Special thread on-site screwing-on anti-damage device and screwing-on operation method

Abstract

The invention relates to a special thread on-site screwing-on anti-damage device and a screwing-on operation method.The special thread on-site screwing-on anti-damage device comprises a lifting assembly, a slip assembly, a compensation tension spring and a balance plate, and the lifting assembly is connected with the bottom face of the balance plate; the two ends of the compensation tension spring are fixedly connected with the top face of the balance plate and the slip assembly respectively. The device has the beneficial effects that after the lifting assembly moves the to-be-screwed-on oil casing to a proper position, the self weight of the to-be-screwed-on oil casing is balanced with the elastic force of the compensation tension spring, so that the to-be-screwed-on oil casing can easily float up and down in a short distance near a pair of wellhead tongs. The oil casing to be screwed on can be easily adjusted in a small range at a wellhead, one operator can complete the adjustment and screwing-on work, and the success rate of screwing-on is high.

Description

Technical Field

[0001] The present invention relates to the field of wellhead equipment for oil and gas development in the oil and gas industry, and particularly relates to a special thread on-site make-up anti-damage device and a make-up operation method. Background Art

[0002] With the further development of oil and gas exploration, many oil and gas fields in the western and southwestern regions of China have harsh environments such as high temperature (greater than 140 °C), high pressure (greater than 100 MPa), deep well depth (greater than 5000 m), and high corrosive media (CO2, H2S, Cl － ) etc., which put more stringent requirements on the performance of oil and casing pipes. At present, the main connection method for oil and casing pipes in ultra-deep high-temperature and high-pressure gas wells is to use special thread joints. The quality of on-site threading directly affects the structural integrity and sealing integrity of the entire pipe string during service. Due to the complex on-site operation environment, factors such as the self-weight of the oil and casing pipes, misalignment of the wellhead, swing of the traveling block, and wind force during the make-up process will all affect the accuracy of the male thread of the oil and casing pipes entering the thread groove of the coupling, resulting in the problem of unable to accurately and efficiently align the threads. If problems such as inaccurate thread alignment, wrong threading, insufficient or excessive make-up torque occur during on-site operation, it will cause damage to the threads. At the same time, due to the barrel effect of special thread sealing, leakage and other failures are likely to occur first at the weak points, posing a great threat to the safety of the entire pipe string. Therefore, in view of the above problems, the present invention designs and develops a special thread on-site make-up anti-damage device and a make-up operation method to solve the above problems of on-site special thread alignment and ensure the safe and effective exploitation of oil and gas wells. Summary of the Invention

[0003] The technical problem to be solved by the present invention is how to ensure the reliability and convenience of on-site special thread make-up.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: A special thread on-site make-up anti-damage device includes a lifting assembly, a slip assembly, a compensating spring, and a balance plate. The lifting assembly is connected to the bottom surface of the balance plate, and both ends of the compensating spring are fixedly connected to the top surface of the balance plate and the slip assembly respectively.

[0005] The beneficial effects of the present invention are as follows: The lifting assembly is used to drive the balance plate to lift, thereby driving the slip assembly to lift. The slip assembly is engaged with the oil and casing pipe to be made up, driving the oil and casing pipe to be made up to move. When the lifting assembly moves the oil and casing pipe to be made up to a suitable position, the self-weight of the oil and casing pipe to be made up is balanced with the elastic force of the compensating spring, so that the oil and casing pipe to be made up can easily float up and down in a short distance near the wellhead tongs. The oil and casing pipe to be made up can be easily adjusted within a small range at the wellhead, and an operator can complete the adjustment and make-up work, with a high success rate of thread alignment.

[0006] Based on the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the lifting assembly includes a telescopic mechanism and a wellhead support plate, and two ends of the telescopic mechanism are respectively connected to the wellhead support plate and the balance plate.

[0008] The beneficial effect of adopting the above further scheme is: the telescopic mechanism drives the balance plate to rise and fall, and the wellhead support plate is placed at the wellhead, which plays the role of positioning and supporting the special threaded on-site anti-damage device installed at the wellhead, so as to ensure the safety and reliability of the anti-damage device.

[0009] Furthermore, the lifting assembly includes a plurality of the telescopic mechanisms, and the plurality of the telescopic mechanisms are arranged at intervals.

[0010] The beneficial effect of adopting the above further solution is: multiple telescopic mechanisms are provided to ensure the stability of the lifting and lowering of the balance board.

[0011] Furthermore, the telescopic mechanism is a cylinder, a hydraulic cylinder or an electric telescopic rod.

[0012] Furthermore, the cava assembly includes a cava shell and a plurality of cava decomposition teeth, wherein the plurality of cava decomposition teeth are arranged in sequence along the circumferential direction to form a ring-shaped cava tooth body, the outer wall of the cava tooth body and the inner wall of the cava shell are inverted frustum shapes, the cava shell is sleeved on the outside of the cava tooth body and is fixedly connected to the compensation tension spring.

[0013] The beneficial effect of adopting the above further scheme is that the slip body and the slip shell adopt an inverted truncated cone-shaped side wall. When the slip shell rises relative to the slip body, the slip shell gathers the multiple slip decomposition teeth, and the multiple slip decomposition teeth hold the oil casing to be buckled. When the slip shell descends relative to the slip body, the slip shell separates from the slip body, so that the multiple slip decomposition teeth are loosened, and the slip decomposition teeth loosen the slip decomposition teeth.

[0014] Furthermore, a high friction block is fixed to the inner wall of each slip decomposition tooth body.

[0015] The beneficial effect of adopting the above further solution is that the high friction block is used to increase the friction between the slip decomposition tooth body and the oil casing to be buckled. When the slip shell is lowered relative to the slip tooth body, the slip decomposition tooth body can hold the oil casing to be buckled and keep it in place, so that it is easy to separate from the slip shell.

[0016] Furthermore, the balance plate has a balance plate oil pipe through hole.

[0017] The beneficial effect of adopting the above further scheme is that the oil pipe through hole of the balance plate is used for the oil casing to be fastened to pass through, so that the oil casing to be fastened is in the middle of the anti-damage device for fastening, and the whole device is subjected to balanced force.

[0018] Furthermore, a plurality of compensating tension springs are provided, and the plurality of compensating tension springs are arranged at intervals.

[0019] The beneficial effect of adopting the above further solution is: By providing a plurality of compensating tension springs, sufficient elastic force is ensured.

[0020] Furthermore, it further includes a telescopic guide rod, both ends of the telescopic guide rod are fixedly connected to the top surface of the balance plate and the slip assembly respectively, and the compensating tension spring is sleeved outside the telescopic guide rod.

[0021] The beneficial effect of adopting the above further solution is: The telescopic guide rod plays a guiding role for the compensating tension spring to prevent the compensating tension spring from being deflected.

[0022] The present invention also provides a make-up operation method, which is realized by using the special thread on-site make-up anti-damage device described above, and includes the following steps:

[0023] Step 1: Place the special thread on-site make-up anti-damage device on the wellhead casing collar at the wellhead.

[0024] Step 2: Hoist the oil casing to be made up to the position of the special thread on-site make-up anti-damage device.

[0025] Step 3: Install the slip assembly on the outer wall of the oil casing to be made up, and move the slip assembly upward through the lifting assembly to lock the slip assembly with the oil casing to be made up.

[0026] Step 4: Perform a make-up operation on the oil casing to be made up and the wellhead casing collar.

[0027] Step 5: Move the slip assembly downward through the lifting assembly and release the oil casing to be made up.

[0028] Step 6: Lower the oil casing to be made up that has been made up into the wellhead.

[0029] The beneficial effect is: The self-weight of the oil casing to be made up is balanced with the elastic force of the compensating tension spring, so that the oil casing to be made up can easily float up and down in a short distance near the wellhead tongs. The oil casing to be made up can be easily adjusted within a small range at the wellhead, and an operator can complete the adjustment and make-up work. The make-up operation method has high operation efficiency and high make-up success rate.

[0030] In summary, the beneficial effects of the special thread on-site make-up anti-damage device and the make-up operation method are as follows:

[0031] 1. The special thread on-site make-up anti-damage device of the present invention has a simple structure, good stability, strong adaptability, and will not generate additional complex processes and equipment for the on-site operation of lowering the oil casing.

[0032] 2. The on-site threading anti-damage device for special threads of the present invention is convenient to operate on-site and has high efficiency. When performing the threading operation of oil casing pipes by means of the device and method of the present invention, the influence of factors such as the self-gravity of the oil casing pipes, misalignment of the wellhead, swing of the hook, and wind force can be completely overcome. Moreover, the position of the oil casing pipes at the wellhead can be easily adjusted within a small range, and one operator can complete the adjustment and threading work, with a high success rate of threading.

[0033] 3. The on-site threading anti-damage device for special threads of the present invention can meet the usage requirements of oil casing pipes of different sizes on-site.

[0034] 4. The on-site threading anti-damage device for special threads of the present invention can significantly reduce the influence of the on-site environment and is applicable to various harsh working conditions and construction conditions. And an intelligent monitoring device is designed on the auxiliary device, which can monitor and analyze the entire device and operation in real time, enabling the on-site and the background to timely understand the threading situation, with a high degree of intelligence. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a structural diagram of the on-site threading anti-damage device for special threads of the present invention;

[0036] Figure 2 is an exploded view of the slip assembly of the present invention;

[0037] Figure 3 is a structural diagram of the slip assembly of the present invention.

[0038] In the drawings, the list of components represented by each reference numeral is as follows:

[0039] 1. Oil casing pipe to be threaded; 2. Slip assembly; 3. Compensation tension spring; 4. Balance plate; 5. Telescopic mechanism; 6. Wellhead support plate; 7. Wellhead collar; 8. Oil casing pipe that has been threaded and run in; 9. Slip housing; 10. Split slip teeth; 11. High-friction block; 12. Tooth connector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The principles and features of the present invention will be described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0041] As Figures 1 - 3 shown, this embodiment provides an on-site threading anti-damage device for special threads, including a lifting assembly, a slip assembly 2, a compensation tension spring 3, and a balance plate 4. The lifting assembly is connected to the bottom surface of the balance plate 4, and the two ends of the compensation tension spring 3 are respectively fixedly connected to the top surface of the balance plate 4 and the slip assembly 2.

[0042] The lifting component is used to drive the balance plate 4 to lift, thereby driving the slip component 2 to lift. The slip component 2 is connected to the oil casing 1 to be made up, driving the oil casing 1 to be made up to move. When the lifting component moves the oil casing 1 to be made up to a suitable position, the dead weight of the oil casing 1 to be made up is balanced with the elastic force of the compensation tension spring 3, so that the oil casing 1 to be made up can easily float up and down within a short distance near the wellhead tongs. The oil casing 1 to be made up can be easily adjusted within a small range at the wellhead, and an operator can complete the adjustment and make-up work, with a high make-up success rate.

[0043] Among them, the length of the compensation tension spring 3, that is, the lifting component, can be adjusted according to different specifications of on-site oil casings and on-site requirements.

[0044] Optionally, the balance plate 4 is a rectangular, circular or other shaped plate.

[0045] Among them, the compensation tension spring 3 adopts a mechanical spring energy storage structure. By setting a tension spring force with a high safety factor, when the lifting component compensates the oil casing 1 to be made up to a suitable position, the dead weight of the oil casing 1 to be made up is balanced with the elastic force of the compensation tension spring 3, achieving the purpose that the oil casing can easily float up and down within a short distance near the wellhead tongs.

[0046] On the basis of the above technical solution, the lifting component includes a telescopic mechanism 5 and a wellhead support plate 6. Two ends of the telescopic mechanism 5 are respectively connected to the wellhead support plate 6 and the balance plate 4.

[0047] The telescopic mechanism 5 drives the balance plate 4 to lift. The wellhead support plate 6 is placed at the wellhead, playing the role of installing and positioning and supporting the make-up anti-damage device for special thread on-site at the wellhead to ensure the safety and reliability of the make-up anti-damage device.

[0048] Optionally, the wellhead support plate 6 is a rectangular, circular or other shaped plate.

[0049] Specifically, both the balance plate 4 and the wellhead support plate 6 are made of steel materials, used to connect the compensation tension spring 3 and the telescopic mechanism 5, meeting the requirements of synchronous operation and stability of the compensation tension spring 3 and the telescopic mechanism 5.

[0050] Optionally, two ends of the telescopic mechanism 5 are respectively fixedly connected or hinged to the wellhead support plate 6 and the balance plate 4.

[0051] On the basis of the above technical solution, the lifting component includes a plurality of the telescopic mechanisms 5, and the plurality of telescopic mechanisms 5 are arranged at intervals.

[0052] Arranging a plurality of telescopic mechanisms 5 ensures the stability of the balance plate 4 during lifting.

[0053] On the basis of the above technical solution, the telescopic mechanism 5 is a cylinder, a hydraulic cylinder or an electric telescopic rod.

[0054] Specifically, the telescopic mechanism 5 is a double-acting air cylinder or a hydraulic cylinder.

[0055] Based on the above technical solution, the cava assembly 2 includes a cava shell 9 and a plurality of cava decomposition tooth bodies 10, and the plurality of cava decomposition tooth bodies 10 are arranged in sequence along the circumferential direction to form a ring-shaped cava tooth body, and the outer wall of the cava tooth body and the inner wall of the cava shell 9 are inverted frustum shapes. The cava shell 9 is sleeved on the outside of the cava tooth body and fixedly connected to the compensation tension spring 3.

[0056] The slip teeth and the slip shell 9 are matched with an inverted truncated cone-shaped side wall. When the slip shell 9 rises relative to the slip teeth, the slip shell 9 gathers the multiple slip decomposition teeth 10, and the multiple slip decomposition teeth 10 hold the oil casing 1 to be buckled. When the slip shell 9 descends relative to the slip teeth, the slip shell 9 separates from the slip teeth, so that the multiple slip decomposition teeth 10 are released, and the slip decomposition teeth 10 release the slip decomposition teeth 10.

[0057] In one specific example, there are four slip decomposition teeth 10. According to the diameter of the oil casing, the slip decomposition teeth 10 can also be set to other numbers.

[0058] Specifically, two adjacent slip decomposition tooth bodies 10 are connected by a tooth body connector 12. Each slip decomposition tooth body 10 has a groove at one end in the circumferential direction and the tooth body connector 12 at the other end, and the tooth body connector 12 is inserted into the groove of the adjacent slip decomposition tooth body 10. Furthermore, the tooth body connector 12 has a spring, and the spring applies an elastic force to the adjacent slip decomposition tooth body 10 to make it away from the tooth body connector 12, so that when the slip shell 9 is separated from the slip decomposition tooth body 10, it can be ensured that the multiple slip decomposition tooth bodies 10 are separated along the circumferential direction.

[0059] On the basis of the above technical solution, a high friction block 11 is fixed to the inner wall of each slip decomposition tooth body 10 .

[0060] The high friction block 11 is used to increase the friction between the slip decomposition tooth body 10 and the oil casing 1 to be buckled. When the slip shell 9 drops relative to the slip tooth body, the slip decomposition tooth body 10 can hold the oil casing 1 to be buckled and keep it in place, so that it is easy to separate from the slip shell 9.

[0061] Optionally, the high friction block 11 is made of high friction system materials such as hard alloy, wear-resistant material, metal or non-metal.

[0062] For the slip assembly 2, specifically, the extension and retraction of the telescopic mechanism 5 drives the slip shell 9 to move up and down, thereby clamping or releasing the oil casing 1 to be fastened. More specifically, when the telescopic mechanism 5 is retracted, the high friction block 11 is tightly held with the oil casing 1 to be fastened, so that the slip decomposition tooth body 10 remains in place, and the slip shell 9 drops accordingly under the action of gravity, and the slip decomposition tooth body 10 and the slip shell 9 are separated along the truncated table surface, and the adjacent slip decomposition tooth bodies 10 are loosened in the circumferential direction under the action of the spring of the tooth body connector 12, thereby releasing the oil casing 1 to be fastened, as shown in FIG. Figure 2 When the telescopic mechanism 5 is extended, the slip shell 9 rises along the truncated table surface, so that the multiple slip decomposition teeth 10 are tightly clamped in the circumferential direction, thereby prompting the inner high friction blocks 11 of the slip decomposition teeth 10 to tightly clamp the oil casing 1 to be fastened, thereby achieving the operation of clamping the oil casing 1 to be fastened.

[0063] On the basis of the above technical solution, the balance plate 4 has a balance plate oil pipe through hole.

[0064] The oil pipe through hole of the balance plate is used for the oil casing 1 to be fastened to pass through, so that the oil casing 1 to be fastened is in the middle of the anti-damage device for fastening, and the whole device is balanced in force.

[0065] On the basis of the above technical solution, the compensating tension spring 3 is provided in plurality, and the plurality of compensating tension springs 3 are arranged at intervals.

[0066] A plurality of compensating tension springs 3 are provided to ensure sufficient elastic force.

[0067] Specifically, a plurality of compensating tension springs 3 are evenly distributed around the oil pipe through hole of the balance plate, and a plurality of telescopic mechanisms 5 are evenly distributed around the oil pipe through hole of the balance plate.

[0068] In one specific example, there are two compensating tension springs 3 and two telescopic mechanisms 5. Depending on the requirements of on-site operations and the specifications of the oil casing, the compensating tension springs 3 and the telescopic mechanisms 5 can also be set to other numbers. The numbers of the compensating tension springs 3 and the telescopic mechanisms 5 can be the same or different.

[0069] On the basis of the above technical solution, it also includes a telescopic guide rod, the two ends of which are fixedly connected to the top surface of the balance plate 4 and the slip assembly 2 respectively, and the compensation tension spring 3 is sleeved on the outside of the telescopic guide rod.

[0070] The telescopic guide rod guides the compensating tension spring 3 to prevent the compensating tension spring 3 from being deflected.

[0071] Furthermore, a tension spring protection cover is also provided on the outside of the compensation tension spring 3. The tension spring protection cover can be made of any material with certain protective capabilities, such as metal or non-metal. The tension spring protection cover is retractable and can be equipped with an intelligent monitoring device to perform real-time monitoring and evaluation of the working state, load, elongation, etc. of the tension spring.

[0072] Specifically, the on-site make-up anti-damage device for special threads in this embodiment includes a slip assembly 2, a compensating spring 3, a balance plate 4, a telescopic mechanism 5, and a wellhead support plate 6 that are connected in sequence from top to bottom.

[0073] This embodiment also provides a make-up operation method, which is implemented by using the on-site make-up anti-damage device for special threads, and includes the following steps:

[0074] Step 1: Place the on-site make-up anti-damage device for special threads on the wellhead collar 7 at the wellhead.

[0075] Step 2: Lift and install the oil casing 1 to be made up to the location of the on-site make-up anti-damage device for special threads.

[0076] Step 3: Install the slip assembly 2 on the outer wall of the oil casing 1 to be made up, and move the slip assembly 2 upward through the lifting assembly to lock the slip assembly 2 with the oil casing 1 to be made up.

[0077] Among them, the slip assembly 2 can be locked with the oil casing 1 to be made up through a locking structure such as a bolt, or the slip assembly 2 adopts the structure of the slip housing 9 and multiple slip split teeth 10 in the above embodiment, and the lifting assembly moves the slip housing 9 upward, so that the slip housing 9 is locked with multiple slip split teeth 10.

[0078] Step 4: Perform a make-up operation on the oil casing 1 to be made up and the wellhead collar 7.

[0079] Step 5: Move the slip assembly 2 downward through the lifting assembly and release the oil casing 1 to be made up.

[0080] Step 6: Lower the oil casing 1 that has completed the make-up into the wellhead.

[0081] The self-weight of the oil casing 1 to be made up is balanced with the elastic force of the compensating spring 3, so that the oil casing 1 to be made up can easily float up and down in a short distance near the wellhead tongs. The oil casing 1 to be made up can be easily adjusted within a small range at the wellhead, and an operator can complete the adjustment and make-up work. The operation efficiency of this make-up operation method is high and the make-up success rate is high.

[0082] Before the above Step 1, it also includes: selecting appropriate models of the telescopic mechanism 5, compensating spring 3, and slip assembly 2 according to the specifications of the oil casing to be compensated and the operation requirements; and assembling the slip assembly 2, compensating spring 3, balance plate 4, telescopic mechanism 5, and wellhead support plate 6 in sequence from top to bottom into a whole.

[0083] The step 1 specifically includes: placing the special threaded on-site anti-damage device on the wellhead coupling 7 of the wellhead casing 8 that has been screwed in, and making the telescopic mechanism 5 in an extended state, and fixing the wellhead support plate 6 on the wellhead.

[0084] The step 2 specifically includes: lifting the oil casing 1 to be fastened from the platform, and allowing the oil casing 1 to be fastened to pass through the through hole in the middle of the wellhead support plate 6 and the balance plate oil pipe through hole of the balance plate 4.

[0085] The step 3 is specifically as follows: installing the slip assembly 2 on the outer wall of the oil casing 1 to be fastened, and moving the slip shell 9 upward through the lifting assembly, so that the slip shell 9 slides along the circular table surface of the slip decomposition tooth 10, clamping the oil casing 1 to be fastened and lifting the oil casing 1 to be fastened.

[0086] At this time, the oil casing 1 to be threaded is in a zero-gravity state under the action of the compensation tension spring 3 of the special thread on-site threading anti-damage device, and the threads of the oil casing 1 to be threaded can be easily threaded, led, and threaded.

[0087] The step 5 is specifically as follows: the telescopic mechanism 5 is contracted, the slip housing 9 is lowered, a plurality of slip decomposition teeth are loosened along the circumferential direction, and the oil casing 1 to be buckled is loosened.

[0088] After step 6, the method further includes: repeating steps 2-6 until all the oil casings 1 to be made up are made up.

[0089] Example 1

[0090] When the 3-1 / 2in oil pipe (7.34mm wall thickness) needs to be buckled up and down on the site, the weight of a single oil pipe can be calculated to be 150kg according to the design. Therefore, a compensating tension spring 3 with a mechanical spring force storage structure is selected, and the maximum working load of a single tension spring is 240kg, and there are two tension springs in total. A telescopic mechanism 5 with a double-acting cylinder design is selected, and the maximum working tensile lowering load of the telescopic mechanism 5 is 240kg; a slip assembly 2 with a load force of about 2500kg is selected, and the friction clamping teeth (high friction block 11) on the inside of the slip assembly 2 can be made of a polymer high friction coefficient material to ensure that the oil pipe is not damaged during the clamping process; the tension spring protection cover outside the compensating tension spring 3 is made of high-strength metal material, and the tension spring protection cover is designed with a sliding sleeve telescopic structure. An intelligent monitoring device is designed on the tension spring to monitor and upload the working status, load, elongation, etc. of the tension spring in real time.

[0091] Through calculation and verification, the load of the pipe string + lower slip assembly 2 is 155kg, the calculated safety factor of the compensation tension spring 3 is 3.2, the calculated safety factor of the telescopic mechanism 5 is 3, and the safety factor of the slip assembly 2 is greater than 7.

[0092] After arriving at the site, assemble the slip assembly 2, compensation spring 3, balance plate 4, telescopic mechanism 5 and wellhead support plate 6 from top to bottom in sequence to form a whole; place the special threaded on-site make-up anti-damage device on the make-up and run-in coupling of the oil casing 8 at the wellhead, and make the cylinder of the telescopic mechanism 5 in the extended state; lift the tubing out from the platform, and make the tubing pass through the middle of the special threaded on-site make-up anti-damage device; the telescopic mechanism 5 extends to lift the slip assembly 2, so that the slip housing 9 on the slip assembly 2 slides along the conical surface to clamp the tubing and lift the tubing; at this time, the tubing is in a zero-gravity state under the action of the compensation spring 3 of the special threaded on-site make-up anti-damage device for oil casing, and the tubing threads can be easily butted, guided and made up; the telescopic mechanism 5 contracts the cylinder, lowers the slip assembly 2 on the special threaded on-site make-up anti-damage device for tubing, the split teeth of the slip on the slip assembly 2 release the tubing, and lower the tubing that has been made up, and repeat the above steps.

[0093] Embodiment 2:

[0094] When on-site operations of making up and running in the 7-6 / 8in casing (wall thickness 15.11mm) are required, according to the design, the weight of a single casing can be calculated as 680kg. Therefore, a compensation spring 3 with a hydraulic spring energy storage structure is selected, the maximum working load of a single spring is 1000kg, and a total of two springs are combined. A telescopic mechanism 5 with a double-acting hydraulic cylinder design is selected, and the maximum working stretching and lowering load of the telescopic mechanism 5 is 600kg; a slip assembly 2 with a load capacity of about 2500kg is selected, and the friction holding teeth (high friction blocks 11) on the inner side of the slip assembly 2 can be made of a high friction coefficient material of copper + WC to ensure that the casing is not damaged during the holding process; the spring protection cover outside the compensation spring 3 is made of high-strength metal material, and the spring protection cover is designed with a sliding sleeve telescopic structure, and an intelligent monitoring device is designed on the spring to monitor and upload the working state, load, elongation amount, etc. of the spring in real time.

[0095] Through calculation and verification, the load of the pipe string + the lower slip assembly 2 is 685kg, the calculated safety factor of the compensation spring 3 is 2.9, the calculated safety factor of the telescopic mechanism 5 is 1.7, and the safety factor of the slip assembly 2 is greater than 3.5.

[0096] After arriving at the site, assemble the slip assembly 2, compensating spring, balance plate, telescopic mechanism 5 and wellhead support plate in sequence from top to bottom to form an integral body; place the special thread on-site make-up anti-damage device on the made-up casing coupling at the wellhead, and make the cylinder of the telescopic mechanism 5 in the extended state; lift the casing to be made up out of the platform, and make the tubing pass through the middle of the special thread on-site make-up anti-damage device; extend the telescopic mechanism 5 to lift the slip assembly 2, so that the split teeth of the slips on the slip assembly 2 slide along the conical surface to clamp the casing and lift the casing; at this time, the casing is in a zero-gravity state under the action of the compensating spring 3 of the special thread on-site make-up anti-damage device for oil and casing, and the casing threads can be easily butted, guided and made up; contract the cylinder of the telescopic mechanism 5, lower the slip assembly 2 on the special thread on-site make-up anti-damage device for casing, and the split teeth of the slips on the slip assembly 2 slide along the conical surface to release the casing, and lower the made-up casing. Repeat the above steps.

[0097] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0098] In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0099] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0100] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0101] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. 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 circumstances.

[0102] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A special thread on-site make-up anti-damage device, characterized in that, It includes a lifting assembly, a slip assembly (2), a compensating tension spring (3) and a balance plate (4). The lifting assembly is connected to the bottom surface of the balance plate (4), and the two ends of the compensating tension spring (3) are respectively fixedly connected to the top surface of the balance plate (4) and the slip assembly (2).

2. The special thread on-site make-up anti-damage device according to claim 1, characterized in that, The lifting assembly includes a telescopic mechanism (5) and a wellhead support plate (6). The two ends of the telescopic mechanism (5) are respectively connected to the wellhead support plate (6) and the balance plate (4).

3. The on-site threading anti-damage device with special threads according to claim 2, characterized in that, The lifting assembly includes a plurality of the telescopic mechanisms (5), and the plurality of telescopic mechanisms (5) are arranged at intervals.

4. A special thread on-site make-up anti-damage device according to claim 2, characterized in that, The telescopic mechanism (5) is a cylinder, a hydraulic cylinder or an electric telescopic rod.

5. A special thread on-site make-up anti-damage device according to claim 1, characterized in that, The slip assembly (2) includes a slip housing (9) and a plurality of slip split teeth (10). The plurality of slip split teeth (10) are arranged in sequence along the circumferential direction to form an annular slip tooth body. The outer wall of the slip tooth body and the inner wall of the slip housing (9) are frustum-shaped, and the slip housing (9) is sleeved outside the slip tooth body and fixedly connected to the compensating tension spring (3).

6. The on-site make-up anti-damage device with special threads according to claim 5, characterized in that A high-friction block (11) is fixedly installed on the inner wall of each slip split tooth (10).

7. A special thread on-site make-up anti-damage device according to claim 1, characterized in that, The balance plate (4) has a balance plate tubing through hole.

8. A special thread on-site make-up anti-damage device according to claim 1, characterized in that, A plurality of the compensating tension springs (3) are provided, and the plurality of compensating tension springs (3) are arranged at intervals.

9. A special thread on-site make-up anti-damage device according to any one of claims 1-8, characterized in that, It further includes a telescopic guide rod. The two ends of the telescopic guide rod are respectively fixedly connected to the top surface of the balance plate (4) and the slip assembly (2), and the compensating tension spring (3) is sleeved outside the telescopic guide rod.

10. A make-up operation method, characterized in that, It is realized by using the special-thread on-site make-up anti-damage device according to any one of claims 1-9, and includes the following steps: Step 1, place the special-thread on-site make-up anti-damage device on the wellhead collar (7) at the wellhead; Step 2, hoist the casing to be made up (1) to the location of the special-thread on-site make-up anti-damage device; Step 3, install the slip assembly (2) on the outer wall of the casing to be made up (1), and move the slip assembly (2) upward through the lifting assembly to lock the slip assembly (2) with the casing to be made up (1); Step 4, perform a make-up operation on the casing to be made up (1) and the wellhead collar (7); Step 5, move the slip assembly (2) downward through the lifting assembly and release the casing to be made up (1); Step 6, lower the casing to be made up (1) that has been made up into the wellhead.

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