Gas well gas-liquid underground separation upper-injection and lower-production method, system and operation system

Abstract

The invention provides a gas well gas-liquid underground separation injection upper and production lower method, system and operation system, the injection upper and production lower operation system comprises a ground production and injection pipeline, a shaft and an injection and production pipe column, and the injection and production pipe column comprises a bypass one-way valve, an annular one-way packer and a packer which are sequentially connected from top to bottom; the upper injection and lower production method comprises the steps that S10, casing pressure is emptied, so that the casing pressure of an oil casing annulus is reduced, and liquid, from a gas production layer, in an injection and production pipe column is promoted to enter the oil casing annulus through a bypass one-way valve; s20, underground water injection is conducted; in the step S10, the pipe column pipeline is disconnected from the gas production pipeline, and the oil sleeve pipeline is communicated with the gas production pipeline; in the step S20, the pipe column pipeline and the oil sleeve pipeline are communicated and are both disconnected with the gas production pipeline, or the oil sleeve pipeline is connected with an external pressure supply device, or pressure building is carried out, and the technical problem that gas well drainage gas production is difficult is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas field drainage and gas production, and in particular to a gas well gas-liquid downhole separation upper injection and lower production method, system and operation system. Background Art

[0002] During the exploration and development of gas fields, many liquid-accumulating wells have appeared. Especially in the middle and late stages of gas well production, the gas wells themselves lack energy and are unable to carry out liquid, resulting in the gas wells being drowned and unable to achieve production capacity. In addition, the production layers of some gas wells are gas and water in the same layer. When the water cannot be discharged, the gas will also be unable to be produced. In particular, the exploitation of gas layers in water-rich areas is currently a problem.

[0003] In addition, all water and liquid produced by gas wells need to be transported to specially established treatment plants or purification plants for secondary treatment before they can be reinjected into special water injection wells. The cost is high. Some gas wells are large water wells, and it is common to produce tens of thousands of cubic meters of natural gas and hundreds of cubic meters of liquid every day. Sometimes it will cause the gas gathering station to fail to transport it in time and shut down the well. After the well is shut down, the gas well will drown due to its own liquid accumulation.

[0004] At present, drainage technologies such as gas lift, bubble drainage, plunger, velocity string, and negative pressure gas production are difficult to solve the problem of tapping the potential and resuming production of submerged gas wells. In addition, the above technologies will bring out produced fluid while producing gas, and the produced fluid needs to be processed, which has insurmountable defects.

[0005] In summary, in the prior art, gas wells have the technical problem that it is difficult to drain water and produce gas. Summary of the invention

[0006] The purpose of the present invention is to provide a method, system and operating system for gas well gas-liquid downhole separation injection and production, so as to solve the technical problem that it is difficult to drain water and produce gas in gas wells.

[0007] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0008] The present invention provides a gas well gas-liquid downhole separation injection and production method, which adopts an injection and production operation system;

[0009] The injection-up and production-down operation system comprises a surface production-injection pipeline, a wellbore and an injection-production pipe string arranged in the wellbore, and an oil casing annulus is formed between the injection-production pipe string and the wellbore;

[0010] The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus;

[0011] The gas well formation has a gas production layer and a water injection layer, the gas production layer is located below the water injection layer, the packer is arranged between the gas production layer and the water injection layer, and the lower end opening of the injection and production pipe string extends to the gas production layer;

[0012] The surface production and injection pipeline comprises:

[0013] A pipe string pipeline connected to the inner cavity of the injection and production pipe string;

[0014] An oil casing pipeline connected to the oil casing annulus;

[0015] Gas pipeline;

[0016] The injection-up and extraction-down method comprises:

[0017] Step S10, venting the casing pressure to reduce the casing pressure of the oil-casing annulus, and causing the liquid from the gas production layer in the injection-production string to enter the oil-casing annulus through the bypass one-way valve;

[0018] Step S20, injecting water downhole;

[0019] In the step S10, the column pipeline is disconnected from the gas production pipeline, and the oil casing pipeline is connected to the gas production pipeline;

[0020] In the step S20, the tubing string pipeline is connected to the oil casing pipeline and both are disconnected from the gas production pipeline; or, the oil casing pipeline is disconnected from the tubing string pipeline and the gas production pipeline and the oil casing pipeline is connected to an external pressure supply device; or, the inside of the injection and production tubing string is pressurized to force liquid and gas to enter the oil casing annulus through the bypass one-way valve.

[0021] In a preferred embodiment, the surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve, the tubing line is connected to the first pipeline node through the first control valve, the oil casing line is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

[0022] In a preferred embodiment, the second control valve and the fourth control valve are opened, and the first control valve is closed to implement step S10; the first control valve and the second control valve are opened, and the fourth control valve is closed to implement step S20; or the first control valve and the second control valve are closed to build up pressure inside the injection and production string, forcing liquid and gas to enter the casing annulus through the bypass one-way valve to implement step S20.

[0023] In a preferred embodiment, the tubing string pipeline is provided with an oil pressure gauge, and the oil casing pipeline is provided with a casing pressure gauge.

[0024] In a preferred embodiment, step S20 is performed after the oil pressure of the oil pressure gauge is higher than the casing pressure of the casing pressure gauge.

[0025] In a preferred embodiment, the injection-up and extraction-down method comprises:

[0026] Step S30, holding the pressure to increase the oil pressure in the injection and production string;

[0027] Close the first control valve to implement step S30;

[0028] The step S30 is performed before the step S20.

[0029] In a preferred embodiment, the surface production and injection pipeline includes a third control valve, a fifth control valve and a high-pressure gas source, and the high-pressure gas source serves as the external pressure supply device; the oil casing pipeline is connected to the second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve;

[0030] The second pipeline node is connected to the high-pressure gas source through the third control valve.

[0031] In a preferred embodiment, the second control valve, the fifth control valve and the fourth control valve are opened, and the first control valve and the third control valve are closed to implement the step S10; the fifth control valve is closed, and the second control valve and the third control valve are opened to connect the oil casing pipeline with the high-pressure gas source to implement the step S20.

[0032] In a preferred embodiment, when the step S20 is implemented, the first control valve and the fourth control valve are kept open to collect gas.

[0033] In a preferred embodiment, the surface production and injection pipeline includes a third control valve, a fifth control valve, a sixth control valve and a compressor, and the compressor serves as the external pressure supply device; the oil casing pipeline is connected to the second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; the second pipeline node is connected to the outlet of the compressor through the third control valve; and the inlet of the compressor is connected to the first pipeline node through the sixth control valve.

[0034] In a preferred embodiment, the first control valve, the third control valve and the sixth control valve are closed, and the second control valve, the fourth control valve and the fifth control valve are opened to implement step S10; the second control valve, the third control valve, the sixth control valve and the first control valve are opened, the fifth control valve is closed, and the compressor is started to implement step S20.

[0035] In a preferred embodiment, when the step S20 is implemented, the fourth control valve is opened or closed.

[0036] In a preferred embodiment, the injection and production operation system includes a liquid level monitoring device and a controller. The liquid level monitoring device is installed on the top of the injection and production string. The controller is used to control the switching of each control valve according to the monitoring signal of the liquid level monitoring device, the signal of the oil pressure gauge and the signal of the casing pressure gauge.

[0037] In a preferred embodiment, the injection-up and extraction-down method further comprises:

[0038] Step S40, normal gas collection;

[0039] When implementing the step S40, the first control valve and the fourth control valve are opened, and the second control valve is closed;

[0040] The step S10, the step S20, and the step S40 are performed sequentially.

[0041] Alternatively, the step S10, the step S40, and the step S20 are implemented in sequence.

[0042] In a preferred embodiment, the step S10, the step S20, the step S40, the step S10, and the step S20 are implemented in sequence.

[0043] The present invention provides a gas well gas-liquid downhole separation injection and production operation system, which is applied to the above-mentioned gas well gas-liquid downhole separation injection and production method;

[0044] The injection-up and production-down operation system comprises a surface production-injection pipeline, a wellbore and an injection-production pipe string arranged in the wellbore, and an oil casing annulus is formed between the injection-production pipe string and the wellbore;

[0045] The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus;

[0046] The gas well formation has a gas production layer and a water injection layer, the gas production layer is located below the water injection layer, the packer is arranged between the gas production layer and the water injection layer, and the lower end opening of the injection and production pipe string extends to the gas production layer;

[0047] The surface production and injection pipeline comprises:

[0048] A pipe string pipeline connected to the inner cavity of the injection and production pipe string;

[0049] An oil casing pipeline connected to the oil casing annulus;

[0050] Gas pipeline;

[0051] The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve.

[0052] The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

[0053] The present invention provides a gas well gas-liquid downhole separation injection and production system, which is applied to the above-mentioned gas well gas-liquid downhole separation injection and production method;

[0054] The injection-up and production-down system comprises a surface production-injection pipeline and an injection-production string, wherein the injection-production string is used to be arranged in a wellbore and to form an oil casing annulus between the wellbore;

[0055] The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus;

[0056] The packer is used to be arranged between the gas production layer and the water injection layer of the gas well formation, and the lower end opening of the injection and production pipe string can extend to the gas production layer;

[0057] The surface production and injection pipeline comprises:

[0058] A pipe string pipeline connected to the inner cavity of the injection and production pipe string;

[0059] An oil casing pipeline connected to the oil casing annulus;

[0060] Gas pipeline;

[0061] The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve.

[0062] The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

[0063] In a preferred embodiment, the injection and production string includes an oil pipe, a drill pipe, or a small casing.

[0064] In a preferred embodiment, the bypass one-way valve adopts a structure in which the valve core and the valve body are separated, the valve body is directly connected to the oil pipe coupling of the injection and production string, and the valve core can be repeatedly cast in and out.

[0065] In a preferred embodiment, the packer has a slip anchoring function, and the packer can be connected to the oil pipe of the injection and production string by inserting the pipe back.

[0066] In a preferred embodiment, the system is powered by large-scale electricity from the well site, a generator, or wind power and solar power from the well site.

[0067] In a preferred embodiment, the surface production and injection pipeline includes a third control valve, a fifth control valve and a high-pressure gas source, and the high-pressure gas source serves as the external pressure supply device; the oil casing pipeline is connected to the second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; the second pipeline node is connected to the high-pressure gas source through the third control valve.

[0068] In a preferred embodiment, the surface production and injection pipeline includes a third control valve, a fifth control valve, a sixth control valve and a compressor, and the compressor serves as the external pressure supply device; the oil casing pipeline is connected to the second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; the second pipeline node is connected to the outlet of the compressor through the third control valve; and the inlet of the compressor is connected to the first pipeline node through the sixth control valve.

[0069] In a preferred embodiment, the tubing string pipeline is connected to an oil pressure gauge, and the oil casing pipeline is connected to a casing pressure gauge.

[0070] In a preferred embodiment, the injection and production system includes a liquid level monitoring device and a controller. The liquid level monitoring device is installed on the top of the injection and production string. The controller is used to control the switching of each control valve according to the monitoring signal of the liquid level monitoring device, the signal of the oil pressure gauge and the signal of the casing pressure gauge.

[0071] The characteristics and advantages of the present invention are:

[0072] The gas-liquid downhole separation injection and production method for gas wells provided by the present invention comprises the following steps: step S10, casing pressure is vented through the gas production pipeline to reduce the casing pressure in the casing annulus; then the pipe column pipeline is connected to the gas production pipeline to carry out normal gas production, and the casing pressure difference is used to promote the liquid from the gas production layer in the injection and production column to enter the casing annulus through the bypass one-way valve, thereby lowering the liquid level in the injection and production column and raising the liquid level in the casing annulus; then, by implementing step S20, the gas in the injection and production column is used to push the casing annulus liquid level down, and the liquid level is re-injected into the water injection layer through the annulus one-way packer to lower the liquid level in the injection and production column. The injection and production method adopts the rodless water injection and oil pipe gas production method to carry out gas well drainage and gas production, and is particularly suitable for liquid accumulation wells and large water and gas wells, and can effectively avoid the ground treatment of produced liquid, realize the direct downhole separation and re-injection of produced liquid without reaching the ground, lower the wellbore liquid level, and achieve the purpose of oil casing annulus water injection and oil pipe gas production. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0074] Figure 1 A schematic diagram of an embodiment of a gas-liquid downhole separation and injection and production operation system for a gas well provided by the present invention;

[0075] Figure 2 A schematic diagram of another embodiment of the gas-liquid downhole separation and injection and production system for a gas well provided by the present invention;

[0076] Figure 3 A schematic diagram of another embodiment of the gas-liquid downhole separation and injection and production system for a gas well provided by the present invention;

[0077] Figure 4 A schematic diagram of an embodiment of a method for downhole gas-liquid separation and injection and production in a gas well provided by the present invention;

[0078] Figure 5 This is a schematic diagram of another embodiment of the gas-liquid downhole separation and injection and production method for a gas well provided by the present invention.

[0079] Description of Figure Numbers:

[0080] 1. Oil pipe;

[0081] 2. Bypass check valve; 3. Annular check packer; 4. Packer; 5. Bell mouth;

[0082] 6. Liquid level monitoring device;

[0083] 7. First control valve; 8. Oil pressure gauge;

[0084] 9. Controller; 10. Casing pressure gauge;

[0085] 11. Second control valve; 12. Third control valve; 13. Fourth control valve;

[0086] 14. High pressure gas source;

[0087] 15. Fifth control valve; 16. Compressor; 17. Sixth control valve;

[0088] 21. First pipeline node; 22. Second pipeline node;

[0089] 23. Pipeline; 24. Oil casing pipeline; 25. Gas production pipeline;

[0090] 31. Valve No. 1; 32. Valve No. 2; 33. Valve No. 3; 34. Valve No. 4; 35. Valve No. 5; 36. Valve No. 6; 37. Valve No. 7; 38. Valve No. 8; 39. Valve No. 9.

[0091] 40. Wellbore; 41. Surface casing; 42. Gas casing; 43. Oil casing annulus; 44. Injection and production string;

[0092] 50. Water and liquid; 51. Gas production layer; 52. Water injection layer. DETAILED DESCRIPTION

[0093] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0094] Solution 1

[0095] The present invention provides a gas-liquid downhole separation and injection-down production method for a gas well, which adopts an injection-down production operation system;

[0096] like Figure 1-Figure 3 As shown, the injection-up and production-down operation system includes a surface production-injection pipeline, a wellbore 40, and an injection-production string 44 disposed in the wellbore 40, and an oil casing annulus 43 is formed between the injection-production string 44 and the wellbore 40;

[0097] The injection and production string 44 includes a bypass check valve 2, an annular check packer 3, and a packer 4 connected in sequence from top to bottom. The bypass check valve 2 has a one-way conduction structure from the inner cavity of the injection and production string 44 to the oil casing annulus 43. The annular check packer 3 adopts a downwardly openable and upwardly closed structure. The packer 4 is used to isolate the oil casing annulus 43.

[0098] The gas well formation has a gas production layer 51 and a water injection layer 52, the gas production layer 51 is located below the water injection layer 52, the packer 4 is arranged between the gas production layer 51 and the water injection layer 52, and the lower end opening of the injection and production pipe string 44 extends to the gas production layer 51;

[0099] The surface production and injection pipeline includes:

[0100] A pipe string line 23 connected to the inner cavity of the injection and production pipe string 44;

[0101] The oil casing pipeline 24 connected to the oil casing annulus 43;

[0102] Gas production pipeline 25;

[0103] The injection and sampling method includes:

[0104] Step S10, the casing pressure is vented to reduce the casing pressure of the casing annulus 43, so as to promote the liquid from the gas production layer 51 in the injection and production string 44 to enter the casing annulus 43 through the bypass check valve 2;

[0105] Step S20, injecting water downhole;

[0106] In step S10, the column pipeline 23 is disconnected from the gas production pipeline 25, and the oil casing pipeline 24 is connected to the gas production pipeline 25;

[0107] In step S20, the tubing string pipeline 23 is connected to the oil casing pipeline 24 and both are disconnected from the gas production pipeline 25; or, the oil casing pipeline 24 is disconnected from the tubing string pipeline and the gas production pipeline and the oil casing pipeline is connected to an external pressure supply device; or, the inside of the injection and production tubing string is pressurized to force the liquid and gas to enter the inside of the oil casing annulus through the bypass one-way valve 2.

[0108] The present invention provides a method for gas-liquid downhole separation and injection and production in a gas well. In step S10, the casing pressure is vented through the gas production pipeline 25 to reduce the casing pressure in the casing annulus 43; then the tubing string pipeline 23 is connected to the gas production pipeline 25 to perform normal gas production, and the casing pressure difference is used to promote the liquid from the gas production layer 51 in the injection and production string 44 to enter the casing annulus 43 through the bypass one-way valve 2, thereby lowering the liquid level in the injection and production string 44 and raising the liquid level in the casing annulus 43; thereafter, by implementing step S20, the gas in the injection and production string 44 is used to push the liquid level in the casing annulus 43 to drop, and the gas is reinjected into the water injection layer 52 through the annulus one-way packer 3 to lower the liquid level in the injection and production string 44. The injection-up and production-down method uses rodless water injection and oil pipe 1 gas production to drain gas wells and produce gas, which is particularly suitable for liquid-accumulated wells and large-water-gas wells. It can effectively avoid the ground treatment of produced fluid, realize direct underground separation and reinjection of produced fluid before it reaches the ground, lower the wellbore liquid level, and achieve the purpose of oil casing annulus 43 water injection and oil pipe 1 gas production.

[0109] The wellbore 40 is formed by casing or an uncemented open hole wall. Specifically, the casing includes a surface casing 41 and a gas casing 42 to form a wellbore; the injection and production string 44 includes an oil pipe 1 or a drill pipe or a small casing; and the surface injection and production pipeline serves as a surface supporting system. Further, the lower end opening of the injection and production string 44 is connected to a bell mouth 5, such as Figure 1 As shown, the injection and production string 44 in the wellbore includes an oil pipe 1, the lower end of the oil pipe 1 is connected to a bell mouth 5, and the oil pipe 1 above the bell mouth 5 is connected in sequence to a packer 4, an annular one-way packer 3 and a bypass one-way valve 2; the bypass one-way valve 2 is similar to a gas lift valve, and has a one-way conduction structure from the oil pipe 1 to the oil casing annulus 43; the annular one-way packer 3 adopts a downwardly openable and upwardly closed structure, so that the liquid can only flow downward in one direction; after the packer 4 is set, the oil casing annulus 43 can be isolated. Preferably, the packer 4 also has a slip anchoring function to prevent the pipe string from moving up and down, and the packer 4 can be connected to the upper oil pipe 1 by inserting and re-inserting, so as to avoid the direct pulling out of the packer 4 when the pipe string is lifted for subsequent well repair, resulting in the overflow of the early injection water;

[0110] The bypass check valve 2 can adopt a structure in which the valve core and the valve body are separated. The valve body is similar to a working cylinder and is directly connected to the oil pipe 1 coupling. The valve core can be repeatedly thrown and salvaged, which is convenient for the maintenance of the bypass check valve 2. The valve core can be thrown and salvaged by wire operation according to actual conditions, and the construction cost is low.

[0111] In one embodiment, the surface production and injection pipeline includes a first control valve 7, a second control valve 11 and a fourth control valve 13. The column pipeline 23 is connected to the first pipeline node 21 through the first control valve 7, the oil casing pipeline 24 is connected to the first pipeline node 21 through the second control valve 11, and the gas production pipeline 25 is connected to the first pipeline node 21 through the fourth control valve 13. The first control valve 7, the second control valve 11 and the fourth control valve 13 are used to control the connection and disconnection between the pipelines, so as to implement the operations such as casing pressure venting, normal gas production and downhole water injection in steps.

[0112] Figure 1 In the injection-production operation system shown, the second control valve 11 and the fourth control valve 13 are opened, and the first control valve 7 is closed to implement step S10; the first control valve 7 and the second control valve 11 are opened, and the fourth control valve 13 is closed to implement step S20; or, the first control valve and the second control valve are closed, and the liquid and gas are forced to enter the casing annulus through the bypass one-way valve by holding the pressure inside the injection-production string to implement step S20, so that the gas or liquid in the injection-production string 44 with higher pressure pushes the liquid level in the casing annulus 43 to drop and is reinjected into the water injection layer 52 until the liquid level in the oil pipe 1 drops to the required position, which is conducive to ensuring the reliable control and stable progress of oil pressure venting and downhole water injection.

[0113] Furthermore, the tubing string pipeline 23 is provided with an oil pressure gauge 8, and the oil casing pipeline 24 is provided with a casing pressure gauge 10. The oil pressure of the oil pipe 1 is detected by the oil pressure gauge 8, and the casing pressure of the oil casing annulus 43 is detected by the casing pressure gauge 10.

[0114] Figure 1 In the injection-up and production-down operation system shown, after the oil pressure on the oil pressure gauge 8 is higher than the casing pressure on the casing pressure gauge 10 , step S20 is implemented to utilize the gas in the oil pipe 1 with a higher pressure to push the liquid in the oil casing annulus 43 back into the water injection layer 52 .

[0115] In one embodiment, the injection-up and production-down method includes: step S30, holding pressure to increase the oil pressure in the injection-production string 44; closing the first control valve 7 to implement step S30; step S30 is implemented before step S20. By holding pressure, the oil pressure meets the requirement of injecting water from the casing annulus 43 into the water injection layer 52. Specifically, in step S30, the first control valve 7 is closed, and the pressure is held for a period of time, and the gas from the gas production layer 51 enters the oil pipe 1 to increase the oil pressure until the requirement is met.

[0116] In one embodiment, the surface production and injection pipeline includes a third control valve 12, a fifth control valve 15 and a high-pressure gas source 14, and the high-pressure gas source 14 is used as an external pressure supply device; the oil-casing pipeline 24 is connected to the second pipeline node 22 through the second control valve 11, and the second pipeline node 22 is connected to the first pipeline node 21 through the fifth control valve 15; the second pipeline node 22 is connected to the high-pressure gas source 14 through the third control valve 12. The first control valve 7, the second control valve 11, the third control valve 12, the fourth control valve 13 and the fifth control valve 15 are used to control the connection and disconnection between the pipelines, so as to implement the oil pressure venting, normal gas production, downhole water injection and other operations in steps; and the oil-casing annulus gas injection comes from the high-pressure gas source 14, and the high-pressure gas source 14 can use a booster to pressurize the gas from other gas wells, gas transmission pipelines, or gas storage tanks, and can also directly introduce high-pressure gas, such as a high-pressure gas well, so that it meets the requirements of oil-casing annulus water injection without relying on the gas in the injection and production string 44. Specifically, the high-pressure gas source 14 may include a compressor 16 or a pump, which pressurizes the gas from other gas wells, gas pipelines, or gas storage tanks to meet the water injection requirements of the oil casing annulus 43.

[0117] Figure 2In the injection-up and production-down operation system shown, the fifth control valve 15, the second control valve 11 and the fourth control valve 13 are opened, and the first control valve 7 and the third control valve 12 are closed to implement step S10; the fifth control valve 15 is closed, and the second control valve 11 and the third control valve 12 are opened to connect the oil casing pipeline 24 with the high-pressure gas source 14 to implement step S20, so that the high-pressure gas from the high-pressure gas source 14 pushes the oil casing annulus 43 liquid through the annulus one-way packer 3 to be injected back into the water injection layer 52, which is beneficial to ensure the reliable control and stable progress of oil pressure venting and downhole water injection.

[0118] Preferably, when implementing step S20, the first control valve 7 and the fourth control valve 13 are kept open to extract gas, thereby achieving gas extraction while injecting water.

[0119] In one embodiment, the surface production and injection pipeline includes a third control valve 12, a fifth control valve 15, a sixth control valve 17 and a compressor 16, wherein the compressor 16 serves as an external pressure supply device; the oil casing pipeline 24 is connected to the second pipeline node 22 through the second control valve 11, and the second pipeline node 22 is connected to the first pipeline node 21 through the fifth control valve 15; the second pipeline node 22 is connected to the outlet of the compressor 16 through the third control valve 12; and the inlet of the compressor 16 is connected to the first pipeline node 21 through the sixth control valve 17.

[0120] The first control valve 7, the second control valve 11, the third control valve 12, the fourth control valve 13, the fifth control valve 15 and the sixth control valve 17 are used to control the connection and disconnection between the pipelines, so as to implement the oil pressure venting, downhole water injection and gas production operations in steps; the oil casing annulus gas injection comes from the injection and production string 44 of the well, and is pressurized by the compressor 16. When the oil pressure of the injection and production string 44 of the well is insufficient, the gas that needs to be pressurized in the injection and production string 44 of the well is pressurized, so that the gas in the injection and production string 44 of the well is fully utilized, which is beneficial to saving resources.

[0121] Figure 3 In the injection-production operation system shown, the first control valve 7, the third control valve 12 and the sixth control valve 17 are closed, and the second control valve 11, the fourth control valve 13 and the fifth control valve 15 are opened to implement step S10; the second control valve 11, the third control valve 12, the sixth control valve 17 and the first control valve 7 are opened, the fifth control valve 15 is closed, and the compressor 16 is started to implement step S20 to pressurize the gas coming from the injection and production tubing 44 of the well, and push the water and liquid 50 in the casing annulus 43 through the annulus one-way packer 3 to be injected back into the water injection layer 52.

[0122] Preferably, when implementing step S20 , the fourth control valve 13 is opened or closed, and while producing gas, a portion of the gas from the well injection and production string 44 is pressurized to push the fluid in the casing annulus 43 back into the water injection layer 52 .

[0123] In one embodiment, the injection and production operation system includes a liquid level monitoring device 6 and a controller 9. The liquid level monitoring device 6 is installed at the top of the injection and production string 44. The controller 9 is used to control the switch of each control valve according to the monitoring signal of the liquid level monitoring device 6, the signal of the oil pressure gauge 8 and the signal of the casing pressure gauge 10. The liquid level monitoring device 6 is used to monitor the liquid level height in the injection and production string 44 downhole, so as to control the start or stop of downhole water injection according to the liquid level height in the injection and production string 44. The first control valve 7, the second control valve 11, the third control valve 12, the fourth control valve 13, the fifth control valve 15 and the sixth control valve 17 can all be automatic control valves. The liquid level monitoring device 6 can be an automatic liquid level monitoring device and is electrically connected to the controller 9 respectively. The controller 9 controls the switch of each control valve according to the above-mentioned injection and production method, so as to realize the automatic implementation of the oil casing venting, downhole water injection and other gas production steps.

[0124] In one embodiment, the injection and production method further includes: step S40, normal gas production; when implementing step S40, the first control valve 7 and the fourth control valve 13 are opened, and the second control valve 11 is closed. Step S40 adopts the method of oil pipe gas production, and normal gas production is carried out by connecting the pipe column pipeline 23 with the gas production pipeline 25. After a period of gas production, if the liquid level in the downhole oil pipe 1 is high, step S20 is performed to reduce the liquid level in the oil pipe 1. After the liquid level in the oil pipe 1 drops to the required position, step S10 can be implemented again, and then step S40 is implemented for normal gas production. After implementing step S20, the pressure of the oil casing annulus 43 is high. If step S40 is directly implemented for normal gas production, the liquid in the production process cannot enter the oil casing annulus 43 from the bypass check valve 2. The steps S20-step S10-step S40 are implemented in sequence, which is conducive to increasing the time of normal gas production as much as possible.

[0125] In one embodiment, step S10, step S40, and step S20 are performed sequentially, that is, Figure 4 As shown, after the casing pressure is vented, normal gas production is carried out, and then downhole water injection is implemented, which is conducive to achieving a longer normal gas production process and ensuring the water injection effect. Step S10, step S40, and step S20 are implemented in sequence, and step S10 and step S40 are continuously implemented in a reciprocating cycle.

[0126] In another embodiment, step S10, step S20, and step S40 are performed sequentially, that is, Figure 5 As shown, after the casing pressure is vented, water is injected into the well, and then normal gas production is carried out; thereafter, the casing pressure can be further vented, and then water is injected into the well.

[0127] The specific operations of each control valve when implementing step S10, step S40, and step S20 have been described above and will not be repeated here.

[0128] Further, Figure 1-Figure 3 In the above-injection and below-production operation system shown, step S10 and step S20 can be repeatedly implemented, that is, casing pressure venting and downhole water injection can be repeated until the liquid level in the oil pipe 1 drops to the required position to ensure subsequent normal gas production.

[0129] The method of injecting water and producing gas from above adopts the method of automatic liquid level monitoring, rodless water injection, and oil pipe 1 gas production to solve the problem of gas well drainage and gas production. The method of injecting water and producing gas from above may also include the following steps:

[0130] Step 1: Wellbore preparation:

[0131] Identify the gas well. If the gas well is an old well, it is necessary to pull out the original well string. Pull out the original well string and clean the well and scrape the casing as needed. If the gas well is a new well, it is also necessary to pull out the original well string if there is an original well string and clean the well as needed.

[0132] Then select the water injection layer 52 at the bottom of the gas well to ensure that there is a good barrier between the water injection layer 52 and the gas production layer 51 to avoid leakage interference between layers. If there is no ready-made water injection layer 52, perforation, injection or cutting can be used to make a patch hole on a dry layer below the gas production layer 51 as the water injection layer 52, and the water injection test must be qualified.

[0133] Step 2: lower the injection and production string 44:

[0134] The injection and production string 44 of the present invention is lowered into the wellbore to seat the annular one-way packer 3 on the water injection layer 52, and the packer 4 is seated between the water injection layer 52 and the gas production layer 51, and should be close to the water injection layer 52, so that the bypass one-way valve 2 is located above the annular one-way packer 3.

[0135] Step 3: Install the ground supporting system:

[0136] After the gas wellhead is installed, one of the three types of ground supporting systems can be installed according to the actual situation of the gas source on site.

[0137] Step 4: Debug and run:

[0138] First, open the oil pipe 1 passage and the casing annulus 43 passage valves on the side of the oil pressure gauge 8 and the casing pressure gauge 10 of the gas production wellhead itself.

[0139] (1) Targeting Figure 1 The ground supporting system shown, taking an embodiment as an example, the controller 9 is configured as follows:

[0140] Implement step S10, casing pressure venting: first close the first control valve 7, open the second control valve 11 and the fourth control valve 13, and vent the casing pressure through the gas production pipeline 25 to reduce the casing pressure of the casing pressure gauge 10 to the limit;

[0141] Step S40 is implemented, normal gas production: the second control valve 11 is closed, the first control valve 7 and the fourth control valve 13 are opened, and normal gas production is performed. The oil-casing pressure difference is used to cause the liquid from the gas production layer 51 in the downhole tubing 1 to automatically enter the oil-casing annulus 43 through the bypass check valve 2, thereby lowering the liquid level in the tubing 1 and raising the liquid level in the oil-casing annulus 43;

[0142] When the liquid level monitoring device 6 detects that the liquid level in the downhole oil pipe 1 is high, step S20 is then implemented: when the oil pressure of the oil pressure gauge 8 is higher than the casing pressure of the casing pressure gauge 10, and the requirement of injecting water from the oil-casing annulus 43 to the water injection layer 52 is met, the fourth control valve 13 is closed, and the first control valve 7 is opened, and the second control valve 11 is ensured to be continuously opened, so that the higher-pressure gas in the oil pipe 1 pushes the liquid level in the oil-casing annulus 43 to drop, and is re-injected into the water injection layer 52 through the annulus one-way packer 3. The operation can be repeated until the liquid level in the oil pipe 1 drops to the required position.

[0143] Then, step S40 is implemented: the fourth control valve 13 is opened, and the second control valve 11 is closed to perform normal gas extraction.

[0144] If the oil pressure does not meet the requirement of injecting water from the casing annulus 43 to the water injection layer 52, step S30 is implemented: close the first control valve 7, hold the pressure for a period of time, wait for the gas from the gas production layer 51 to enter the oil pipe 1 to increase the oil pressure until the requirement is met. Then start the controller 9, test it, and ensure normal operation.

[0145] (2) Targeting Figure 2 The ground supporting system shown, taking an embodiment as an example, the controller 9 is configured as follows:

[0146] Implement step S10, casing pressure venting: first close the first control valve 7 and the third control valve 12, open the second control valve 11, the fourth control valve 13, and the fifth control valve 15, and vent the casing pressure through the gas production pipeline 25 to reduce the casing pressure of the casing pressure gauge 10 to the limit;

[0147] Implement step S40, normal gas production: close the second control valve 11, the third control valve 12, and the fifth control valve 15, open the first control valve 7, open the fourth control valve 13, and perform normal gas production. By using the oil-casing pressure difference, the liquid from the gas production layer 51 in the downhole oil pipe 1 is automatically driven into the oil-casing annulus 43 through the bypass check valve 2, thereby lowering the liquid level in the oil pipe 1 and raising the liquid level in the oil-casing annulus 43.

[0148] When the liquid level monitoring device 6 detects that the liquid level in the downhole oil pipe 1 is high, step S20 is then implemented: the second control valve 11 and the third control valve 12 are opened, the fifth control valve 15 is closed, and the first control valve 7 and the fourth control valve 13 are kept open for normal gas production, so that the high-pressure gas from the gas source pushes the oil casing annulus 43 liquid through the annulus one-way packer 3 and is reinjected into the water injection layer 52. The operation can be repeated until the liquid level in the oil pipe 1 drops to the required position.

[0149] Then, step S10 is performed again: close the first control valve 7 and the third control valve 12, open the fifth control valve 15, and continue to open the second control valve 11 and the fourth control valve 13 to vent the casing pressure; then, gas is collected normally according to the method of the aforementioned step S40. Then, the controller 9 is started, tested, and normal operation is ensured.

[0150] (3) Targeting Figure 3 The ground supporting system shown, taking an embodiment as an example, the controller 9 is configured as follows:

[0151] Implement step S10, casing pressure venting: first close the first control valve 7, the third control valve 12, and the sixth control valve 17, open the second control valve 11, the fourth control valve 13, and the fifth control valve 15, and vent the casing pressure through the gas production pipeline 25 to reduce the casing pressure of the casing pressure gauge 10 to the limit;

[0152] Implement step S40, normal gas production: close the second control valve 11, the third control valve 12, the fifth control valve 15, and the sixth control valve 17, open the first control valve 7, open the fourth control valve 13, and perform normal gas production. By using the oil-casing pressure difference, the liquid from the gas production layer 51 in the downhole tubing 1 is automatically driven into the oil-casing annulus 43 through the bypass check valve 2, thereby lowering the liquid level in the tubing 1 and raising the liquid level in the oil-casing annulus 43.

[0153] When the liquid level monitoring device 6 detects that the liquid level in the downhole oil pipe 1 is high, step S20 is then implemented to open the second control valve 11, the third control valve 12, and the sixth control valve 17, open the first control valve 7, close the fifth control valve 15, and the fourth control valve 13 can be opened or closed, and then the compressor 16 is started to pressurize the gas coming from the oil pipe of the well, and the liquid in the oil casing annulus 43 is pushed back to the water injection layer 52 through the annulus one-way packer 3. The operation can be repeated until the liquid level in the oil pipe 1 drops to the required position.

[0154] Then, step S10 is performed again: the compressor 16, the first control valve 7, the third control valve 12, and the sixth control valve 17 are closed, the fifth control valve 15 is opened, and the second control valve 11 and the fourth control valve 13 are opened to vent the casing pressure; then gas is collected normally, and the method of the aforementioned step S40 is followed. Then, the controller 9 is started, tested, and normal operation is ensured.

[0155] Solution 2

[0156] The present invention provides a gas well gas-liquid downhole separation injection and production operation system, which is applied to the above-mentioned gas well gas-liquid downhole separation injection and production method; Figure 1-Figure 3 As shown, the injection-up and production-down operation system includes a surface production-injection pipeline, a wellbore 40, and an injection-production string 44 disposed in the wellbore 40, and an oil casing annulus 43 is formed between the injection-production string 44 and the wellbore 40;

[0157] The injection and production string 44 includes a bypass check valve 2, an annular check packer 3, and a packer 4 connected in sequence from top to bottom. The bypass check valve 2 has a one-way conduction structure from the inner cavity of the injection and production string 44 to the oil casing annulus 43. The annular check packer 3 adopts a downwardly openable and upwardly closed structure. The packer 4 is used to isolate the oil casing annulus 43.

[0158] The gas well formation has a gas production layer 51 and a water injection layer 52, the gas production layer 51 is located below the water injection layer 52, the packer 4 is arranged between the gas production layer 51 and the water injection layer 52, and the lower end opening of the injection and production pipe string 44 extends to the gas production layer 51;

[0159] The surface production and injection pipeline includes:

[0160] A pipe string line 23 connected to the inner cavity of the injection and production pipe string 44;

[0161] The oil casing pipeline 24 connected to the oil casing annulus 43;

[0162] Gas production pipeline 25;

[0163] The surface production and injection pipeline includes a first control valve 7, a second control valve 11 and a fourth control valve 13.

[0164] The tubing string pipeline 23 is connected to the first pipeline node 21 through the first control valve 7 , the oil casing pipeline 24 is connected to the first pipeline node 21 through the second control valve 11 , and the gas production pipeline 25 is connected to the first pipeline node 21 through the fourth control valve 13 .

[0165] The gas-liquid separation and up-hole production of gas wells are implemented through the injection-up-and-down production system, and the rodless water injection and oil pipe 1 gas production method is used to carry out gas well drainage and gas production, thereby avoiding the surface treatment of the produced liquid, and achieving direct underground separation and reinjection of the produced liquid before it reaches the ground, thereby lowering the wellbore liquid level and achieving the purpose of injecting water into the casing annulus 43 and producing gas through the oil pipe 1. It is particularly suitable for liquid-accumulated wells and large-water-gas wells.

[0166] The bypass check valve 2 and the annular check packer 3 are preferably arranged above the water injection layer 52. Figure 1As shown, the surface production and injection pipeline can also be provided with valve No. 1 31, valve No. 2 32, valve No. 33, valve No. 4 34, valve No. 5 35, valve No. 6 36, valve No. 7 37, valve No. 8 38 and valve No. 9 39. Preferably, the liquid level monitoring device 6 is installed on the top of the oil pipe 1 channel at the gas production wellhead. Taking the gas production wellhead of valve No. 9 39 as an example, it should be installed on the top of valve No. 7 37.

[0167] The other parts of the surface supporting system can be divided into several types according to the source of gas injection into the casing annulus 43.

[0168] In one embodiment, the gas injection into the casing annulus 43 comes from the high-pressure gas in the well oil pipe 1, such as Figure 1 As shown, the ground supporting system needs to be equipped with a controller 9, a first control valve 7, a second control valve 11, a fourth control valve 13, an oil pressure gauge 8, and a casing pressure gauge 10. The first control valve 7 and the second control valve 11 are connected in series between the side outlet of the gas wellhead oil pipe 1 and the side outlet of the oil casing annulus 43 through pipelines. On the same side of the first control valve 7 and the second control valve 11, the fourth control valve 13 is also connected between the pipelines converging together to the gas production pipeline 25. The oil pressure gauge 8 is connected to the pipeline between the side outlet of the oil pipe 1 at the gas wellhead and the first control valve 7; the casing pressure gauge 10 is connected to the pipeline between the side outlet of the oil casing annulus 43 at the gas wellhead and the second control valve 11; taking the No. 9 valve 39 gas wellhead as an example, the first control valve 7 and the second control valve 11 are connected in series between the No. 9 valve 39 and the No. 6 valve 36 through pipelines, the left side of the fourth control valve 13 is connected to the pipeline between the first control valve 7 and the second control valve 11, and the right side is connected to the gas pipeline 25; the oil pressure gauge 8 is connected to the pipeline between the No. 9 valve 39 and the first control valve 7, and the casing pressure gauge 10 is connected to the pipeline between the No. 6 valve 36 and the second control valve 11.

[0169] The controller 9 can be connected to the first control valve 7, the second control valve 11, the fourth control valve 13, the oil pressure gauge 8, the casing pressure gauge 10, and the liquid level monitoring device 6 by wireless or wired means. The controller 9 can be installed at any position. Preferably, the controller 9 is installed on the upper part of the second control valve 11, close to the ground, to facilitate personnel debugging. Figure 1 The gas well gas-liquid downhole separation injection and production operation system shown in the figure is suitable for gas wells with sufficient formation pressure and large oil-casing pressure difference. The power supply of the whole system can come from the well site power supply, generator or well site wind power and solar power supply.

[0170] In another embodiment, the surface supporting system is suitable for injecting gas into the casing annulus 43 from other gas wells, gas pipelines, nitrogen generators or gas storage tanks. Figure 1 Compared with the embodiment shown in FIG. 1 , the difference of this embodiment is that Figure 2As shown: the third control valve 12 and the fifth control valve 15 need to be connected, wherein the fifth control valve 15 is connected to the pipeline between the first control valve 7 and the second control valve 11, and is also located on the pipeline between the first control valve 7 and the fourth control valve 13; the right side of the third control valve 12 is connected to the gas production pipeline 25 through pipelines, and the left side is connected to the first control valve 7 and the fifth control valve 15, specifically located on the pipeline between the gas production pipeline 25 and the first control valve 7, and is also located on the pipeline between the high-pressure gas source 14 and the fifth control valve 15. The controller 9 can be connected to the first control valve 7, the second control valve 11, the third control valve 12, the fourth control valve 13, the fifth control valve 15, the oil pressure gauge 8, the casing pressure gauge 10, and the liquid level monitoring device 6 in a wireless or wired manner.

[0171] In another embodiment, the ground supporting system is suitable for the gas from the well oil pipe 1 that needs to be pressurized. Figure 2 Compared with the embodiment shown in FIG. 1 , the difference of this embodiment is that Figure 3 As shown: the high-pressure gas source 14 is replaced by a compressor 16, the other end of the compressor 16 is connected to the lower end of the sixth control valve 17 through a pipeline, and the upper end of the sixth control valve 17 is connected to the pipeline between the first control valve 7 and the fourth control valve 13 to pressurize the gas produced from the oil pipe 1 of the well.

[0172] The injection and production operation system provided by the present invention uses gas as a medium to realize water injection and gas production in the same well, solving the gas production problems in liquid-filled wells and water-rich areas. In addition, the downhole injection and production pipe string 44 has a simple structure and a very low failure rate. The ground supporting system can be adjusted in real time according to the on-site well conditions, and can achieve unmanned operation through automation and intelligence, with low operating costs. The method of automatic liquid level monitoring, rodless water injection, and oil pipe 1 gas production can be adopted to solve the problem of gas well drainage and gas production. The present invention is applicable to vertical wells, directional wells, and horizontal wells, and meets the needs of gas-liquid downhole separation, water injection, and gas production in the full cycle of gas wells from production to the late production period.

[0173] Option 3

[0174] The present invention provides a gas well gas-liquid downhole separation injection and production system, which is applied to the above-mentioned gas well gas-liquid downhole separation injection and production method;

[0175] The injection-up and production-down system comprises a surface production-injection pipeline and an injection-production pipe string, wherein the injection-production pipe string is used to be arranged in a wellbore and to form an oil casing annulus between the wellbore;

[0176] The injection and production string includes a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom. The bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the annular space of the oil casing. The annular check packer adopts a downwardly openable and upwardly closed structure. The packer is used to isolate the annular space of the oil casing.

[0177] The packer is used to be arranged between the gas production layer and the water injection layer of the gas well formation, and the lower end opening of the injection and production pipe string can extend to the gas production layer;

[0178] The surface production and injection pipeline includes:

[0179] A pipe string line connected to the inner cavity of the injection and production pipe string;

[0180] The oil casing pipeline connected to the oil casing annulus;

[0181] Gas pipeline;

[0182] The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve.

[0183] The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

[0184] The injection and production system can be matched with the original structure of the wellbore 40 of the gas production well to form an injection and production operation system. Figure 1-Figure 3 As shown, the injection and production system may include a liquid level monitoring device, a controller, a bypass check valve, a check valve, a packer, and various control valves, etc. The liquid level monitoring device, the controller, the bypass check valve, the check valve, the packer, and various control valves, etc. have been described above and will not be repeated here. The gas well gas-liquid downhole separation injection and production system provided by the present invention has all or at least part of the technical features and effects of the above-mentioned operating system except the wellbore, which will not be repeated here.

[0185] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A method for underground gas-liquid separation and injection and production in a gas well, It is characterized in that Adopt the injection-up and mining-down operation system; The injection-up and production-down operation system comprises a surface production-injection pipeline, a wellbore and an injection-production pipe string arranged in the wellbore, and an oil casing annulus is formed between the injection-production pipe string and the wellbore; The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus; The gas well formation has a gas production layer and a water injection layer, the gas production layer is located below the water injection layer, the packer is arranged between the gas production layer and the water injection layer, and the lower end opening of the injection and production pipe string extends to the gas production layer; The surface production and injection pipeline comprises: A pipe string pipeline connected to the inner cavity of the injection and production pipe string; An oil casing pipeline connected to the oil casing annulus; Gas pipeline; The injection-up and extraction-down method comprises: Step S10, venting the casing pressure to reduce the casing pressure of the oil-casing annulus, and causing the liquid from the gas production layer in the injection-production string to enter the oil-casing annulus through the bypass one-way valve; Step S20, injecting water downhole; In the step S10, the column pipeline is disconnected from the gas production pipeline, and the oil casing pipeline is connected to the gas production pipeline; In the step S20, the tubing string pipeline is connected to the oil casing pipeline and both are disconnected from the gas production pipeline; or, the oil casing pipeline is disconnected from the tubing string pipeline and the gas production pipeline and the oil casing pipeline is connected to an external pressure supply device; or, the inside of the injection and production tubing string is pressurized to force liquid and gas to enter the oil casing annulus through the bypass one-way valve.

2. The gas-liquid downhole separation and injection and production method for gas wells according to claim 1, It is characterized in that The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve. The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

3. The gas-liquid downhole separation and injection and production method for gas wells according to claim 2, It is characterized in that Open the second control valve and the fourth control valve, and close the first control valve, to implement step S10; Open the first control valve and the second control valve, and close the fourth control valve to implement the step S20; or close the first control valve and the second control valve to hold the pressure inside the injection and production string, forcing the liquid and gas to enter the casing annulus through the bypass one-way valve to implement the step S20.

4. The gas-liquid downhole separation and injection and production method for gas wells according to claim 3, It is characterized in that The tubing string pipeline is provided with an oil pressure gauge, and the oil casing pipeline is provided with a casing pressure gauge.

5. The gas-liquid downhole separation and injection and production method for a gas well according to claim 4, It is characterized in that After the oil pressure of the oil pressure gauge is higher than the casing pressure of the casing pressure gauge, step S20 is implemented.

6. The gas-liquid downhole separation and injection and production method for gas wells according to claim 3, It is characterized in that The injection-up and extraction-down method comprises: Step S30, holding the pressure to increase the oil pressure in the injection and production string; Close the first control valve to implement step S30; The step S30 is performed before the step S20.

7. The gas-liquid downhole separation and injection and production method for gas wells according to claim 2, It is characterized in that The surface production and injection pipeline includes a third control valve, a fifth control valve and a high-pressure gas source, and the high-pressure gas source serves as the external pressure supply device; The oil casing pipeline is connected to a second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; The second pipeline node is connected to the high-pressure gas source through the third control valve.

8. The gas-liquid downhole separation and injection and production method for gas wells according to claim 7, It is characterized in that Open the second control valve, the fifth control valve and the fourth control valve, and close the first control valve and the third control valve to implement step S10; The fifth control valve is closed, and the second control valve and the third control valve are opened to connect the oil casing pipeline with the high-pressure gas source, so as to implement step S20.

9. The gas-liquid downhole separation and injection and production method for gas wells according to claim 8, It is characterized in that When the step S20 is implemented, the first control valve and the fourth control valve are kept open to collect gas.

10. The gas-liquid downhole separation and injection and production method for gas wells according to claim 2, It is characterized in that The surface production and injection pipeline includes a third control valve, a fifth control valve, a sixth control valve and a compressor, and the compressor serves as the external pressure supply device; The oil casing pipeline is connected to a second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; The second pipeline node is connected to the outlet of the compressor through the third control valve; The inlet of the compressor is connected to the first line node via the sixth control valve.

11. The gas-liquid downhole separation and injection and production method for a gas well according to claim 10, It is characterized in that Close the first control valve, the third control valve and the sixth control valve, and open the second control valve, the fourth control valve and the fifth control valve to implement step S10; The second control valve, the third control valve, the sixth control valve and the first control valve are opened, the fifth control valve is closed, and the compressor is started to implement step S20.

12. The gas-liquid downhole separation and injection and production method for a gas well according to claim 11, It is characterized in that When the step S20 is implemented, the fourth control valve is opened or closed.

13. The gas-liquid downhole separation and injection and production method for a gas well according to claim 4, It is characterized in that The injection and production operation system includes a liquid level monitoring device and a controller. The liquid level monitoring device is installed on the top of the injection and production pipe string. The controller is used to control the switching of each control valve according to the monitoring signal of the liquid level monitoring device, the signal of the oil pressure gauge and the signal of the casing pressure gauge.

14. The gas-liquid downhole separation and injection and production method for a gas well according to claim 1, It is characterized in that The injection-up and extraction-down method also includes: Step S40, normal gas collection; When implementing the step S40, the first control valve and the fourth control valve are opened, and the second control valve is closed; The step S10, the step S20, and the step S40 are performed sequentially. Alternatively, the step S10, the step S40, and the step S20 are implemented in sequence.

15. The gas-liquid downhole separation and injection and production method for a gas well according to claim 14, It is characterized in that The step S10, the step S20, the step S40, the step S10, and the step S20 are implemented in sequence.

16. A gas well gas-liquid downhole separation injection and production operation system, It is characterized in that The method for downhole gas-liquid separation and injection and production in a gas well as described in any one of claims 1 to 15; The injection-up and production-down operation system comprises a surface production-injection pipeline, a wellbore and an injection-production pipe string arranged in the wellbore, and an oil casing annulus is formed between the injection-production pipe string and the wellbore; The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus; The gas well formation has a gas production layer and a water injection layer, the gas production layer is located below the water injection layer, the packer is arranged between the gas production layer and the water injection layer, and the lower end opening of the injection and production pipe string extends to the gas production layer; The surface production and injection pipeline comprises: A pipe string pipeline connected to the inner cavity of the injection and production pipe string; An oil casing pipeline connected to the oil casing annulus; Gas pipeline; The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve. The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

17. A gas well gas-liquid downhole separation injection and production system, It is characterized in that The method for downhole gas-liquid separation and injection and production in a gas well as described in any one of claims 1 to 15; The injection-up and production-down system comprises a surface production-injection pipeline and an injection-production string, wherein the injection-production string is used to be arranged in a wellbore and to form an oil casing annulus between the wellbore; The injection and production string comprises a bypass check valve, an annular check packer, and a packer connected in sequence from top to bottom, wherein the bypass check valve has a one-way conduction structure from the inner cavity of the injection and production string to the oil casing annulus, the annular check packer adopts a downwardly openable and upwardly closed structure, and the packer is used to isolate the oil casing annulus; The packer is used to be arranged between the gas production layer and the water injection layer of the gas well formation, and the lower end opening of the injection and production pipe string can extend to the gas production layer; The surface production and injection pipeline comprises: A pipe string pipeline connected to the inner cavity of the injection and production pipe string; An oil casing pipeline connected to the oil casing annulus; Gas pipeline; The surface production and injection pipeline includes a first control valve, a second control valve and a fourth control valve. The tubing string pipeline is connected to the first pipeline node through the first control valve, the oil casing pipeline is connected to the first pipeline node through the second control valve, and the gas production pipeline is connected to the first pipeline node through the fourth control valve.

18. A gas-liquid downhole separation and injection and production system for gas wells according to claim 17, It is characterized in that The injection and production string includes an oil pipe, a drill pipe or a small casing.

19. A gas well gas-liquid downhole separation injection and production system according to claim 18, It is characterized in that The bypass one-way valve adopts a structure in which the valve core and the valve body are separated, the valve body is directly connected to the oil pipe coupling of the injection and production string, and the valve core can be repeatedly cast in and out.

20. A gas-liquid downhole separation and injection and production system for gas wells according to claim 17, It is characterized in that The packer has a slip anchoring function, and the packer can be connected to the oil pipe of the injection and production string by inserting and re-inserting the pipe.

21. A gas-liquid downhole separation and injection and production system for gas wells according to claim 17, It is characterized in that The power supply of the injection and production system is derived from the large-scale electricity of the well site, a generator, or the wind power and solar power of the well site.

22. A gas well gas-liquid downhole separation injection and production system according to claim 17, It is characterized in that The surface production and injection pipeline includes a third control valve, a fifth control valve and a high-pressure gas source, and the high-pressure gas source serves as the external pressure supply device; The oil casing pipeline is connected to a second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; The second pipeline node is connected to the high-pressure gas source through the third control valve.

23. A gas-liquid downhole separation and injection and production system for gas wells according to claim 17, It is characterized in that The surface production and injection pipeline includes a third control valve, a fifth control valve, a sixth control valve and a compressor, and the compressor serves as the external pressure supply device; The oil casing pipeline is connected to a second pipeline node through the second control valve, and the second pipeline node is connected to the first pipeline node through the fifth control valve; The second pipeline node is connected to the outlet of the compressor through the third control valve; The inlet of the compressor is connected to the first line node via the sixth control valve.

24. A gas-liquid downhole separation and injection and production system for gas wells according to claim 17, It is characterized in that The tubing string pipeline is connected to an oil pressure gauge, and the oil casing pipeline is connected to a casing pressure gauge.

25. A gas-liquid downhole separation and injection and production system for gas wells according to claim 24, It is characterized in that The injection and production system includes a liquid level monitoring device and a controller. The liquid level monitoring device is installed on the top of the injection and production string. The controller is used to control the switching of each control valve according to the monitoring signal of the liquid level monitoring device, the signal of the oil pressure gauge and the signal of the casing pressure gauge.

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