Casing annular air channeling treatment device and method

Abstract

The invention relates to the technical field of natural gas development, in particular to a casing annular air channeling treatment device and method. The casing annular air channeling treatment device comprises a casing assembly, a high-pressure nitrogen pipeline, a closed discharge pipeline, a plugging agent injection pipeline, a fluid injection pipeline and a liquid level detector, the high-pressure nitrogen pipeline, the closed discharge pipeline, the plugging agent injection pipeline, the fluid injection pipeline and the liquid level detector are all communicated with the casing assembly, a high-pressure nitrogen source is arranged at the end of the high-pressure nitrogen pipeline, a closed discharge tank is arranged at the end of the closed discharge pipeline, and an injection pump is arranged at the end of the plugging agent injection pipeline. A fluid injection device is arranged at the end part of the fluid injection pipeline, and a control valve for controlling the on-off of the pipeline is correspondingly arranged in each pipeline. The invention aims to overcome the defect that in the prior art, gas wells with different well conditions cannot adopt a unified treatment device to treat the problem of annular gas channeling in the natural gas development process in time, and provides the casing annular gas channeling treatment device and method, so that the treatment can be performed by adopting a unified method aiming at different gas well conditions, and the treatment efficiency is improved. The treatment cost and the treatment difficulty are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas development, and more specifically, to a casing ring air cross-talk control device and method. Background Art

[0002] In the process of natural gas development, as the exploitation time increases, the problem of gas well annulus pressure increases year by year, causing safety hazards in many gas wells. In fact, for different environments and different gas well depths, the corresponding cement return height mud line distance is different. If the casing annulus is generally injected with plugging agents or plugging agents are injected through the insertion method to plug the casing annulus air channel, the uncertainty of the casing annulus situation will increase the difficulty of construction and the success rate of plugging is low. Therefore, it is difficult to use a unified treatment device to achieve timely treatment of the annular air channeling problem that occurs during the development of natural gas, which leads to an increase in treatment costs and an increase in the difficulty of treatment. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiency of the prior art that it is impossible to use a unified management device to timely manage the annular air crossflow problem occurring in the process of natural gas development for gas wells of different depths, and to provide a casing annular air crossflow management device and method, which can adopt a unified method to manage different gas well conditions, thereby greatly reducing the cost and difficulty of management.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] Provided is a casing ring air crosstalk control device, comprising a casing assembly, a high-pressure nitrogen pipeline, a closed-drain pipeline, a plugging agent injection pipeline, a fluid injection pipeline, and a liquid level detector, all of which are connected to the casing assembly; a high-pressure nitrogen source is provided at the end of the high-pressure nitrogen pipeline, a closed-drain tank is provided at the end of the closed-drain pipeline, an injection pump is provided at the end of the plugging agent injection pipeline, a fluid injection device is provided at the end of the fluid injection pipeline, and a control valve for controlling the on-off of the pipeline is correspondingly provided in each pipeline.

[0006] The casing assembly of the present invention is inserted into a gas well, and then different pipelines are selectively connected to the casing assembly according to different well conditions of the gas well to perform different treatment operations; the high-pressure nitrogen pipeline transports the high-pressure nitrogen source to the casing assembly to balance the pressure of the gas channeling layer to avoid gas channeling affecting the plugging effect during the treatment process; the closed-drain pipeline can discharge the liquid input into the casing assembly to the closed-drain irrigation for temporary storage; the plugging agent injection pipeline injects the plugging agent into the casing assembly through an injection pump for plugging; the fluid injection pipeline can inject foam drainage liquid or cleaning liquid into the casing assembly through a fluid injection device, and can also inject plugging agent, and corresponding operations are performed according to implementation needs.

[0007] Furthermore, the casing assembly includes a first casing, a second casing, a casing hanger, and a casing spool, the second casing is sleeved on the outside of the first casing and the two are connected by the casing hanger arranged on the top, the casing spool is sleeved on the outside of the second casing, and each pipeline is connected to the second casing respectively. The first casing is hung with the second casing by the casing hanger, and the second casing is connected to each pipeline by the casing spool.

[0008] Furthermore, the fluid injection equipment is divided into a simple injection equipment and a sealed injection equipment. Different injection equipment is required for different gas wells, wherein the simple injection equipment does not have a sealing and pressure-maintaining function, while the sealed injection equipment has a sealing and pressure-maintaining function.

[0009] Furthermore, the simple injection device includes a flange and a body connected in sequence, a first elastic hose is inserted into the body, a quick connector is provided at one end of the first elastic hose, the first quick connector is connected to a first traction head, the other end of the first elastic hose protrudes from the flange, and also includes a first rotating shaft and a first rotating cylinder, a steering channel is formed between the first rotating shaft and the first rotating cylinder, and the first traction head and the first quick connector are arranged along the steering channel. The flange and the body provide support for the first elastic hose, and liquid can be injected into the sleeve assembly through the first elastic hose. The liquid includes but is not limited to bubble drainage liquid, cleaning liquid, and plugging agent.

[0010] Furthermore, the sealing injection device includes a working cylinder, a plunger, and a push rod which are sequentially sleeved from the outside to the inside, the working cylinder and the plunger are connected by a screw, and a sealing ring is installed between the working cylinder and the plunger, and the end of the push rod is alternately installed with a pressure ring and a sealing ring, and also includes a second elastic hose, the second elastic hose is sequentially plugged with the push rod and the plunger, and one end of the second elastic hose protrudes from the push rod, and the other end protrudes from the plunger, and the end of the second elastic hose protruding from the plunger is provided with a second quick connector, and the second quick connector is connected with a second traction head, and also includes a second rotating shaft and a second rotating cylinder, a steering channel is formed between the second rotating shaft and the second rotating cylinder, and the second traction head and the second quick connector are arranged along the steering channel. The sealing ring installed between the working cylinder and the plunger can achieve sealing between the two, and the setting of the sealing ring can also directly seal the push rod and the plunger, thereby achieving pressure-maintaining injection of liquid.

[0011] The present invention also provides a casing ring air crosstalk control method, which is applied to the casing ring air crosstalk control device as described above, and the specific steps are as follows:

[0012] S1: Get the distance H1 from the cement return line to the mud line;

[0013] S2: Determine the distance H1 from the cement return line to the mud line. If H1>150m, proceed to step S3; if H1≤150m, proceed to step S8;

[0014] S3: Measure the distance H between the annular liquid surface and the mud line;

[0015] S4: Determine the distance H between the annular liquid surface and the mud line. If H≤100m, proceed to S5; if H>100m, proceed to step S6;

[0016] S5: Use a sealed injection device to inject the bubble drainage liquid through the fluid injection pipeline, and then inject nitrogen to discharge the liquid through the closed drainage pipeline until no liquid returns during the bubble drainage;

[0017] S6: Use the high-pressure nitrogen pipeline to inject nitrogen into the gas breakthrough annulus to restore the pressure to P1;

[0018] S7: Determine whether the plugging agent has been injected. If the plugging agent has been injected, jump to S11. If the plugging agent has not been injected, inject the plugging agent through the plugging agent injection pipeline, and then jump to S11.

[0019] S8: Determine whether the annular space pressure can be reduced to zero. If so, proceed to step S9; if not, proceed to step S10;

[0020] S9: Use a simple injection device to inject the cleaning liquid through the fluid injection pipeline, and then inject the plugging agent. During the plugging agent injection process, part of the cleaning liquid is discharged through the closed discharge pipeline, and then enter step S6;

[0021] S10: Use a sealed injection device to inject cleaning fluid through the fluid injection pipeline, and then inject the plugging agent. During the plugging agent injection process, part of the cleaning fluid is discharged through the closed discharge pipeline. The pressure in the gas channeling annulus is judged. If it is greater than P1, the pressure is released to P1 and the next step is entered. If it is less than P1, the step is entered into step S6;

[0022] S11: The process ends.

[0023] The present invention first determines whether the casing annulus air channeling well is suitable for the method by means of cement return height, annular space liquid level position, annular space gas channeling, etc. For wells where the cement return height is below the mudline, the distance H1 of the cement return height above the mudline is greater than 150m, the annular space liquid level is below the mudline, and the distance H1 of the annular space liquid level above the mudline is less than 100m, the annular space liquid level is lowered to a position below the mudline greater than 100m from the mudline by foam drainage, and nitrogen is injected into the annulus to control gas channeling in the formation during the operation, and a specific performance plugging agent is used to form a perfect plugging ring below the mudline above the annular space liquid level; for wells where the cement return height is below the mudline, the distance H1 of the cement return height above the mudline is greater than 150m, and the annular space liquid level is below the mudline, the distance H1 of the annular space liquid level above the mudline is less than 100m, the annular space liquid level is lowered to a position below the mudline greater than 100m from the mudline by foam drainage, and nitrogen is injected into the annulus to control gas channeling in the formation during the operation, and a specific performance plugging agent is used to form a perfect plugging ring below the mudline above the annular space liquid level; m, the annulus liquid level is below the mud line. For wells where the annulus liquid level is more than 100m away from the mud line, during the annulus nitrogen injection control operation, gas in the formation is prevented from rising, and a plugging agent with specific performance is used to form a perfect plugging ring below the mud line above the annulus liquid level. For wells where the cement return height is less than 150m away from the mud line H1, appropriate injection equipment is selected according to the annulus pressure release situation, and after the hose is lowered to the cement surface, cleaning fluid and plugging agent with specific performance are injected in sequence to form a perfect plugging ring above the cement surface. In this way, the casing annulus air channeling can be effectively blocked without moving the tubing and affecting the gas well production, thereby improving the treatment effect and reducing the operation cost.

[0024] Preferably, the step S11 further includes a detection step: after the plugging agent is completely solidified, whether there is gas channeling is detected by annular pressure to determine whether the plugging is qualified. If qualified, the process ends; if unqualified, the plugging agent continues to be injected until the plugging is qualified.

[0025] Preferably, the gas channeling phenomenon is judged on the basis that: annular space pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs.

[0026] Preferably, the volume of the bubbling liquid injected in step S5 is at least 1 times the volume of the annulus above the traction head; and the volume of the cleaning liquid injected in steps S9 and S10 is at least 1.2 times the volume of the annulus above the traction head.

[0027] Preferably, the plugging agent is immiscible with the drainage liquid or the cleaning liquid; and when the distance H1 to the high mud line of cement return is ≤150m, the density of the plugging agent used is greater than that of the cleaning liquid; when the distance H1 to the high mud line of cement return is greater than 150m, the density of the plugging agent used is less than that of the drainage liquid.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] According to different conditions of gas wells, whether the distance H1 from the cement return height to the mud line is greater than 150m, and whether the distance H from the annulus liquid level to the mud line is greater than 100m can be used as the basis for judgment. Different measures can be taken to specifically treat the problem of casing annulus air channeling in the process of natural gas development, so as to achieve effective plugging of casing annulus air channeling without affecting gas well production, improve treatment effect and reduce operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a casing ring air crosstalk control device in Example 1 and Example 3 of the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of a simple injection device.

[0032] Figure 3 This is a schematic diagram of the structure of the sealing injection equipment.

[0033] Figure 4 This is a schematic structural diagram of a casing ring air cross-flow control device in Example 4 of the present invention.

[0034] Figure 5 It is a structural schematic diagram of a casing ring air crosstalk control device in Example 5 and Example 6 of the present invention.

[0035] Figure 6 The present invention is a flow chart of a method for controlling air leakage in a casing ring.

[0036] The illustrations are as follows:

[0037] 1. First control valve; 2. Second control valve; 3. Liquid level detector; 4. High-pressure pipeline; 5. Four-way valve; 6. High-pressure nitrogen pipeline; 7. Closed-drain pipeline; 8. Plugging agent injection pipeline; 9. High-pressure nitrogen source; 10. Closed-drain tank; 11. Injection pump; 12. Fluid injection pipeline; 13. Fluid injection equipment; 14. First casing; 15. Second casing; 16. Casing hanger; 17. Casing four-way; 18. Three-way valve; 19. Flange; 20. Body; 21. First elastic hose ; 22. First quick connector; 23. First traction head; 24. First rotating shaft; 25. First rotating drum; 26. Working drum; 27. Plunger; 28. Push rod; 29. ​​Sealing ring; 30. Pressing ring; 31. Sealing ring; 32. Second elastic hose; 33. Second quick connector; 34. Second traction head; 35. Second rotating shaft; 36. Second rotating drum; A is sea level; B is mud line; C is cement return height; H is the distance between the annulus liquid level and the mud line; H1 is the distance between the cement return height and the mud line. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0040] Example 1

[0041] like Figure 1 The figure shows a first embodiment of a casing ring air crosstalk control device of the present invention, comprising a casing assembly, a high-pressure nitrogen pipeline 6, a closed-drain pipeline 7, a plugging agent injection pipeline 8, a fluid injection pipeline 12, and a liquid level detector 3, all of which are connected to the casing assembly. A high-pressure nitrogen source 9 is provided at the end of the high-pressure nitrogen pipeline 6, a closed-drain tank 10 is provided at the end of the closed-drain pipeline 7, an injection pump 11 is provided at the end of the plugging agent injection pipeline 8, and a fluid injection device 13 is provided at the end of the fluid injection pipeline 12. Control valves for controlling the on-off of the pipelines are provided in corresponding pipelines.

[0042] Different pipelines of the present invention have different functions. In actual application scenarios, the on and off of each pipeline can be controlled as needed. Moreover, in different application scenarios, when certain pipelines are not needed, the pipeline can be omitted in the casing ring air crosstalk control device.

[0043] As an embodiment of the present invention, the casing assembly includes a first casing 14, a second casing 15, a casing hanger 16, and a casing spool 17. The second casing 15 is sleeved on the outside of the first casing 14 and the two are connected by the casing hanger 16 arranged at the top. The casing spool 17 is sleeved on the outside of the second casing 15, and each pipeline is respectively connected to the second casing 15. The casing assembly is inserted below the mud line B at the sea level A, and a liquid level difference is also formed in the first casing 14 and the second casing 15, so there is a distance H1 between the cement return height C and the mud line B, and a distance H between the annular liquid level and the mud line B.

[0044] As an embodiment of the present invention, a first control valve 1 is provided on one side of the casing assembly, and a second control valve 2 is provided on the other side, so that the fluid injection device 13 is connected to the first control valve 1, and the high-pressure nitrogen pipeline 6, the closed exhaust pipeline 7, and the plugging agent injection pipeline 8 are all connected to the second control valve 2. Among them, the high-pressure nitrogen pipeline 6, the closed exhaust pipeline 7, and the plugging agent injection pipeline 8 can be connected to the second control valve 2 through the high-pressure pipeline 4.

[0045] As one embodiment of the present invention, the fluid injection device 13 is a simple injection device. Figure 2 As shown, the simple injection device does not have a pressure-maintaining function and can only inject liquid into the sleeve assembly.

[0046] Specifically, the simple injection device includes a flange 19 and a main body 20 connected in sequence, a first elastic hose 21 is inserted in the main body 20, a first quick connector 22 is provided at one end of the first elastic hose 21, the first quick connector 22 is connected to a first traction head 23, the other end of the first elastic hose 21 protrudes from the flange 19, and also includes a first rotating shaft 24 and a first rotating drum 25, a turning channel is formed between the first rotating shaft 24 and the first rotating drum 25, and the first traction head 23 and the first quick connector 22 are arranged along the turning channel.

[0047] Example 2

[0048] The following is a second embodiment of a casing ring air channeling control device of the present invention. This embodiment is similar to the first embodiment, except that: Figure 3 As shown, the fluid injection device 13 is a sealed injection device. The sealed injection device has a sealing and pressure-maintaining function, and can maintain pressure while injecting liquid.

[0049] Specifically, the sealing injection device includes a working cylinder 26, a plunger 27, and a push rod 28 which are sequentially sleeved from the outside to the inside. The working cylinder 26 and the plunger 27 are connected by a screw, and a sealing ring 29 is installed between the working cylinder 26 and the plunger 27. The end of the push rod 28 is alternately installed with a pressure ring 30 and a sealing ring 31. It also includes a second elastic hose 32, which is sequentially plugged into the push rod 28 and the plunger 27, and one end of the second elastic hose 32 protrudes from the push rod 28, and the other end protrudes from the plunger 27. A second quick connector 33 is provided at the end of the second elastic hose 32 protruding from the plunger 27. The second quick connector 33 is connected to a second traction head 34. It also includes a second rotating shaft 35 and a second rotating cylinder 36. A steering channel is formed between the second rotating shaft 35 and the second rotating cylinder 36, and the second traction head 34 and the second quick connector 33 are arranged along the steering channel.

[0050] Example 3

[0051] like Figure 6The first embodiment of a casing ring air crosstalk control method of the present invention is shown, which is applied to the casing ring air crosstalk control device as described above, and the specific steps are as follows:

[0052] A1: Get the distance H1 from the cement return line to the top of the mud line;

[0053] A2: Determine the distance H1 of the cement return line. When H1>150m, proceed to step A3. When H1≤150m, refer to Example 5.

[0054] A3: Measure the distance H between the annular liquid surface and the mud line;

[0055] A4: Determine the distance H between the annular liquid surface and the mud line. When H≤100m, proceed to A5. When H>100m, refer to Example 4.

[0056] A5: Use a sealed injection device to inject the bubble discharge liquid through the fluid injection pipeline 12, and then inject nitrogen to discharge the liquid through the closed discharge pipeline 7 until no liquid returns from the bubble discharge;

[0057] The foaming liquid is a cleaning liquid with a suitable concentration of foaming agent added, which can simultaneously achieve the purpose of cleaning the casing wall and assisting drainage; the performance requirements of the cleaning liquid are: ① cleaning the casing wall to improve the bonding performance of the plugging agent and the casing; ② effectively inhibiting casing corrosion.

[0058] The volume of the injected bubble drainage liquid is at least 1 times the volume of the annular space above the traction head; preferably 1.2 times;

[0059] A6: Use high-pressure nitrogen pipeline 6 to inject nitrogen into the gas breakthrough annulus to restore the pressure to P1;

[0060] A7: Use the plugging agent injection pipeline 8 to inject the plugging agent.

[0061] The performance requirements of the plugging agent are as follows: ① good fluidity and no solid phase; ② insoluble in cleaning fluid and drainage fluid; ③ compatible with drainage agent, defoamer and other additives; ④ density is less than drainage fluid, and the density difference is greater than 0.1g / cm 3 ; ⑤ The pressure bearing capacity of the plugging agent after solidification is greater than 1.5 times the annular pressure P1; ⑥ The temperature resistance meets the annular temperature of ±10℃ during the production process; ⑦ The thickening time is greater than 2 times the plugging agent injection time.

[0062] It also includes a detection step: after the plugging agent is completely solidified, whether there is gas channeling through the annular pressure is detected to determine whether the plugging is qualified. If it is qualified, it goes to A8, if it is unqualified, it returns to step A6;

[0063] Among them, the judgment basis of gas channeling is: the annular pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs;

[0064] A8: The process is complete.

[0065] like Figure 1 As shown, the casing ring air crosstalk control device used in this embodiment connects the high-pressure nitrogen pipeline 6, the closed exhaust pipeline 7, and the plugging agent injection pipeline 8 through the four-way valve 5 and is connected to one end of the second control valve 2 via the high-pressure pipeline 4. The other end of the second control valve 2 is connected to the casing assembly, and the fluid injection pipeline 12, the casing assembly, and the liquid level detector 3 are all connected to the first control valve 1.

[0066] For example, the annular air leakage between the first casing 14 and the second casing 15 of Well X caused casing pressure. After checking the well history data, the annular cement return height was 450m (H1) below the mudline. The on-site record of the annular pressure of gas leakage was 7MPa, and the adjacent annular pressures were 2.3MPa (P2) and 0.5MPa (P3), respectively. The first control valve 1 and the second control valve 2 were closed, and the liquid level detector 3 was connected to the first control valve 1. The pressure test of the pipeline, valve, etc. was qualified. The first control valve 1 was opened to release the gas in the gas leakage annulus. The liquid level detector 3 could not accurately measure the position of the annular liquid level. The annular pressure was released to 0. During the pressure relief process, the adjacent annular pressures P2 and P3 basically did not change. H1>150m, H could not be accurately measured, and P2 and P3 basically did not change during the pressure relief process. It was judged that the present invention is suitable for the plugging of air leakage in the casing annulus of Well X. Close the first control valve 1, open the second control valve 2, connect the closed exhaust pipeline 7 with the casing assembly, remove the liquid level detector 3, connect the first control seal injection device, rotate the push rod 28 to seal the sealing ring 31 and the second elastic hose 32, open the first control valve 1, push the front end of the plunger 27 into the casing annulus to make the second elastic hose 32 on the plunger 27 turn to the channel vertically downward, insert the second elastic hose 32 into the casing annulus, and the second elastic hose 32 is pumped at a density of 1.10g / cm 3 The cleaning liquid causes the second traction head 34 to drag the second elastic hose 32 downward, and the second elastic hose 32 is lowered to 150m below the mud line. 0.3% of the foaming agent is added to the cleaning liquid to prepare the foaming liquid, and the hose is pumped for 10m 3 Bubble drainage, nitrogen bubbles are injected into the second elastic hose 32 until no liquid returns, the defoaming agent is slowly pumped in and the hose is recovered at the same time, the second traction head 34 is received in the plunger 27, the plunger 27 withdraws from the first control valve 1, and the first control valve 1 is connected to the annulus pressure monitoring instrument and the pressure relief valve. Close the drainage pipeline 7, connect the high-pressure nitrogen pipeline 6, and use high-pressure nitrogen to inject nitrogen into the gas leakage annulus to restore the pressure to 7MPa. Close the high-pressure nitrogen pipeline 6, connect the plugging agent injection pipeline 8, and use the injection pump 11 to inject a 50m long plugging agent segment into the gas leakage annulus, and close the second control valve 2 and wait for solidification. The injected plugging agent is a solid-free resin plugging agent with a viscosity of 300mPa·s and a density of 1.00g / cm 3The plugging agent has good compatibility with additives such as foaming agent and defoaming agent. The pressure bearing strength of the plugging agent after solidification is greater than 35MPa, and the temperature resistance is 0℃-90℃ (the annular temperature range is 30℃-53℃ during the production process). The thickening time is 120min (the plugging agent is in place for 30min), and the solidification time is 300min. After solidification for 12h, open the first control valve 1 and the pressure relief valve to remove the annular pressure, close the pressure relief valve to monitor the annular pressure for 24h, and the pressure is 0, which means that the plugging is qualified. Open the second control valve 2 and the pressure relief valve, use the injection pump 11 to fill the annular space with anti-corrosion liquid, dismantle the equipment and pipelines, restore the first control valve 1 and the second control valve 2 to the state before the operation, and hand it over to the production personnel to monitor the annular pressure changes. If the pressure rises, release the pressure in time.

[0067] The present invention realizes effective blocking of air channeling in the casing ring without moving the pipe column and affecting the production of the gas well, thereby improving the treatment effect and reducing the operation cost.

[0068] Example 4

[0069] like Figure 4 The second embodiment of the casing annulus air channeling treatment method of the present invention is shown. This embodiment is similar to the embodiment 3, except that the distance H between the annulus liquid level and the mud line is greater than 100 m.

[0070] B1: Use the high-pressure nitrogen pipeline 6 to inject nitrogen into the gas breakthrough annulus to restore the pressure to P1;

[0071] B2: Use the plugging agent injection pipeline 8 to inject the plugging agent.

[0072] It also includes a detection step: after the plugging agent is completely solidified, whether there is gas channeling through the annular pressure is detected to determine whether the plugging is qualified. If it is qualified, it goes to B3; if it is unqualified, it returns to step B1;

[0073] Among them, the judgment basis of gas channeling is: the annular pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs;

[0074] Among them, the judgment basis of gas channeling is: the annular pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs;

[0075] B3: The process ends.

[0076] The casing ring air crosstalk control device used in this embodiment connects the high-pressure nitrogen pipeline 6 and the plugging agent injection pipeline 8 through the three-way valve 18 and is connected to one end of the second control valve 2 via the high-pressure pipeline 4. The other end of the second control valve 2 is connected to the casing assembly, and the casing assembly and the liquid level detector 3 are both connected to the first control valve 1.

[0077] For example: The annular gas leakage between the first casing 14 and the second casing 15 of Well X caused casing pressure. After checking the well history data, the annular cement return height was 230m (H1) below the mudline. The on-site record of the annular pressure of gas leakage was 6.5MPa (P1), and the adjacent annular pressures were 0 (Pi). The first control valve 1 and the second control valve 2 were closed, and the first control valve 1 was connected to the liquid level detector 3. The pipeline, valve, etc. were tested for 10MPa and 15min. No leakage or pressure drop was found, and the pressure test was qualified. The first control valve 1 was opened to release the gas in the gas leakage annulus. The liquid level of the annular space was measured by the liquid level detector 3 to be 158m (H) below the mudline. The annular pressure was continuously released until it stabilized at 0.5MPa. During the pressure relief process, the adjacent annular pressure remained 0. H1>150m, H>100m, during the pressure relief of the gas channeling annulus P1, the adjacent annulus Pi remains unchanged; close the first control valve 1, connect the high-pressure nitrogen pipeline 6, open the second control valve 2, and use high-pressure nitrogen to inject nitrogen into the gas channeling annulus until the pressure is restored to 6.5MPa. Close the high-pressure nitrogen pipeline 6, connect the plugging agent injection pipeline 8, inject a 50m long plugging agent segment into the gas channeling annulus through the injection pump 11, and close the second control valve 2 for solidification. The injected plugging agent is a solid-free resin plugging agent with a viscosity of 300mPa·s and a density of 1.00g / cm 3 (Annular space liquid density 1.2g / cm 3 ), the pressure strength of the plugging agent after solidification is greater than 35MPa, the temperature resistance is 0℃-90℃ (the annular temperature range is 25℃-50℃ during the production process), the thickening period is 120min (the plugging agent is in place for 30min), and the solidification time is 300min. During the solidification period, clean the plugging agent injection pump 11 and pipelines, remove the liquid level detector 3, and connect the first control valve 1 to the annular pressure monitoring instrument and the pressure relief valve. After solidification for 12 hours, open the first control valve 1 and the pressure relief valve to relieve the annular pressure, close the pressure relief valve to monitor the annular pressure for 24 hours, and the pressure is 0, which means that the plugging is qualified. Open the second control valve 2 and the pressure relief valve, use the injection pump 11 to fill the annulus with anti-corrosion liquid, dismantle the equipment and pipelines, restore the first control valve 1 and the second control valve 2 to the state before the operation, and hand it over to the production personnel to monitor the annular pressure changes. If the pressure rises, release the pressure in time.

[0078] Example 5

[0079] like Figure 5 The second embodiment of the casing ring air channeling control method of the present invention is shown. This embodiment is similar to the third embodiment, except that it is applied to the cement return high mud line distance H1≤150m. The specific steps are as follows:

[0080] C1: Determine whether the annular space pressure can be reduced to zero. If so, proceed to step C2. If not, refer to Example 6.

[0081] C2: Use a simple injection device to inject the cleaning liquid through the fluid injection pipeline 12, and then inject the blocking agent. During the blocking agent injection process, part of the cleaning liquid is discharged through the closed discharge pipeline 7, and enter step C3;

[0082] The cleaning fluid performance requirements are: ① Clean the casing wall to improve the bonding performance of the plugging agent and the casing; ② Effectively inhibit casing corrosion. The volume of the injected cleaning fluid is at least 1.2 times the volume of the annulus above the traction head; preferably 1.5 times;

[0083] The performance requirements of the plugging agent are: ① good fluidity and no solid phase; ② insoluble in the cleaning fluid; ③ greater density than the cleaning fluid, with a density difference greater than 0.1g / cm 3 ; ④ The pressure bearing capacity of the plugging agent after solidification is greater than 1.5 times the annular pressure P1; ⑤ The temperature resistance meets the annular temperature of ±10℃ during the production process; ⑥ The thickening time is greater than 2 times the plugging agent injection time.

[0084] C3: Use the high-pressure nitrogen pipeline 6 to inject nitrogen into the gas breakthrough annulus to restore the pressure to P1;

[0085] It also includes a detection step: after the plugging agent is completely solidified, whether there is gas channeling through the annular pressure is detected to determine whether the plugging is qualified. If it is qualified, it goes to C4; if it is unqualified, it returns to step C2;

[0086] Among them, the judgment basis of gas channeling is: the annular pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs;

[0087] C4: The process ends.

[0088] The casing ring air crosstalk control device used in this embodiment connects the high-pressure nitrogen pipeline 6, the closed exhaust pipeline 7 and one end of the second control valve 2 via the three-way valve 18 via the high-pressure pipeline 4, and the other end of the second control valve 2 is connected to the casing assembly, and the fluid injection pipeline 12, the casing assembly, and the liquid level detector 3 are all connected to the first control valve 1.

[0089] For example: The annular gas leakage between the first casing 14 and the second casing 15 of Well X caused casing pressure. After checking the well history data, the cement return height of the annular space was 105m (H1) below the mudline. The on-site record of the annular pressure of gas leakage was 4.5MPa (P1), and the adjacent annular pressures were all 0 (Pi). The annular pressure P1 was released to 0, and the adjacent annular pressure remained 0 during the pressure relief process. H1<150m, the adjacent annular Pi did not change during the pressure relief of the gas leakage annular space P1, P1 could be depressurized to 0, and a simple injection device was selected as the fluid injection device 13. The pipeline, valve, etc. were pressure tested at 10MPa and 15min, and no leakage or pressure drop was found, and the pressure test was qualified. Open the first control valve 1 and the second control valve 2, connect the closed exhaust pipeline 7, install a simple injection device on the first control valve 1, make the first elastic hose 21 turn the channel vertically downward, insert the first elastic hose 21 equipped with the first traction head 23 through the turning channel into the casing annulus, and the first elastic hose 21 is pumped at a density of 1.06g / cm 3 The cleaning fluid causes the first traction head 23 to drag the first elastic hose 21 downward, and the first elastic hose 21 is lowered to the annular cement surface, and continues to pump 11m 3 Stop the pump after cleaning the liquid. Use the first elastic hose 21 to pump 30m of plugging agent into the gas channeling annulus. After the plugging agent is injected, recycle the first elastic hose 21, dismantle the simple injection equipment, connect the first control valve 1 to the annulus pressure monitoring instrument and the pressure relief valve, close the pressure relief valve, close the exhaust pipeline 7, connect the high-pressure nitrogen pipeline 6, inject nitrogen to restore the annulus pressure to 4.5MPa, close the second control valve 2, and wait for solidification under pressure. The injected plugging agent is a solid phase resin plugging agent with a viscosity of 380mPa·s and a density of 1.20g / cm 3 After the plugging agent solidifies, the pressure bearing strength is greater than 35MPa, the temperature resistance is 0-90℃ (the annular temperature range is 30℃-52℃ during the production process), the thickening time is 120min (the plugging agent injection time is 30min), and the solidification time is 300min. After solidification for 12h, open the pressure relief valve to release the annular pressure, close the pressure relief valve and observe for 24h. The annular pressure rises slightly. The pressure relief valve is opened and the discharge is basically liquid, indicating that there is no gas channeling phenomenon, and the plugging is judged to be qualified. Disassemble the equipment and pipelines, restore the first control valve 1 and the second control valve 2 to the state before the operation, and hand it over to the production personnel to monitor the annular pressure changes. If the pressure rises, release the pressure in time.

[0090] Example 6

[0091] like Figure 5 The second embodiment of the casing annulus air channeling control method of the present invention is shown. This embodiment is similar to the embodiment 5, except that it is applied when the annulus pressure cannot be released to zero. The specific steps are as follows:

[0092] D1: Use a sealed injection device to inject cleaning liquid through the fluid injection pipeline 12, and then inject the plugging agent. During the plugging agent injection process, part of the cleaning liquid is discharged through the closed discharge pipeline 7;

[0093] The volume of the injected cleaning fluid is at least 1.2 times the volume of the annular space above the traction head; preferably 1.5 times;

[0094] The plugging agent is not miscible with the cleaning fluid, and the density of the plugging agent used is greater than that of the cleaning fluid;

[0095] D2: Determine the pressure in the gas leakage annulus. If it is greater than P1, the pressure is released to P1 and the process goes to D4. If it is less than P1, the process goes to step D3.

[0096] D3: Use the high-pressure nitrogen pipeline 6 to inject nitrogen into the gas breakthrough annulus to restore the pressure to P1;

[0097] D4: Detection step: After the plugging agent is completely solidified, the annular pressure is used to detect whether there is gas channeling to determine whether the plugging is qualified. If qualified, proceed to D5; if not, return to step D1;

[0098] Among them, the judgment basis of gas channeling is: the annular pressure increases significantly and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs; otherwise, it is considered that no gas channeling occurs;

[0099] D5: The process ends.

[0100] The casing ring air crosstalk control device used in this embodiment connects the high-pressure nitrogen pipeline 6, the closed exhaust pipeline 7 and one end of the second control valve 2 via the three-way valve 18 via the high-pressure pipeline 4, and the other end of the second control valve 2 is connected to the casing assembly, and the casing assembly, the fluid injection pipeline 12, and the liquid level detector 3 are all connected to the first control valve 1.

[0101] For example: The annular air leakage between the first casing 14 and the second casing 15 of the X1 well caused casing pressure. After checking the well history data, the annular cement return height was 118m (H1) below the mudline. The on-site record of the annular pressure of the gas leakage was 7.5MPa (P1), and the adjacent annular pressures were all 0 (Pi). The annular pressure P1 was released to 0, and the adjacent annular pressure remained 0 during the pressure relief process. H1<150m, the adjacent annular Pi did not change during the pressure relief of the gas leakage annular P1, and P1 was released to 0.8MPa and stable, and a sealed injection device was selected as the fluid injection device 13. The pipeline, valve, etc. were pressure tested at 10MPa and 15min, and no leakage or pressure drop was found, and the pressure test was qualified. Close the first control valve 1, open the second control valve 2, connect the closed exhaust pipeline 7, connect the first control valve 1 to the sealing injection equipment, rotate the push rod 28 to seal the sealing ring 31 and the second elastic hose 32, slowly open the first control valve 1, push the front end of the plunger 27 into the casing annulus to make the second elastic hose 32 on the plunger 27 turn to the channel vertically downward, insert the second elastic hose 32 into the casing annulus, and the pumping density of the second elastic hose 32 is 1.06g / cm 3 The cleaning fluid causes the second traction head 34 to drag the second elastic hose 32 downward, and the second elastic hose 32 is lowered to the annular cement surface, and continues to pump 12m 3 After the cleaning liquid is removed, the pump is stopped. Nitrogen is injected into the second elastic hose 32 to discharge the cleaning liquid for 2m 3 , close the second control valve 2, continue to inject nitrogen to restore the annular pressure to 7.5 MPa, and use the second elastic hose 32 to pump 1.5 m 3 The plugging agent is used for segment plugging. During the plugging agent injection process, the pressure is maintained at 7.5MPa-8MPa by adjusting the second control valve 2 and closing the exhaust pipeline 7. The plugging agent injected is a solid phase free resin plugging agent with a viscosity of 380mPa·s and a density of 1.20g / cm 3 After the plugging agent solidifies, the pressure bearing strength is greater than 35MPa, the temperature resistance is 0℃-90℃ (the annular temperature range is 28℃-55℃ during the production process), the thickening time is 120min (the plugging agent injection time is 30min), and the solidification time is 300min. After the plugging agent is injected, the second elastic hose 32 and the second traction head 34 are recovered and put into the plunger 27. The plunger 27 withdraws from the first and control valves, and the first control valve 1 is closed to wait for solidification with pressure. During the solidification period, the sealing injection equipment is removed, and the first control valve 1 is connected to the annular pressure monitoring instrument and the pressure relief valve. After solidification for 12 hours, the first control valve 1 is opened, and the annular pressure is discharged through the pressure relief valve. The pressure relief valve is closed and observed for 24 hours. The annular pressure is 0, indicating that there is no gas channeling phenomenon, and the plugging is judged to be qualified. Disassemble the equipment and pipelines, restore the first control valve 1 and the second control valve 2 to the state before the operation, monitor the dynamic changes of the annular pressure, and release the pressure in time if the pressure rises.

[0102] The present invention determines the cement return height, annular space gas channeling, etc., and then lowers the elastic hose to the cement surface and injects cleaning fluid and plugging agent with specific performance in sequence to form a perfect plugging ring on the upper part of the cement surface. In this way, the air channeling of the casing annulus can be effectively blocked without moving the pipe string and affecting the production of the gas well, thereby improving the control effect and reducing the operating cost.

[0103] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A casing ring air channeling control device, characterized in that: The invention comprises a casing assembly, a high-pressure nitrogen pipeline (6), a closed-drain pipeline (7), a plugging agent injection pipeline (8), a fluid injection pipeline (12), and a liquid level detector (3) all of which are connected to the casing assembly. A high-pressure nitrogen source (9) is provided at the end of the high-pressure nitrogen pipeline (6), a closed-drain tank (10) is provided at the end of the closed-drain pipeline (7), an injection pump (11) is provided at the end of the plugging agent injection pipeline (8), and a fluid injection device (13) is provided at the end of the fluid injection pipeline (12). Control valves for controlling the on-off of the pipelines are provided in the corresponding pipelines.

2. The casing ring air cross-flow control device according to claim 1 is characterized in that: The casing assembly comprises a first casing (14), a second casing (15), a casing hanger (16), and a casing cross-connection (17); the second casing (15) is sleeved on the outside of the first casing (14), and the two are connected via the casing hanger (16) arranged on the top; the casing cross-connection (17) is sleeved on the outside of the second casing (15), and each pipeline is respectively connected to the second casing (15).

3. The casing ring air cross-flow control device according to claim 1 or 2, characterized in that: The fluid injection device (13) is divided into a simple injection device and a sealed injection device.

4. The casing ring air cross-flow control device according to claim 3 is characterized in that: The simple injection device comprises a flange (19) and a body (20) which are connected in sequence. A first elastic hose (21) is inserted into the body (20). One end of the first elastic hose (21) is provided with a first quick connector (22). The first quick connector (22) is connected to a first traction head (23). The other end of the first elastic hose (21) protrudes from the flange (19). The device further comprises a first rotating shaft (24) and a first rotating drum (25). A turning channel is formed between the first rotating shaft (24) and the first rotating drum (25). The first traction head (23) and the first quick connector (22) are arranged along the turning channel.

5. The casing ring air cross-flow control device according to claim 3 is characterized in that: The sealing injection device comprises a working cylinder (26), a plunger (27), and a push rod (28) which are sequentially sleeved from the outside to the inside, the working cylinder (26) and the plunger (27) are connected by a screw, and a sealing ring (29) is installed between the working cylinder (26) and the plunger (27), and a pressure ring (30) and a sealing ring (31) are alternately installed at the end of the push rod (28), and also comprises a second elastic hose (32), the second elastic hose (32) is sequentially plugged into the push rod (28) and the plunger (27), and the first One end of the second elastic hose (32) protrudes from the push rod (28), and the other end protrudes from the plunger (27). The end of the second elastic hose (32) protruding from the plunger (27) is provided with a second quick connector (33). The second quick connector (33) is connected to a second traction head (34), and further comprises a second rotating shaft (35) and a second rotating cylinder (36). A turning channel is formed between the second rotating shaft (35) and the second rotating cylinder (36). The second traction head (34) and the second quick connector (33) are arranged along the turning channel.

6. A method for treating air leakage in casing ring, characterized in that: Applied to the casing ring air cross-flow control device as claimed in claim 3, the specific steps are as follows: S1: Get the distance H1 from the cement return line to the mud line; S2: Determine the distance H1 from the cement return line to the mud line. If H1>150m, proceed to step S3; if H1≤150m, proceed to step S8; S3: Measure the distance H between the annular liquid surface and the mud line; S4: Determine the distance H between the annular liquid surface and the mud line. If H≤100m, proceed to S5; if H>100m, proceed to step S6; S5: using a sealed injection device to inject the foaming liquid through the fluid injection pipeline (12), and then injecting nitrogen to discharge the liquid through the closed discharge pipeline (7) until no liquid is returned during the foaming; S6: injecting nitrogen into the gas breakthrough annulus through the high-pressure nitrogen pipeline (6) to restore the pressure to P1; S7: judging whether the plugging agent has been injected, if the plugging agent has been injected, jumping to S11, if the plugging agent has not been injected, injecting the plugging agent through the plugging agent injection pipeline (8), and then jumping to S11; S8: Determine whether the annular space pressure can be reduced to zero. If so, proceed to step S9; if not, proceed to step S10; S9: using a simple injection device to inject cleaning liquid through the fluid injection pipeline (12), and then injecting the plugging agent. During the plugging agent injection process, part of the cleaning liquid is discharged through the closed discharge pipeline (7), and then proceeding to step S6; S10: Use a sealed injection device to inject a cleaning liquid through a fluid injection pipeline (12), and then inject a plugging agent. During the plugging agent injection process, part of the cleaning liquid is discharged through a closed discharge pipeline (7). The pressure in the gas channeling annulus is determined. If it is greater than P1, the pressure is released to P1 and the next step is entered. If it is less than P1, the step S6 is entered. S11: The process ends.

7. The method for treating air cross-flow in casing ring according to claim 6, characterized in that: The step S11 also includes a detection step: after the plugging agent is completely solidified, whether there is gas channeling is detected by annular pressure to determine whether the plugging is qualified. If it is qualified, the process ends; if it is unqualified, the plugging agent is continuously injected until the plugging is qualified.

8. The method for treating air cross-flow in casing ring according to claim 7, characterized in that: The basis for judging the gas channeling phenomenon is: annular space pressure increases significantly, and a large amount of gas is discharged during pressure relief, indicating that gas channeling has occurred; otherwise, it is considered that no gas channeling has occurred.

9. The method for treating air cross-flow in a casing ring according to any one of claims 6 to 8, characterized in that: The volume of the bubble drainage liquid injected in step S5 is at least 1 times the volume of the annulus above the traction head; the volume of the cleaning liquid injected in steps S9 and S10 is at least 1.2 times the volume of the annulus above the traction head.

10. The method for treating air cross-flow in casing ring according to claim 6, characterized in that: The plugging agent is not miscible with the foam drainage liquid or the cleaning liquid; and when the distance H1 of the cement return high mud line is ≤150m, the density of the plugging agent used is greater than that of the cleaning liquid; when the distance H1 of the cement return high mud line is greater than 150m, the density of the plugging agent used is less than that of the foam drainage liquid.

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