] Example 2: As shown in the attached document Figure 1 To be continued Figure 9As shown, the deep well straight well ball seat fishing tool specifically comprises an upper joint 1, an outer cylinder 2, a spring 3, an upper sealing snap ring 4, a lower sealing snap ring 5, a central pipe 6, a variable diameter female cone 8, an ultra-thin sleeve milling cylinder 9 and alloy sleeve milling teeth 10; wherein the upper joint 1 is connected with the upper fishing pipe column and connected with the outer cylinder 2, playing a role of bearing and connection; the upper end of the outer cylinder 2 is connected with the upper joint 1, and the lower end is connected with the variable diameter female cone 8, so as to fix and protect the spring 3, the upper sealing snap ring 4, the lower sealing snap ring 5 and the central pipe 6 from being affected by external force; the spring 3 is in a free state when not fishing, the upper sealing snap ring 4 and the lower sealing snap ring 5 are communicated with the pressure relief hole of the outer cylinder 2, and fluid can pass through smoothly, after the fish is caught, the fish top pushes the lower sealing snap ring 5 and transmits the upper sealing snap ring 4 to compress the spring 3, when the lower sealing snap ring 5 passes through the pressure relief hole, the flow channel is blocked by the sealing ring, there is no fluid passage, at this time, the pump injection forms a pressure build-up state; the upper sealing snap ring 4 and the lower sealing snap ring 5 cooperate with each other to seal the pressure and transmit the fish ballast; the central pipe 6 is a circulating liquid flow channel, supporting and protecting the spring 3 to prevent fluid erosion; the variable diameter female cone 8 catches the fish top, makes a thread during operation, and gradually catches the fish through the variable diameter thread making way.
[0033] Before using the tool, first place the central pipe 6 in the outer cylinder 2, then place the spring 3 in the annulus between the central pipe 6 and the outer cylinder 2, connect the upper joint 1 to the outer cylinder 2, place the sealing ring in the sealing ring groove 7 and the lower sealing snap ring 5, press the upper sealing snap ring 4 on the top of the spring 3, press the lower sealing snap ring 5 and the upper sealing snap ring 4 tightly, connect the variable diameter female cone 8 to the outer cylinder 2, and then connect the ultra-thin sleeve milling cylinder 9 to the lower end, thereby completing the connection of the tool. Finally, connect the upper joint 1 with the upper fishing pipe column, and lower it into the well one by one. Then implement the rotation of the guide shoe to guide the fish into the inside of the fishing tool. Specifically, after the assembled tool is connected and fastened with the fishing pipe column, it is lowered into the well, the pipe column is moved to the fish top position, the guide shoe contacts the fish top, and then the fish top is guided into the guide shoe under the guidance of the inner cylinder, at this time the fish top is guided into the inside of the guide shoe. Then the fish is fished and gripped. Specifically, after the assembled tool is connected and fastened with the fishing pipe column, it is lowered into the well, the fish top is guided into the guide shoe, the pipe column is rotated and continuously lowered, at this time the fish top continuously forms a new thread under the action of the variable diameter female cone and continuously penetrates into the inside of the female cone, the fish top and the female cone are continuously engaged, and finally the fish top is gripped. Then detect whether the fish top is guided in. Specifically, during the fish fishing and gripping stage, the pipe column is rotated and pressed down, and at the same time, the pump injection is also carried out from the inside of the pipe column, or the pump injection is carried out after the gripping action is completed, when the pump injection is carried out, the pump injection pressure rises obviously, indicating that the fish top has pushed the lower sealing snap ring to move upward, and the sealing ring has exceeded the pressure relief port, forming a flow channel closure, at this time the fish detection is completed, the wellbore can be pulled out, and the deep well ball seat fishing operation is completed.
[0034] The embodiment is aimed at the fishing difficulty of ball seat falling, and can fish the large-size ball seat in the casing with a diameter of 2 inches or more, solve the problems of large fishing difficulty, complex process and easy sticking, realize the purpose of one-trip wellbore dredging and clean completion, can quickly fish the fallen ball seat, reduce the construction operation time, improve the operation efficiency, and reduce the influence of complex construction. 1 The embodiment is aimed at the fishing difficulty of ball seat falling, and can fish the large-size ball seat in the casing with a diameter of 2 inches or more, solve the problems of large fishing difficulty, complex process and easy sticking, realize the purpose of one-trip wellbore dredging and clean completion, can quickly fish the fallen ball seat, reduce the construction operation time, improve the operation efficiency, and reduce the influence of complex construction.
[0035] Embodiment 3: The embodiment provides a use method of a deep straight well ball seat falling fishing tool, including the following steps: Step one: connect the deep straight well ball seat falling fishing tool with the pipe string, and lower into the well one by one; Step two: after lowering to the top of the ball seat, test the top position of the ball seat, and pump and circulate the test fluid in the pipe string to test the friction; Step three: introduce the ball seat, pressurize and rotate the pipe string at the same time; Step four: pump from the pipe string, test the pumping pressure, and detect whether the fishing is successful; Step five: if it is detected that the fishing is not successful, repeat steps three to four until the fishing is detected to be successful; Step six: take out the pipe string and the deep straight well ball seat falling fishing tool from the wellbore.
[0036] In the embodiment, the deep straight well ball seat falling fishing tool in step one can be selected according to the falling object in the well, wherein the ultra-thin casing milling module is used for the case that the falling object in the well is long-term stationary, and whether to install the module can be determined according to the pressure coverage condition; and the variable-diameter female cone grabbing module and the fish detection module are mandatory modules.
[0037] In the embodiment, the tool connection in step one should be fully screwed, the number of external leakage screws should not exceed 2 turns, and the torque should meet the standard; the pipe string is connected and lowered into one by one, and the lowering speed is controlled at 2-3 min / rod to prevent the deep straight well ball seat falling fishing tool from being deformed and damaged due to sudden resistance.
[0038] In the embodiment, after lowering to the top of the ball seat in step two, the lifting suspension weight is first tested slowly and recorded, and then the position of the ball seat is tested; when testing, the observation of the suspension weight drop is not greater than 2 t.
[0039] In the embodiment, after determining the position of the ball seat in step two, the suspension weight is slowly lifted and compared with the suspension weight during the lifting test in step two, and the error is less than 0.5 t.
[0040] In the embodiment, the friction is tested by circulating in the pipe string in step two, the displacement is not greater than 0.2 m 3 / min, the test time is not less than 10 min, and the inlet and outlet densities are less than 0.02 g / cm 3 .
[0041] In this embodiment, the pressurization range in step three is 2-5t, and the pressurization and rotation are carried out simultaneously. The rotation is stopped when the number of rotations is not less than 15 or the torque is greater than 2500 N·m.
[0042] In this embodiment, during step four, when pumping from the tubing, observe whether the pressure continues to rise; when the pressure is greater than 5 MPa above the friction resistance tested in step two, it is determined that the fish has been retrieved; when the pressure is less than 5 MPa above the friction resistance tested in step two, but greater than the friction resistance tested, repeat steps three to four; when the pressure is equal to the friction resistance tested in step two, it is determined that the fish has not been retrieved.
[0043] In this embodiment, when lifting the well casing and the deep well vertical well ball retrieval tool in step six, the lifting speed should be controlled to be no less than 3 minutes per casing, and fluid should be injected into the casing and casing.
[0044] This embodiment addresses the difficulty of retrieving objects dropped from a ball-shaped well, enabling operations in deep wells and 5... 1 The method of retrieving large-sized ball seats inside casings of 2 inches and above solves the problems of high difficulty, complex procedures, and easy sticking of drill bits in conventional retrieval methods. It achieves the goal of clearing and cleaning the well in one trip, and can quickly retrieve detached ball seats, reducing construction time, improving work efficiency, and reducing the impact of construction complexity.
[0045] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.
Claims
1. A tool for retrieving objects dropped into a deep vertical well, characterized in that... Includes an ultra-thin milling module, a variable diameter female cone gripping module, and a fish-falling detection module; Among them, the ultra-thin milling module is used for fish top introduction and milling of ash plugs to reduce impurity coverage; Among them, the variable diameter female cone gripping module is used for gripping the top of a round or elliptical fish; The fish detection module is used to seal the pressure relief hole by relative displacement after the fish is introduced, and then pump and measure the pressure to detect whether the fish has been grabbed.
2. The deep well vertical well ball-shaped object retrieval tool according to claim 1, characterized in that... The ultra-thin milling sleeve module is a cylindrical body. The upper part is fixedly connected to the variable diameter female cone gripping module, and the lower part is a circular opening structure. The inner diameter of the ultra-thin milling sleeve module is larger than the maximum outer diameter of the ball seat, and the top of the milling sleeve is inlaid with alloy.
3. The deep well vertical well ball-shaped object retrieval tool according to claim 1, characterized in that... The variable-diameter female cone gripping module is a cylindrical body, with its upper part fixedly connected to the fish detection module. The interior is a variable-diameter female cone, with the inner diameter gradually decreasing from bottom to top.
4. The deep well vertical well ball-shaped object retrieval tool according to claim 1, characterized in that... The fish detection module is a cylindrical body, connected to the tubing at the top, and has a pressure relief hole inside.
5. The deep well vertical well ball-shaped object retrieval tool according to claim 1, 2, 3, or 4, characterized in that... Specifically, it includes an upper connector, an outer cylinder, a spring, an upper sealing ring, a lower sealing ring, a central tube, a reducing female cone, an ultra-thin milling sleeve, and alloy milling teeth. The upper connector is connected to the upper retrieval string and also to the outer cylinder. The upper end of the outer cylinder is connected to the upper connector, and the lower end is connected to the reducing female cone. The upper and lower sealing rings cooperate with each other. The central tube serves as a circulating fluid channel, supporting and protecting the spring. The alloy milling teeth are embedded in the top of the ultra-thin milling sleeve.
6. A method for using a deep well vertical well ball-shaped object retrieval tool, characterized in that... Includes the following steps: Step 1: Connect the deep well vertical well ball seat retrieval tool to the tubing string and lower them into the well one by one; Step 2: After descending to the top of the ball seat, probe the position of the top of the ball seat and test the fluid friction by pumping fluid through the tubing. Step 3: Introduce the ball seat, apply pressure while rotating the tubing; Step 4: Pump water into the tubing, test the pumping pressure, and check if the fish has been retrieved. Step 5: If no catch is detected, repeat steps 3 and 4 until a catch is detected; Step Six: Remove the tubing string and the deep well vertical well ball retrieval tool from the wellbore.
7. The method of using the deep well vertical well ball-shaped object retrieval tool according to claim 6, characterized in that... In step two, after descending to the top of the ball seat, slowly lift it up to test the suspended weight and record it. Then, probe the position of the ball seat. When probing, observe that the suspended weight drops by no more than 2t.
8. The method of using the deep well vertical well ball-shaped object retrieval tool according to claim 6 or 7, characterized in that... In step two, the friction is tested by circulating the tubing internally; the displacement is no greater than 0.2m. 3 The test duration is no less than 10 minutes, and the inlet and outlet densities are less than 0.02 g / cm³. 3 .
9. The method of using the deep well vertical well ball-shaped object retrieval tool according to claim 6 or 7, characterized in that... In step three, the pressurization range is 2-5t. Pressurization and rotation are carried out simultaneously. The rotation is stopped when the number of rotations is not less than 15 or the torque is greater than 2500 N·m.
10. The method of using the deep well vertical well ball-shaped object retrieval tool according to claim 6 or 7, characterized in that... In step four, when pumping from the tubing, observe whether the pressure continues to rise; when the pressure is more than 5 MPa greater than the friction resistance tested in step two, it is determined that the fish has been retrieved; when the pressure is less than 5 MPa but greater than the friction resistance tested in step two, repeat steps three and four; when the pressure is equal to the friction resistance tested in step two, it is determined that the fish has not been retrieved.