Expandable pipe anchoring process and tool enabling large-diameter thin-wall back- insertion pipe anchoring
By using expansion tube anchoring technology and tools, the problem of anchoring large-diameter thin-walled back-insertion tubes and back-insertion cylinders was solved, which improved the stability and efficiency of fracturing operations and reduced subsequent operating costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NAT PETROLEUM CORP
- Filing Date
- 2024-12-30
- Publication Date
- 2026-06-30
AI Technical Summary
In existing technologies, there is a lack of effective anchoring mechanism between the large-diameter thin-walled reinsertion tube and the reinsertion sleeve, which makes the reinsertion tube prone to detachment or sealing failure during fracturing operations, affecting the stability and efficiency of the operation.
An expansion tube anchoring process and tools are adopted. The vulcanized rubber seal and expansion head between the expansion tube and the insertion tube are squeezed to achieve relative fixation between the insertion tube and the insertion cylinder. The piston rod of the expansion tube tool drives the expansion head to move downward, squeezing the expansion tube to fit against the original sleeve wall to form a limiting force and ensure sealing.
It achieves stable anchoring of large-diameter thin-walled reinsertion tubes and reinsertion sleeves, ensuring sealing reliability during fracturing operations, improving construction efficiency, and reliably uncoupling expansion tubes after construction, reducing the cost of subsequent operations.
Smart Images
Figure CN122304635A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wellbore reconstruction technology for old wells in low-permeability oil and gas field reservoirs. Specifically, it relates to an expansion tube anchoring process and tools that can achieve anchoring of large-diameter thin-walled reinsertion tubes. Background Technology
[0002] Currently, the main technologies for repeated fracturing of old wells in low-permeability tight oil blocks include double-sealed single-clamp repeated volumetric fracturing and wellbore reconstruction combined with bridge-fracturing. For wellbore reconstruction, there are many mature tools, tubing strings, and wellhead accessories available on the market. During the insertion operation, the insertion tubing and the insertion sleeve are mostly locked by male and female threads. After locking, it can prevent the insertion tubing from being pulled out by the upper part under the force during fracturing. After fracturing, when retrieving the insertion tubing string, simply rotate the insertion tubing string, and the threads between the insertion tubing and the insertion sleeve will be unthreaded, and finally the insertion tubing string can be separated and retrieved.
[0003] As reservoir stimulation technology accelerates towards volumetric fracturing methods with large displacement, large fluid volume, and large sand volume, wellbore reconstruction technology is also being forced to move towards thin-walled, large-diameter systems. However, for large-diameter, thin-walled re-insertion tool systems, conventional male and female thread locking and unthreading, slip anchoring, and anchor claw anchoring mechanisms are difficult to design due to the constraints of the thin-walled conditions.
[0004] In current large-diameter thin-walled tube re-insertion systems, the re-insertion tube and the re-insertion cylinder do not have the function of anchoring the re-insertion tube after reconnection. During fracturing operations, the re-insertion tube is frequently pushed off the re-insertion cylinder or the re-insertion seal fails due to high-frequency vibration of the tubing string, resulting in fracturing failure and production delays. Summary of the Invention
[0005] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to propose an expansion tube anchoring process and tool that enables anchoring of large-diameter thin-walled reinsertion tubes, thereby achieving relative fixation and limiting of the reinsertion tube and reinsertion cylinder in a large-diameter thin-walled tube reinsertion system, ensuring the stability and reliability of the reinsertion seal during fracturing operations.
[0006] To achieve the above objectives, the present invention provides an expansion tube anchoring tool for anchoring large-diameter thin-walled reinsertion tubing, comprising a reinsertion tool string, an expansion tool string, a reinsertion cylinder, and an expansion tool activation ball; the reinsertion tool string includes an expansion tube; the top of the expansion tube is connected to a small casing of the reinsertion tubing string, and the bottom is connected to the reinsertion tube; the bottom of the reinsertion cylinder is connected to the original cementing small casing, and the top is inserted into the bottom of the reinsertion tube; the expansion tool string includes an expansion tool piston rod and an expansion tool outer cylinder; the expansion tool outer cylinder can be temporarily fixed to the inner wall of the small casing of the reinsertion tubing string; the piston of the expansion tool piston rod engages with the expansion tool outer cylinder. Inside, the bottom section of the piston rod of the expansion tool extends downward through the outer cylinder of the expansion tool and is connected to an expansion head on its outer surface; the bottom end of the piston rod of the expansion tool is open, and when the starting ball of the expansion tool is located at the expansion head, the starting ball of the expansion tool can block the opening; the small sleeve and the expansion tube are detachably connected, and the expansion tube has a reduced diameter section in the middle, and the outer wall of the reduced diameter section is covered with vulcanized expansion rubber. When the starting ball of the expansion tool blocks the piston rod of the expansion tool, the internal pressure of the expansion tool string will increase. When the piston rod of the expansion tool moves downward under the pressure drive, the expansion head can gradually squeeze the reduced diameter section of the expansion tube, so that the reduced diameter section and the expansion rubber are adhered to the original sleeve wall to form a limiting force.
[0007] In a preferred embodiment of this solution, a rubber seal is provided at the bottom of the insertion tube, and the bottom of the insertion tube and the insertion cylinder are sealed together by the rubber seal. The rubber seal forms a sealing effect at the contact surface between the insertion tube and the insertion cylinder, and can withstand high temperature and high pressure sealing.
[0008] In a preferred embodiment of this solution, the tube expansion tool string further includes a hydraulic anchor, and the outer cylinder of the tube expansion tool can be anchored to the inner wall of the small sleeve of the insertion tube column by the hydraulic anchor.
[0009] In a preferred embodiment of this solution, the piston rod of the tube expander is detachably fixed inside the outer cylinder of the tube expander via a tube expander starter screw. When the piston rod of the tube expander is subjected to a certain vertical force, the detachable connection between the piston rod and the outer cylinder of the tube expander can be automatically released.
[0010] In a preferred embodiment of this solution, the bottom of the outer cylinder of the tube expander is also provided with a pressure relief hole for the tube expander piston. When the piston surface of the tube expander piston rod slides past the pressure relief hole, the internal pressure of the tube expander string is relieved, and at the same time, the expander head has completely squeezed the reduced diameter section of the expansion tube to the wall.
[0011] In a preferred embodiment of this solution, the expansion tube and the insertion tube are an integrated structure; or
[0012] The bottom of the expansion tube is detachably connected to the insertion tube.
[0013] In a preferred embodiment of this solution, the top of the expansion tube is detachably connected to the small sleeve of the insertion tube column.
[0014] In a preferred embodiment of this solution, a tailpipe hanger is connected to the original cementing casing, the tailpipe hanger is mounted on the inner wall of the original casing, and the return sleeve is connected to the top of the tailpipe hanger.
[0015] In a preferred embodiment of this solution, the top of the outer cylinder of the expansion tool is connected to the hydraulic anchor via an upper connector of the expansion tool, and a sealing element is provided between the upper connector of the expansion tool and the outer cylinder of the expansion tool.
[0016] In a preferred embodiment of this solution, a second sealing element is provided at the contact point between the piston surface of the piston rod of the expansion tool and the outer cylinder of the expansion tool; a third sealing element is provided at the contact point between the bottom of the outer cylinder of the expansion tool and the piston rod of the expansion tool; and a fourth sealing element is provided at the junction of the front end of the piston rod of the expansion tool and the expansion head.
[0017] In another aspect, the present invention provides a process for anchoring large-diameter thin-walled re-insertion tubes, employing the aforementioned expansion tube anchoring tool, and comprising the following steps:
[0018] S1. Install the return sleeve onto the original cementing casing or tailpipe hanger:
[0019] The return sleeve is inserted into the well along with the original cementing casing. After the bottom of the return sleeve is connected to the original cementing casing, or after it is connected to the original cementing casing via the tailpipe hanger, cementing is carried out.
[0020] S2. Remove the insertion tool string containing the return sleeve and the original cementing casing:
[0021] Remove the feed tool string that was inserted into the lower insertion cylinder;
[0022] Then, a re-insertion tool string is inserted through a tubing column to seal the re-insertion tube with the re-insertion cylinder for re-insertion;
[0023] Pressure testing inside the wellbore was conducted to verify the seal after re-insertion, ensuring a qualified seal.
[0024] S3. Insert the tube expansion tool string (the insertion is achieved through the tube expansion tool string) and start the tube expansion operation:
[0025] After the tubing string of the expansion tool is lowered to the position, the starting ball of the expansion tool is dropped into the tubing from the wellhead. The starting ball will be placed in the expansion head to achieve sealing and pressure build-up. At the same time, the outer cylinder of the expansion tool is fixed to the inner wall of the small casing of the back insertion string. The piston rod of the expansion tool will drive the expansion head to move downward due to the piston force. The downward movement of the expansion head will squeeze and expand the expansion tube to achieve expansion and anchoring.
[0026] S4. Remove the tube expansion tool string from your hand;
[0027] S5. Fracturing operation.
[0028] In this scheme, after the reinsertion tube is reinserted into the reinsertion cylinder, the reinsertion sealing performance needs to be verified. After the reinsertion sealing performance is verified by pressure testing at the wellhead, the tube expansion tool string is lowered. After the string is lowered into place, pumping circulation is performed first. After the circulation is normal, the tube expansion tool starter ball is dropped from the wellhead tubing. The ball is placed in the expansion head and pressurized, and then the tube expansion tool can be started to perform the tube expansion operation.
[0029] Furthermore, in a preferred embodiment of this solution, the expansion tool string further includes a hydraulic anchor, and the outer cylinder of the expansion tool can be anchored to the inner wall of the small sleeve of the insertion string by the hydraulic anchor. Step S3 specifically involves:
[0030] After the tubing expansion tool string is lowered to the desired position, the expansion tool initiation ball is dropped into the tubing from the wellhead. The initiation ball will settle inside the expansion head to achieve sealing and pressure buildup, increasing the pressure inside the tubing expansion tool string. The hydraulic anchor connected to the upper end of the tubing expansion tool string will then activate and anchor to the inner wall of the small casing of the return tubing string, thus fixing the outer cylinder of the expansion tool to the inner wall of the small casing of the return tubing string. The piston rod of the expansion tool will drive the expansion head downward due to the piston force, and the downward movement of the expansion head will expand the tubing, achieving tubing expansion and anchoring.
[0031] In a preferred embodiment of this solution, step S5 specifically includes: pumping fracturing operations from the small casing of the reinsertion tubing string. During operations, the wellbore is under high pressure, which exerts an upward force on the reinsertion tubing. The magnitude of this upward force is proportional to the pressure value and the annular cross-sectional area between the sealing surface of the reinsertion tubing and its inner diameter. Based on the original casing inner diameter parameters, by designing the dimensions of the expansion tube and expansion rubber, the adhesion and limiting force between the expanded expansion tube and expansion rubber and the original casing wall can overcome the upward force on the reinsertion tubing, ensuring that the reinsertion seal remains effective and reliable throughout the operations until the fracturing of the entire well section is successfully completed, thereby improving operational efficiency.
[0032] In a preferred embodiment of this solution, the process of anchoring a large-diameter thin-walled re-insertion tube, wherein the small sleeve of the re-insertion tube is threadedly connected to the expansion tube, further includes step S6:
[0033] S6. After the fracturing operation is completed, remove the small casing of the reinserted tubing string:
[0034] Rotate the small casing of the return tubing string to unlatch the threads connecting it to the expansion tubing, then pull out the small casing. The expansion tubing and the return tubing will remain in the wellbore.
[0035] In a preferred embodiment of this solution, the piston rod of the expansion tool is detachably fixed to the outer cylinder of the expansion tool via an expansion tool activation shear pin. The outer cylinder of the expansion tool can be hydraulically anchored to the inner wall of the small sleeve of the insertion pipe. Step S3 specifically includes the following steps:
[0036] After the tubing expansion tool string is lowered to the desired position, the expansion tool initiation ball is dropped into the tubing from the wellhead. The initiation ball will settle inside the expansion head to achieve sealing and pressure buildup. At this time, the hydraulic anchor claws extend outward and engage with the inner wall of the small casing of the reinsertion string. Simultaneously, the expansion tool piston rod will tend to move downward due to the piston force. When the pressure rises to a certain value, the expansion tool piston rod will shear the expansion tool initiation shear pin due to the piston force. The expansion tool piston rod will drive the expansion head to move downward. The downward movement of the expansion head will squeeze and expand the expansion tube. The adhesion between the reduced diameter section and the expansion rubber and the original casing wall forms a limiting force, realizing the expansion and anchoring of the tubing.
[0037] This invention proposes an expansion tube anchoring process and tool for anchoring large-diameter thin-walled re-insertion tubes. This method achieves expansion anchoring between the thin-walled re-insertion tube and the inner wall of the original sleeve. The expansion tube is installed on the re-insertion tube, and after successful insertion and sealing, a tube expansion tool string is lowered in. A ball is thrown to apply pressure and expand the tube. Once expanded, the tube adheres to the inner wall of the original sleeve, thus anchoring the re-insertion tube. For subsequent removal of the re-insertion tube, simply rotating the tube unthreads the reverse threads connecting the small sleeve and the expansion tube, allowing for easy removal of the tube.
[0038] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:
[0039] (1) The expansion tube anchoring tool proposed in this invention, which can realize the anchoring of large-diameter thin-walled back-insertion pipe, includes a back-insertion pipe tool string, an expansion tube tool string, a back-insertion cylinder, and an expansion tube tool starting ball; the back-insertion pipe tool string includes a back-insertion pipe and an expansion pipe; the bottom of the back-insertion cylinder is connected to the original cementing casing via a tailpipe hanger, and the top is inserted into the bottom of the back-insertion pipe; the expansion tube tool string includes an expansion tube tool piston rod and an expansion tube tool outer cylinder, and the bottom of the expansion tube tool piston rod is provided with an expansion head; the back-insertion cylinder and the back-insertion pipe are back-inserted. After the back-insertion seal is verified to be qualified, the expansion tube tool string can be lowered, and the expansion head is used to perform the expansion operation. After the expansion is completed, the outer diameter of the expansion tube expands and becomes larger. The vulcanized expansion rubber on it expands and adheres to the inner wall of the original casing, so that the back-insertion pipe system and the original casing are relatively fixed, that is, the back-insertion pipe system is anchored on the original casing. Overall, the relative anchoring or fixing between the back-insertion pipe and the back-insertion cylinder is realized.
[0040] (2) The process provided by this invention for anchoring large-diameter thin-walled re-insertion pipes involves, after confirming the re-insertion seal is qualified, inserting a dedicated expansion tube with a matching expansion tool. The expansion head is then expanded by injecting a ball into the tubing and applying pressure. The inner and outer diameters of the expanded tube increase simultaneously after expansion, and the vulcanized expansion rubber around it also expands. After expansion, the rubber adheres tightly to the inner wall of the original casing, forming a tight fit that prevents relative sliding between the expansion tube and the original casing, thus generating a certain axial anchoring force. Adjusting the rubber expansion allowance generates sufficient axial anchoring force. Anchoring force is used to anchor the reinserted casing. After the reinserted casing is axially anchored, subsequent fracturing operations can be carried out, and the stable and reliable reinserted casing sealing state can be reliably guaranteed during the construction process. After fracturing is completed, the expansion tube has threads with a different thread direction than the small casing. By rotating the tubing string at the wellhead, the threads connecting the small casing and the expansion tube can be unthreaded. After unthreading, the upper reinserted small casing can be pulled out without affecting subsequent operations such as running the production pump, and without increasing the well construction cost on the completion casing, which meets the current wellbore reconstruction and reinsertion technology. Attached Figure Description
[0041] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:
[0042] Figure 1 The diagram shows an exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled back-insertion casing, after the back-insertion casing is run into the well and cemented.
[0043] Figure 2 This diagram illustrates another exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled back-insertion tubes.
[0044] Figure 3 The diagram shows a schematic representation of the state of the expansion tube after it has been re-inserted into the reconnection sleeve, illustrating an exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes.
[0045] Figure 4 This diagram illustrates a state diagram of the ball-throwing pressure-initiating tube expansion operation procedure, representing an exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes.
[0046] Figure 5 This diagram illustrates a fully expanded tube state, representing an exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes.
[0047] Figure 6This diagram illustrates the state after the expansion tube tool string is removed following the completion of the expansion tube installation process and tool of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes.
[0048] Figure 7 This diagram illustrates an exemplary embodiment of the expansion tube anchoring process and tool of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes. It shows the state of the remaining expansion tube and re-insertion tube after the rotating tube column is unfastened and the upper re-insertion sleeve is removed.
[0049] Key reference numerals in the attached drawings: 1. Inner wall of the original casing; 2. Re-insertion tube; 3. Cementing material; 4. Small casing of the re-insertion string; 5. Expansion tube; 6. Expansion rubber; 7. Re-insertion tube; 8. Rubber seal; 9. Hydraulic anchor; 10. Upper connector of the expansion tool; 11. Seal 1; 12. Seal 2; 13. Outer cylinder of the expansion tool; 14. Piston rod of the expansion tool; 15. Piston pressure relief hole of the expansion tool; 16. Seal 3; 17. Starting shear pin of the expansion tool; 18. Seal 4; 19. Expansion head; 20. Starting ball of the expansion tool. Detailed Implementation
[0050] In the following sections, the expansion tube anchoring tool and process of the present invention, which enables anchoring of large-diameter thin-walled re-insertion tubes, will be described in detail with reference to exemplary embodiments.
[0051] It should be noted that terms such as "first," "second," "third," and "fourth" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "up," "down," "front," "back," "left," "right," "inner," and "outer" are merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.
[0052] Figure 1 The diagram shows the state of the reinsertion sleeve after it has been run into the well and cemented, according to an exemplary embodiment of the present invention. Figure 2 A schematic diagram of the insertion tube tool string structure of an exemplary embodiment of the present invention is shown. Figure 3 This diagram illustrates the state of the insertion tube after it has been inserted back into the reconnection sleeve, according to an exemplary embodiment of the present invention. Figure 4 The diagram shows a state diagram of the ball-throwing pressure-initiating tube expansion operation procedure of an exemplary embodiment of the present invention. Figure 5 This diagram illustrates the state of the expansion tube after all expansion tubes have been fully expanded, according to an exemplary embodiment of the present invention. Figure 6 This diagram illustrates the state of the tube after the tube expansion tool string is removed following the completion of tube expansion, according to an exemplary embodiment of the present invention. Figure 7 The diagram illustrates an exemplary embodiment of the present invention, showing the state of the upper re-insertion sleeve after the rotating tube is unhooked, and the remaining expansion tube and re-insertion tube.
[0053] Exemplary Example 1
[0054] refer to Figures 1-5 As shown, an expansion tube anchoring tool for large-diameter thin-walled re-insertion tubing includes a re-insertion tool string, an expansion tool string, a re-insertion cylinder 2, and an expansion tool activation ball 20. The re-insertion tool string, from bottom to top, includes a re-insertion tube 7, an expansion tube 5, and a re-insertion tubing string small casing 4. The bottom of the re-insertion cylinder 2 is connected to the original cementing small casing or tailpipe hanger, and its top is inserted into the bottom of the re-insertion tube 7. The expansion tool string includes an expansion tool piston rod 14 and an expansion tool outer cylinder 13. The expansion tool outer cylinder 13 can be temporarily fixed to the inner wall of the re-insertion tubing string small casing 4.
[0055] The piston rod 14 of the expansion tool is piston-fitted into the outer cylinder 13 of the expansion tool, and the bottom section of the piston rod 14 extends downward through the outer cylinder 13 of the expansion tool, with an expansion head 19 on its outer surface; the bottom end of the piston rod 14 is open, and when the expansion tool activation ball 20 is located at the expansion head 19, the expansion tool activation ball 20 can block the opening; the re-insertion tube column small sleeve 4 and the expansion tube 5 are detachably connected, and the expansion tube 5 has a reduced diameter section in the middle, and the outer wall of the reduced diameter section is provided with vulcanized expansion rubber 6. When the expansion tool activation ball 20 blocks the piston rod 14 of the expansion tool, the internal pressure of the expansion tool string will increase. When the piston rod 14 of the expansion tool moves downward under pressure, the expansion head 19 can gradually squeeze the reduced diameter section of the expansion tube 5, so that the reduced diameter section and the expansion rubber 6 form a limiting force with the original inner wall 1 of the sleeve.
[0056] In this exemplary embodiment, the bottom of the insertion tube 7 is provided with a rubber seal 8, and the bottom of the insertion tube 7 and the insertion cylinder 2 are sealed and inserted through the rubber seal 8.
[0057] In this exemplary embodiment, the tube expansion tool string further includes a hydraulic anchor 9, and the outer cylinder 13 of the tube expansion tool can be anchored to the inner wall of the small sleeve 4 of the insertion tube column by the hydraulic anchor 9.
[0058] In this exemplary embodiment, the piston rod 14 of the tube expander tool is detachably fixed inside the outer cylinder 13 of the tube expander tool via the tube expander tool activation shear 17. When the piston rod 14 of the tube expander tool is subjected to a certain vertical force, the detachable connection between the piston rod 14 of the tube expander tool and the outer cylinder 13 of the tube expander tool can be automatically released.
[0059] refer to Figures 4-7 As shown in this exemplary embodiment, the bottom of the outer cylinder 13 of the tube expander tool is also provided with a tube expander tool piston pressure relief hole 15. When the piston surface of the tube expander tool piston rod 14 slides past the tube expander tool piston pressure relief hole 15, the internal pressure of the tube expander tool string is relieved, the expansion head 19 retracts, and at the same time, the expansion head 19 has completely squeezed the reduced diameter section of the expansion tube 5 to adhere to the wall.
[0060] In this exemplary embodiment, a tailpipe hanger is connected to the original cementing casing, and the return sleeve 2 is connected to the top of the tailpipe hanger.
[0061] Optionally, in this exemplary embodiment, the expansion tube 5 is detachably connected to the insertion tube 7 and the insertion tube post sleeve 4 via threads.
[0062] In this exemplary embodiment, the top of the outer cylinder 13 of the expansion tool is connected to the hydraulic anchor 9 via an upper connector 10 of the expansion tool, and a sealing element 11 is provided between the upper connector 10 of the expansion tool and the outer cylinder 13 of the expansion tool.
[0063] In this exemplary embodiment, a second seal 12 is provided at the contact point between the piston surface of the piston rod 14 of the tube expander and the outer cylinder 13 of the tube expander; a third seal 16 is provided at the contact point between the bottom of the outer cylinder 13 of the tube expander and the piston rod 14 of the tube expander; and a fourth seal 18 is provided at the junction of the front end of the piston rod 14 of the tube expander and the expander head 19.
[0064] Exemplary Example 2
[0065] The process for anchoring large-diameter, thin-walled re-insertion tubes utilizes the aforementioned expansion tube anchoring tool and includes the following steps:
[0066] S1. Install the return sleeve 2 onto the original cementing casing or tailpipe hanger:
[0067] The return sleeve 2 is inserted into the well along with a small casing. After the bottom of the return sleeve 2 is connected to the original cementing small casing, or after it is connected to the original cementing small casing via the tailpipe hanger, cementing is carried out.
[0068] S2. Take out the insertion tool string of the return sleeve 2 and the original cementing casing;
[0069] Then, the insertion tool string is lowered through a tubing string to seal the insertion pipe 7 with the insertion sleeve 2 during insertion; the wellbore is pressurized to verify the sealing performance after insertion and ensure that the seal is qualified.
[0070] S3. Lower the tube expansion tool string, which is lowered through a special tool tubing. Once it is in place, start the tube expansion operation.
[0071] After the re-insertion seal is qualified, the expansion tool string is lowered to the designed position. The expansion tool initiation ball 20 is dropped into the tubing from the wellhead. The expansion tool initiation ball 20 will be placed in the expansion head 19 to achieve sealing and pressure build-up. The internal pressure of the expansion tool string is increased, and the hydraulic anchor tool connected to the upper end of the expansion tool string is activated and anchored to the inner wall of the small casing 4 of the re-insertion string. At the same time, the outer cylinder 13 of the expansion tool is fixed to the inner wall of the small casing 4 of the re-insertion string. The piston rod 14 of the expansion tool will drive the expansion head 19 to move downward due to the piston force. The downward movement of the expansion head 19 squeezes the expansion tube 5 to achieve expansion and anchoring.
[0072] S4. Remove the tube string from the expansion tool;
[0073] S5. Fracturing Operation:
[0074] Pumping fracturing was performed from inside the small sleeve 4 of the reinsertion tubing;
[0075] S6. Reinsert the tubing and remove it:
[0076] After the fracturing operation is completed, rotate the small casing 4 of the return tubing string to unthread the thread connecting the small casing 4 and the expansion tube 5, and then pull out the small casing 4; the expansion tube 5 and the return tubing 7 will remain in the wellbore.
[0077] In this exemplary embodiment, step S5 specifically includes: pumping fracturing operations from the small casing 4 of the reinsertion tubing string. During the operation, the wellbore is under high pressure, which exerts an upward force on the reinsertion tubing 7. The magnitude of the upward force is proportional to the pressure value and the annular cross-sectional area between the sealing surface of the reinsertion tubing 7 and its inner diameter. Based on the original casing inner diameter parameters, by designing the size parameters of the expansion tube 5 and the expansion rubber 6, the fitting and limiting force between the expanded expansion tube 5 and the expansion rubber 6 and the inner wall 1 of the original casing can overcome the upward force on the reinsertion tubing 7, ensuring that the reinsertion seal remains effective and reliable during the operation until the fracturing operation of the entire well section is successfully completed, thereby improving the operation efficiency.
[0078] In this exemplary embodiment, the piston rod 14 of the expansion tool is detachably fixed to the outer cylinder 13 of the expansion tool via the expansion tool activation shear pin 17. The outer cylinder 13 of the expansion tool can be anchored to the inner wall of the small sleeve 4 of the insertion tube column via the hydraulic anchor 9. Then, step S3 specifically includes the following steps:
[0079] After the re-insertion seal is qualified, the expansion tool string is lowered to the designed position. The expansion tool initiation ball 20 is dropped into the tubing from the wellhead. The expansion tool initiation ball 20 will be placed in the expansion head 19 to achieve sealing and pressure buildup. At this time, the hydraulic anchor 9's anchor claws extend outward and bite into the inner wall of the small casing 4 of the re-insertion tubing string. At the same time, the expansion tool piston rod 14 will tend to move downward due to the piston force. When the pressure rises to a certain value, the expansion tool piston rod 14 will shear the expansion tool initiation shear pin 17 due to the piston force. The expansion tool piston rod 14 will drive the expansion head 19 to move downward. The downward movement of the expansion head 19 squeezes and expands the expansion tube 5. The fit between the reduced diameter section and the expansion rubber 6 and the original casing inner wall 1 forms a limiting force, realizing the expansion and anchoring.
[0080] Example 1
[0081] An expansion tube anchoring tool that enables anchoring of large-diameter thin-walled re-insertion tubes includes a re-insertion tool string, an expansion tool string, a re-insertion cylinder 2, and an expansion tool starting ball 20.
[0082] Among them, reference Figure 2 , Figure 3 As shown, the insertion tube tool string includes, from bottom to top, the insertion tube 7, the expansion tube 5, and the insertion tube column sleeve 4, and the three are threaded together; the top of the insertion cylinder 2 is inserted into the bottom of the insertion tube 7.
[0083] refer to Figure 1 As shown, the well completion operation of the return casing 2 tool is as follows: During wellbore reconstruction, the return casing 2 is connected to the tailpipe hanger, which connects to and sends it into the old wellbore. The lower end of the tailpipe hanger is connected to the original cementing casing of the corresponding length for the wellbore reconstruction section. After being lowered into place, the tailpipe hanger is set up.
[0084] refer to Figures 2-3 As shown, after the casing is set up, cement or resin and other cementing materials 3 are squeezed into the small casing until they rise to the height above the backfill tube 2. After flushing out the excess cementing material 3, the lower wellbore reconstruction operation is completed, leaving the backfill tube 2 for backfilling operations.
[0085] refer to Figures 4-7 After removing the insertion sleeve 2 and the original cementing casing, the insertion sleeve tool string can be lowered through a tubing string to seal the insertion sleeve 7 with the insertion sleeve 2. Then, pressure is applied in the wellbore to verify the sealing performance after insertion. After ensuring the seal is qualified, the expansion tool string is lowered to carry out the expansion operation and achieve expansion anchoring.
[0086] For further details, please refer to Figure 4 , Figure 5 As shown, in this embodiment, the tube expander string includes a tube expander piston rod 14 and a tube expander outer cylinder 13. The tube expander outer cylinder 13 can be anchored to the inner wall of the small sleeve 4 of the insertion tube column by a hydraulic anchor 9. The piston of the tube expander piston rod 14 is piston-fitted into the tube expander outer cylinder 13, and after the bottom section of the tube expander piston rod 14 extends downward through the tube expander outer cylinder 13, an expansion head 19 is provided on its outer surface.
[0087] Meanwhile, in this embodiment, the bottom end of the piston rod 14 of the expansion tool is open. When the starting ball 20 of the expansion tool is located at the expansion head 19, the starting ball 20 of the expansion tool can block the opening. The small sleeve 4 of the insertion tube and the expansion tube 5 are connected by a threaded detachable connection. The expansion tube 5 has a reduced diameter section in the middle, and the outer wall of the reduced diameter section is provided with vulcanized expansion rubber 6. When the starting ball 20 of the expansion tool blocks the piston rod 14 of the expansion tool, the internal pressure of the expansion tool string will increase. When the piston rod 14 of the expansion tool moves down under pressure, the expansion head 19 can gradually squeeze the reduced diameter section of the expansion tube 5, so that the reduced diameter section and the expansion rubber 6 form a limiting force between the original sleeve inner wall 1 and the original sleeve.
[0088] Furthermore, in this embodiment, the piston rod 14 of the tube expander tool is detachably fixed inside the outer cylinder 13 of the tube expander tool via the tube expander tool activation shear 17. When the piston rod 14 of the tube expander tool is subjected to a certain vertical force, the detachable connection between the piston rod 14 of the tube expander tool and the outer cylinder 13 of the tube expander tool can be automatically released.
[0089] In this embodiment, a rubber seal 8 is provided at the bottom of the insertion tube 7, and the bottom of the insertion tube 7 and the insertion cylinder 2 are sealed and inserted through the rubber seal 8.
[0090] Further, refer to Figures 5-7 As shown, in this embodiment, the bottom of the outer cylinder 13 of the tube expander tool is also provided with a tube expander tool piston pressure relief hole 15. When the piston surface of the tube expander tool piston rod 14 slides past the tube expander tool piston pressure relief hole 15, the internal pressure of the tube expander tool string is relieved, the expander head 19 retracts, and the reduced diameter section has been completely squeezed and adhered to the wall.
[0091] Furthermore, in this scheme, the top of the outer cylinder 13 of the expansion tool is connected to the hydraulic anchor 9 via an upper connector 10 of the expansion tool, and a sealing element 11 is provided between the upper connector 10 of the expansion tool and the outer cylinder 13 of the expansion tool.
[0092] To further ensure the pressurization effect during expansion, a second seal 12 is provided at the contact point between the piston surface of the piston rod 14 of the expansion tool and the outer cylinder 13 of the expansion tool; a third seal 16 is provided at the contact point between the bottom of the outer cylinder 13 of the expansion tool and the piston rod 14 of the expansion tool; and a fourth seal 18 is provided at the connection point between the front end of the piston rod 14 of the expansion tool and the expansion head.
[0093] Example 2
[0094] The process for anchoring large-diameter thin-walled re-insertion tubes employs the expansion tube anchoring tool of Example 1 and includes the following steps:
[0095] S1. Install the return sleeve 2 onto the original cementing casing:
[0096] The return sleeve 2 is inserted into the well along with a small casing. After the bottom of the return sleeve 2 is connected to the original cementing small casing, cementing is carried out.
[0097] S2. Take out the insertion tool string of the reinsertion tube 2 and the original cementing casing; then, insert the reinsertion tool string through a tubing string to seal the reinsertion tube 7 with the reinsertion tube 2; pressurize the wellbore to verify the sealing performance after reinsertion and ensure that the seal is qualified.
[0098] S3. Lowering the tube expansion tool string (which is lowered through a special tool tubing) and starting the tube expansion operation:
[0099] After the re-insertion seal is qualified, the expansion tool string is lowered to the designed position. The expansion tool initiation ball 20 is dropped into the tubing from the wellhead. The expansion tool initiation ball 20 will be placed in the expansion head 19 to achieve sealing and pressure build-up, and the outer cylinder 13 of the expansion tool will be fixed to the inner wall of the small sleeve 4 of the re-insertion tubing string. The piston rod 14 of the expansion tool will drive the expansion head 19 to move downward due to the piston force. The expansion head 19 moves downward to squeeze the expansion tube 5, thereby achieving expansion and anchoring.
[0100] S4. After completing the tube expansion operation in step S3, pull out the tube expansion tool string;
[0101] S5. Fracturing Operation:
[0102] Pumping fracturing was performed from inside the small sleeve 4 of the reinsertion tubing;
[0103] S6. After fracturing, retrieve the insertion string:
[0104] The small casing 4 of the re-insertion tubing is pulled out, causing the threads connecting the small casing 4 and the expansion tube 5 to unravel. The expansion tube 5 and the re-insertion tubing 7 will remain in the wellbore.
[0105] In this embodiment, step S5 specifically includes: pumping fracturing operations from the small casing 4 of the reinsertion tubing string. During the operation, the wellbore is under high pressure, which exerts an upward force on the reinsertion tubing 7. The magnitude of the upward force is proportional to the pressure value and the annular cross-sectional area between the sealing surface of the reinsertion tubing 7 and its inner diameter. Based on the original casing inner diameter parameters, by designing the size parameters of the expansion tube 5 and the expansion rubber 6, the fitting and limiting force between the expanded expansion tube 5 and the expansion rubber 6 and the inner wall 1 of the original casing can overcome the upward force on the reinsertion tubing 7, ensuring that the reinsertion seal remains effective and reliable during the operation until the fracturing operation of the entire well section is successfully completed, thereby improving the construction efficiency.
[0106] In this embodiment, step S3 specifically includes the following steps: After the re-insertion seal is qualified, the expansion tool string is lowered to the designed position, and the expansion tool starting ball 20 is sent into the tubing from the wellhead. The expansion tool starting ball 20 will be located in the expansion head 19 to achieve sealing and pressure build-up. At this time, the hydraulic anchor 9's anchor claws extend outward and bite into the inner wall of the small casing 4 of the re-insertion tubing string. At the same time, the expansion tool piston rod 14 will have a downward tendency due to the piston force. When the pressure rises to a certain value, due to the piston force, the expansion tool piston rod 14 will shear the expansion tool starting shear pin 17. The expansion tool piston rod 14 will drive the expansion head 19 to move downward. The downward movement of the expansion head 19 squeezes and expands the expansion tube 5. The fit between the reduced diameter section and the expansion rubber 6 and the original casing inner wall 1 forms a limiting force, realizing the expansion and anchoring.
[0107] Example 3
[0108] This invention relates to a process for anchoring large-diameter thin-walled tubing re-insertion. The process generally involves six steps: 1) Re-insertion tube 2 is inserted into the well along with the original cementing casing and cementing is performed; 2) Re-insertion tube 7 is run in and the seal is verified; 3) The expansion tool string is run in to initiate the expansion operation; 4) The expansion tool string is retrieved; 5) Fracturing is performed; 6) The re-insertion string is rotated and released. The difference between this process and existing conventional large-diameter thin-walled tubing re-insertion systems is that, during the running of re-insertion tube 7, an expansion tube system is connected to the tubing string. After the re-insertion seal is verified, the expansion tool string is run in to perform the expansion operation. After expansion, the outer diameter of the expansion tube 5 increases, and the vulcanized expansion rubber 6 on it expands and adheres to the inner wall 1 of the original casing, thus creating a relative fixation between the re-insertion tube system and the original casing. In other words, the re-insertion tube system is anchored to the original casing, achieving relative anchoring or fixation between the re-insertion tube 7 and the re-insertion tube 2.
[0109] The specific implementation steps of this process are as follows:
[0110] 1. Insert the casing 2 into the well along with the small casing and perform cementing.
[0111] by Figure 1 For example, the well completion operation of the reinsertion sleeve 2 tool involved in this invention is as follows: During wellbore reconstruction, the reinsertion sleeve 2 is connected to the tailpipe hanger, which connects to and sends it into the old wellbore. The lower end of the tailpipe hanger is connected to the original cementing casing of the corresponding matching length for the wellbore reconstruction section. After being lowered into place, the tailpipe hanger is set up. After setting up, cement or resin and other cementing materials 3 are squeezed into the small casing until they rise to the level of the reinsertion sleeve 2. After flushing out the excess cementing material 3, it is allowed to solidify, thus completing the lower wellbore reconstruction operation and leaving the reinsertion sleeve 2 for reinsertion operations.
[0112] 2. Insert the re-insertion tubing and verify the re-insertion seal.
[0113] like Figure 1 , Figure 2 As shown, this is the tool string of the insertion tubing system used during the insertion operation. Its structure, from bottom to top, consists of: insertion tubing 7, expansion tubing 5, and the small casing 4 of the insertion tubing string. After determining the insertion tool string is in place by measuring the length of the inserted tubing string, a trial insertion is performed. The tubing string is slowly lowered while observing changes in the suspended weight and depth. When the suspended weight decreases but the depth decreases only slightly or not at all, it can be preliminarily determined that insertion tubing 7 has been inserted into the insertion sleeve 2. At this point, a pump truck can be connected to the wellhead for pressure testing to verify whether the rubber seal 8 between insertion tubing 7 and insertion sleeve 2 has achieved a sealing effect. If the seal is satisfactory, the next step, expansion tubing operation, can proceed.
[0114] III. Inserting the tube expander tool string and starting the tube expander operation
[0115] As attached Figure 4As shown, after verifying the successful insertion and sealing, the expansion tool initiation ball 20 is dropped into the tubing from the wellhead, and the pump truck is started to pump the ball. Ultimately, the expansion tool initiation ball 20 will settle inside the expansion head 19 to achieve sealing and pressure buildup. At this time, the hydraulic anchor 9 tool will start working due to the pressure inside the tubing; that is, the hydraulic anchor 9's anchor claws extend outwards and engage with the inner wall of the small casing 4 of the insertion and re-insertion string. Simultaneously, the expansion tool piston rod 14 will tend to move downwards due to the piston force. (Reference) Figure 4 , Figure 5 As shown, when the pressure rises to a certain value, due to the piston force, the piston rod 14 of the expansion tool will shear off the expansion tool's starting shear pin 17. The piston rod 14 of the expansion tool will drive the expansion head 19 to move downward. The higher the pressure inside the oil pipe, the better the anchoring effect of the hydraulic anchor 9. At the same time, the load on the expansion tube 5 is also greater when the expansion head 19 moves downward to squeeze it. By adjusting and setting the piston force of the piston rod 14 of the expansion tool and the axial load when the expansion tube 5 starts to squeeze, the expansion tool string can be anchored by the hydraulic anchor 9, so that the expansion head 19 moves downward to squeeze the expansion tube 5.
[0116] When the expansion tube 5 is squeezed by the expansion head 19, the vulcanized expansion rubber 6 on the outer wall of the expansion tube 5 will also expand and increase in outer diameter simultaneously. By carefully designing and calculating the outer diameter, wall thickness, and expansion rubber 6 dimensions of the expansion tube 5, it can be ensured that after the expansion head 19 squeezes, the expansion rubber 6 expands and tightly adheres to the inner wall 1 of the original casing, achieving limiting and anchoring between the expansion tube 5 and the inner wall 1 of the original casing, thereby achieving limiting and anchoring between the return tubing system and the original casing. Furthermore, because the return tubing 2 is fixed to the inner wall 1 of the original casing with cementing material 3, it is considered that limiting and anchoring has been achieved between the return tubing 7 and the return tubing 2. After a certain stroke, the piston face of the expansion tool piston rod 14 slides past the expansion tool piston pressure relief hole 15, releasing the pressure inside the tubing. Simultaneously, the expansion head 19 reaches its stroke position, squeezing and adhering all the reduced-diameter sections of the expansion tube 5 to the wall. At this point, lifting the tubing string will pull the expansion tool tube out of the wellbore. The reinsertion tube 7 and expansion tube system were left inside the wellbore, and anchoring was achieved after reinsertion.
[0117] IV. Expanding tube tool string
[0118] V. Fracturing Construction
[0119] like Figure 6 , Figure 7As shown, during fracturing operations, the process involves pumping fracturing through the small casing 4 of the reinsertion tubing string. The wellbore is under high pressure during operation, which exerts an upward force on the reinsertion tubing 7. The magnitude of this upward force is proportional to the pressure value and the annular cross-sectional area between the sealing surface of the reinsertion tubing 7 and its inner diameter. Based on the original casing inner diameter parameters, the dimensions of the expansion tube 5 and expansion rubber 6 are designed to ensure that the fitting and limiting force between the expanded expansion tube 5 and expansion rubber 6 and the inner wall 1 of the original casing can overcome the upward force on the reinsertion tubing 7. This ensures that the reinsertion seal remains effective and reliable throughout the operation, until the fracturing of the entire well section is successfully completed, thereby improving operational efficiency.
[0120] VI. Reinsertion of the insertion string by rotation and release
[0121] like Figure 6 , Figure 7 As shown, after the well fracturing operation is completed, the reinsertion tubing system still achieves reliable reinsertion sealing, and the expansion tubing 5 system still achieves reliable expansion and anchoring. To facilitate subsequent tooling operations and reduce well construction costs, the reinsertion tubing 4 needs to be retrieved after fracturing. This is done by rotating the tubing string at the wellhead to unlatch the threads connecting the reinsertion tubing 4 and the expansion tubing 5. After complete unlatching, the upper reinsertion tubing 4 can be retrieved from the wellbore, providing more space for subsequent well completion operations. The expansion tubing 5 and the reinsertion tubing 7 will remain in the wellbore, but this will not affect subsequent oil and gas production operations.
[0122] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.
Claims
1. An expansion tube anchoring tool capable of anchoring large-diameter thin-walled re-insertion tubes, characterized in that: Includes a re-insertion tool string, a tube expansion tool string, a re-insertion cylinder (2), and a tube expansion tool starter ball (20); The insertion tool string includes an expansion tube (5); The expansion tube (5) has a small sleeve (4) for inserting back into the tube at its top and a back-insertion tube (7) for its bottom. The bottom of the back-insertion tube (2) is connected to the original cementing casing, and the top of the tube is inserted into the bottom of the back-insertion tube (7). The tube expander string includes a tube expander piston rod (14) and a tube expander outer cylinder (13); The outer cylinder (13) of the expansion tool can be temporarily fixed to the inner wall of the small sleeve (4) of the insertion column; The piston rod (14) of the tube expander is fitted inside the outer cylinder (13) of the tube expander, and the bottom section of the piston rod (14) of the tube expander extends downward through the outer cylinder (13) of the tube expander and is connected to the expansion head (19) on its outer surface. The bottom end of the piston rod (14) of the tube expander is open. When the tube expander start ball (20) is located at the expander head (19), the tube expander start ball (20) can block the opening. The insert tube (4) and expansion tube (5) are detachably connected. The expansion tube (5) has a reduced diameter section in the middle and vulcanized expansion rubber (6) on the outer wall of the reduced diameter section. When the expansion tool activation ball (20) blocks the expansion tool piston rod (14), the internal pressure of the expansion tool string will increase. When the expansion tool piston rod (14) moves down under pressure, the expansion head (19) can gradually squeeze the reduced diameter section of the expansion tube (5), so that the reduced diameter section and the expansion rubber (6) form a limiting force with the original sleeve inner wall (1).
2. The expansion tube anchoring tool for realizing large-diameter thin-walled re-insertion tube anchoring according to claim 1, characterized in that: The bottom of the insertion tube (7) is provided with a rubber seal (8), and the bottom of the insertion tube (7) and the insertion cylinder (2) are sealed after insertion through the rubber seal (8).
3. The expansion tube anchoring tool for realizing large-diameter thin-walled re-insertion tube anchoring according to claim 1, characterized in that: The tube expansion tool string also includes a hydraulic anchor (9), and the outer cylinder (13) of the tube expansion tool can be anchored to the inner wall of the small sleeve (4) of the insertion tube column by the hydraulic anchor (9).
4. The expansion tube anchoring tool for realizing large-diameter thin-walled re-insertion tube anchoring according to claim 1, characterized in that: The piston rod (14) of the tube expander tool is detachably fixed inside the outer cylinder (13) of the tube expander tool via the tube expander tool start-up shear pin (17). When the piston rod (14) of the tube expander tool is subjected to a certain vertical force, the detachable connection between the piston rod (14) of the tube expander tool and the outer cylinder (13) of the tube expander tool can be automatically released.
5. The expansion tube anchoring tool according to claim 1, which enables anchoring of large-diameter thin-walled re-insertion tubes, is characterized in that: The bottom of the outer cylinder (13) of the tube expander is also provided with a piston pressure relief hole (15). When the piston surface of the piston rod (14) of the tube expander slides past the piston pressure relief hole (15), the internal pressure of the tube expander string is relieved, and at the same time, the expansion head (19) has completely squeezed the reduced diameter section of the expansion tube (5) to the wall.
6. The expansion tube anchoring tool according to claim 1, which enables anchoring of large-diameter thin-walled re-insertion tubes, is characterized in that: The expansion tube (5) and the insertion tube (7) can be an integrated structure; or The bottom of the expansion tube (5) is detachably connected to the insertion tube (7).
7. The expansion tube anchoring tool according to claim 1, which enables anchoring of large-diameter thin-walled re-insertion tubes, is characterized in that: The top of the expansion tube (5) is detachably connected to the small sleeve (4) of the insertion tube column.
8. The expansion tube anchoring tool according to claim 1, which enables anchoring of large-diameter thin-walled re-insertion tubes, is characterized in that: The original cementing casing is connected to a tailpipe hanger, and the back-insertion cylinder (2) is connected to the top of the tailpipe hanger.
9. Process for the anchoring of large-diameter thin-walled back-plug tubes, characterized in that, The expansion tube anchoring tool according to any one of claims 1 to 8 is used, and includes the following steps: S1. Install the return sleeve (2) onto the original cementing casing or tailpipe hanger: The return sleeve (2) is inserted into the well along with the original cementing casing. After the bottom of the return sleeve (2) is connected to the original cementing casing or after it is connected to the original cementing casing via the tailpipe hanger, cementing is carried out. S2. Take out the insertion tool string of the return sleeve (2) and the original cementing casing; Then, the insertion tube tool string is inserted through a tube column to seal the insertion tube (7) with the insertion cylinder (2) for insertion. Pressure testing inside the wellbore was conducted to verify the seal after re-insertion, ensuring a qualified seal. S3. Insert the tube expansion tool string and start the tube expansion operation; After the tubing expansion tool string is lowered to the position, the tubing expansion tool starter ball (20) is dropped into the tubing from the wellhead. The tubing expansion tool starter ball (20) will be placed in the expansion head (19) to achieve sealing and pressure build-up. At the same time, the outer cylinder (13) of the tubing expansion tool is fixed to the inner wall of the small sleeve (4) of the back insertion string. The piston rod (14) of the tubing expansion tool will drive the expansion head (19) to move downward due to the piston force. The expansion head (19) moves downward to squeeze the expansion tube (5) and achieve tubing expansion anchoring. S4. Remove the tube expansion tool string from your hand; S5. Fracturing operation.
10. The process according to claim 9, characterized in that, Step S5 specifically includes: Pumping fracturing is carried out from the small casing (4) of the reinsertion tubing string. During construction, the wellbore is under high pressure, which will exert an upward force on the reinsertion tubing (7). The magnitude of the upward force is proportional to the pressure value and the annular cross-sectional area between the sealing surface of the reinsertion tubing (7) and the inner diameter of the reinsertion tubing (7). Based on the inner diameter parameters of the original casing, by designing the size parameters of the expansion tube (5) and the expansion rubber (6), the fitting and limiting force between the expanded expansion tube (5) and the expansion rubber (6) and the inner wall (1) of the original casing can overcome the upward force on the reinsertion tubing (7), ensuring that the reinsertion seal is always effective and reliable during construction, until the fracturing construction of the entire well section is successfully completed, thereby improving the construction efficiency.
11. The process according to claim 9, characterized in that, The threaded connection between the small sleeve (4) and the expansion tube (5) of the re-insertion tube, which enables anchoring of large-diameter thin-walled re-insertion tubes, further includes step S6: S6. After the fracturing operation is completed, remove the small casing of the reinserted tubing string: Rotate the small sleeve (4) of the insertion tube to unravel the thread connecting the small sleeve (4) and the expansion tube (5), and then remove the small sleeve (4).
12. The process according to claim 9, characterized in that, The piston rod (14) of the tube expander tool is detachably fixed to the outer cylinder (13) of the tube expander tool via the tube expander tool activation shear pin (17). The outer cylinder (13) of the tube expander tool can be anchored to the inner wall of the small sleeve (4) of the insertion tube column by a hydraulic anchor (9). Step S3 specifically includes the following steps: After the tubing string of the expansion tool is lowered to the position, the expansion tool starting ball (20) is dropped into the tubing from the wellhead. The expansion tool starting ball (20) will be placed in the expansion head (19) to achieve sealing and pressure build-up. At this time, the hydraulic anchor (9) extends outward and bites into the inner wall of the small casing (4) of the back insertion string. At the same time, the expansion tool piston rod (14) will tend to move downward due to the piston force. When the pressure rises to a certain value, the expansion tool piston rod (14) will shear the expansion tool starting shear pin (17) due to the piston force. The expansion tool piston rod (14) will drive the expansion head (19) to move downward. The expansion head (19) moves downward and squeezes the expansion tube (5). The shrinking section and the expansion rubber (6) are adhered to the inner wall (1) of the original casing to form a limiting force, thereby realizing the expansion and anchoring.