Hydraulic drive underground motor pump assembly and gas production system

Abstract

The invention aims at providing a hydraulic drive underground motor pump assembly and a gas production system, the near end of a plunger assembly is located in a pipe cavity of an inner pipe of an upper double-layer pipe column and is in sliding sealing connection with the inner pipe of the upper double-layer pipe column, and the far end of the plunger assembly penetrates through a connector assembly, is located in an inner pipe of a lower double-layer pipe column and is located at the near end of a fixing valve; the connector assembly is in sliding sealing connection with the plunger assembly. A compression cavity is defined by the plunger assembly, the near end of the connector assembly and the inner pipe of the upper double-layer pipe column, and the inner pipe of the upper double-layer pipe column is provided with a flow guide hole communicating with the compression cavity and a gap between the inner pipe and the outer pipe of the upper double-layer pipe column. An inner pipe of the upper double-layer pipe column is communicated with an inner cavity of the plunger assembly, and the one-way valve assembly is located in a pipe cavity and / or at the end of the plunger assembly. According to the invention, the drainage and gas production problems of deep and large-displacement wells can be solved; and meanwhile, the problems of low mining efficiency, high cost, low reliability and short service life of the existing injection pump are solved.

Description

Technical Field

[0001] This invention relates to the field of downhole motor pump technology for deep coalbed methane extraction, and particularly to a hydraulically driven downhole motor pump assembly and gas extraction system. Background Technology

[0002] In deep coalbed methane (commonly known as gas) extraction operations, hydraulically driven downhole motor pumps are key underground drainage equipment. Their working principle involves using high-pressure hydraulic fluid generated at a surface pumping station, which is then transported underground through pipelines to drive the hydraulically driven downhole motor pump, extracting water from the coal seam and thus achieving drainage and gas extraction.

[0003] The core drawback of existing hydraulically driven downhole motor-pump assemblies lies in their excessively high requirements for the power hydraulic pressure driving the pump. With the increasing depth of coalbed methane extraction, especially in deep-ground mining scenarios, overcoming the enormous hydrostatic pressure and pipeline resistance in deep wells necessitates a significant increase in the power hydraulic pressure supplied from the surface to ensure the downhole motor-pump can operate normally and achieve the required pumping head. However, this demand for high pressure brings a series of problems: Limited capabilities of surface equipment: Conventional surface power equipment (such as high-pressure plunger pumps) has technical limitations in terms of output pressure. When the mining depth reaches a certain level, the required hydraulic pressure will exceed the rated operating pressure range of conventional equipment, making surface equipment expensive or unable to meet the process requirements of deep mining.

[0004] The manufacturing difficulty and cost of the equipment have increased dramatically: In order to meet the higher working pressure, it is necessary to develop and manufacture high-power ground power equipment and its supporting high-pressure manifold system that can withstand ultra-high pressure. This not only places extremely high demands on the strength and sealing performance of materials and the processing technology of the equipment, increasing the manufacturing difficulty exponentially, but also leads to a significant increase in equipment investment and operation and maintenance costs.

[0005] Reduced system reliability and service life: Under ultra-high pressure conditions, all components of the hydraulic drive system (including surface pumps, high-pressure pipelines, downhole motor seals, etc.) are subjected to extremely high alternating stress, which can easily lead to fatigue damage, seal failure, and abnormal wear. This significantly reduces the operational reliability and service life of the entire system, increases the frequency of equipment replacement and maintenance, and affects the continuity and economy of coalbed methane extraction. Summary of the Invention

[0006] The purpose of this invention is to provide a hydraulically driven downhole motor pump assembly and a gas production system to solve the problems of low extraction efficiency, high cost, low reliability, and short service life of existing hydraulically driven downhole motor pump assemblies and gas production systems, which are caused by excessive pressure of the power fluid required when the hydraulically driven downhole motor pump assembly is working.

[0007] To solve the above-mentioned technical problems, the present invention provides a hydraulically driven downhole motor pump assembly, including an upper double-layer tubing string, a plunger assembly, a connector assembly, a one-way valve assembly, a lower double-layer tubing string, and a fixed valve; the distal ends of the upper double-layer tubing string are respectively connected to the proximal ends of the connector assembly, the proximal ends of the lower double-layer tubing string are connected to the connector assembly, and the fixed valve is connected to the distal end of the inner tube of the lower double-layer tubing string; the proximal end of the plunger assembly is located within the cavity of the inner tube of the upper double-layer tubing string and is slidably sealed to the inner tube of the upper double-layer tubing string, and the distal end of the plunger assembly passes through the connector assembly and... Located within the inner tube of the lower double-layer tubing and near the fixed valve, the connector assembly is slidably and sealingly connected to the plunger assembly; the plunger assembly, the near end of the connector assembly, and the inner tube of the upper double-layer tubing form a compression chamber; the inner tube of the upper double-layer tubing has a guide hole that connects the compression chamber and the gap between the inner and outer tubes of the upper double-layer tubing; the inner tube of the upper double-layer tubing communicates with the inner cavity of the plunger assembly; the one-way valve assembly is disposed on the plunger assembly, and the one-way valve assembly is located within the cavity and / or at the end of the plunger assembly.

[0008] Optionally, the plunger assembly is slidably connected to the inner tube of the lower double-layer tubing, and an auxiliary cavity is formed between the connector assembly, the plunger assembly, and the inner tube of the lower double-layer tubing. A connecting hole is provided on the wall of the auxiliary cavity. One end of the connecting hole communicates with the auxiliary cavity, and the other end communicates with the inner cavity of the plunger assembly, and / or communicates with the gap between the inner tube of the lower double-layer tubing and the outer tube of the lower double-layer tubing.

[0009] Optionally, the plunger assembly includes a motor plunger, a hollow tie rod plunger, and a pump plunger connected sequentially from top to bottom. The motor plunger is slidably and sealingly connected to the inner tube of the upper double-layer tubing. The proximal end of the hollow tie rod plunger is located within the cavity of the inner tube of the upper double-layer tubing, and the distal end of the hollow tie rod plunger passes through the connector assembly and is located within the inner tube of the lower double-layer tubing. The hollow tie rod plunger is partially slidably and sealingly connected to the connector assembly. The pump plunger is located within the inner tube of the lower double-layer tubing and is slidably and sealingly connected to the inner tube of the lower double-layer tubing. The auxiliary cavity is formed between the connector assembly, the pump plunger, the hollow tie rod plunger, and the inner tube of the lower double-layer tubing. The other end of the connecting hole communicates with the inner cavity of the hollow tie rod plunger.

[0010] Optionally, the one-way valve assembly includes a drain valve and a traveling valve assembly, wherein the drain valve is located between the motor plunger and the hollow tie rod plunger, and the traveling valve assembly is located on the pump plunger.

[0011] Optionally, the traveling valve assembly includes an upstream traveling valve and a downstream traveling valve, wherein the upstream traveling valve is located between the proximal end of the pump plunger and the hollow tie rod plunger, and the downstream traveling valve is located at the distal end of the pump plunger.

[0012] Optionally, the distal end of the motor plunger is provided with a lower buffer, and the proximal end of the connector assembly is provided with a lower buffer cavity that mates with the lower buffer.

[0013] Optionally, it also includes a diverter, an inner connector assembly, and an outer connector. The inner connector assembly is disposed within the lumen of the outer connector, and an annular cavity is formed between the two. The proximal end of the diverter is connected to the inner connector assembly and the outer connector, and the distal end of the diverter is connected to the inner and outer tubes of the upper double-layer tubing, such that the gap between the inner and outer tubes of the upper double-layer tubing is in communication with the inner tube of the inner connector assembly, and the gap between the inner connector assembly and the outer connector is in communication with the lumen of the inner tube of the upper double-layer tubing.

[0014] Optionally, the internal connector assembly includes a setting connector and a setting tube head, the setting tube head being connected to the setting connector, and the setting connector being connected to the shunt connector.

[0015] Optionally, the distal end of the diverter is provided with an upper buffer chamber, and the proximal end of the motor plunger is provided with an upper buffer that cooperates with the upper buffer chamber.

[0016] The present invention also provides a gas production system, including a surface power system and the above-mentioned hydraulically driven downhole motor pump assembly, wherein the surface power system provides power fluid to the hydraulically driven downhole motor pump assembly.

[0017] The present invention provides a hydraulically driven downhole motor pump assembly and gas production system, which has the following beneficial effects: First, since the distal ends of the upper double-layer tubing are connected to the proximal ends of the connector assembly, and the proximal end of the plunger assembly is located within the cavity of the inner tube of the upper double-layer tubing and is slidably and sealingly connected to the inner tube of the upper double-layer tubing, the plunger assembly, the proximal ends of the connector assembly, and the inner tube of the upper double-layer tubing form a compression chamber. The inner tube of the upper double-layer tubing has a guide hole that connects the compression chamber to the gap between the inner and outer tubes of the upper double-layer tubing. Therefore, after injecting kinetic fluid between the inner and outer tubes of the upper double-layer tubing, the kinetic fluid can flow into the compression chamber through the guide hole from the gap between the inner and outer tubes of the upper double-layer tubing, thereby pushing the plunger assembly, which is slidably and sealingly connected to the inner tube of the upper double-layer tubing, to slide upwards, i.e., pushing the plunger assembly to move upwards. Because the proximal end of the lower double-layer tubing is connected to the connector assembly, the fixed valve is connected to the distal end of the inner tube of the lower double-layer tubing, and the distal end of the plunger assembly passes through the connector assembly and is located inside the inner tube of the lower double-layer tubing, and is located near the fixed valve, the connector assembly and the plunger assembly are in a sliding seal connection. The one-way valve assembly is disposed on the plunger assembly and is located inside the lumen and / or at the end of the plunger assembly. Therefore, when the plunger assembly moves upward, the volume of the working chamber formed by the inner tube of the lower double-layer tubing and the plunger assembly between the fixed valve and the one-way valve assembly increases, resulting in a decrease in pressure within the working chamber, making the pressure in the working chamber lower than the pressure at the bottom of the well. Therefore, the fixed valve opens, and gas and fluid from the bottom of the well enter the working chamber. Because the pressure in the working chamber is lower, the pressure of the fluid near the one-way valve assembly will also be greater than the pressure in the working chamber. Therefore, the one-way valve assembly remains closed, thereby achieving fluid extraction from the bottom of the well. Furthermore, after the power fluid is injected into the inner tube of the upper double-layer tubing, it flows in and compresses the plunger assembly downwards. This forces the power fluid in the compression chamber into the gap between the inner and outer tubes of the upper double-layer tubing and discharges it upwards. Simultaneously, the downward movement of the plunger assembly compresses the working chamber formed by the inner tube of the lower double-layer tubing and the plunger assembly between the fixed valve and the check valve assembly. This reduces the volume of the working chamber, resulting in a pressure greater than the bottom hole pressure and the pressure of the power fluid near the check valve assembly. Consequently, the fixed valve closes, the check valve assembly opens, and the gas and fluid drawn into the working chamber are discharged into the upper part of the plunger assembly and out through the inner tube of the upper double-layer tubing, thus completing the gas and fluid collection at the bottom hole. Moreover, because the connector assembly and the plunger assembly are slidably sealed together, the power fluid in the compression chamber cannot enter the working chamber. Therefore, when the plunger assembly moves upward or downward, the hydraulic fluid in the compression chamber acts on the proximal ends of the connector assembly and the plunger assembly, preventing it from entering the working chamber. This significantly reduces leakage in the plunger assembly and improves pump efficiency. Furthermore, because the connector assembly and the plunger assembly are slidably sealed together, the pressure transmission path of the hydraulic fluid to the distal end of the plunger assembly is cut off.This means that almost all the pressure provided by the surface power equipment is used to push the plunger assembly upwards, without being wasted on counteracting "virtual loads" caused by structural leaks or design flaws. Therefore, the operating pressure of the surface power equipment can be reduced, for example, by more than 15%, thereby improving the efficiency of deep coalbed methane extraction, reducing the cost of extraction equipment, and increasing reliability and service life.

[0018] Secondly, since the plunger assembly is slidably connected to the inner tube of the lower double-layer tubing, and an auxiliary cavity is formed between the connector assembly, the plunger assembly, and the inner tube of the lower double-layer tubing, and a connecting hole is provided on the cavity wall of the auxiliary cavity, the effective cross-sectional area of ​​the plunger assembly of the hydraulically driven downhole motor pump assembly can be increased from the original case where there was a gap between it and the inner tube of the lower double-layer tubing to the case where there is no gap between it and the inner tube of the lower double-layer tubing. This increases the displacement of the hydraulically driven downhole motor pump assembly, and different plunger assemblies can be replaced for different displacement requirements, improving the pump's versatility. Furthermore, by providing a connecting hole on the cavity wall of the auxiliary cavity, air or liquid stagnation can be prevented, thus preventing the pump from malfunctioning.

[0019] Secondly, since the other end of the connecting hole is connected to the inner cavity of the hollow tie rod plunger, the auxiliary cavity can draw in high-pressure gas and liquid discharged from the working cavity during the plunger assembly's descent. This balances the pressure on the upper and lower ends of the pump plunger or hollow tie rod plunger, thus preventing instability. If the other end of the connecting hole is connected to the gap between the inner and outer tubes of the lower double-layer tubing, the pressure in this gap is the same as the bottom hole pressure. Since the pressure of the gas and liquid entering the auxiliary cavity during the plunger assembly's descent is lower than the pressure in the working cavity, the pressure on the upper and lower ends of the pump plunger or hollow tie rod plunger becomes unbalanced, leading to instability. Therefore, connecting the other end of the connecting hole to the inner cavity of the hollow tie rod plunger is a preferred solution. Furthermore, the plunger assembly is specifically defined as a motor plunger, a hollow tie rod plunger, and a pump plunger connected in sequence, achieving a clear division of functional modules. The motor plunger is mainly responsible for being driven by the power fluid within the upper double-layer tubing, the pump plunger is mainly responsible for pumping operations within the lower double-layer tubing, and the hollow tie rod plunger serves as a connecting and force-transmitting component, while its hollow structure provides a channel for fluids (such as produced fluid or power fluid). This segmented design reduces the manufacturing difficulty of individual parts and facilitates maintenance and replacement.

[0020] Then, since the drain valve is located between the motor plunger and the hollow tie rod plunger, and the traveling valve assembly is located on the pump plunger, at the beginning of the plunger assembly's downward movement, the fixed valve closes under the pressure of the gas and liquid in the working chamber, while the traveling valve assembly opens under the pressure of the gas and liquid in the working chamber. Before the drain valve opens, some gas in the working chamber can enter the auxiliary chamber, thus allowing for partial venting. Furthermore, the one-way valve assembly is divided into a drain valve and a traveling valve assembly. The drain valve, located between the motor plunger and the hollow tie rod plunger, is mainly responsible for draining the gas-liquid mixture discharged from the working chamber into the upper channel of the plunger assembly; the traveling valve assembly, located on the pump plunger, is responsible for controlling the unidirectional flow between the working chamber and the upper region of the pump plunger. This split arrangement optimizes the flow channel design, making fluid flow smoother and reducing local resistance losses. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the piston assembly of the hydraulically driven downhole motor pump assembly during upward movement in an embodiment of the present invention; Figure 2 This is a schematic diagram of the plunger assembly of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention during its downward movement; Figure 3 This is a schematic diagram of the structure of the plunger assembly of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention, when it begins to descend and the drain valve has not yet opened. Figure 4 This is a partial structural schematic diagram of the plunger assembly of the hydraulically driven downhole motor pump assembly during its upward movement in an embodiment of the present invention; Figure 5 This is another partial structural schematic diagram of the plunger assembly of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention when it moves upward; Figure 6 This is a partial structural diagram of the plunger assembly of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention when it moves upward; Figure 7 This is a schematic diagram of the hydraulically driven downhole motor pump assembly in another embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 100 - Upper double-layer tubing; 110 - Motor plunger outer cylinder; 120 - Upper outer tube; 200 - Plunger assembly; 210 - Motor plunger; 211 - Lower buffer; 2111 - First start port; 212 - Upper buffer; 2121 - Second start port; 220 - Hollow tie rod plunger; 230 - Pump plunger; 300 - Connector assembly; 310 - Intermediate connector; 320 - Tie rod sealing cylinder; 330 - Lower buffer chamber; 400 - One-way valve assembly; 410 - Drain valve; 420 - Floating valve assembly; 421 - Upstream moving valve; 422 - Downstream moving valve; 500 - Lower double-layer tubing; 510 - Pump plunger outer cylinder; 520 - Lower outer tube; 600-Fixed Valve; 710 - Compression chamber; 720 - Guide hole; 730 - Auxiliary chamber; 740 - Connecting hole; 750 - Settling zone; 760 - Working chamber; 810 - Diverter; 811 - Upper buffer chamber; 820 - Inner connector assembly; 821 - Setting connector; 822 - Setting tube head; 830 - Outer connector; 900-bottom connector. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 1 This is a schematic diagram of the piston assembly 200 of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention during upward movement. Figure 2 This is a schematic diagram of the plunger assembly 200 of the hydraulically driven downhole motor pump assembly during downward movement, as described in this embodiment of the invention. Figure 3 This is a schematic diagram of the plunger assembly 200 of the hydraulically driven downhole motor pump assembly in this embodiment of the invention, when it begins to descend and the drain valve 410 has not yet opened. Figure 4 This is a partial structural diagram of the plunger assembly 200 of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention during its upward movement. Figure 5 This is another partial structural schematic diagram of the plunger assembly 200 of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention during its upward movement. Figure 6 This is a partial structural diagram of the plunger assembly 200 of the hydraulically driven downhole motor pump assembly in an embodiment of the present invention when it is moving upward. This embodiment provides a hydraulically driven downhole motor pump assembly, including an upper double-layer tubing string 100, a plunger assembly 200, a connector assembly 300, a one-way valve assembly 400, a lower double-layer tubing string 500, and a fixed valve 600. The distal end of the upper double-layer tubing 100 is connected to the proximal end of the connector assembly 300, the proximal end of the lower double-layer tubing 500 is connected to the connector assembly 300, and the fixed valve 600 is connected to the distal end of the inner tube of the lower double-layer tubing 500. The proximal end of the plunger assembly 200 is located within the cavity of the inner tube of the upper double-layer tubing 100 and is slidably and sealingly connected to the inner tube of the upper double-layer tubing 100. The distal end of the plunger assembly 200 passes through the connector assembly 300 and is located within the inner tube of the lower double-layer tubing 500 and is located near the fixed valve 600. The connector assembly 300 is slidably and sealingly connected to the plunger assembly 200. The plunger assembly 200, the proximal end of the connector assembly 300, and the inner tube of the upper double-layer tubing 100 enclose a compression cavity 710. The inner tube of the upper double-layer tubing 100 has a guide hole 720 that connects the compression cavity 710 and the gap between the inner tube and the outer tube of the upper double-layer tubing 100. The inner tube of the upper double-layer tubing 100 is connected to the inner cavity of the plunger assembly 200. The one-way valve assembly 400 is disposed on the plunger assembly 200 and is located inside the cavity and / or at the end of the plunger assembly 200.

[0030] Since the distal ends of the upper double-layer tubing 100 are respectively connected to the proximal ends of the connector assembly 300, the proximal end of the plunger assembly 200 is located in the cavity of the inner tube of the upper double-layer tubing 100 and is slidably sealed to the inner tube of the upper double-layer tubing 100. The plunger assembly 200, the proximal ends of the connector assembly 300 and the inner tube of the upper double-layer tubing 100 form a compression cavity 710. The inner tube of the upper double-layer tubing 100 has a guide hole 720 that connects the compression cavity 710 and the gap between the inner tube and the outer tube of the upper double-layer tubing 100. Therefore, after injecting power fluid between the inner and outer tubes of the upper double-layer tubing 100, the power fluid can flow into the compression chamber 710 through the guide hole 720 from the gap between the inner and outer tubes of the upper double-layer tubing 100, thereby pushing the plunger assembly 200, which is slidably and sealingly connected to the inner tube of the upper double-layer tubing 100, to slide upward, that is, pushing the plunger assembly 200 to move upward.

[0031] Because the proximal end of the lower double-layer tubing 500 is connected to the connector assembly 300, the fixed valve 600 is connected to the distal end of the inner tube of the lower double-layer tubing 500, the distal end of the plunger assembly 200 passes through the connector assembly 300 and is located inside the inner tube of the lower double-layer tubing 500, and is located near the fixed valve 600, the connector assembly 300 and the plunger assembly 200 are slidably sealed together, and the one-way valve assembly 400 is disposed on the plunger assembly 200, and the one-way valve assembly 400 is located inside the lumen and / or at the end of the plunger assembly 200, when the plunger assembly 200 moves upward, the volume of the working chamber 760 formed by the inner tube of the lower double-layer tubing 500 and the plunger assembly 200 between the fixed valve 600 and the one-way valve assembly 400 increases, resulting in a decrease in pressure within the working chamber 760, and causing the pressure in the working chamber 760 to be lower than the pressure at the bottom of the well. Therefore, the fixed valve 600 will open, and the gas and liquid at the bottom of the well will enter the working chamber 760. Since the pressure in the working chamber 760 is low, the pressure of the liquid near the one-way valve assembly 400 will also be greater than the pressure in the working chamber 760. Therefore, the one-way valve assembly 400 will remain closed, thereby achieving the suction of liquid from the bottom of the well.

[0032] Furthermore, after injecting kinetic fluid into the inner tube of the upper double-layer tubing 100, the kinetic fluid can flow in from the inner tube of the upper double-layer tubing 100 and compress the plunger assembly 200 to move downwards, thereby forcing the kinetic fluid in the compression chamber 710 into the gap between the inner and outer tubes of the upper double-layer tubing 100 and discharging it upwards; simultaneously, due to the downward movement of the plunger assembly 200, the plunger assembly 200 can compress the space between the fixed valve 600 and the one-way valve assembly 400 formed by the inner tube of the lower double-layer tubing 500. The working chamber 760 formed by the tube and the plunger assembly 200 results in a smaller volume of the working chamber 760. Therefore, the pressure inside the working chamber 760 will be greater than the bottom hole pressure and greater than the pressure of the power fluid near the one-way valve assembly 400. As a result, the fixed valve 600 closes and the one-way valve assembly 400 opens, allowing the gas and liquid drawn into the working chamber 760 to be discharged into the upper part of the plunger assembly 200 and discharged through the inner tube of the upper double-layer tubing string 100, thereby completing the gas and liquid collection at the bottom hole.

[0033] Furthermore, because the connector assembly 300 is slidably sealed to the plunger assembly 200, the hydraulic fluid in the compression chamber 710 cannot enter the working chamber 760. Therefore, when the plunger assembly 200 moves upward or downward, the hydraulic fluid in the compression chamber 710 acts on the proximal ends of the connector assembly 300 and the plunger assembly 200, preventing it from entering the working chamber 760. This significantly reduces leakage in the plunger assembly 200 and improves pump efficiency.

[0034] Furthermore, because the connector assembly 300 is slidably sealed to the plunger assembly 200, the pressure transmission path of the power fluid to the distal end of the plunger assembly 200 can be cut off. This means that almost all the pressure provided by the surface power equipment is used to push the plunger assembly 200 upward, without being wasted on counteracting "virtual loads" caused by structural leaks or design flaws. Therefore, the operating pressure of the surface power equipment can be reduced, for example, by more than 15%, thereby improving the extraction efficiency of deep coalbed methane, reducing extraction costs, and improving reliability and service life.

[0035] Furthermore, the plunger assembly 200 is slidably connected to the inner tube of the lower double-layer tubing 500, and an auxiliary cavity 730 is formed between the connector assembly 300, the plunger assembly 200, and the inner tube of the lower double-layer tubing 500. A connecting hole 740 is provided on the cavity wall of the auxiliary cavity 730. One end of the connecting hole 740 communicates with the auxiliary cavity 730, and the other end communicates with the inner cavity of the plunger assembly 200, and / or communicates with the gap between the inner tube and the outer tube of the lower double-layer tubing 500.

[0036] Because the plunger assembly 200 is slidably connected to the inner tube of the lower double-layer tubing 500, and an auxiliary cavity 730 is formed between the connector assembly 300, the plunger assembly 200, and the inner tube of the lower double-layer tubing 500, and a connecting hole 740 is provided on the cavity wall of the auxiliary cavity 730, the effective cross-sectional area of ​​the plunger assembly 200 of the hydraulically driven downhole motor pump assembly can be increased from the original case where there was a gap between it and the inner tube of the lower double-layer tubing 500 to the case where there is no gap between it and the inner tube of the lower double-layer tubing 500. This increases the displacement of the hydraulically driven downhole motor pump assembly, and different plunger assemblies 200 can be replaced for different displacement requirements, improving the pump's versatility. Furthermore, by providing a connecting hole 740 on the cavity wall of the auxiliary cavity 730, air or liquid stagnation can be prevented, thus preventing the pump from malfunctioning.

[0037] Furthermore, the plunger assembly 200 includes a motor plunger 210, a hollow tie rod plunger 220, and a pump plunger 230 connected sequentially from top to bottom. The motor plunger 210 is slidably and sealingly connected to the inner tube of the upper double-layer tubing 100. The proximal end of the hollow tie rod plunger 220 is located within the cavity of the inner tube of the upper double-layer tubing 100, and the distal end of the hollow tie rod plunger 220 passes through the connector assembly 300 and is located within the inner tube of the lower double-layer tubing 500. The plug 220 is slidably and sealingly connected to the connector assembly 300. The pump plunger 230 is located inside the inner tube of the lower double-layer tube column 500. The pump plunger 230 is slidably and sealingly connected to the inner tube of the lower double-layer tube column 500. The auxiliary cavity 730 is formed between the connector assembly 300, the pump plunger 230, the hollow tie rod plunger 220 and the inner tube of the lower double-layer tube column 500. The other end of the connecting hole 740 communicates with the inner cavity of the hollow tie rod plunger 220.

[0038] Since the other end of the connecting hole 740 is connected to the inner cavity of the hollow tie rod plunger 220, during the downward movement of the plunger assembly 200, the auxiliary cavity 730 can draw in the high-pressure gas and liquid discharged from the working cavity 760, so that the pressure on the upper and lower ends of the pump plunger 230 or the hollow tie rod plunger 220 is balanced, thereby preventing the pump plunger 230 or the hollow tie rod plunger 220 from becoming unstable. If the other end of the connecting hole 740 is connected to the gap between the inner and outer tubes of the lower double-layer tubing 500, the pressure in the gap between the inner and outer tubes of the lower double-layer tubing 500 will be the same as the bottom hole pressure. Since the gas-liquid pressure entering the auxiliary chamber 730 during the downward movement of the plunger assembly 200 is lower than the pressure in the working chamber 760, the pressure on the upper and lower ends of the pump plunger 230 or the hollow tie rod plunger 220 will become unbalanced, leading to instability of the pump plunger 230 or the hollow tie rod plunger 220. Therefore, connecting the other end of the connecting hole 740 to the inner cavity of the hollow tie rod plunger 220 is a preferred solution. Furthermore, specifying the plunger assembly 200 as a motor plunger 210, a hollow tie rod plunger 220, and a pump plunger 230 connected in sequence achieves a clear division of functional modules. The motor plunger 210 is primarily responsible for being driven by the power fluid within the upper double-layer tubing 100, the pump plunger 230 is primarily responsible for pumping operations within the lower double-layer tubing 500, and the hollow tie rod plunger 220 serves as a connecting and force-transmitting component, while its hollow structure provides a channel for fluids (such as produced fluid or power fluid). This segmented design reduces the manufacturing difficulty of individual parts and facilitates maintenance and replacement.

[0039] Furthermore, the one-way valve assembly 400 includes a drain valve 410 and a traveling valve assembly 420. The drain valve 410 is located between the motor plunger 210 and the hollow tie rod plunger 220, and the traveling valve assembly 420 is located on the pump plunger 230.

[0040] Since the drain valve 410 is located between the motor plunger 210 and the hollow tie rod plunger 220, and the traveling valve assembly 420 is located on the pump plunger 230, at the beginning of the plunger assembly 200's downward movement, the fixed valve 600 closes under the pressure of the gas and liquid in the working chamber 760, and the traveling valve assembly 420 opens under the pressure of the gas and liquid in the working chamber 760. Before the drain valve 410 opens, some of the gas in the working chamber 760 can enter the auxiliary chamber 730, thereby allowing for partial venting. Furthermore, the one-way valve assembly 400 is divided into a drain valve 410 and a traveling valve assembly 420. The drain valve 410 is located between the motor plunger 210 and the hollow tie rod plunger 220, and is mainly responsible for draining the gas-liquid mixture discharged from the working chamber 760 into the upper channel of the plunger assembly 200. The traveling valve assembly 420 is located on the pump plunger 230 and is responsible for controlling the one-way flow between the working chamber 760 and the upper region of the pump plunger 230. This split arrangement optimizes the flow channel design, makes the fluid flow smoother, and reduces local resistance loss.

[0041] Specifically, the drain valve 410 is installed at the distal end of the motor plunger 210, and the hollow pull rod plunger 220 is installed at the distal end of the drain valve 410.

[0042] Specifically, the traveling valve assembly 420 includes an upstream traveling valve 421 and a downstream traveling valve 422. The upstream traveling valve 421 is located between the proximal end of the pump plunger 230 and the hollow tie rod plunger 220, and the downstream traveling valve 422 is located at the distal end of the pump plunger 230. The traveling valve assembly 420 is further subdivided into the upstream traveling valve 421 and the downstream traveling valve 422, forming a two-stage seal. This redundant design greatly improves the reliability of the unidirectional seal. Under high pressure or conditions with many impurities, even if one valve experiences a slight leak or jamming, the other valve can still maintain a sealing effect, effectively preventing backflow of the produced fluid and ensuring pump efficiency and operational stability. In other embodiments, refer to... Figure 7 , Figure 7 This is a schematic diagram of the hydraulically driven downhole motor pump assembly in another embodiment of the present invention. The traveling valve group 420 includes only one traveling valve, and the traveling valve is located at the distal end of the pump plunger 230.

[0043] Preferably, a lower buffer 211 is provided at the distal end of the motor plunger 210, and a lower buffer cavity 330 that cooperates with the lower buffer 211 is provided at the proximal end of the connector assembly 300. By providing the lower buffer 211 and the lower buffer cavity 330, the impact and vibration of the plunger assembly 200 reaching the bottom dead center can be reduced, the anti-surge distance between the pump plunger 230 and the fixed valve 600 can be significantly reduced, ensuring the operating stroke length of the pump plunger 230 and extending the service life of the motor; at the same time, the fluid flow between the pump plunger 230 and the fixed valve 600 is increased, solid phase precipitation is reduced, and the possibility of sand and wax buildup on the fixed valve 600 is significantly reduced.

[0044] Preferably, the lower buffer 211 has a first initiation port 2111 for the flow of power fluid. During the upward or downward movement of the plunger assembly 200, the first initiation port 2111 can increase the contact area between the power fluid and the lower buffer 211, preventing the plunger assembly 200 from jamming or failing to start due to insufficient contact area with the power fluid when it reaches the dead point.

[0045] The hydraulically driven downhole motor pump assembly also includes a diverter 810, an inner connector assembly 820, and an outer connector 830. The inner connector assembly 820 is disposed within the cavity of the outer connector 830, forming an annular cavity between them. The proximal end of the diverter 810 connects the inner connector assembly 820 and the outer connector 830, and the distal end of the diverter 810 connects the inner and outer tubes of the upper double-layer tubing string 100. This allows the gap between the inner and outer tubes of the upper double-layer tubing string 100 to communicate with the inner tube of the inner connector assembly 820, and the gap between the inner connector assembly 820 and the outer connector 830 to communicate with the cavity of the inner tube of the upper double-layer tubing string 100. This avoids deformation of the inner connector assembly 820 under the action of high-pressure liquid when the plunger assembly 200 moves upward when high-pressure liquid is directly introduced into the gap between the inner connector assembly 820 and the outer connector 830, thus improving the service life of the hydraulically driven downhole motor pump.

[0046] Furthermore, the inner connector assembly 820 includes a setting connector 821 and a setting tube head 822, the setting tube head 822 being connected to the setting connector 821, and the setting connector 821 being connected to the shunt connector 810.

[0047] Preferably, the distal end of the diverter 810 is provided with an upper buffer chamber 811, and the proximal end of the motor plunger 210 is provided with an upper buffer 212 that cooperates with the upper buffer chamber 811. By providing the upper buffer 212 and the upper buffer chamber 811, the impact and vibration of the plunger assembly 200 reaching the top dead center can be reduced, thus extending the service life of the motor; at the same time, it increases the fluid flow between the pump plunger 230 and the fixed valve 600, reduces solid phase precipitation, and significantly reduces the possibility of sand or wax buildup on the fixed valve 600.

[0048] Furthermore, the upper buffer 212 is provided with a second start port 2121 for the flow of power fluid. During the upward or downward movement of the plunger assembly 200, the second start port 2121 can increase the contact area between the power fluid and the lower buffer 211, preventing the plunger assembly 200 from jamming or failing to start due to insufficient contact area with the power fluid when it reaches the dead point.

[0049] Preferably, the lower part of the cavity between the upper double-layer tubing 100 and the connector assembly 300, which is lower than the flow guide hole 720, forms a sand settling zone 750, which can prevent sand and other particles in the power fluid from entering the gap between the motor plunger 210 and the pump barrel, thus preventing the motor plunger 210 from getting stuck or worn.

[0050] Specifically, the inner tube of the upper double-layer tubing 100 is the outer cylinder 110 of the motor plunger, and the outer tube of the upper double-layer tubing 100 is the upper outer tube 120.

[0051] Specifically, the inner tube of the lower double-layer tubing 500 is the pump plunger outer cylinder 510, and the outer tube of the lower double-layer tubing 500 is the lower outer tube 520.

[0052] Preferably, both the fixed valve 600 and the one-way valve assembly 400 are coated with an anti-scaling film or treated with PVD to increase the wear resistance of the device, prevent scaling, and extend its service life.

[0053] Preferably, it also includes a lower connector 900, which is connected to the distal end of the outer tube of the lower double-layer tube column 500.

[0054] Specifically, the connector assembly 300 includes an intermediate connector 310 and a pull rod sealing cylinder 320. The pull rod sealing cylinder 320 is connected to the distal end of the intermediate connector 310 and is slidably sealed to the hollow pull rod plunger 220. The inner and outer tubes of the upper double-layer tubing 100 are respectively connected to the proximal end of the intermediate connector 310. The inner tube of the lower double-layer tubing 500 is connected to the distal end of the pull rod sealing cylinder 320, and the outer tube of the lower double-layer tubing 500 is connected to the distal end of the intermediate connector 310.

[0055] The lower buffer cavity 330 is disposed on the proximal end of the intermediate joint 310.

[0056] In this embodiment, the hydraulically driven downhole motor pump assembly reciprocates up and down under the drive of the power fluid. The drainage process of the hydraulically driven downhole motor pump assembly includes an upstroke and a downstroke, and these two strokes are performed cyclically to achieve drainage. The specific working process of the hydraulically driven downhole motor pump assembly is as follows: Top Stroke: The power fluid is pressurized into high-pressure power fluid by the ground power unit and injected into the cavity of the inner tube of the inner connector assembly 820. After passing through the diverter 810, it enters the annular space formed by the outer cylinder 110 of the motor plunger and the upper outer tube 120, and then enters the compression chamber 710 through the guide hole 720. It then enters the compression chamber 710 through the first start port 2111 and pushes the motor plunger 210 upward. At this time, the volume of the auxiliary chamber 730 decreases and it is in the discharge state. When the upper buffer 2... 12. After entering the upper buffer chamber 811, the hydraulically driven downhole motor pump assembly reaches the top dead center and the upstroke ends. During this process, the fixed valve 600 of the hydraulically driven downhole motor pump assembly opens, the floating valve group 420 closes, and the drain valve 410 opens. The downhole motor pump completes the liquid suction process. The liquid above the floating valve 421 is discharged to the surface through the gap between the inner tube of the inner tube of the upper double-layer tubing string 100 and the inner connector assembly 820 and the outer connector 830. The surface production phenomenon is liquid discharge.

[0057] Downstroke: The power fluid is pressurized into high-pressure power fluid by the surface power unit and injected from the gap between the inner connector assembly 820 and the outer connector 830. After passing through the diverter 810, it enters the inner cavity of the outer cylinder 110 of the motor plunger and pushes the motor plunger 210 downward. At this time, the volume of the auxiliary cavity 730 increases and it is in the suction state. When the lower buffer 211 enters the lower buffer cavity 330, the downstroke ends after the hydraulically driven downhole motor pump assembly reaches the bottom dead center. During this process, the fixed valve 600 of the hydraulically driven downhole motor pump assembly is closed, the upstream moving valve 421 is opened, the downstream moving valve 422 is opened, and the drain valve 410 is opened. The produced fluid enters the pump cavity above the moving valve group 420.

[0058] Then, the upstroke is repeated. The produced fluid in the inner cavity of the motor plunger 210 and the inner cavity of the hollow tie rod plunger 220 is mixed with the power fluid and flows back to the ground through the gap between the inner connector assembly 820 and the outer connector 830.

[0059] Before switching from the upstroke to the downstroke, the plunger assembly 200 stops moving upward, and the check valve assembly 400 and the fixed valve 600 reset and close. Before switching from the downstroke to the upstroke, the plunger assembly 200 stops moving downward, and the check valve assembly 400 and the fixed valve 600 reset and close.

[0060] This embodiment also provides a gas production system, including a surface power unit and the above-mentioned hydraulically driven downhole motor pump assembly, wherein the surface power unit provides power fluid to the hydraulically driven downhole motor pump assembly.

[0061] In the above embodiments, the distal end refers to the end closer to the bottom of the well after the hydraulically driven downhole motor pump assembly is installed downhole, and the proximal end is the end farther from the bottom of the well.

[0062] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A hydraulically driven downhole motor pump assembly, characterized in that, It includes an upper double-layer tubing string, a plunger assembly, a connector assembly, a one-way valve assembly, a lower double-layer tubing string, and a stationary valve; The distal ends of the upper double-layer tubing are connected to the proximal ends of the connector assembly, the proximal ends of the lower double-layer tubing are connected to the connector assembly, and the fixed valve is connected to the distal end of the inner tube of the lower double-layer tubing. The proximal end of the plunger assembly is located inside the lumen of the inner tube of the upper double-layer tubing and is slidably and sealingly connected to the inner tube of the upper double-layer tubing. The distal end of the plunger assembly passes through the connector assembly and is located inside the inner tube of the lower double-layer tubing and is slidably and sealingly connected to the proximal end of the fixed valve. The plunger assembly, the proximal end of the connector assembly, and the inner tube of the upper double-layer tubing form a compression cavity. The inner tube of the upper double-layer tubing has a guide hole that connects the compression cavity and the gap between the inner and outer tubes of the upper double-layer tubing. The inner tube of the upper double-layer tubing is connected to the inner cavity of the plunger assembly, and the one-way valve assembly is disposed on the plunger assembly, and the one-way valve assembly is located inside the cavity and / or at the end of the plunger assembly.

2. The hydraulically driven downhole motor pump assembly as described in claim 1, characterized in that, The plunger assembly is slidably connected to the inner tube of the lower double-layer tubing, and an auxiliary cavity is formed between the connector assembly, the plunger assembly, and the inner tube of the lower double-layer tubing. A connecting hole is provided on the wall of the auxiliary cavity. One end of the connecting hole is connected to the auxiliary cavity, and the other end is connected to the inner cavity of the plunger assembly, and / or connected to the gap between the inner tube of the lower double-layer tubing and the outer tube of the lower double-layer tubing.

3. The hydraulically driven downhole motor pump assembly as described in claim 2, characterized in that, The plunger assembly includes a motor plunger, a hollow tie rod plunger, and a pump plunger connected sequentially from top to bottom. The motor plunger is slidably and sealingly connected to the inner tube of the upper double-layer tubing. The proximal end of the hollow tie rod plunger is located inside the cavity of the inner tube of the upper double-layer tubing, and the distal end of the hollow tie rod plunger passes through the connector assembly and is located inside the inner tube of the lower double-layer tubing. The hollow tie rod plunger is partially slidably and sealingly connected to the connector assembly. The pump plunger is located inside the inner tube of the lower double-layer tubing and is slidably and sealingly connected to the inner tube of the lower double-layer tubing. The auxiliary cavity is formed between the connector assembly, the pump plunger, the hollow tie rod plunger, and the inner tube of the lower double-layer tubing. The other end of the connecting hole communicates with the inner cavity of the hollow tie rod plunger.

4. The hydraulically driven downhole motor pump assembly as described in claim 3, characterized in that, The one-way valve assembly includes a drain valve and a traveling valve assembly. The drain valve is located between the motor plunger and the hollow tie rod plunger, and the traveling valve assembly is located on the pump plunger.

5. The hydraulically driven downhole motor pump assembly as described in claim 4, characterized in that, The traveling valve assembly includes an upstream traveling valve and a downstream traveling valve. The upstream traveling valve is located between the proximal end of the pump plunger and the hollow tie rod plunger, and the downstream traveling valve is located at the distal end of the pump plunger.

6. The hydraulically driven downhole motor pump assembly as described in claim 4 or 5, characterized in that, The distal end of the motor plunger is provided with a lower buffer, and the proximal end of the connector assembly is provided with a lower buffer cavity that mates with the lower buffer.

7. The hydraulically driven downhole motor pump assembly as described in claim 4 or 5, characterized in that, It also includes a diverter, an inner connector assembly, and an outer connector. The inner connector assembly is disposed within the lumen of the outer connector, and an annular cavity is formed between the two. The proximal end of the diverter connects the inner connector assembly and the outer connector, and the distal end of the diverter connects the inner tube and the outer tube of the upper double-layer tubing, such that the gap between the inner tube and the outer tube of the upper double-layer tubing is in communication with the inner tube of the inner connector assembly, and the gap between the inner connector assembly and the outer connector is in communication with the lumen of the inner tube of the upper double-layer tubing.

8. The hydraulically driven downhole motor pump assembly as described in claim 7, characterized in that, The internal connector assembly includes a setting connector and a setting tube head, the setting tube head being connected to the setting connector, and the setting connector being connected to the shunt connector.

9. The hydraulically driven downhole motor pump assembly as described in claim 7, characterized in that, The distal end of the diverter is provided with an upper buffer chamber, and the proximal end of the motor plunger is provided with an upper buffer that cooperates with the upper buffer chamber.

10. A gas extraction system, characterized in that, It includes a surface power system and a hydraulically driven downhole motor pump assembly as described in any one of claims 1-9, wherein the surface power system provides power fluid to the hydraulically driven downhole motor pump assembly.

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