A double-acting closed-loop liquid-driven rodless drainage gas production system

Abstract

This invention discloses a double-acting closed-loop fluid-driven rodless drainage gas production system, relating to the field of oilfield oil and gas lift equipment technology. It includes a surface power system, a downhole double-acting pump unit, and a skid-mounted unit. The surface power system includes a screw pump and a drive motor, which drives the screw pump to rotate forward and backward to reverse the direction of the power fluid. A wellhead sealing device is installed at the top of the downhole double-acting pump unit. The downhole double-acting pump unit includes a double-acting pump, with a central pipe and tubing connected at the top. During the upward stroke of the double-acting pump, the spent power fluid and produced fluid are discharged through the central pipe; during the downward stroke, the spent power fluid and produced fluid are discharged through the tubing. This invention utilizes the forward and reverse rotation of the screw pump to reverse the direction of the power fluid, eliminating the need for a reversing valve device and improving the reliability of the power system. By using a downhole double-acting pump unit, produced fluid is discharged from the wellbore during both the upward and downward strokes, increasing the pump's displacement and operating efficiency while enabling the surface power system to form a closed loop.

Description

Technical Field

[0001] This invention relates to the field of oilfield oil and gas lift equipment technology, and in particular to a double-acting closed-loop circulating liquid-driven rodless drainage gas production system. Background Technology

[0002] Currently, the most widely used drainage and gas production technology in coalbed methane and shale gas wells is the rod pump system. This system relies on a surface power unit for power and connects to a pump at the bottom of the well via a sucker rod to achieve drainage and gas production. The advantages of this technology are its simple structure and stable operation. However, it is only suitable for vertical or shallowly deviated wells. If applied to directional or horizontal wells, the sucker rod and tubing will experience uneven wear, leading to frequent maintenance in a short period, resulting in reduced production and significantly increased maintenance costs. Since coalbed methane wells are mostly directional or horizontal wells, the pump needs to be installed in steeply deviated or horizontal sections. Furthermore, as development progresses, the formation water and gas production in coalbed methane and shale gas wells fluctuate greatly, and the rod pump system cannot intelligently adjust the drainage volume.

[0003] To address the aforementioned issues and meet the diverse drainage and production process requirements of coalbed methane and shale gas wells, the hydraulically driven rodless drainage and gas production system has emerged as a novel drainage and production technology and has been applied in oilfields. For example, CN211692416U discloses a hydraulically driven rodless drainage and gas production device and a two-position four-way reversing valve. The power fluid, after being pressurized by a high-pressure water pump, alternately enters the central pipe and tubing through two different flow channels controlled by the hydraulic station, driving the downhole plunger pump to perform up-and-down reciprocating motion to achieve the purpose of draining formation produced fluid. However, the inventors discovered several issues: First, the system is open-type, meaning there is an open water tank on the surface. The power fluid, waste power fluid, and produced fluid all need to enter the water tank first, and then be output through different pipelines. A small amount of natural gas carried in the produced fluid will be directly released into the atmosphere, which does not meet the environmental protection and safety requirements of the well site. Second, because the produced water is used directly as the power fluid, there are no mature two-position four-way directional valves suitable for water media on the market. This causes the valve core of the directional valve to wear out severely in a short period of time, requiring regular maintenance and replacement, which increases the workload and cost of maintenance. Third, the plunger pump at the bottom of the well is a single-acting pump. During one stroke, only the upper stroke discharges produced fluid from the wellbore, and no produced fluid is discharged from the wellbore during the lower stroke. The load is very small, resulting in large pressure fluctuations in the power fluid during the upper and lower strokes and low efficiency. Fourth, due to limitations in casing size and the inability to use excessively high power fluid pressure, large-diameter oil pumps cannot be used at the bottom of the well, resulting in oil pumps that cannot meet the requirements for large displacement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a double-acting closed-loop fluid-driven rodless drainage gas production system. A screw pump system is used as the power source on the surface, utilizing the forward and reverse rotation of the screw pump to achieve the reversal of the power fluid, eliminating the need for a reversing valve and improving the reliability of the power system. Furthermore, a downhole double-acting pump unit is employed, with produced fluid discharged from the wellbore during both the upper and lower strokes, increasing the pump's displacement and operating efficiency. The produced fluid from the upper and lower strokes of the double-acting pump is discharged to the surface through separate channels via a central pipe and tubing, eliminating the need for an open water tank on the surface. Simultaneously, this enables the surface power system to form a closed loop.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] An embodiment of the present invention provides a double-acting closed-loop liquid-driven rodless drainage gas extraction system, comprising:

[0007] The ground power system includes a screw pump and a drive motor, wherein the drive motor is used to drive the screw pump to rotate in both directions to change the direction of the power fluid; the screw pump has a first screw pump port at one end near the drive motor and a second screw pump port at the other end;

[0008] A downhole dual-acting pump unit with a wellhead sealing device installed at its top. The downhole dual-acting pump unit includes a dual-acting pump, and the top of the dual-acting pump is connected to a central pipe and an oil pipe, with the oil pipe coaxially arranged on the outside of the central pipe.

[0009] The skid-mounted cabinet includes a first gas-liquid separation device and a second gas-liquid separation device. The first gas-liquid separation device is connected between the first interface of the screw pump and the wellhead sealing device, and the second gas-liquid separation device is connected between the second interface of the screw pump and the wellhead sealing device.

[0010] During the upward stroke of the double-acting pump, the waste fluid and produced fluid are discharged through the central pipe, and during the downward stroke of the double-acting pump, the waste fluid and produced fluid are discharged through the oil pipe.

[0011] As a further implementation, when the screw pump rotates forward, the first port of the screw pump serves as a low-pressure suction port, and the second port of the screw pump serves as a high-pressure output port; the produced fluid and the waste power fluid discharged from the central pipe enter through the first port of the screw pump, and after being pressurized by the screw pump, they are output as power fluid from the second port of the screw pump into the oil pipe to drive the double-acting pump to achieve the upper stroke;

[0012] When the screw pump reverses, the second port of the screw pump serves as a low-pressure suction port, and the first port of the screw pump serves as a high-pressure output port. The produced fluid and the waste power fluid discharged from the oil pipe enter through the second port of the screw pump, and after being pressurized by the screw pump, they are output as power fluid from the first port of the screw pump into the central pipe to drive the double-acting pump to achieve the next stroke.

[0013] As a further implementation, the skid-mounted cabinet is provided with a first skid-mounted cabinet interface and a second skid-mounted cabinet interface on one side, and a third skid-mounted cabinet interface, a fourth skid-mounted cabinet interface and a fifth skid-mounted cabinet interface on the other side.

[0014] The first interface of the skid-mounted cabinet is connected to the first interface of the screw pump, and a first check valve, a first gas-liquid separator and a first electromagnetic shut-off valve are sequentially connected between the first interface and the third interface of the skid-mounted cabinet; a second check valve is connected between the output end of the first check valve and the output end of the first electromagnetic shut-off valve.

[0015] As a further implementation, the second interface of the skid-mounted cabinet is connected to the second interface of the screw pump, and a third check valve, a second gas-liquid separation device, and a fourth electromagnetic shut-off valve are sequentially connected between the second interface of the screw pump and the fifth interface of the skid-mounted cabinet; the fourth check valve is connected between the input end of the third check valve and the output end of the fourth electromagnetic shut-off valve.

[0016] As a further implementation, the first gas-liquid separation device and the second gas-liquid separation device each include an outer cylinder and a central cylinder fixed inside the outer cylinder. The top of the outer cylinder is provided with a first interface for the gas-liquid separation device, and the two sides of the outer cylinder are symmetrically provided with a second interface for the gas-liquid separation device and a third interface for the gas-liquid separation device.

[0017] The central cylinder is provided with a side connector, which is connected to the third interface of the gas-liquid separator.

[0018] As a further implementation, a second electromagnetic shut-off valve is connected between the fourth interface of the skid-mounted cabinet and the first interface of the first gas-liquid separator, and a third electromagnetic shut-off valve is connected between the fourth interface of the skid-mounted cabinet and the first interface of the second gas-liquid separator.

[0019] The fourth interface of the skid-mounted cabinet is connected to the third electromagnetic shut-off valve, and one end of the shut-off valve is connected to the water inlet.

[0020] As a further implementation, the double-acting pump includes a pump barrel assembly and a plunger assembly, with the plunger assembly located inside the pump barrel assembly.

[0021] As a further implementation, the pump assembly includes an outer tube, inside which is provided an inlet pipe. The bottom ends of both the outer tube and the inlet pipe are connected to the top end of a double-connector, and the bottom end of the double-connector is connected to a second inlet valve cover.

[0022] The top of the inlet pipe is connected in sequence to a sealed pump cylinder and a power pump cylinder, and a central pipe connector is installed at the top of the power pump cylinder; a drainage pump cylinder is provided inside the inlet pipe, and the bottom of the drainage pump cylinder is connected to a first inlet valve cover, and a first drainage valve cover is provided inside the drainage pump cylinder.

[0023] As a further implementation, the plunger assembly includes a power plunger, the bottom of which is connected to a second drain valve cover via a sealing plunger; the bottom end of the second drain valve cover is connected to the top end of the drain plunger, and the top and bottom ends of the drain plunger are not connected.

[0024] The dual-port connector is provided with a first channel and a second channel, the top of the first drain valve cover is provided with a third channel, and the side is provided with a fourth channel.

[0025] As a further implementation, a first drain valve is provided inside the first drain valve cover, a second drain valve is provided inside the second drain valve cover, a first inlet valve is provided inside the first inlet valve cover, and a second inlet valve is provided inside the second inlet valve cover.

[0026] The power plunger and the power pump barrel form two power hydraulic chambers, and the drainage plunger and the drainage pump barrel form two drainage pump chambers.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) This invention uses a screw pump system on the ground as a power source and uses the forward and reverse rotation of the screw pump to realize the reversal of the power fluid. There is no need to use a reversing valve device on the ground, which improves the working reliability of the system. The downhole unit uses a double-acting pump as a pumping pump. Under the same pump diameter as the single-acting pump, the upper and lower stroke loads and power fluid pressure tend to be close, which not only increases the pumping capacity, but also improves the pumping efficiency.

[0029] (2) The double-acting pump of the present invention enables the produced fluid of the upper and lower strokes to be discharged to the ground through different channels, eliminating the need for an open water tank on the ground. During the upper stroke of the double-acting pump, the produced fluid of the first pump chamber and the waste fluid in the central pipe are discharged to the ground through the central pipe. A portion of the waste fluid is directly pressurized by the screw pump through the first interface of the screw pump and used as the driving fluid for the upper stroke, while the excess portion enters the drainage network. During the lower stroke of the double-acting pump, the produced fluid of the second pump chamber and the waste fluid in the oil pipe are discharged to the ground through the oil pipe. A portion of the waste fluid is directly pressurized by the screw pump through the second interface of the screw pump and used as the driving fluid for the lower stroke, while the excess portion enters the drainage network. Therefore, the produced fluid can avoid being exposed to the air, thereby achieving a closed-loop circulation. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0031] Figure 1 This is a schematic diagram of the system's travel according to one or more embodiments of the present invention;

[0032] Figure 2This is a schematic diagram of the system under one or more embodiments of the present invention;

[0033] Figure 3 This is a schematic diagram of a double-acting pump structure according to one or more embodiments of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the first gas-liquid separation device according to one or more embodiments of the present invention.

[0035] Among them, 1. screw pump, 2. drive motor, 3. skid-mounted cabinet, 4. center tube, 5. tubing, 6. casing, 7. sealing device, 8. double-acting pump, 9. wellhead seal, 10. wellhead four-way valve, 11. upper stroke high-pressure power fluid, 12. upper stroke produced fluid and waste power fluid, 13. second drainage pump chamber fluid inlet, 14. lower stroke high-pressure power fluid, 15. lower stroke produced fluid and waste power fluid, 16. first drainage pump chamber fluid inlet, 17. produced gas;

[0036] 101. Screw pump first interface; 102. Screw pump second interface; 301. Skid-mounted cabinet first interface; 302. Skid-mounted cabinet second interface; 303. Skid-mounted cabinet third interface; 304. Skid-mounted cabinet fourth interface; 305. Skid-mounted cabinet fifth interface; 306. Water inlet; 307. Shut-off valve; 308. First check valve; 309. Second check valve; 310. Third check valve; 311. Fourth check valve; 312. First gas-liquid separator; 313. Second gas-liquid separator; 314. First electromagnetic shut-off valve; 315. Second electromagnetic shut-off valve; 316. Third electromagnetic shut-off valve; 317. Fourth electromagnetic shut-off valve;

[0037] 312-1. Outer cylinder; 312-2. Central cylinder; 312-3. Side connector; 312-4. First interface of the first gas-liquid separator; 312-5. Second interface of the first gas-liquid separator; 312-6. Third interface of the first gas-liquid separator; 313-1. First interface of the second gas-liquid separator; 313-2. Second interface of the second gas-liquid separator; 313-3. Third interface of the second gas-liquid separator.

[0038] 801. Central pipe connector, 802. Outer pipe, 803. Power pump barrel, 804. Sealed pump barrel, 805. Drainage pump barrel, 806. Inlet pipe, 807. First drain valve cover, 808. First drain valve, 809. First inlet valve cover, 810. First inlet valve, 811. Double-way connector, 812. Second inlet valve cover, 813. Second inlet valve, 814. Power plunger, 815. Sealed plunger, 816. Second drain valve cover, 817. Second drain valve, 818. Drainage plunger, 819. Second power hydraulic chamber, 820. First power hydraulic chamber, 821. First drainage pump chamber, 822. Second drainage pump chamber;

[0039] 803-1. First through hole, 805-1. Second through hole, 807-1. Third channel, 807-2. Fourth channel, 811-1. First channel, 811-2. Second channel, 815-1. Third through hole;

[0040] 901. Wellhead sealing first interface; 902. Wellhead sealing second interface; 1001. Wellhead four-way interface. Detailed Implementation

[0041] Example 1:

[0042] In a typical embodiment of the present invention, such as Figures 1-4 As shown, a double-acting closed-loop liquid-driven rodless drainage gas production system is presented.

[0043] Because existing hydraulically driven rodless drainage gas production devices are usually open-type, they do not meet the environmental protection and safety requirements of the well site; and directly using produced water as the power fluid can easily lead to severe wear of the valve core of the reversing valve in a short period of time, increasing maintenance workload and costs; the plunger pump at the bottom of the well is a single-acting pump, which results in large pressure changes in the upper and lower strokes of the power fluid and low efficiency; at the same time, its oil pump cannot meet the requirements of large displacement.

[0044] Based on this, this embodiment provides a double-acting closed-loop circulating fluid-driven rodless drainage gas production system. A screw pump system is used as the power source on the surface, utilizing the forward and reverse rotation of the screw pump to achieve the reversal of the power fluid, eliminating the need for a surface reversing valve device and improving the operational reliability of the power system. The downhole unit is designed with a double-acting pump structure, with produced fluid discharged from the wellbore during both the upper and lower strokes, increasing the pump's displacement and operating efficiency. Furthermore, the produced fluid from the upper and lower strokes of the double-acting pump is discharged to the surface through different channels via a central pipe and tubing, eliminating the need for an open water tank on the surface. During the upper stroke of the double-acting pump, a portion of the waste power fluid and produced fluid discharged to the surface through the central pipe is directly pressurized by the screw pump and used as the power fluid for the upper stroke, while the excess enters the external transmission pipeline network. Similarly, during the lower stroke of the double-acting pump, a portion of the waste power fluid and produced fluid discharged to the surface through the tubing is directly pressurized by the screw pump and used as the power fluid for the lower stroke, while the excess enters the external transmission pipeline network. Therefore, the fluid discharged from the wellbore is not exposed to the atmosphere, and the surface power system achieves a closed loop.

[0045] The above-mentioned drainage gas extraction system will now be described in detail with reference to the accompanying drawings.

[0046] like Figure 1 and Figure 2 As shown, the drainage and gas production system includes a surface power system, a downhole dual-acting pump unit, a skid-mounted cabinet 3, and a wellhead sealing device.

[0047] Specifically, the ground power system, i.e., the screw pump system, includes a drive motor 2 and a screw pump 1. The drive motor 2 is connected to the screw pump 1 and is used to drive the screw pump 1 to run, causing the rotor of the screw pump 1 to rotate within the stator of the screw pump 1. A first screw pump interface 101 is provided at one end of the screw pump 1 closest to the drive motor 2, and a second screw pump interface 102 is provided at the other end. The skid-mounted cabinet 3 is connected through the first screw pump interface 101 and the second screw pump interface 102.

[0048] When screw pump 1 rotates forward, the first port 101 of the screw pump serves as a low-pressure suction port, and the second port 102 of the screw pump serves as a high-pressure output port. The produced liquid and the waste fluid enter through the low-pressure suction port, are pressurized by screw pump 1, and are output as power fluid through the high-pressure output port. When screw pump 1 rotates in reverse, the second port 102 of the screw pump serves as a low-pressure suction port, and the first port 101 of the screw pump serves as a high-pressure output port. The produced liquid and the waste fluid enter through the low-pressure suction port, are pressurized by screw pump 1, and are output as power fluid through the high-pressure output port.

[0049] The skid-mounted cabinet 3 includes reserved interfaces, check valves, gas-liquid separators, electromagnetic shut-off valves, shut-off valve 307, and water inlet 306. Five reserved interfaces are provided: skid-mounted cabinet first interface 301, skid-mounted cabinet second interface 302, skid-mounted cabinet third interface 303, skid-mounted cabinet fourth interface 304, and skid-mounted cabinet fifth interface 305. Four check valves are provided: first check valve 308, second check valve 309, third check valve 310, and fourth check valve 311. Two gas-liquid separators are provided: first gas-liquid separator 312 and second gas-liquid separator 313. Four electromagnetic shut-off valves are provided: first electromagnetic shut-off valve 314, second electromagnetic shut-off valve 315, third electromagnetic shut-off valve 316, and fourth electromagnetic shut-off valve 317. The skid-mounted cabinet 3 also includes high-pressure pipelines connecting the various components.

[0050] In this embodiment, the first interface 301 and the second interface 302 of the skid-mounted cabinet are located on one side of the skid-mounted cabinet 3, and the third interface 303, the fourth interface 304 and the fifth interface 305 of the skid-mounted cabinet are located on the other side of the skid-mounted cabinet 3.

[0051] like Figure 1 and Figure 2 As shown, a first one-way valve 308, a first gas-liquid separator 312, and a first electromagnetic shut-off valve 314 are sequentially arranged between the first interface 301 and the third interface 303 of the skid-mounted cabinet. Adjacent components are connected by high-pressure pipelines. The output end of the first one-way valve 308 is connected to the first interface 301 of the skid-mounted cabinet, the input end of the first one-way valve 308 is connected to the second interface 312-5 of the first gas-liquid separator, and the third interface 312-6 of the first gas-liquid separator is connected to the first electromagnetic shut-off valve 314.

[0052] The input end of the second one-way valve 309 is connected between the first interface 301 of the skid-mounted cabinet and the output end of the first one-way valve 308. The output end of the second one-way valve 309 is connected between the first electromagnetic shut-off valve 314 and the third interface 303 of the skid-mounted cabinet. The second electromagnetic shut-off valve 315 is connected between the first interface 312-4 of the first gas-liquid separator and the fourth interface 304 of the skid-mounted cabinet.

[0053] Between the second interface 302 and the fifth interface 305 of the skid-mounted cabinet, a third one-way valve 310, a second gas-liquid separator 313 and a fourth electromagnetic shut-off valve 317 are sequentially arranged, and adjacent components are connected by high-pressure pipelines; the output end of the third one-way valve 310 is connected to the second interface 302 of the skid-mounted cabinet, the input end of the third one-way valve 310 is connected to the second interface 313-2 of the second gas-liquid separator, and the third interface 313-3 of the second gas-liquid separator is connected to the fourth electromagnetic shut-off valve 317.

[0054] The input end of the fourth one-way valve 311 is connected between the second port 302 of the skid-mounted cabinet and the output end of the third one-way valve 310, and the output end is connected between the fourth solenoid shut-off valve 317 and the fifth port 305 of the skid-mounted cabinet. The third solenoid shut-off valve 316 is connected between the first port 313-1 of the second gas-liquid separator and the fourth port 304 of the skid-mounted cabinet. One end of the shut-off valve 307 is connected between the third solenoid shut-off valve 316 and the fourth port 304 of the skid-mounted cabinet, and the other end is connected to the water inlet 306; the water inlet 306 is used to fill the high-pressure pipeline with water before the system is started.

[0055] like Figure 4 As shown, the first gas-liquid separation device 312 includes an outer cylinder 312-1, a central cylinder 312-2, and a side connector 312-3. The central cylinder 312-2 is located at the center inside the outer cylinder 312-1, and its height is lower than that of the outer cylinder 312-1. The upper end of the outer cylinder 312-1 is provided with a first interface 312-4 for the first gas-liquid separation device, and two interfaces are symmetrically arranged on both sides of its lower part, namely a second interface 312-5 and a third interface 312-6 for the first gas-liquid separation device. The bottom end of the central cylinder 312-2 is fixedly connected to the bottom end of the outer cylinder 312-1, and the lower side of the central cylinder 312-2 is connected to the side connector 312-3, which is connected to the third interface 312-6 of the first gas-liquid separation device.

[0056] When the gas-liquid mixture discharged from the wellbore through the central pipe 4 enters through the third port 312-6 of the first gas-liquid separator, it moves upward along the inside of the central pipe 312-2 and completes gas-liquid separation at the top of the outer pipe 312-1. The liquid then flows downward along the annulus between the outer pipe 312-1 and the central pipe 312-2 and is output from the second port 312-5 of the first gas-liquid separator.

[0057] The second gas-liquid separation device 313 has the same structure as the first gas-liquid separation device 312, and includes a first interface 313-1, a second interface 313-2, and a third interface 313-3.

[0058] like Figure 1 and Figure 2 As shown, the downhole dual-acting pump unit includes a central pipe 4, an oil pipe 5, a sealing device 7, and a dual-acting pump 8. The top of the dual-acting pump 8 is connected to the wellhead sealing device through the oil pipe 5. The central pipe 4 passes through the wellhead sealing device and the oil pipe 5 in sequence, and the bottom of the central pipe 4 is connected to the top of the dual-acting pump 8 through the sealing device 7.

[0059] like Figure 3 As shown, the double-acting pump 8 includes a pump barrel assembly and a plunger assembly. The pump barrel assembly includes an outer tube 802, and an inlet pipe 806 is provided inside the outer tube 802. The bottom end of the outer tube 802 and the bottom end of the inlet pipe 806 are both connected to the top end of a double-connector 811. The bottom end of the double-connector 811 is connected to a second inlet valve cover 812. The top end of the inlet pipe 806 is sequentially connected to a sealed pump barrel 804 and a power pump barrel 803. A center pipe connector 801 is installed at the top end of the power pump barrel 803.

[0060] The inlet pipe 806 is equipped with a drainage pump cylinder 805. The bottom end of the drainage pump cylinder 805 is connected to the top end of the first inlet valve cover 809. The bottom end of the first inlet valve cover 809 is connected to the top end of the double-connector 811. The top end of the drainage pump cylinder 805 is connected to the bottom end of the sealing pump cylinder 804. The drainage pump cylinder 805 is equipped with a first drain valve cover 807, which is located above the first inlet valve cover 809.

[0061] The plunger assembly is integrally housed within the pump barrel assembly. The plunger assembly includes a power plunger 814, which has an open top and a bottom end connected to the top of a sealing plunger 815. The bottom end of the sealing plunger 815 is connected to the top of a second drain valve cover 816, and the bottom end of the second drain valve cover 816 is connected to the top of a discharge plunger 818. The top and bottom ends of the discharge plunger 818 are not connected.

[0062] The first drain valve cover 807 houses the first drain valve 808, the second drain valve cover 816 houses the second drain valve 817, the first inlet valve cover 809 houses the first inlet valve 810, and the second inlet valve cover 812 houses the second inlet valve 813. All three valves—the first drain valve 808, the second drain valve 817, the first inlet valve 810, and the second inlet valve 813—are one-way valves; they are open when the valve is raised and set when it is lowered.

[0063] Furthermore, the power pump cylinder 803 has a first through hole 803-1 in the lower circumferential direction; the drainage pump cylinder 805 has a second through hole 805-1 in the upper circumferential direction; the double-connector 811 has a first channel 811-1 and a second channel 811-2. The first drain valve cover 807 has a third channel 807-1 at the top and a fourth channel 807-2 on the side.

[0064] The power plunger 814 and the power pump barrel 803 are clearance-fitted, the sealing plunger 815 and the sealing pump barrel 804 are clearance-fitted, and the discharge plunger 818 and the discharge pump barrel 805 are clearance-fitted. The power plunger 814 and the power pump barrel 803 form two power hydraulic chambers: the upper chamber of the power plunger 814 is the second power hydraulic chamber 819, and the lower chamber of the power plunger 814 is the first power hydraulic chamber 820. The discharge plunger 818 and the discharge pump barrel 805 form two discharge pump chambers: the upper chamber of the discharge plunger 818 is the first discharge pump chamber 821, and the lower chamber of the discharge plunger 818 is the second discharge pump chamber 822. The plunger assembly, through the alternating action of the power hydraulic fluid in the first power hydraulic chamber 820 and the second power hydraulic chamber 819, can reciprocate up and down within the pump barrel assembly.

[0065] In this embodiment, the cross-sectional areas of the power plunger 814 and the discharge plunger 818 are both larger than the cross-sectional area of ​​the sealing plunger 815.

[0066] The wellhead sealing device includes a wellhead four-way 10 and a wellhead sealing element 9. The bottom end of the wellhead four-way 10 is connected to the casing 6. A wellhead four-way interface 1001 is provided on one side of the wellhead four-way 10, which is connected to the venting network. The bottom end of the wellhead sealing element 9 is connected to the tubing 5. A first wellhead sealing interface 901 is provided at the top of the wellhead sealing element 9, and a second wellhead sealing interface 902 is provided on the side of the wellhead sealing element 9.

[0067] The top end of the tubing 5 is connected to the wellhead seal 9, and the wellhead cross 10 is installed at the junction of the wellhead seal 9 and the tubing 5; and the connection section between the tubing 5 and the wellhead seal 9 forms a flared structure.

[0068] like Figure 1 and Figure 2 As shown, the first interface 101 of the screw pump is connected to the first interface 301 of the skid-mounted cabinet via a high-pressure pipeline; the second interface 102 of the screw pump is connected to the second interface 302 of the skid-mounted cabinet via a high-pressure pipeline; the third interface 303 of the skid-mounted cabinet is connected to the first interface 901 of the wellhead seal via a high-pressure pipeline; the fifth interface 305 of the skid-mounted cabinet is connected to the second interface 902 of the wellhead seal via a high-pressure pipeline; the fourth interface 304 of the skid-mounted cabinet is connected to the drainage network via a high-pressure pipeline; and the four-way interface 1001 of the wellhead is connected to the exhaust network via a high-pressure pipeline.

[0069] The working principle of the double-acting closed-loop liquid-driven rodless drainage gas production system in this embodiment is as follows:

[0070] Before system startup: Shut-off valve 307, first solenoid shut-off valve 314, second solenoid shut-off valve 315, third solenoid shut-off valve 316, and fourth solenoid shut-off valve 317 are in the open state. Water is injected from the water inlet 306 until the high-pressure pipeline is full. After water injection is completed, shut-off valve 307 is in the normally closed state.

[0071] The system is running normally: such as Figure 1 As shown, during the upward stroke, the third solenoid shut-off valve 316 and the fourth solenoid shut-off valve 317 are closed, while the first solenoid shut-off valve 314 and the second solenoid shut-off valve 315 are open. The drive motor 2 drives the screw pump 1 to rotate forward. At this time, the first port 101 of the screw pump serves as a low-pressure inlet, and the second port 102 of the screw pump serves as a high-pressure outlet. The power fluid is pressurized by the screw pump 1 and output from the second port 102 of the screw pump. After passing through the second port 302 of the skid-mounted cabinet, the third check valve 310 is blocked, and the fluid passes sequentially through the fourth check valve 311, the fifth port 305 of the skid-mounted cabinet, and the wellhead seal. After interface 902, the upper stroke high-pressure power fluid 11 reaches the first power fluid chamber 820 through the first through hole 803-1. The upper stroke high-pressure power fluid 11 acts on the annular cross section of the power plunger 814 and the sealing plunger 815, driving the plunger assembly to move upward. At this time, the first drain valve 808 and the second inlet valve 813 are closed, and the second drain valve 817 and the first inlet valve 810 are opened. The second drainage pump chamber inlet fluid 13 enters the second drainage pump chamber 822 after passing through the second channel 811-2, the first inlet valve 810 and the fourth channel 807-2 in sequence, completing the liquid inlet process of the second drainage pump chamber 822.

[0072] Simultaneously, the liquid in the first production pump chamber 821 enters the central pipe 4 through the third through hole 815-1 and the second discharge valve 817, completing the discharge process of the first production pump chamber 821. The waste power fluid in the second power fluid chamber 819 enters the central pipe 4. The upper stroke produced fluid and waste power fluid 12 pass through the central pipe 4 and the wellhead sealing first interface 901 in sequence, and enter the skid-mounted cabinet third interface 303 through the high-pressure pipeline. The second one-way valve 309 is closed, and the liquid passes through the first electromagnetic shut-off valve 314 and the first gas-liquid separator third interface 312-6 in sequence, entering the first gas-liquid separator 312 to complete the gas-liquid separation. A portion of the upstream produced liquid and the waste power liquid 12 pass through the second interface 312-5 of the first gas-liquid separator, and then through the first one-way valve 308, the first interface 301 of the skid-mounted cabinet, and the first interface 101 of the screw pump, entering the screw pump 1 as the power liquid for the upstream stroke of the system; another portion of the upstream produced liquid and the waste power liquid 12, along with the gas at the top of the first gas-liquid separator 312, pass through the first interface 312-4 of the first gas-liquid separator, and then sequentially through the second electromagnetic shut-off valve 315 and the fourth interface 304 of the skid-mounted cabinet into the drainage network.

[0073] like Figure 2 As shown, during the downward stroke, the first solenoid shut-off valve 314 and the second solenoid shut-off valve 315 are closed, while the third solenoid shut-off valve 316 and the fourth solenoid shut-off valve 317 are open. The drive motor 2 drives the screw pump 1 to reverse. At this time, the second port 102 of the screw pump serves as the low-pressure inlet, and the first port 101 of the screw pump serves as the high-pressure outlet. The power fluid is pressurized by the screw pump 1 and output from the first port 101 of the screw pump. After passing through the first port 301 of the skid-mounted cabinet, the first check valve 308 is closed, and the fluid passes sequentially through the second check valve 309 and the third port 301 of the skid-mounted cabinet. After the wellhead seal 901 is completed, the high-pressure power fluid 14 in the lower stroke reaches the second power fluid chamber 819. The high-pressure power fluid 14 in the lower stroke acts on the cross section of the power plunger 814, driving the plunger assembly downward. At this time, the second drain valve 817 and the first inlet valve 810 are closed, and the first drain valve 808 and the second inlet valve 813 are opened. The first drainage pump chamber fluid 16 enters the first drainage pump chamber 821 after passing through the second inlet valve 813, the first channel 811-1 and the second through hole 805-1 in sequence, completing the fluid intake process of the first drainage pump chamber 821.

[0074] Simultaneously, the liquid in the second production pump chamber 822 sequentially enters the annular space between the central tube 4 and the tubing 5 through the fourth channel 807-2, the first discharge valve 808, and the third channel 807-1, completing the discharge process of the second production pump chamber 822. The waste power fluid in the first power fluid chamber 820 enters the annular space between the central tube 4 and the tubing 5 through the first through hole 803-1. The downstream produced fluid and the waste power fluid 15 sequentially pass through the annular space between the central tube 4 and the tubing 5, the wellhead sealing second interface 902, and enter the skid-mounted cabinet fifth interface 305 through the high-pressure pipeline. The fourth one-way valve 311 is closed, and the liquid enters the second gas-liquid separator 313 through the fourth electromagnetic shut-off valve 317 and the third interface 313-3 of the second gas-liquid separator, completing the gas-liquid separation. A portion of the downstream product fluid and the waste power fluid 15 pass through the second interface 313-2 of the second gas-liquid separator, and then through the third check valve 310, the second interface 302 of the skid-mounted cabinet, and the second interface 102 of the screw pump, entering the screw pump 1 as the power fluid for the downstream stroke of the system; another portion of the downstream product fluid and the waste power fluid 15, along with the gas at the top of the second gas-liquid separator 313, pass through the first interface 313-1 of the second gas-liquid separator, and then sequentially through the third electromagnetic shut-off valve 316 and the fourth interface 304 of the skid-mounted cabinet into the drainage network.

[0075] By continuously rotating forward and reverse, the screw pump 1 drives the downhole double-acting pump 8 to continuously lift the liquid in the casing 6 to the surface, causing the liquid level in the casing 6 to drop. When the liquid level in the casing 6 drops to a certain level, gas production begins in the casing 6, and the produced gas 17 enters the exhaust pipe network through the wellhead four-way interface 1001.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A double-acting closed-loop liquid-driven rodless drainage gas extraction system, characterized in that, include: The ground power system includes a screw pump and a drive motor, wherein the drive motor is used to drive the screw pump to rotate in both directions to change the direction of the power fluid; the screw pump has a first screw pump port at one end near the drive motor and a second screw pump port at the other end; A downhole dual-acting pump unit with a wellhead sealing device installed at its top. The downhole dual-acting pump unit includes a dual-acting pump, and the top of the dual-acting pump is connected to a central pipe and an oil pipe, with the oil pipe coaxially arranged on the outside of the central pipe. The skid-mounted cabinet includes a first gas-liquid separation device and a second gas-liquid separation device. The first gas-liquid separation device is connected between the first interface of the screw pump and the wellhead sealing device, and the second gas-liquid separation device is connected between the second interface of the screw pump and the wellhead sealing device. During the upper stroke of the double-acting pump, the waste fluid and produced fluid are discharged through the central pipe, and during the lower stroke of the double-acting pump, the waste fluid and produced fluid are discharged through the oil pipe. The double-acting pump includes a pump barrel assembly and a plunger assembly, with the plunger assembly located inside the pump barrel assembly. The pump barrel assembly includes an outer tube, with an inlet pipe inside the outer tube. The bottom ends of both the outer tube and the inlet pipe are connected to the top end of a double-connector, and the bottom end of the double-connector is connected to a second inlet valve cover. A sealed pump barrel and a power pump barrel are sequentially connected to the top end of the inlet pipe, with a center pipe connector installed at the top end of the power pump barrel. A discharge pump barrel is located inside the inlet pipe, with its bottom end connected to a first inlet valve cover. A first discharge valve cover is located inside the discharge pump barrel. The plunger assembly includes a power plunger, the bottom of which is connected to a second drain valve cover via a sealing plunger; the bottom of the second drain valve cover is connected to the top of the drain plunger, and the top and bottom of the drain plunger are not connected; the double-port connector is provided with a first channel and a second channel, the top of the first drain valve cover is provided with a third channel, and the side is provided with a fourth channel; a first drain valve is provided inside the first drain valve cover, a second drain valve is provided inside the second drain valve cover, a first inlet valve is provided inside the first inlet valve cover, and a second inlet valve is provided inside the second inlet valve cover; The power plunger and the power pump barrel form two power hydraulic chambers, and the drainage plunger and the drainage pump barrel form two drainage pump chambers.

2. The double-acting closed-loop circulating liquid-driven rodless drainage gas extraction system according to claim 1, characterized in that, When the screw pump rotates forward, the first port of the screw pump serves as a low-pressure suction port, and the second port of the screw pump serves as a high-pressure output port. The produced fluid and the waste power fluid discharged from the central pipe enter through the first port of the screw pump, and after being pressurized by the screw pump, they are output as power fluid from the second port of the screw pump into the oil pipe to drive the double-acting pump to achieve the upper stroke. When the screw pump reverses, the second port of the screw pump serves as a low-pressure suction port, and the first port of the screw pump serves as a high-pressure output port. The produced fluid and the waste power fluid discharged from the oil pipe enter through the second port of the screw pump, and after being pressurized by the screw pump, they are output as power fluid from the first port of the screw pump into the central pipe to drive the double-acting pump to achieve the next stroke.

3. The double-acting closed-loop circulating liquid-driven rodless drainage gas extraction system according to claim 1, characterized in that, The skid-mounted cabinet is provided with a first skid-mounted cabinet interface and a second skid-mounted cabinet interface on one side, and a third skid-mounted cabinet interface, a fourth skid-mounted cabinet interface and a fifth skid-mounted cabinet interface on the other side. The first interface of the skid-mounted cabinet is connected to the first interface of the screw pump, and a first check valve, a first gas-liquid separator and a first electromagnetic shut-off valve are sequentially connected between the first interface and the third interface of the skid-mounted cabinet; a second check valve is connected between the output end of the first check valve and the output end of the first electromagnetic shut-off valve.

4. The double-acting closed-loop circulating liquid-driven rodless drainage gas extraction system according to claim 3, characterized in that, The second interface of the skid-mounted cabinet is connected to the second interface of the screw pump, and a third check valve, a second gas-liquid separator and a fourth electromagnetic shut-off valve are sequentially connected between the second interface of the screw pump and the fifth interface of the skid-mounted cabinet; the fourth check valve is connected between the input end of the third check valve and the output end of the fourth electromagnetic shut-off valve.

5. A double-acting closed-loop circulating liquid-driven rodless drainage gas extraction system according to claim 3 or 4, characterized in that, The first gas-liquid separation device and the second gas-liquid separation device each include an outer cylinder and a central cylinder fixed inside the outer cylinder. The top of the outer cylinder is provided with a first interface of the gas-liquid separation device, and the second interface and the third interface of the gas-liquid separation device are symmetrically arranged on both sides of the outer cylinder. The central cylinder is provided with a side connector, which is connected to the third interface of the gas-liquid separator.

6. A double-acting closed-loop circulating liquid-driven rodless drainage gas extraction system according to claim 5, characterized in that, A second electromagnetic shut-off valve is connected between the fourth interface of the skid-mounted cabinet and the first interface of the first gas-liquid separator, and a third electromagnetic shut-off valve is connected between the fourth interface of the skid-mounted cabinet and the first interface of the second gas-liquid separator. The fourth interface of the skid-mounted cabinet is connected to the third electromagnetic shut-off valve, and one end of the shut-off valve is connected to the water inlet.

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