A casing annulus air channel treatment device and method

Abstract

The present application relates to natural gas development technical field, more particularly, it relates to a kind of casing annular gas channeling treatment device and method.The casing annular gas channeling treatment device includes casing assembly, high-pressure nitrogen pipeline, closed discharge pipeline, plugging agent injection pipeline, fluid injection pipeline, liquid level detector, all being communicated with casing assembly, high-pressure nitrogen pipeline end is equipped with high-pressure nitrogen source, closed discharge pipeline end is equipped with closed discharge tank, plugging agent injection pipeline end is equipped with injection pump, fluid injection pipeline end is equipped with fluid injection equipment, corresponding control valve for controlling pipeline on-off is provided in each pipeline.The purpose of the present application is to overcome the deficiency that the existing technology cannot use uniform treatment device to treat the annular gas channeling problem in natural gas development process for different well conditions, provide a kind of casing annular gas channeling treatment device and method, can be treated using uniform method for different gas well conditions, greatly reduce the cost and the difficulty of treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas development, and more particularly to a casing annulus air crosstalk control device and method. Background Art

[0002] During natural gas development, the problem of annular pressure in gas wells increases year by year as production time increases, posing safety risks to many gas wells. In fact, the distance from cement return to the mudline varies depending on the environment and the depth of the gas well. If a plugging agent is injected into the casing annulus in a general manner or through a cannulation method to block the air channeling through the casing annulus, the uncertainty of the casing annulus condition will increase the difficulty of construction and reduce the success rate of plugging. Therefore, it is difficult to use a unified treatment device to achieve timely treatment of annular air channeling problems during natural gas development, resulting in increased treatment costs and increased difficulty. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiency of the prior art that a unified treatment device cannot be used to timely treat the annular air crosstalk problem that occurs during the natural gas development process for gas wells of different depths, and to provide a casing annular air crosstalk treatment device and method, which can adopt a unified method to treat different gas well conditions, thereby greatly reducing the cost and difficulty of treatment.

[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. The end of the high-pressure nitrogen pipeline is provided with a high-pressure nitrogen source, the end of the closed-drain pipeline is provided with a closed-drain tank, the end of the plugging agent injection pipeline is provided with an injection pump, and the end of the fluid injection pipeline is provided with a fluid injection device. 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, thereby preventing gas channeling from affecting the sealing effect during the treatment process; the closed drainage pipeline can discharge the liquid input into the casing assembly to the closed drainage tank for temporary storage; the plugging agent injection pipeline injects the plugging agent into the casing assembly through an injection pump for sealing; 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 provided at the top. The casing spool is sleeved on the outside of the second casing, and each pipeline is connected to the second casing. The casing hanger is used to hang the first and second casings, and the casing spool is used to connect the second casing to each pipeline.

[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. Among them, 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] The simplified injection device further comprises a flange and a main body connected in sequence. A first elastic hose is inserted into the main body. One end of the first elastic hose is provided with a quick connector, which is connected to a first traction head. The other end of the first elastic hose protrudes from the flange. The device also comprises a first rotating shaft and a first rotating drum. A diversion channel is formed between the first rotating shaft and the first rotating drum. The first traction head and the first quick connector are arranged along the diversion channel. The flange and main body provide support for the first elastic hose, allowing liquid to be injected into the cannula assembly through the first elastic hose. Liquids include, but are not limited to, foam drainage fluid, cleaning fluid, and plugging agents.

[0010] Furthermore, the sealed 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. The end of the push rod is alternately installed with a pressure ring and a sealing ring. The device also includes a second elastic hose, which is sequentially plugged into 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. 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 to a second traction head. The device also includes a second rotating shaft and a second rotating cylinder, and a steering channel is formed between the second rotating shaft and the second rotating cylinder. 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 a seal between the two. Moreover, the provision of the sealing ring can also directly seal the push rod and the plunger, thereby achieving pressure-maintained injection of the 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 described above, and the specific steps are as follows:

[0012] S1: Get the distance H1 between the cement return line and the high mud line;

[0013] S2: Determine the distance H1 from the cement return 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 ≤ 100 m, proceed to S5; if H > 100 m, proceed to 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 to the bubble drainage;

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

[0018] S7: Determine whether the plugging agent has been injected. If so, jump to S11. If not, 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 cleaning fluid through the fluid injection pipeline, and then inject the blocking agent. During the blocking agent injection process, part of the cleaning fluid 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 exhaust pipeline. 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 process proceeds to step S6.

[0022] S11: The process ends.

[0023] The present invention first determines whether the casing annulus air channeling well is suitable for this method based on cement return height, annular space liquid level position, annular space gas channeling situation, etc. For wells with cement return height below the mudline, cement return height above the mudline distance H1 greater than 150m, annular space liquid level below the mudline, and annular space liquid level below the mudline distance H less than 100m, the annular space liquid level is lowered to a position below the mudline greater than 100m by foam drainage, annular space nitrogen is injected to control gas channeling in the formation during the operation, and a special performance plugging agent is used to form a complete plugging ring below the mudline above the annular space liquid level; for wells with cement return height below the mudline, cement return height above the mudline distance H1 greater than 150m, and annular space liquid level below the mudline distance H less than 100m, the annular space liquid level is lowered to a position below the mudline greater than 100m by foam drainage, and nitrogen is injected into the annular space to control gas channeling in the formation during the operation. m, the annular liquid level is below the mudline. For wells where the annular liquid level is more than 100m away from the mudline, annular nitrogen injection is used to control gas upward in the formation during the operation, and a specific performance plugging agent is used to form a complete plugging ring below the mudline above the annular liquid level; for wells where the cement return height is less than 150m away from the mudline, appropriate injection equipment is selected according to the annular pressure relief situation, and after lowering the hose to the cement surface, a cleaning fluid and plugging agent with specific performance are injected in sequence to form a complete plugging ring above the cement surface; thereby, effective plugging of air channeling through the casing annulus is achieved without moving the tubing string or affecting the production of the gas well, thereby improving the treatment effect and reducing the operating cost.

[0024] Preferably, the step S11 further includes a 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, the process ends; if unqualified, the plugging agent is continuously injected until the plugging is qualified.

[0025] Preferably, the gas channeling phenomenon is judged based on: an obvious increase in annular pressure and a large amount of gas discharged during pressure relief indicate that gas channeling has occurred; otherwise, it is considered that no gas channeling has occurred.

[0026] Preferably, the volume of the foaming 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 fluid or the cleaning fluid; 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 fluid; 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 drainage fluid.

[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 of cement return height to the mud line is greater than 150m and whether the distance H of annular 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 annular air channeling occurring in the process of natural gas development. In this way, the casing annular air channeling can be effectively blocked without affecting the production of gas wells, thereby improving the treatment effect and reducing the operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This 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 structural schematic diagram of a casing ring air crosstalk control device in Example 4 of the present invention.

[0034] Figure 5 This is a structural schematic diagram of a casing ring air crosstalk control device in Examples 5 and 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 icon marks are explained 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. Pressure 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 with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise 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, which includes a casing assembly, a high-pressure nitrogen pipeline 6, a closed exhaust 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 exhaust tank 10 is provided at the end of the closed exhaust 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. A control valve for controlling the on-off of the pipeline is provided in each pipeline.

[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 pipelines can be omitted in the casing ring air channeling control device.

[0043] As one 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 outside the first casing 14, and the two are connected by the casing hanger 16 installed at the top. The casing spool 17 is sleeved outside the second casing 15, and each pipeline is connected to the second casing 15. The casing assembly is inserted below the mudline B at sea level A. A liquid level difference is also formed in the first casing 14 and the second casing 15. Therefore, a distance H1 is formed between the cement return height C and the mudline B, and a distance H is formed between the annular liquid level and the mudline B.

[0044] As one 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 into 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. 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, which 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 ends of the push rod 28 are 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. The end of the second elastic hose 32 protruding from the plunger 27 is provided with a second quick connector 33, and 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, and a steering 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 steering channel.

[0050] Example 3

[0051] like Figure 6The first embodiment of the present invention is a method for controlling air crosstalk in a casing ring, which is applied to the above-mentioned casing ring air crosstalk control device. The specific steps are as follows:

[0052] A1: Get the distance H1 between the cement return line and the high-cement line;

[0053] A2: Determine the distance H1 from the cement return line. If H1 > 150m, proceed to step A3. If 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 level and the mud line. If H ≤ 100m, proceed to A5. If H > 100m, refer to Example 4.

[0056] A5: Use sealed injection equipment to inject the foaming liquid through the fluid injection pipeline 12, and then inject nitrogen to discharge the liquid through the closed drainage pipeline 7 until no liquid returns from the foaming.

[0057] The foaming drainage fluid is a cleaning fluid 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 fluid 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 annulus above the traction head; preferably 1.2 times;

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

[0060] A7: Use the plugging agent injection pipe 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] The process also includes a 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, the process proceeds to step A8; if unqualified, the process returns to step A6;

[0063] The judgment criteria for gas channeling are: a significant increase in annular pressure and a large amount of gas discharged during pressure relief indicate gas channeling; otherwise, 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, in Well X, air channeling between the first and second casings 14 and 15 caused casing pressure. Well history revealed that the cement return height in the annulus was 450 m below the mudline (H1). Field records showed that the annular pressure of the channeling annulus was 7 MPa, while the adjacent annular pressures were 2.3 MPa (P2) and 0.5 MPa (P3), respectively. The first and second control valves 1 and 2 were closed, and the liquid level detector 3 was connected to the first control valve 1. The pipelines, valves, and other components passed the pressure test. The first control valve 1 was opened to release gas from the channeling annulus. The liquid level detector 3 was unable to accurately measure the annular liquid level. The annular pressure was vented to zero, and the adjacent annular pressures P2 and P3 remained essentially unchanged during the venting process. Since H1 was greater than 150 m, H could not be accurately measured. P2 and P3 remained essentially unchanged during the venting process, indicating that the present invention is suitable for plugging air channeling in the casing annulus of Well X. Close the first control valve 1, open the second control valve 2, connect the closed exhaust pipe 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, and turn the second elastic hose 32 on the plunger 27 to the channel vertically downward. Insert the second elastic hose 32 into the casing annulus. The pumping density of the second elastic hose 32 is 1.10g / 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 150m below the mud line. 0.3% of the foaming agent is added to the cleaning fluid to prepare the foaming fluid, and the hose pump is injected for 10m 3 Bubble drainage, nitrogen is injected into the second elastic hose 32 to drain the bubbles until no liquid returns, defoaming agent is slowly pumped in while the hose is recovered, the second traction head 34 is put into the plunger 27, the plunger 27 withdraws from the first control valve 1, and the first control valve 1 is connected to the annular space 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-phase resin plugging agent with a viscosity of 300mPa·s and a density of 1.00g / cm 3The plugging agent is highly compatible with additives such as foaming agents and defoamers. After solidification, the plugging agent exhibits a pressure-bearing strength greater than 35 MPa and is temperature-resistant from 0°C to 90°C (the annular temperature ranges from 30°C to 53°C during production). The thickening period is 120 minutes (the plugging agent takes 30 minutes to reach its intended location), and the curing time is 300 minutes. 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 and monitor the annular pressure for 24 hours. If the pressure is zero, the plugging is considered qualified. Open the second control valve 2 and the pressure relief valve, and use the injection pump 11 to fill the annular space with anti-corrosion fluid. Dismantle the equipment and pipelines, restore the first and second control valves 1 and 2 to their pre-operation conditions, and have production personnel monitor the annular pressure changes. If the pressure rises, release the pressure promptly.

[0067] The present invention can effectively block air crosstalk in the casing ring without moving the pipe string 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 control method of the present invention is shown. This embodiment is similar to the third embodiment, except that the distance H between the annulus liquid level and the mud line is greater than 100m.

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

[0071] B2: Use the plugging agent injection pipe 8 to inject the plugging agent,

[0072] The process also includes a 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, the process proceeds to step B3; if unqualified, the process returns to step B1.

[0073] The judgment criteria for gas channeling are: a significant increase in annular pressure and a large amount of gas discharged during pressure relief indicate gas channeling; otherwise, no gas channeling occurs.

[0074] The judgment criteria for gas channeling are: a significant increase in annular pressure and a large amount of gas discharged during pressure relief indicate gas channeling; otherwise, 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, in Well X, annular gas leakage between the first and second casings 14 and 15 caused casing pressure. Well history revealed that the cement return height in the annulus was 230 m below the mudline (H1). On-site recordings revealed annular pressure of 6.5 MPa (P1), while the adjacent annular pressures were all 0 (Pi). The first and second control valves 1 and 2 were closed, and the first control valve 1 was connected to a liquid level gauge 3. A 15-minute pressure test at 10 MPa was conducted on the pipelines, valves, and other components. No leakage or pressure drop was detected, indicating a satisfactory pressure test. The first control valve 1 was opened to release gas from the leakage annulus. The liquid level gauge 3 measured the annular liquid level at 158 ​​m below the mudline (H). The annular pressure was continuously released until it stabilized at 0.5 MPa. During the pressure release process, the adjacent annular pressure remained at 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 returns to 6.5MPa. Close the high-pressure nitrogen pipeline 6, connect the plugging agent injection pipeline 8, and inject a 50m long plugging agent segment into the gas channeling annulus through the injection pump 11. 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 3 (annular liquid density 1.2g / cm 3 After solidification, the plugging agent has a pressure bearing strength greater than 35 MPa and a temperature resistance of 0°C-90°C (the annular temperature range during production is 25°C-50°C). The thickening period is 120 minutes (the plugging agent takes 30 minutes to arrive), and the curing time is 300 minutes. 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 pressure relief valve. After a 12-hour solidification period, open the first control valve 1 and the pressure relief valve to relieve the annular pressure. Close the pressure relief valve and monitor the annular pressure for 24 hours. If the pressure is zero, the plugging is considered 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 fluid, dismantle the equipment and pipelines, and restore the first control valve 1 and the second control valve 2 to their pre-operation state. Have production personnel monitor the annular pressure changes and release the pressure promptly if the pressure rises.

[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 when the distance from the cement return line to the mud line H1 is less than 150m. The specific steps are as follows:

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

[0081] C2: Inject the cleaning fluid through the fluid injection line 12 by using a simple injection device, and then inject the plugging agent. During the plugging agent injection process, part of the cleaning fluid is discharged through the closed discharge line 7 and enters step C3;

[0082] The performance requirements of the cleaning fluid are: ① improving the cementing performance of the plugging agent with the casing wall; ② effectively inhibiting the corrosion of the casing. The volume of the injected cleaning fluid is at least 1.2 times the volume of the annulus at the upper part of the tractor head; and preferably 1.5 times;

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

[0084] C3: Inject nitrogen into the gas channeling annulus through the high-pressure nitrogen line 6 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 phenomenon is detected through the annulus pressure to determine whether the plugging is qualified. If qualified, it enters C4, if not qualified, it returns to step C2;

[0086] Among them, the basis for judging the gas channeling phenomenon is: the annulus pressure rises obviously, and a large amount of gas is discharged during pressure relief, which indicates that gas channeling occurs, otherwise it is considered that no gas channeling phenomenon occurs;

[0087] C4: The process is completed.

[0088] The casing annulus gas channeling treatment device applied in this embodiment is connected with the high-pressure nitrogen line 6, the closed discharge line 7, and the high-pressure line 4 through the three-way valve 18 and one end of the second control valve 2, and the other end of the second control valve 2 is connected with the casing assembly. The fluid injection line 12, the casing assembly, and the liquid level detector 3 are all connected with the first control valve 1.

[0089] For example, in Well X, annular gas leakage between the first and second casings (14, 15) caused casing pressure. Well history revealed that the cement return height in the annulus was 105 meters below the mudline (H1). Field records showed that the annular pressure due to gas leakage was 4.5 MPa (P1), while the adjacent annular pressures were all 0 (Pi). The annular pressure P1 was vented to 0, and the adjacent annular pressures remained at 0 during the venting process. H1 was less than 150 meters. During the venting of gas leakage annulus P1, there was no change in the adjacent annular pressures (Pi). P1 could be vented to 0, and a simple injection device was selected as the fluid injection device. A 15-minute pressure test at 10 MPa was conducted on the pipelines, valves, and other components. No leaks or pressure drops were observed, indicating the test was qualified. Open the first control valve 1 and the second control valve 2, connect the closed exhaust pipe 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 injected with 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 After cleaning the liquid, stop the pump. Use the first elastic hose 21 to pump a 30m plugging agent segment into the gas channeling annulus. After the plugging agent is injected, retract the first elastic hose 21, remove the simple injection equipment, connect the first control valve 1 to the annular space pressure monitoring instrument and pressure relief valve, close the pressure relief valve and the exhaust pipe 7, connect the high-pressure nitrogen pipe 6, inject nitrogen to restore the annular space pressure to 4.5MPa, close the second control valve 2, and wait for solidification under pressure. The injected plugging agent is a solid-free resin plugging agent with a viscosity of 380mPa·s and a density of 1.20g / cm 3 After solidification, the plugging agent has a pressure bearing strength greater than 35 MPa and a temperature resistance of 0-90°C (the annular temperature range during production is 30-52°C). The stone thickening interval is 120 minutes (the plugging agent injection time is 30 minutes), and the curing time is 300 minutes. After solidification for 12 hours, the annular pressure is released by opening the pressure relief valve. After closing the pressure relief valve and observing for 24 hours, the annular pressure rises slightly. Opening the pressure relief valve releases mostly liquid, indicating no gas channeling and the plugging is considered qualified. Dismantle the equipment and pipelines, restore the first control valve 1 and the second control valve 2 to their pre-operation conditions, and have production personnel monitor the annular pressure changes. If pressure rises, release the pressure promptly.

[0090] Example 6

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

[0092] D1: using the sealing injection equipment to inject the cleaning fluid through the fluid injection pipeline 12, and then injecting the plugging agent, during the plugging agent injection process, part of the cleaning fluid 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 annulus in the upper part of the tractor 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: judging the pressure in the gas channeling annulus, if greater than P1, then pressure relief to P1, entering D4, if less than P1, then entering step D3;

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

[0097] D4: detection step: after the plugging agent completely solidifies, detecting whether there is a gas channeling phenomenon by annulus pressure to determine whether the plugging is qualified, if qualified, then entering D5, if not qualified, then returning to step D1;

[0098] Wherein, the basis for judging the gas channeling phenomenon is: the annulus pressure rises obviously, and a large amount of gas is discharged during pressure relief, indicating that gas channeling occurs, otherwise it is considered that no gas channeling phenomenon occurs;

[0099] D5: the process is ended.

[0100] The casing annulus gas channeling treatment device applied in the embodiment is connected with the high-pressure nitrogen gas pipeline 6, the closed discharge pipeline 7, and the second control valve 2 through the three-way valve 18, and is connected with the casing assembly through the high-pressure pipeline 4 and the second control valve 2, the casing assembly, the fluid injection pipeline 12, and the liquid level detector 3 are all connected with the first control valve 1.

[0101] For example, in Well X1, annular gas leakage between the first and second casings (14, 15) caused casing pressure. Well history revealed that the cement return height in the annulus was 118 meters below the mudline (H1). Field records showed that the annular pressure due to gas leakage was 7.5 MPa (P1), while the adjacent annular pressures were all 0 (Pi). The annular pressure P1 was released to 0, and the adjacent annular pressures remained at 0 during the release process. H1 < 150 m. During the release of the gas leakage annulus P1, the adjacent annular pressures Pi remained unchanged. P1 was released to a stable 0.8 MPa, and a sealed injection device was selected as the fluid injection device 13. A pressure test of 10 MPa for 15 minutes was conducted on the pipelines, valves, and other components. No leaks or pressure drops were observed, indicating a satisfactory pressure test. 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, and turn the second elastic hose 32 on the plunger 27 to the channel vertically downward. Insert the second elastic hose 32 into the casing annulus. 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 1.5m 3 The plugging agent is blocked. 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 pipe 7. The plugging agent injected is a solid phase resin plugging agent with a viscosity of 380mPa·s and a density of 1.20g / cm 3 After solidification, the plugging agent has a pressure bearing strength greater than 35 MPa and a temperature resistance of 0°C-90°C (the annular temperature range during production is 28°C-55°C). The plugging period is 120 minutes (the plugging agent injection time is 30 minutes), and the curing time is 300 minutes. After the plugging agent is injected, the second elastic hose 32 and the second traction head 34 are retracted into the plunger 27. The plunger 27 is withdrawn from the first and control valves. The first control valve 1 is closed and the plugging agent is allowed to solidify under pressure. During this time, the sealing injection equipment is removed and the first control valve 1 is connected to the annular pressure monitoring instrument and pressure relief valve. After a 12-hour solidification period, the first control valve 1 is opened and the annular pressure is relieved through the pressure relief valve. The pressure relief valve is closed and observed for 24 hours. The annular pressure is zero, indicating no gas channeling and the plugging is considered qualified. The equipment and pipelines are dismantled, and the first and second control valves 1 and 2 are restored to their pre-operation conditions. The dynamic changes in the annular pressure are monitored and any pressure increases are promptly relieved.

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

[0103] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for treating air leakage in casing ring, characterized in that: The invention is applied to a casing ring air channeling control device, which comprises a casing assembly, a high-pressure nitrogen pipeline (6), a closed exhaust 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. The high-pressure nitrogen pipeline (6) is provided with a high-pressure nitrogen source (9), the closed exhaust pipeline (7) is provided with a closed exhaust tank (10), the plugging agent injection pipeline (8) is provided with an injection pump (11), and the fluid injection pipeline (12) is provided with a fluid injection device (13). A control valve for controlling the on-off of the pipeline is correspondingly provided in each pipeline; the fluid injection device (13) is divided into a simple injection device and a sealed injection device; the specific steps of the casing ring air channeling control method are as follows: S1: Get the distance H1 between the cement return line and the high mud line; S2: Determine the distance H1 from the cement return 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 ≤ 100 m, proceed to S5; if H > 100 m, proceed to S6. S5: Use a sealed injection device to inject the bubble drainage liquid through the fluid injection pipeline (12), and then inject nitrogen to discharge the liquid through the closed drainage pipeline (7) until no liquid returns from the bubble drainage; S6: Use the high-pressure nitrogen pipeline (6) to inject nitrogen into the gas channeling annulus to restore the pressure to P1; 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 using the plugging agent injection pipeline (8), and then jump 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: Use a simple injection device to inject the cleaning fluid through the fluid injection pipeline (12), and then inject the blocking agent. During the blocking agent injection process, part of the cleaning fluid is discharged through the closed discharge pipeline (7), and then enter step S6; S10: Use a sealed injection device to inject cleaning fluid through the fluid injection pipeline (12), and then inject the plugging agent. During the plugging agent injection process, part of the cleaning fluid is discharged through the closed discharge pipeline (7). 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 process proceeds to step S6. S11: The process ends.

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

3. The method for treating air crosstalk in casing ring according to claim 1 or 2, characterized in that: The simple injection device comprises a flange (19) and a body (20) 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), and further comprises a first rotating shaft (24) and a first rotating drum (25), a steering 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 steering channel.

4. The method for treating air crosstalk in casing ring according to claim 1 or 2, 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 the end of the push rod (28) is alternately installed with a pressure ring (30) and a sealing ring (31), and further 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 includes a second rotating shaft (35) and a second rotating drum (36). A turning channel is formed between the second rotating shaft (35) and the second rotating drum (36). The second traction head (34) and the second quick connector (33) are arranged along the turning channel.

5. The method for treating air crosstalk in casing ring according to claim 1, characterized in that: Before step S11, a detection step is also included: 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, the process ends; if unqualified, the plugging agent is continuously injected until the plugging is qualified.

6. The method for treating air crosstalk in casing ring according to claim 5, characterized in that: The basis for judging the gas channeling phenomenon is: an obvious increase in annular space pressure and a large amount of gas discharged during pressure relief indicate that gas channeling has occurred; otherwise, it is considered that no gas channeling has occurred.

7. The method for treating air crosstalk in casing ring according to claim 1, characterized in that: The blocking agent is not miscible with the drainage fluid or the cleaning fluid; and when the distance H1 of the cement return high mud line is ≤150m, the density of the blocking agent used is greater than that of the cleaning fluid; when the distance H1 of the cement return high mud line is greater than 150m, the density of the blocking agent used is less than that of the drainage fluid.

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