Same-well water injection gas production system and process

Abstract

The invention discloses a same-well water injection gas production system and process, and belongs to the technical field of oil and gas collection. The system comprises an injection-production pipe column system arranged in an underground well, and an underground pump arranged in the injection-production pipe column system and used for providing power for water injection and gas production in the underground well; the power liquid circulation system is arranged on the ground, communicates with the injection-production pipe column system and is used for providing lifting power for operation of the underground pump; the device comprises an injection-production string system, a gas-liquid separator, a packer, a one-way valve and an exhaust pipe, the packer separates an injection layer and a production layer of an underground well, the gas-liquid separator carries out gas-liquid separation on fluid of the production layer, the one-way valve is used for preventing liquid of the injection layer from entering the production layer, and the exhaust pipe is communicated with the injection-production string system; the device is mainly used for water injection gas production in the same well, the problems of invalid circulation and large energy waste due to the fact that drainage gas production water is lifted to the ground and then injected into the stratum are solved, natural gas originally exploited in uneconomic reservoirs can be exploited, and the economic service life of gas field exploitation is prolonged.

Description

Technical Field

[0001] The invention relates to a system and process for producing gas by water injection in a same well, belonging to the technical field of oil and gas production. Background Art

[0002] In natural gas extraction, as the formation pressure decreases, the produced water in the formation cannot be carried out, causing accumulation and crushing the formation. Drainage gas extraction is currently an effective method, but the produced water is injected into the formation, which has problems such as many ground equipment, large investment, high energy consumption, and environmental pollution. Generally, the same well reinjection method is adopted, mainly including electric submersible pumps, jet pumps, rod pumps, etc. These methods alleviate the major problem of surface water treatment, but there are problems in the following aspects: 1. For wells with high mineralization and easy scaling, submersible pumps, jet pumps, and rod pumps all have scaling problems, and the pump inspection cycle is short; 2. The pumping depth of electric submersible pumps, jet pumps and rod pumps is small, and they cannot be lifted in deep wells (depth greater than 3000m) due to structural factors; 3. When using ESP in directional wells and wells with large “doglegs”, there are problems with cable extrusion and pump shaft distortion. In addition, in low-displacement wells, the heat from the ESP motor cannot be removed. 4. The jet pump has low pump efficiency and large energy waste.

[0003] In the prior art, for example, the Chinese invention patent application with application number 202010272834.3 discloses a method and string for gas production by reinjection and drainage in the same well. The invention directly injects the water produced by the gas layer into the low-pressure layer, does not require surface treatment, does not consume water production energy, and has no additional operating costs; the liquid level in the well can always be maintained at the lowest state, so that the gas layer production capacity can be maximized. Another example is the Chinese invention patent application with application number 202411430484.3, which discloses a hydraulic lift oil production system. This invention solves the technical problems in the prior art that eccentric wear or high investment, high maintenance costs, and short life are easily caused during the oil pumping process of high-angle well development. However, the above technologies are still limited in their use scenarios, and the pump efficiency needs to be improved. Summary of the invention

[0004] 1. Technical issues to be resolved The technical problem to be solved by the present invention is to solve the problems of the existing same-well injection and production technology in which drainage and gas production water is lifted to the ground and then injected into the formation, resulting in ineffective circulation, large energy waste, limited usage scenarios, and the need to improve pump efficiency.

[0005] (II) Technical solution In order to solve the above technical problems, the present invention provides a same-well water injection and gas production system, which is used for water injection and gas production in an underground well, wherein the underground well is provided with an injection layer and a production layer, and comprises: Injection and production string system: set up in underground wells to provide channels for water injection and gas production; Downhole pump: installed in the injection and production string system to provide power for water injection and gas production in underground wells; Power fluid circulation system: It is installed on the ground and connected with the injection and production string system to provide lifting power for the downhole pump operation; It also includes a gas-liquid separator, a packer, a one-way valve and an exhaust pipe, wherein the packer separates the injection layer and the production layer of the underground well, the gas-liquid separator separates the fluid of the production layer into gas and liquid, the one-way valve is used to prevent the liquid of the injection layer from entering the production layer, and the exhaust pipe is connected to the injection and production string system; The downhole pump is a two-stage plunger pump, a flow channel running through the entire downhole pump is arranged in the middle thereof, and a fixed valve and a floating valve are arranged on the flow channel; under the action of the downhole pump, the fluid in the produced layer first passes through the gas-liquid separator for gas-liquid separation, and then the gas is discharged from the underground well along the exhaust pipe, and the liquid rises along the flow channel and is injected back into the injection layer.

[0006] Furthermore, the injection and production tubing system includes casing and oil pipes, the oil pipes are arranged in the middle of the casing, and an annular gap is formed between the two. The packer is arranged inside the lower end of the casing, and the downhole pump is arranged in the oil pipe. An annulus is left between the downhole pump and the oil pipe. A gas-liquid separator is arranged at the lower end of the oil pipe, and a one-way valve is arranged at the lower end of the gas-liquid separator. The upper end of the oil pipe is connected to the power fluid circulation system.

[0007] Furthermore, the downhole pump includes an upper plunger pump, a lower plunger pump and a hollow connecting rod connecting the two, the upper plunger pump and the lower plunger pump are both two-stage plunger structures, the upper plunger pump includes an upper large pump barrel, an upper small pump barrel and an upper large plunger and an upper small plunger used in conjunction with the two respectively; the lower plunger pump includes a lower large pump barrel, a lower small pump barrel and a lower large plunger and a lower small plunger used in conjunction with the two respectively; a gap is left between the upper large pump barrel and the upper small pump barrel; the flow channel runs through the upper plunger pump, the lower plunger pump and the hollow connecting rod, a fixed valve and a floating valve are arranged in the flow channel at the lower large plunger, a bridge injection joint is arranged at the upper end of the upper large pump barrel, the bridge injection joint is connected to the injection layer, and the lower small pump barrel is connected to the gas-liquid separator.

[0008] Furthermore, a filter is provided at the lower end of the oil pipe, and the filter comprises a screen tube and a wire plug provided at the lower end of the screen tube, and the screen tube is provided with screen holes.

[0009] Furthermore, the power fluid circulation system includes a storage tank, a boost pump, a first solenoid valve and a second solenoid valve. The storage tank and the boost pump are connected to form a circulation loop through two pipelines, one of which is provided with a first solenoid valve and a second solenoid valve. The pipeline between the first solenoid valve and the second solenoid valve is connected to the oil pipe, and a valve valve is provided on the exhaust pipe.

[0010] Furthermore, the injection layer is located above the production layer, the exhaust pipe is inserted into the oil pipe, and the bridge-type injection joint is connected to the upper large pump barrel and casing.

[0011] Furthermore, the one-way valve is an upward flow one-way valve, which relies on its own gravity to close the valve.

[0012] Furthermore, the injection layer is located below the production layer, the exhaust pipe is connected to the gap between the oil pipe and the casing, and the bridge-type injection joint is connected to the upper large pump barrel and the oil pipe.

[0013] Furthermore, the one-way valve is a downward flow one-way valve, and a return spring is arranged inside the one-way valve, which relies on the spring to close the valve.

[0014] The present invention also provides a same-well water injection and gas production process of a same-well water injection and gas production system, which comprises the following steps: S1. Upstroke: The power fluid circulation system injects the power fluid in the storage tank from the oil pipe into the hydraulic chamber composed of the upper large pump barrel, the upper small pump barrel, the upper large plunger and the upper small plunger, pushing the upper large plunger and the upper small plunger upward, the pressure in the upper end of the upper large pump barrel increases, and the liquid enters the injection layer from the bridge injection joint; at the same time, the hollow connecting rod at the bottom of the upper small plunger moves upward, and the lower plunger pump is driven upward by the hollow connecting rod. The pressure in the suction chamber of the lower plunger pump decreases, the floating valve is closed, and under the action of the sinking pressure, the fixed valve is opened, and the fluid in the production layer enters the gas-liquid separator, and the separated liquid flows into the suction chamber to complete the liquid suction. At the same time, the separated gas moves upward along the exhaust pipe and is discharged to the ground; S2. Down stroke: When the upper large plunger and the upper small plunger reach the top dead center, the power fluid circulation system draws the power fluid in the oil pipe out of the oil pipe, the upper large plunger and the upper small plunger move downward, and the hollow connecting rod pushes the lower plunger pump downward, the pressure in the suction chamber of the lower plunger pump increases, the fixed valve closes, the floating valve opens, and the liquid in the suction chamber is discharged into the upper chamber of the upper large pump barrel along the flow channel.

[0015] S3, repeat the above process to perform water injection and gas production.

[0016] (III) Beneficial effects The above technical solution of the present invention has the following advantages: 1. The present invention is mainly used for water injection and gas production in the same well. The produced water is directly injected into the injection layer underground to solve the problem of ineffective circulation and large energy waste after the drainage gas production water is lifted to the ground and then injected into the formation. The natural gas in the reservoir that was originally uneconomical to be produced can be produced, extending the economic life of gas field production. The present invention adopts a single oil pipe structure, relying on the opening and closing of the solenoid valve to inject and discharge the power fluid from the oil pipe, and the two are carried out alternately. Since there is no rod column, it is not only suitable for vertical wells, but also for directional wells, complex structure wells, and horizontal wells.

[0017] 2. The use of a surface pump and a frequently started and stopped motor with adjustable speed enables the up and down movement of the downhole oil pump, thereby achieving normal drainage and gas production; the power provided by the power fluid is relatively large, which can meet the injection needs of wells above 50MPa (wellhead pressure), thereby meeting the water injection needs of difficult-to-inject wells; 3. The power fluid enters the large and small pump barrels from the oil pipe, realizing the upward movement of the large and small pistons. Under the action of the hydraulic pressure of the lower feedback pump, the large and small pistons move downward, thereby resetting. The large and small pump barrels and large and small pistons adopt rigid seals, which have the advantages of high sealing reliability and long service life. 4. The use of large flow channel floating valve and fixed valve structure not only reduces the resistance of crude oil pumping, but also can be used in high-angle wells and horizontal wells; sealed plugs are used between the exhaust pipe and the oil pipe, and between the packer and the oil pipe. The sealed plugs are rigidly sealed and have a long service life; 5. The fluid is separated into gas and water before entering the downhole pump. The separated gas moves upward along the outer pipe and enters the exhaust pipe, which reduces the impact of the gas on the pump and has a higher pump efficiency.

[0018] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted by the present invention, and the advantages brought about by the technical features of these technical solutions described above, other technical features of the present invention and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative work.

[0020] Figure 1 This is a schematic diagram of the structural layout of the injection system of the present invention.

[0021] Figure 2 for Figure 1 Schematic diagram of the underground structure.

[0022] Figure 3 This is a schematic diagram of the structural layout of the upper injection and lower injection system of the present invention.

[0023] Figure 4 for Figure 3 Schematic diagram of the underground structure.

[0024] In the figure: 1. injection layer; 2. production layer; 3. gas-liquid separator; 4. packer; 5. one-way valve; 6. exhaust pipe; 7. fixed valve; 8. floating valve; 9. casing; 10. oil pipe; 11. hollow connecting rod; 12. upper large pump barrel; 13. upper small pump barrel; 14. upper large plunger; 15. upper small plunger; 16. lower large pump barrel; 17. lower small pump barrel; 18. lower large plunger; 19. lower small plunger; 20. bridge injection joint; 21. screen tube; 22. thread plug; 23. storage tank; 24. booster pump; 25. first solenoid valve; 26. second solenoid valve; 27. gate valve; 28. return spring. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Embodiment 1, this embodiment discloses a same-well water injection gas production system, which is used for water injection gas production in an underground well, wherein the underground well is provided with an injection layer 1 and a production layer 2, such as Figure 1-Figure 4 As shown in the figure (in the figure, FE is a flow meter, M is a solenoid valve, and the dotted line indicates the communication connection or electrical connection between each component and the external right controller. The control part is conventional existing technology and will not be expanded here), the same well water injection and gas production system includes: Injection and production string system: It is set in the underground well to provide a circulation channel for water injection and gas production, and the injection and production string system is connected to the injection layer 1 and the production layer 2 respectively to realize the fluid circulation during the water injection and gas production process.

[0028] Downhole pump: It is installed in the injection and production tubing system to provide power for water injection and gas production in the underground well, especially for reinjecting the liquid from the production layer 2 into the injection layer 1. It can be understood that it also provides a circulation channel for the liquid in the production layer 2.

[0029] Power fluid circulation system: It is installed on the ground, with power fluid flowing through it, and is connected to the injection and production tubing system. It provides lifting power for the operation of the downhole pump through the circulating power fluid, especially provides lifting driving force for the plunger of the downhole pump.

[0030] The gas production system provided in this embodiment also includes a gas-liquid separator 3, a packer 4, a one-way valve 5 and an exhaust pipe 6. The packer 4 separates the injection layer 1 and the production layer 2 of the underground well to prevent mutual interference and intrusion. The gas-liquid separator 3 separates the fluid of the production layer 2 into gas and liquid. The one-way valve 5 is used to prevent the liquid of the injection layer 1 from entering the production layer 2, in order to prevent the ineffective circulation of water. The exhaust pipe 6 is connected to the injection and production string system and is used to discharge the gas from the production layer 2 that needs to be collected.

[0031] The downhole pump is a two-stage plunger pump. The upper plunger pump is used to rise and fall under the drive of power fluid and to inject liquid back into the injection layer 1. The lower plunger pump is driven by the upper plunger pump to rise and fall while absorbing liquid from the production layer 2. A flow channel running through the entire downhole pump is provided in the middle of the downhole pump for reinjection, and a fixed valve 7 and a floating valve 8 are provided on the flow channel. Under the action of the downhole pump, the fluid in the production layer 2 first passes through the gas-liquid separator 3 for gas-liquid separation, and then the gas is discharged from the underground well along the exhaust pipe 6, and the liquid rises along the flow channel and is injected back into the injection layer 1.

[0032] Since this embodiment has no rod string, it is not only suitable for vertical wells, but also for directional wells, complex structure wells, and horizontal wells.

[0033] In this embodiment, the injection and production string system includes a casing 9 and an oil pipe 10. The oil pipe 10 is arranged in the middle of the casing 9, and an annular space is formed between the two. The packer 4 is arranged inside the lower end of the casing 9. The downhole pump is arranged in the oil pipe 10, and an annular space is left between the downhole pump and the oil pipe 10. A gas-liquid separator 3 is arranged at the lower end of the oil pipe 10 for separating the gas and liquid of the fluid in the production layer 2. A one-way valve 5 is arranged at the lower end of the gas-liquid separator 3. The upper end of the oil pipe 10 is connected to the power fluid circulation system. The power fluid circulation system circulates the power fluid through the oil pipe 10, thereby controlling the downhole pump operation, thereby eliminating the rod column structure.

[0034] In this embodiment, the downhole pump includes an upper plunger pump, a lower plunger pump and a hollow connecting rod 11 connecting the two, that is, a two-stage plunger pump. The upper plunger pump and the lower plunger pump are both two-stage plunger structures (one large and one small two-stage plunger structure), and the upper plunger pump includes an upper large pump barrel 12, an upper small pump barrel 13, and an upper large plunger 14 and an upper small plunger 15 used in conjunction with the two, that is, the upper large plunger 14 and the upper small plunger 15 can slide in the upper large pump barrel 12 and the upper small pump barrel 13 respectively, and the inner cavity height of the upper large pump barrel 12 is much greater than the height of the upper large plunger 14 to form a liquid storage cavity. The lower-level plunger pump includes a lower-level large pump barrel 16, a lower-level small pump barrel 17, and a lower-level large plunger 18 and a lower-level small plunger 19 used in conjunction with the lower-level large pump barrel 16 and the lower-level small pump barrel 17, respectively. That is, the lower-level large plunger 18 and the lower-level small plunger 19 can slide in the lower-level large pump barrel 16 and the lower-level small pump barrel 17, respectively. A gap is left between the upper-level large pump barrel 12 and the upper-level small pump barrel 13, and the oil pipe 10 is connected to the gap. The power fluid from the oil pipe 10 enters the gap to control the lifting of the upper-level large plunger 14 and the upper-level small plunger 15. The flow channel is set through the upper-level plunger pump, the lower-level plunger pump and the hollow connecting rod 11, and a fixed valve 7 and a floating valve 8 are set in the flow channel located at the lower-level large plunger 18. The upper end of the upper large pump barrel 12 is provided with a bridge injection joint 20, which is connected to the injection layer 1, and can discharge the gas discharged along the oil pipe 10 into the exhaust pipe 6, and can also discharge the liquid in the hydraulic cavity out of the oil pipe 10 and enter the injection layer 1 from the oil pipe 10. The lower small pump barrel 17 is connected to the gas-liquid separator 3.

[0035] In this embodiment, a filter is disposed at the lower end of the oil pipe 10, and the filter includes a screen tube 21 and a plug 22 disposed at the lower end of the screen tube 21. The screen tube 21 is provided with dense screen holes. The fluid in the production layer 2 is initially filtered through the filter.

[0036] In this embodiment, the power fluid circulation system includes a storage tank 23, a boost pump 24, a first solenoid valve 25 and a second solenoid valve 26. The storage tank 23 and the boost pump 24 are connected to form a circulation loop through two pipelines, one of which is provided with a first solenoid valve 25 and a second solenoid valve 26. The pipeline between the first solenoid valve 25 and the second solenoid valve 26 is connected to the oil pipe 10. The circulation of the power fluid is realized by opening and closing the first solenoid valve 25 and the second solenoid valve 26. A valve valve 27 is provided on the exhaust pipe 6. In order to keep the boost pump 24 running, a branch storage tank 23 can also be provided on the pipeline between the boost pump 24 and the solenoid valve at its output end.

[0037] Example 2, based on Example 1, this example further refines the structure of the same-well water injection and gas production system according to the positional relationship between the injection layer 1 and the production layer 2 in the underground well. In this example, the injection layer 1 is located above the production layer 2, that is, the system is used for "mining below and injecting above" operations. At this time, the exhaust pipe 6 is inserted into the oil pipe 10, and the bridge injection joint 20 is connected to the upper large pump barrel 12 and the casing 9.

[0038] In this embodiment, the one-way valve 5 is an upward flow one-way valve 5, which relies on its own gravity to close the valve.

[0039] Example 3, based on Example 1, this example further refines the structure of the same-well water injection and gas production system according to the positional relationship between the injection layer 1 and the production layer 2 in the underground well. In this example, the injection layer 1 is located below the production layer 2, that is, the system is used for "production above and injection below" operation. At this time, the exhaust pipe 6 is connected to the gap between the oil pipe 10 and the casing 9, and the bridge injection joint 20 is connected to the upper large pump barrel 12 and the oil pipe 10.

[0040] In this embodiment, the one-way valve 5 is a downward flow one-way valve 5, and a return spring 28 is arranged in the one-way valve 5, which relies on the spring to close the valve.

[0041] Example 4: This example is a same-well water injection gas production process for a same-well water injection gas production system described in Example 2, that is, the system is used for a same-well water injection gas production process for "mining below and injecting above" operations, including the following steps: S1. Upstroke: The power fluid circulation system injects the power fluid in the storage tank 23 from the oil pipe 10, and the power fluid enters the hydraulic chamber composed of the upper large pump barrel 12, the upper small pump barrel 13, the upper large plunger 14 and the upper small plunger 15 (or the gap between the upper large pump barrel 12 and the upper small pump barrel 13). The power fluid pushes the upper large plunger 14 and the upper small plunger 15 upward, and the pressure in the upper end cavity of the upper large pump barrel 12 increases. The liquid in the upper end cavity of the upper large pump barrel 12 is discharged from the bridge injection joint 20, and goes down along the gap between the casing 9 and the oil pipe 10 to enter the injection Enter layer 1; at the same time, the hollow connecting rod 11 at the lower part of the upper small plunger 15 moves upward, and the hollow connecting rod 11 drives the lower plunger pump upward, and the pressure in the suction chamber of the lower plunger pump decreases, and the floating valve 8 is closed. Under the action of the sinking pressure, the fixed valve 7 opens, and the fluid of the production layer 2 is first filtered by the filter, and then enters the gas-liquid separator 3 through the one-way valve 5. The liquid separated by entering the gas-liquid separator 3 flows into the suction chamber of the lower plunger pump to complete the liquid suction. At the same time, the separated gas goes up along the gap between the oil pipe 10 and the downhole pump, enters the exhaust pipe 6, and then moves upward to be discharged to the ground; S2. Down stroke: When the upper large plunger 14 and the upper small plunger 15 reach the top dead center, the power fluid circulation system draws the power fluid in the oil pipe 10 out of the oil pipe 10, the upper large plunger 14 and the upper small plunger 15 move downward, and the hollow connecting rod 11 pushes the lower plunger pump downward (or pushes the lower large plunger 18 and the lower small plunger 19 downward), the pressure in the suction chamber of the lower plunger pump increases, the fixed valve 7 closes, the floating valve 8 opens, and the liquid in the suction chamber is discharged into the upper chamber of the upper large pump barrel 12 along the flow channel.

[0042] S3, repeat the above process to perform water injection and gas production.

[0043] Example 5: This example is a same-well water injection gas production process for a same-well water injection gas production system described in Example 3, that is, the system is used for a same-well water injection gas production process for "upper-mining and lower-injection" operations, including the following steps: S1. Upstroke: The power fluid circulation system injects the power fluid in the storage tank 23 from the oil pipe 10, and the power fluid enters the hydraulic chamber composed of the upper large pump barrel 12, the upper small pump barrel 13, the upper large plunger 14 and the upper small plunger 15 (or the gap between the upper large pump barrel 12 and the upper small pump barrel 13). The power fluid pushes the upper large plunger 14 and the upper small plunger 15 upward, and the pressure in the upper end cavity of the upper large pump barrel 12 increases. The liquid in the upper end cavity of the upper large pump barrel 12 is discharged from the bridge injection joint 20, goes down along the gap between the oil pipe 10 and the downhole pump, and then enters the injection layer 1 after passing through the one-way valve 5 and the filter; at the same time , the hollow connecting rod 11 at the lower part of the upper small plunger 15 moves upward, and the hollow connecting rod 11 drives the lower plunger pump upward, the pressure in the suction chamber of the lower plunger pump decreases, the floating valve 8 is closed, and under the action of the sinking pressure, the fixed valve 7 is opened, and the fluid of the production layer 2 enters the gas-liquid separator 3 (it can be understood that in the gas production system of this embodiment, the production layer 2 and the gas-liquid separator 3 are connected (not shown in the drawings)), and the liquid separated by entering the gas-liquid separator 3 flows into the suction chamber of the lower plunger pump to complete the liquid suction. At the same time, the separated gas goes up along the gap between the oil pipe 10 and the casing 9, enters the exhaust pipe 6, and then moves upward to be discharged to the ground; S2. Down stroke: When the upper large plunger 14 and the upper small plunger 15 reach the top dead center, the power fluid circulation system draws the power fluid in the oil pipe 10 out of the oil pipe 10, the upper large plunger 14 and the upper small plunger 15 move downward, and the hollow connecting rod 11 pushes the lower plunger pump (or pushes the lower large plunger 18 and the lower small plunger 19 downward) downward, the pressure in the suction chamber of the lower plunger pump increases, the fixed valve 7 closes, the floating valve 8 opens, and the liquid in the suction chamber is discharged into the upper chamber of the upper large pump barrel 12 along the flow channel.

[0044] S3, repeat the above process to perform water injection and gas production.

[0045] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A water injection and gas production system in the same well, used for water injection and gas production in an underground well, wherein the underground well is provided with an injection layer (1) and a production layer (2), characterized in that: include: Injection and production string system: set up in underground wells to provide channels for water injection and gas production; Downhole pump: installed in the injection and production string system to provide power for water injection and gas production in underground wells; Power fluid circulation system: It is installed on the ground and connected with the injection and production string system to provide lifting power for the downhole pump operation; It also comprises a gas-liquid separator (3), a packer (4), a one-way valve (5) and an exhaust pipe (6), wherein the packer (4) separates the injection layer (1) and the production layer (2) of the underground well, the gas-liquid separator (3) separates the gas and liquid in the production layer (2), the one-way valve (5) is used to prevent the liquid in the injection layer (1) from entering the production layer (2), and the exhaust pipe (6) is connected to the injection and production string system; The downhole pump is a two-stage plunger pump, the center of which is provided with a flow channel that runs through the entire downhole pump, and a fixed valve (7) and a floating valve (8) are provided on the flow channel; under the action of the downhole pump, the fluid of the production layer (2) first passes through the gas-liquid separator (3) for gas-liquid separation, and then the gas is discharged from the underground well along the exhaust pipe (6), and the liquid rises along the flow channel and is injected back into the injection layer (1).

2. The same well water injection and gas production system according to claim 1, characterized in that: The injection and production string system comprises a casing (9) and an oil pipe (10); the oil pipe (10) is arranged in the middle of the casing (9), and an annular space is formed between the two; the packer (4) is arranged inside the lower end of the casing (9); the downhole pump is arranged in the oil pipe (10), and an annular space is left between the downhole pump and the oil pipe (10); a gas-liquid separator (3) is arranged at the lower end of the oil pipe (10), and a one-way valve (5) is arranged at the lower end of the gas-liquid separator (3); and the upper end of the oil pipe (10) is connected to a power fluid circulation system.

3. The same well water injection and gas production system according to claim 2, characterized in that: The downhole pump comprises an upper plunger pump, a lower plunger pump and a hollow connecting rod (11) connecting the upper plunger pump and the lower plunger pump. The upper plunger pump and the lower plunger pump are both two-stage plunger structures. The upper plunger pump comprises an upper large pump barrel (12), an upper small pump barrel (13), and an upper large plunger (14) and an upper small plunger (15) respectively used in conjunction with the upper plunger pump. The lower plunger pump comprises a lower large pump barrel (16), a lower small pump barrel (17), and a lower large plunger (18) and a lower small plunger (15) respectively used in conjunction with the lower plunger pump. The upper large pump barrel (12) and the lower small pump barrel (13) have a gap therebetween. The flow channel runs through the upper plunger pump, the lower plunger pump and the hollow connecting rod (11). A fixed valve (7) and a floating valve (8) are arranged in the flow channel at the lower large plunger (18). A bridge-type injection joint (20) is arranged at the upper end of the upper large pump barrel (12). The bridge-type injection joint (20) is connected to the injection layer (1). The lower small pump barrel (17) is connected to the gas-liquid separator (3).

4. The same well water injection and gas production system according to claim 3, characterized in that: A filter is provided at the lower end of the oil pipe (10), the filter comprising a screen tube (21) and a thread plug (22) provided at the lower end of the screen tube (21), and the screen tube (21) is provided with screen holes.

5. The same well water injection and gas production system according to claim 4, characterized in that: The power fluid circulation system comprises a storage tank (23), a boost pump (24), a first solenoid valve (25) and a second solenoid valve (26); the storage tank (23) and the boost pump (24) are connected to form a circulation loop via two pipelines, one of which is provided with the first solenoid valve (25) and the second solenoid valve (26); the pipeline between the first solenoid valve (25) and the second solenoid valve (26) is connected to the oil pipe (10); and the exhaust pipe (6) is provided with a valve valve (27).

6. The same well water injection and gas production system according to claim 5, characterized in that: The injection layer (1) is located above the production layer (2), the exhaust pipe (6) is inserted into the oil pipe (10), and the bridge-type injection joint (20) is connected to the upper large pump barrel (12) and the casing (9).

7. The same well water injection and gas production system according to claim 6, characterized in that: The one-way valve (5) is an upward flow one-way valve (5) which closes the valve by its own gravity.

8. The same well water injection and gas production system according to claim 5, characterized in that: The injection layer (1) is located below the production layer (2), the exhaust pipe (6) is connected to the gap between the oil pipe (10) and the casing (9), and the bridge injection joint (20) is connected to the upper large pump barrel (12) and the oil pipe (10).

9. The same well water injection and gas production system according to claim 8, characterized in that: The one-way valve (5) is a downward flow one-way valve (5), and a return spring (28) is arranged inside the one-way valve (5), which relies on the spring to close the valve.

10. The same-well water injection and gas production process of the same-well water injection and gas production system according to claim 5, characterized in that: The following steps are involved: S1. Upstroke: The power fluid circulation system injects the power fluid in the storage tank (23) from the oil pipe (10) into the hydraulic chamber composed of the upper large pump barrel (12), the upper small pump barrel (13), the upper large plunger (14) and the upper small plunger (15), pushing the upper large plunger (14) and the upper small plunger (15) upward, the pressure in the upper end of the upper large pump barrel (12) increases, and the liquid enters the injection layer (1) from the bridge injection joint (20). At the same time, the hollow connecting rod (11) at the bottom of the upper small plunger (15) moves upward, and the hollow connecting rod (11) drives the lower plunger pump upward, and the pressure in the suction chamber of the lower plunger pump decreases, the floating valve (8) closes, and under the action of the sinking pressure, the fixed valve (7) opens, and the fluid of the production layer (2) enters the gas-liquid separator (3), and the separated liquid flows into the suction chamber, completing the liquid suction. At the same time, the separated gas moves upward along the exhaust pipe (6) and is discharged to the ground; S2, down stroke: when the upper large plunger (14) and the upper small plunger (15) reach the top dead center, the power fluid circulation system draws the power fluid in the oil pipe (10) out of the oil pipe (10), the upper large plunger (14) and the upper small plunger (15) move downward, and the hollow connecting rod (11) pushes the lower plunger pump downward, the pressure in the suction chamber of the lower plunger pump increases, the fixed valve (7) closes, the floating valve (8) opens, and the liquid in the suction chamber is discharged along the flow channel into the upper chamber of the upper large pump barrel (12); S3, repeating the above S1 and S2 processes to perform water injection and gas production.

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