A method of completing a well to repair a primary well barrier by a pin connection

Abstract

The application discloses a well completion method for repairing a well primary barrier through a pin connection, and belongs to the technical field of oil well completion. The method first judges the integrity of a well secondary barrier. If the integrity of the well secondary barrier is unqualified, a well completion pipe string is replaced. If the integrity of the well secondary barrier is qualified, the sealing property of a packer seal is judged. If the sealing property of the packer is qualified, the original well pipe is pulled out, the integrity of a field end box end in a well bore is judged according to the pin end state of the original well pipe. If the integrity of the field end box end in the well bore is qualified, a new well completion pipe is lowered into the well bore and is connected with the original well pipe in the well bore through a pin connection for well completion. The application avoids the relatively high well control risk in the complicated treatment process in the operation process of completely replacing the production pipe string for the well completion of the low-pressure and low-efficiency well, causes the risk of the downhole secondary complexity, provides a new idea for the well completion process innovation of the low-pressure and low-efficiency well, and has great field application value and reference significance.

Description

Technical Field

[0001] This invention belongs to the field of oil well completion technology and relates to a well completion method for repairing the primary barrier of a well by means of a snap-fit ​​connection. Background Technology

[0002] In the extraction of energy resources such as oil and natural gas, the integrity and safety of wells are of paramount importance. Damage and leakage of wells not only lead to the waste of resources but can also trigger serious safety accidents.

[0003] Oil and gas well integrity management is a systematic and complex task, encompassing the entire lifecycle of an oil and gas well, from drilling, completion, and workover to production and development. This process requires comprehensive consideration of geological conditions, extraction technology, equipment status, and environmental protection, among other factors, to ensure the stable operation of the well. Taking the Tarim Oilfield as an example, the various challenges it faces during development, such as complex geological structures and harsh natural environments, make wellbore integrity a formidable problem that engineers must confront. Wellbore integrity problems manifest in various forms, including but not limited to wellbore instability leading to collapse, channeling caused by cement sheath failure, perforation of casing due to corrosion, expansion of formation fractures, and wellhead sealing failure. These problems not only directly threaten the primary and secondary integrity of the well, leading to leakage and loss of oil and gas resources, but also seriously affect normal production operations, even forcing well shutdowns for rectification, resulting in significant economic losses for the company.

[0004] To address the challenge of wellbore integrity, the traditional approach is to completely replace the production tubing to repair the well. However, this process is not only technically challenging and complex, but also carries extremely high well control risks. Improper operation can easily lead to catastrophic accidents such as blowouts and lost circulation. Furthermore, replacing the production tubing is costly and inefficient, posing a severe challenge to the company's production operations and economic efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a well completion method that repairs the primary barrier of a well by connecting the snap-fit ​​connection, so as to solve the technical problems of high risk, low efficiency and high cost of the existing technology of repairing well completion by completely replacing the production tubing.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a well completion method for repairing a primary barrier in a well by connecting the snap-fit ​​connection, comprising the following steps: Determine the integrity of the secondary barrier of the well; If the integrity of the secondary barrier of the well is not up to standard, the completion tubing shall be replaced; if the integrity of the secondary barrier of the well is up to standard, the sealing performance of the packer shall be assessed. If the packer's sealing performance is qualified, the original well tubing is pulled out, and the integrity of the field end female thread in the wellbore is judged based on the condition of the male thread end of the original well tubing. If the integrity of the field end thread in the wellbore is qualified, the new completion tubing is run in and connected to the original wellbore string in the wellbore for completion.

[0007] Furthermore, the steps for determining the integrity of the secondary barrier of the well specifically include: conducting a pressure test on the entire wellbore of the production casing; and verifying the sealing performance of each stage of the casing head.

[0008] Furthermore, the method for conducting a pressure test on the entire production casing wellbore specifically includes: testing the entire production casing wellbore at 20 MPa, stabilizing the pressure for 30 minutes, and passing the test if the pressure does not drop.

[0009] Furthermore, if the integrity of the secondary barrier of the well is not up to standard, the completion tubing shall be replaced; if the integrity of the secondary barrier of the well is up to standard, the steps for judging the sealing performance of the packer shall specifically include: after the downhole safety valve is closed, if the oil pressure and casing pressure drop to zero simultaneously when the tubing is disconnected and the casing is connected, it indicates that the packer is sealing well.

[0010] Furthermore, if the packer's sealing performance is qualified, the original well tubing is pulled out, and the integrity of the field-side female thread in the wellbore is determined based on the condition of the male thread end of the original well tubing. This step specifically includes: The last tubing in the original well was pulled out, and the relevant parameters of the male external thread were checked. If all relevant parameters of the male thread meet the standards, randomly select one repair oil pipe and simulate the field end to conduct several threading and unthreading tests with the male thread. If the internal and external threaded joints are intact after each coupling and uncoupling, the internal thread of the coupling nut inside the well shaft will meet the standards in terms of sealing surface, pitch, and taper, and will be eligible for reuse.

[0011] Furthermore, the steps of retrieving the last tubing from the original well and checking the relevant parameters of the male external thread specifically include: observing whether the male external thread has any sticking, whether the sealing surface has any adhesion or corrosion, whether the male external thread and the tapered surface have any blackening, measuring the sealing end face data with a sealing surface gauge to see if it meets the standard, checking the male end for deformation with a pitch gauge, and checking whether the pitch and taper meet the gas-tight tubing standard.

[0012] Furthermore, the fastening test was conducted using a YNJ200 / 15 hydraulic fastening machine; the unfastening test was conducted using a YXD20 hydraulic fastening machine.

[0013] Furthermore, the step of running in new completion tubing and connecting it to the original well tubing string in the wellbore if the integrity of the field end female thread in the wellbore is qualified specifically includes: if the integrity of the field end female thread in the wellbore is qualified, running in new completion tubing to a preset depth, performing tubing string connection and tight connection, then replacing the wellhead, performing a pressure test, and completing the well after the pressure test is qualified.

[0014] Furthermore, the specific method for connecting the tubing string is as follows: rotate and lower the newly completed tubing and pressurize it by 5kN to 20kN; rotate the tubing string forward a total of 150 times, release the torque and return it to the starting position 15 times; lift the tubing string to a suspended weight of 450kN.

[0015] Furthermore, the specific method for tightening the tubing string is as follows: lift the tubing string with a suspended weight of 450kN and 500kN respectively, rotate it clockwise 15 times and counterclockwise 15 times each time, and gradually lift the tubing string with a suspended weight of 770kN, and the tubing is successfully tightened.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a well completion method for repairing the primary barrier of a well through a snap-fit ​​connection. This method, by assessing the integrity of the secondary barrier, can promptly identify and address potential safety hazards. If the secondary barrier's integrity is unsatisfactory, the completion tubing string is replaced promptly, preventing wellbore leaks and other accidents caused by secondary barrier failure, and ensuring long-term stable wellbore operation. After confirming the secondary barrier's integrity, the packer's sealing performance is further assessed. This step ensures the packer's effective isolation function within the wellbore, preventing formation fluid or pressure anomalies from affecting wellbore safety, thus improving the safety and reliability of well completion operations. The innovative step of assessing the integrity of the female thread at the field end of the original well tubing based on the condition of the male thread makes the snap-fit ​​connection more precise and reliable. By confirming the integrity of the female thread, problems such as snap-fit ​​failure or wellbore leaks caused by damaged female threads are avoided, further improving the success rate and efficiency of well completion operations. Finally, the well completion operation was completed by connecting the new completion tubing to the existing tubing string inside the wellbore. This not only simplified the operation process and reduced operating costs, but also ensured an effective connection between the new tubing and the old tubing string, improving the overall stability and service life of the wellbore. This invention was first applied to Well Y7. Compared with traditional well workover processes, it avoided the process of handling the existing tubing string in the lower section, shortened the time for running the completion tubing string, saving approximately 20 days of workover time and 1.1 million yuan in workover costs. This invention avoids the complex handling process and relatively high well control risks associated with completely replacing the production tubing string during well workover and completion operations in low-pressure, low-efficiency wells, which can lead to complications around the well. It provides a new approach to the innovation of well workover and completion processes for low-pressure, low-efficiency wells, and has significant field application value and reference significance. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of well completion according to an embodiment of the present invention; Figure 3 This is a static ladder test tension curve diagram according to an embodiment of the present invention; Figure 4 This is a graph showing the printing tension curve of an embodiment of the present invention; Figure 5 This is a comprehensive columnar section diagram of wells according to an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the integrity of the first and second level barriers in an embodiment of the present invention.

[0019] Among them: 1-New tubing with gas seal; 2-New tubing string and original well tubing connection point; 3-Original well tubing with gas seal; 4-Original well MHR packer; 5-Second well barrier; 6-First well barrier; 7-Downhole safety valve; 8-Packer; 9-Reservoir. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or position relationship, it is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of this invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, so it should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0025] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "install", "connect", "connection" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] The following further describes the present invention in detail with reference to the drawings: See Figure 1 , an example embodiment of the present invention discloses a completion method for repairing the primary barrier of a well through snap connection, including the following steps: Step 1, judge the integrity of the secondary barrier of the well; Conduct a pressure test on the entire production casing wellbore. The entire production casing wellbore is pressured to 20 MPa and stabilized for 30 minutes. If it does not drop, it is qualified; verify the sealing performance of each casing head.

[0027] Step 2, if the integrity of the secondary barrier of the well is unqualified, replace the completion string; if the integrity of the secondary barrier of the well is qualified, judge the sealing performance of the packer 8; After the downhole safety valve 7 is closed, in the case of tubing disconnection and oil-casing communication, if the oil pressure and casing pressure both drop to zero simultaneously, it indicates that the packer 8 has good sealing performance.

[0028] Step 3, if the sealing performance of the packer 8 is qualified, pull out the original well tubing, and judge the integrity of the field end female thread in the wellbore according to the state of the male thread end of the original well tubing; Step 3.1, pull out the last tubing of the original well and detect the relevant parameters of the male external thread; Observe whether there is any sticking in the male external thread, whether there is any adhesion or corrosion on the sealing surface, whether there is any blackening in the male external thread and tapered surface, whether the sealing end face data measured by the sealing surface gauge meets the standard, whether the male end is deformed by the pitch gauge, and whether the pitch and taper meet the gas-tight oil pipe standard.

[0029] Step 3.2: If all relevant parameters of the male external thread meet the standards, randomly select one repair oil pipe and simulate the field end to conduct several threading and unthreading tests with the male thread. The fastening test was conducted using a YNJ200 / 15 hydraulic fastening machine; the unfastening test was conducted using a YXD20 hydraulic fastening machine.

[0030] Step 3.3: If the internal and external threaded joints are intact after each coupling and uncoupling, the internal thread of the coupling nut inside the well shaft will meet the standards in terms of sealing surface, pitch, and taper, and will be compatible with the standard for re-coupling and reuse.

[0031] Step 4: If the integrity of the field end thread in the wellbore is satisfactory, then run the new completion tubing and connect it to the original wellbore string in the wellbore for completion. Figure 2 As shown.

[0032] If the integrity of the field end thread in the wellbore is qualified, insert the new completion tubing to the preset depth, perform tubing string coupling and tightening, then replace the wellhead, perform pressure testing, and complete the well after the pressure test is qualified.

[0033] The specific method for connecting the tubing string is as follows: rotate and lower the new completion tubing and pressurize it by 5kN to 20kN; rotate the tubing string forward a total of 150 times, release the torque and return it to the starting position 15 times; lift the tubing string to a suspended weight of 450kN.

[0034] The specific method for tightening the tubing string is as follows: lift the tubing string with a suspended weight of 450kN and 500kN respectively, rotate it clockwise 15 times and counterclockwise 15 times each time, and gradually lift the tubing string with a suspended weight of 770kN. The tubing is then successfully tightened.

[0035] In this embodiment, it is first determined that the casing of the accessory in the secondary barrier of the well is intact and the cementing quality is qualified, thus confirming that the secondary barrier of the well meets the primary condition for the completion of the well by threading. Secondly, it is determined that the sealing performance of the packer 8 is intact, and the integrity of the male thread of the pulled-out tubing is determined by the integrity of the female thread of the unpulled tubing string in the wellbore to be intact and usable. Finally, after the new completion tubing is run in and threaded with the original tubing string in the same wellbore, the repair of the accessory completion string of the primary barrier (first well barrier 6) is completed.

[0036] Based on the actual working condition analysis of well integrity in field operations, this invention innovatively develops a completion method and process for repairing the primary barrier of a well through a snap-fit ​​connection. Specifically, based on a comprehensive analysis of the integrity data of the primary and secondary well barriers, and addressing the issue of wellhead tubing fracture, without altering the original well packer, a portion of the original well tubing is pulled out by reverse snapping, and a new tubing of the same snap-fit ​​type is precisely connected to the original tubing string, repairing the integrity of the completion tubing string. This restores the integrity of the primary barrier, enabling the well to resume safe and normal production. This invention not only simplifies the operation process and reduces operating costs but also ensures an effective connection between the new tubing and the old tubing string, improving the overall stability and service life of the wellbore. This invention was first applied to well Y7. Compared to traditional well workover processes, it avoids the need for processing the lower portion of the original well tubing string, shortens the well completion tubing string running time, and saves approximately 20 days of workover time and 1.1 million yuan in workover costs. This invention avoids the complex handling process and relatively high well control risks associated with the complete replacement of production tubing during low-pressure, low-efficiency well workover and completion operations, which can lead to complex subsurface issues. It provides a new approach to the innovation of low-pressure, low-efficiency well workover and completion processes and has significant field application value and reference significance.

[0037] The principle of this invention for completing the first-level barrier of a well through a snap-fit ​​connection is as follows: First, it is determined that the casing of the accessories in the second-level barrier of the well is intact and the cementing quality is qualified, thus confirming that the second-level barrier of the well meets the primary condition for snap-fit ​​connection completion; second, it is determined that the packer is intact and the male thread of the retrieved tubing is intact and usable by checking the integrity of the male thread; finally, the new completion tubing is run in and snap-fitted with the original tubing string in the well to complete the repair of the completion string of the accessories of the first-level barrier of the well.

[0038] Example (Drilling process of DN21 well): 1. Downhole working conditions before the application of this invention ① Static ladder test at Y7 well on April 26, 2022 ( Figure 3 The ∅45mm testing tool encountered resistance at a distance of 41.5m from the wellhead, and the tension dropped sharply from 53kg to 15kg, indicating that the wire tension data showed that the well was not flowing smoothly.

[0039] ② Y7 wellhead stamp dated March 20, 2023 ( Figure 4 The well gauge encountered hard resistance at 22.88m and was found to contain iron filings after being pulled out. The ∅60mm tool also encountered hard resistance at 22.88m. The tubing string was determined to be broken based on the shape of the lead stamp.

[0040] ③ Well workover: The fish string was slowly lowered to a depth of 23.88m, where it encountered resistance. The re-exploration position remained unchanged. The fish string was then pulled out (the string assembly from bottom to top: one 4 3 / 4″ reverse threaded drill collar + one 3 1 / 2″ reverse angled drill pipe to the wellhead; one 3 1 / 2″ FOX tubing was pulled out, with a length of 8.36m. The fish head was the tubing body, proving that the tubing broke at 8.36m, forming a misaligned section, and the integrity of the first-level barrier was completely destroyed.

[0041] 2. Integrity assessment of the secondary barrier (secondary well barrier 5).

[0042] See Figure 5 The cementing quality of the 127.00mm perforated section of the casing was qualified. Of the 100m section above the perforated section, 85.5m / 4 sections were qualified, and 14.5m / 4 sections were unqualified. The cementing quality of the section below the perforated section was qualified. The production casing underwent a full-bore pressure test of 20 MPa, maintained the pressure for 30 minutes, and showed no pressure drop, indicating it was qualified. The sealing performance of each casing head was verified on-site by a professional team and found to be intact.

[0043] 3. Well-level barrier accessory packer 8 sealing performance assessment.

[0044] ① Before well workover, after the downhole safety valve 7 is closed, with the tubing disconnected and the casing connected, the oil pressure and casing pressure drop to zero simultaneously, proving that the packer 8 has good sealing performance; ② By Figure 6 Based on the completeness of all attachments and the above information, it can be seen that the Y7 well secondary well barrier integration attachments are in good condition: the cement sheath cementing quality and the sealing integrity of each level of casing head are good; the primary well barrier packer 8 is in good condition, with only the completion string being misaligned, thus compromising its integrity. ③ As long as the integrity of the completion string attached to the primary well barrier is restored, the well will meet production requirements.

[0045] 4. Determine whether the original well tubing field end (female thread) can meet the threading standard by checking the integrity of the male thread of the retrieved tubing.

[0046] ① The male thread of the last tubing in the original well was found to be free of sticking, and the sealing surface was free of adhesion and corrosion; the male thread and tapered surface were free of blackening; the sealing end face measurement showed that the sealing end face data met the standard; the male thread end was found to be free of deformation by the pitch gauge; the pitch and taper test data showed that the pitch and taper met the gas-tight tubing standard. ② Randomly select one repaired oil pipe from the warehouse oil pipes and conduct a threading and unthreading test on the simulated field end with the male thread. The threading and unthreading tests are conducted using a YNJ200 / 15 hydraulic threading machine and a YXD20 hydraulic threading machine. The specific method is as follows: before machine tightening, manually tighten until it cannot be turned anymore. Machine tightening is done by fixing one end of the threading. The torque value is controlled using the standard torque control value of a brand new oil pipe. After three threading and unthreading tests, the internal and external threaded joints are intact after each threading and unthreading test. ③ It can be inferred from this that the internal thread of the coupling nut left in the wellbore meets the standards in terms of sealing surface, pitch and taper, and is in line with the standard for re-threading.

[0047] 5. On-site implementation and application of the invention ① The completion gas lift tubing was connected to a single well depth H: 2937.26m, with no fluid return. ② Connect the square drill bit, tighten the connection, and replace the annular protective fluid with 40m3, ρ:1.10g / cm3, P:0MPa, Q:8-9L / s; ③ When the tubing reached 2967.85m, it encountered resistance of 5kN. The tubing was then adjusted. Tube string coupling: Rotate and lower the tube string, apply pressure of 5-20kN, rotate the tube string forward 150 times, release the torque and return 15 times (apply pressure of 10kN during coupling, the tube string moves down 0.60m), lift the tube string and the suspended weight increases from 430kN to 450kN; Tubing string fastening: Tighten the tubing string, lift the suspended weight to 450kN and 500kN respectively, rotate it 15 times clockwise and 15 times counterclockwise each time, and gradually lift the suspended weight of the tubing string to 770kN. The tubing is now successfully fastened. ④ Replace the wellhead, pass the pressure test, and complete the well. With the integrity of all other accessories for the first and second level barriers in good condition, restore the integrity of the completion tubing by reconnecting the threads. The well then resumes normal production, and the invention has been successfully applied in the field.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection, characterized in that, It includes the following steps: Judge the integrity of the well secondary barrier; If the integrity of the well secondary barrier is unqualified, replace the completion string; If the integrity of the well secondary barrier is qualified, judge the sealing performance of the packer seal; If the sealing performance of the packer is qualified, pull out the original well tubing, and judge the integrity of the field end female thread in the wellbore according to the male thread end state of the original well tubing; If the integrity of the field end female thread in the wellbore is qualified, lower the new completion tubing and connect it to the original well string in the wellbore by threading for completion.

2. The well completion method for repairing the primary barrier of a well by means of a snap-fit ​​connection according to claim 1, characterized in that, The step of judging the integrity of the well secondary barrier specifically includes: conducting a pressure test on the entire wellbore of the production casing; verifying the sealing performance of each stage of the casing head.

3. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 2, characterized in that, The method of conducting a pressure test on the entire wellbore of the production casing specifically includes: conducting a pressure test of 20 MPa on the entire wellbore of the production casing, stabilizing the pressure for 30 minutes, and if it does not drop, it is qualified.

4. The well completion method for repairing the primary barrier of a well by means of a snap-fit ​​connection according to claim 1, characterized in that, If the integrity of the well secondary barrier is unqualified, replace the completion string; If the integrity of the well secondary barrier is qualified, the step of judging the sealing performance of the packer seal specifically includes: after the downhole safety valve is closed, when the tubing is disconnected and the tubing-casing is connected, if the tubing pressure and casing pressure both drop to zero simultaneously, it indicates that the packer has good sealing performance.

5. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 1, characterized in that, The step of pulling out the original well tubing and judging the integrity of the field end female thread in the wellbore according to the male thread end state of the original well tubing if the sealing performance of the packer is qualified specifically includes: Pull out the last tubing of the original well and detect the relevant parameters of the male thread external thread; If all the detected relevant parameters of the male thread external thread meet the standards, randomly select 1 repaired tubing and simulate several make-up and break-out experiments between the field end and the male thread; If the internal and external thread joints are intact after each make-up and break-out, and the internal thread of the collar female thread left in the wellbore meets the standards in terms of detection parameters such as the sealing surface, pitch, and taper, etc., and meets the re-threading and utilization standard.

6. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 5, characterized in that, The step of pulling out the last tubing of the original well and detecting the relevant parameters of the male thread external thread specifically includes: observing whether there is any sticking of the male thread external thread, any adhesion or corrosion of the sealing surface, any blackening of the male thread external thread and the taper surface, whether the sealing end face data measured by the sealing surface gauge meets the standards, detecting whether there is any deformation at the male thread end by the pitch diameter gauge, and detecting whether the pitch and taper meet the standard of gas-tight tubing.

7. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 5, characterized in that, The make-up experiment is carried out by using a YNJ200 / 15 hydraulic threader; the break-out experiment is carried out by using a YXD20 type hydraulic threader.

8. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 5, characterized in that, The step of lowering the new completion tubing and connecting it to the original well string in the wellbore by threading for completion if the integrity of the field end female thread in the wellbore is qualified specifically includes: if the integrity of the field end female thread in the wellbore is qualified, lower the new completion tubing to the preset depth, conduct tubing threading and tubing tightening, then replace the wellhead, conduct a pressure test, and complete the well after the pressure test is qualified.

9. A well completion method for repairing a primary barrier in a well by means of a snap-fit ​​connection according to claim 8, characterized in that, The specific method of tubing threading is: rotate and lower the new completion tubing and apply a pressure of 5 kN to 20 kN; rotate the tubing forward a total of 150 turns and release the torque back by 15 turns; lift the tubing string weight to 450 kN.

10. A well completion method for repairing a primary barrier of a well by means of a snap-fit ​​connection according to claim 8, characterized in that, The specific method of tubing tightening is: lift the tubing string weight to 450 kN and 500 kN respectively, rotate forward 15 turns and release 15 turns twice respectively, gradually lift the tubing string weight to 770 kN, and the tubing threading and tightening are successful.

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