Ground equipment and control system for drainage gas extraction device

Abstract

This invention discloses a surface device and control system for a drainage gas production apparatus. The control system includes an electromagnetic reversing valve, located between the storage tank and the rodless pump of the drainage gas production apparatus, and connected to the power pump of the apparatus. The electromagnetic reversing valve controls the return of the exhausted power fluid and produced fluid discharged by the rodless pump to the storage tank. An electromagnetic ranging displacement sensor is installed on the power pump to monitor the movement position of the piston inside the pump. A control cabinet receives signals from various sensors in the pipeline and controls the opening and closing of the electromagnetic reversing valve. This invention enables different operating modes of the rodless pump through the control system. The closed-loop control system can perform functions such as downhole plunger up and down movement, system self-check cycle, system zeroing cycle, and system pump start-up cycle. Continuous drainage and production are achieved through automated control, solving problems such as low efficiency, low precision, and inability to continuously drain data obtained manually.

Description

Technical Field

[0001] This invention relates to the field of drainage gas extraction technology for natural gas and coalbed methane, and particularly to a ground device and control system for drainage gas extraction devices for natural gas and deep coalbed methane. Background Technology

[0002] The desorption-diffusion-permeation production process of natural gas and coalbed methane is a complex dynamic process that cannot be precisely described. As the extraction process progresses and the extraction depth gradually increases, deep coalbed methane is characterized by high pressure, high gas content, high gas saturation, and low permeability. These characteristics cause problems such as corrosion, uneven wear, gas lock, and pump blockage in the pumping unit lifting system of drainage equipment suitable for shallow coalbed methane.

[0003] Current drainage and gas extraction technologies mostly employ rod pumps. However, using rod pumps in deep coalbed methane drainage can lead to rod wear and frequent well repairs, resulting in discontinuous drainage. To address these issues, researchers have developed rodless pump technology for deep coalbed methane drainage. However, rodless pump drainage also presents challenges, such as short pump lifespan, high cost, and pump jamming. Furthermore, traditional drainage equipment typically relies on manual control, which suffers from low efficiency in data collection, low precision, and the inability to perform continuous drainage.

[0004] Therefore, the applicant intends to provide a new type of drainage gas extraction device and its control system to meet the needs of natural gas and deep coalbed methane drainage extraction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a ground device and control system for a drainage gas extraction device, solving the problems of low efficiency, low precision, and inability to continuously extract data during the drainage process of deep coalbed methane or natural gas in traditional drainage gas extraction devices.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A control system for a drainage gas extraction device, used to control the drainage process of a rodless pump during the drainage of natural gas or deep coalbed methane, comprising:

[0008] An electromagnetic reversing valve is installed between the storage tank and the rodless pump of the drainage gas extraction device and is connected to the power pump of the drainage gas extraction device. The electromagnetic reversing valve is used to control the return of the waste power fluid and extracted fluid discharged by the rodless pump to the storage tank.

[0009] An electromagnetic ranging displacement sensor is installed on the power pump to monitor the movement position of the piston inside the power pump.

[0010] The control cabinet is used to receive signals from various sensors in the pipeline and control the opening and closing of the solenoid directional valves.

[0011] Preferably, it also includes a one-way valve, which is disposed between the power fluid outlet of the storage tank and the power fluid inlet of the rodless pump, to ensure that the power fluid enters the rodless pump from the storage tank in one direction and cannot return to the storage tank through the power fluid outlet of the storage tank.

[0012] Preferably, the one-way valve is disposed on the drain port and the inlet port of the power pump.

[0013] Preferably, the control system further includes:

[0014] A pressure sensor is installed on the pipeline between the power pump and the rodless pump to monitor the pressure in the pipeline and transmit the signal to the control cabinet.

[0015] An automatic venting valve is installed on the wellhead device of the drainage and gas production device to vent gas from the annular pipeline inside the wellhead device. The automatic venting valve is equipped with an electromagnetic safety valve to protect the automatic venting valve and ensure its normal operation. The set pressure of the electromagnetic safety valve is 1.0 to 2.5 MPa.

[0016] Preferably, the electromagnetic reversing valve is two two-position two-way reversing valves, with the inlets of the two two-position two-way reversing valves respectively connected to the two waste fluid outlets of the rodless pump, and the outlets of both connected to the waste fluid inlet of the storage tank. Alternatively, the electromagnetic reversing valve is a two-position three-way reversing valve, with the two inlets respectively connected to the two waste fluid outlets of the rodless pump, and the outlet connected to the waste fluid inlet of the storage tank.

[0017] Preferably, the drainage and gas extraction device includes a closed hydraulic station; the closed hydraulic station includes an oil tank and a plunger pump connected to the oil tank; the plunger pump is equipped with a drive motor; the electromagnetic ranging displacement sensor transmits the monitoring result signal to the control cabinet, which controls the opening of the plunger pump to adjust the oil flow rate and outflow direction, thereby controlling the reversing movement of the piston in the power pump.

[0018] The present invention also provides a surface device for a natural gas or deep coalbed methane drainage and gas extraction device, the surface device being connected to a rodless pump for driving the plunger of the rodless pump to move, thereby realizing the drainage and extraction process of the rodless pump; the surface device includes the above-mentioned control system.

[0019] Preferably, the surface device includes a wellhead device and a surface power system, the surface power system being connected to a rodless pump via the wellhead device; the surface power system includes a reservoir for storing power fluid, a power pump connected to the reservoir, and a closed hydraulic station connected to the power pump;

[0020] The power pump includes a cylinder assembly, two hydraulic cylinders disposed on both sides of the cylinder assembly, a piston slidably disposed in the cylinder assembly and the two hydraulic cylinders, and pump heads disposed at both ends of the power pump; the cylinder assembly contains a cylinder piston and has two oil ports on its sides at both ends; the pump head includes a one-way valve with a drain port and a drain port respectively disposed at its two ends; the drain port is connected to the power fluid outlet of the storage tank, and the drain port is connected to the rodless pump through the wellhead device;

[0021] The closed hydraulic station includes an oil tank and a piston pump connected to the oil tank; the piston pump is equipped with a drive motor, and the oil tank has two oil tank outlets, which are respectively connected to two oil ports of the power pump.

[0022] Preferably, the piston includes a piston rod and piston bodies located at both ends of the piston rod; the hydraulic cylinder piston is fixedly sleeved on the piston rod; the piston rod consists of a long rod and short rods located at both ends of the long rod, and the piston body is provided at the ends of the two short rods away from the long rod; a clamp is sleeved at the connection between the short rod and the long rod to fix the short rod and the long rod of the piston rod in place.

[0023] The present invention also provides a control method for the above-mentioned control system used in a natural gas and deep coalbed methane drainage and gas extraction device, comprising the following steps: the control cabinet receives a signal from an electromagnetic ranging displacement sensor and controls the opening of the plunger pump to adjust the oil flow rate and outflow direction and controls the opening and closing of the electromagnetic reversing valve, thereby controlling the piston of the power pump to move in the corresponding direction within the power pump and discharging the power fluid within the power pump. The power fluid enters the rodless pump, pushes the plunger of the rodless pump to move, and drives the rodless pump to discharge the waste power fluid. The waste power fluid returns to the storage tank via the electromagnetic reversing valve, realizing the upward or downward movement of the plunger of the rodless pump, thereby realizing the drainage and extraction process of the rodless pump.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention enables different operating modes of the rodless pump through a control system. The closed-loop control system can perform functions such as downhole plunger up and down movement, system self-test cycle, system zeroing cycle, and system pump start-up cycle. The hydraulic pipeline structure is simple and easy to maintain.

[0026] This invention enables intelligent automation of the drainage and gas extraction device, effectively reducing the need for manual operation. By analyzing field-collected data such as pressure, flow rate, and temperature signals, as well as PLC controller signals, the working status of drainage and extraction can be more clearly understood, allowing for more reasonable control of the drainage flow rate of the drainage and extraction device, thereby improving the extraction efficiency of deep coalbed methane.

[0027] This invention regulates oil flow by controlling the opening of the plunger pump, thereby controlling the piston speed in the power pump. Position information collected by the electromagnetic displacement sensor on the power pump enables the system's positioning and deceleration functions, preventing damage from impacts that could disrupt production continuity. An automatic vent valve, protected by an electromagnetic safety valve, effectively discharges gas extracted from the effluent, ensuring the normal operation of the drainage and gas extraction device and improving extraction efficiency. Furthermore, a double-layer tubing system, suitable for natural gas and deep coalbed methane extraction, further enhances extraction efficiency.

[0028] The power pump used in this invention uses rubber and other materials with good sealing performance, high wear resistance and fatigue resistance for piston sealing, which can effectively extend the service life of the piston. At the same time, the addition of a clamp structure on the piston rod can solve the problems of long disassembly time of the power pump when replacing the piston and the impact on the accuracy of the power pump, and can also speed up the piston replacement speed. Attached Figure Description

[0029] Figure 1 This is a front view of the ground device of a drainage gas extraction device according to a specific embodiment of the present invention;

[0030] Figure 2 This is a top view of a ground device of a drainage gas extraction device according to a specific embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of a power pump in a drainage gas extraction device according to a specific embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the structure of a power pump head;

[0033] Figure 5 This is a schematic diagram of the one-way valve on the pump head of a power pump.

[0034] Figure 6 This is a schematic diagram of the piston structure of a power pump.

[0035] Figure 7 This is a schematic diagram of the clamp structure of a power pump.

[0036] Figure 8 This is a schematic diagram of the structure of a power pump according to a specific embodiment of the present invention;

[0037] Figure 9 This is a slanted view of the closed hydraulic station in the control system of a drainage gas extraction device according to a specific embodiment of the present invention.

[0038] Figure 10 This is a side view schematic diagram of the closed hydraulic station in the control system of a drainage gas extraction device according to a specific embodiment of the present invention;

[0039] Figure 11 This is a schematic diagram of the main control principle of a drainage gas extraction device in a specific embodiment of the present invention.

[0040] Figure 12 This is a schematic diagram of a closed-loop hydraulic station.

[0041] Figure 13 This is a schematic diagram of a two-position three-way directional valve;

[0042] In the diagram: 1. Rodless pump; 2. Wellhead assembly; 201. Central tubing; 202. Annular tubing; 3. Tubing string; 301. Main tubing; 302. Casing; 4. Reservoir tank; 5. Power pump; 6. Cylinder assembly; 7. Piston; 7. Piston body; 701. Piston core; 701A. Rubber sleeve; 701B. Baffle; 701C. Snap ring; 701D. Sealing ring; 701E. Piston rod; 702. Clamp; 703. Clamp left flap; 703A. Spring washer; 703B. Hex socket screw; 703C. Clamp right flap; 703D. Groove; 703E. Pump head; 8. Left pump head; 801. Right pump head; 802. Check valve; 9. Valve seat; 901. Valve core; 902. Valve cover 903, spring 904, valve disc 905, process hole 906, hydraulic cylinder 10, accumulator 11, heater 12, solenoid directional valve 13, first solenoid directional valve 1301, second solenoid directional valve 1302, control cabinet 14, pressure sensor 15, automatic exhaust valve 16, solenoid safety valve 17, solenoid displacement sensor 18, oil tank 19, plunger pump 20, drive motor 21, radiator 22, flow sensor 23, spring return safety valve 26, diaphragm pressure gauge 27, exhaust valve 28, filter 29, oil tank heater 30, level gauge 31, ball valve 32, temperature transmitter 33. Detailed Implementation

[0043] To better explain the present invention, the main contents of the present invention are further illustrated below with reference to specific embodiments, but the contents of the present invention are not limited to the following embodiments.

[0044] like Figures 1-13 The diagram shows the surface unit and control system of a drainage gas extraction device according to the present invention, which can be used for the drainage and extraction of natural gas and deep coalbed methane. The deep coalbed methane drainage gas extraction device includes a rodless pump 1 and a surface unit. The surface unit includes a wellhead device 2 and a surface power system.

[0045] like Figure 1 and Figure 11 As shown, the rodless pump 1 is installed downhole and connected to the surface power system via the wellhead device 2. The rodless pump 1 and the wellhead device 2 are connected by a tubing string 3. An annular space is formed between the inner and outer tubing of the rodless pump 1. The wellhead device 2 is used for effective control and protection of the wellhead. The rodless pump 1 and wellhead device 2 are existing technologies, and their specific structures will not be described in detail here.

[0046] like Figure 1 As shown, the tubing string 3 has a three-layer structure, consisting of a central tubing 201, a main tubing 301, and a casing 302 from the inside out. The central tubing 201, the main tubing 301, and the annular tubing 202 extend into the wellhead assembly 2. The central tubing 201 contains the central tubing. The space between the central tubing 201 and the main tubing 301 forms the annular tubing 202. The casing 302 protects the central tubing 201 and the main tubing 301. The central pipeline is connected to the annular space of the rodless pump 1. The power fluid entering the central pipeline will enter the lower end of the plunger of the rodless pump 1 from the annular space under the action of the ground power system, pushing the plunger of the rodless pump 1 to move upward. The annular pipeline 202 is connected to the core of the rodless pump 1. The power fluid entering the annular pipeline 202 will directly enter the upper end of the plunger of the rodless pump 1 from the annular pipeline 202 under the action of the ground power system, pushing the plunger of the rodless pump 1 to move downward.

[0047] like Figures 1-2 As shown, the surface power system includes a reservoir 4 for storing power fluid, a power pump 5 connected to the reservoir 4, and a closed hydraulic station connected to the power pump 5. The power pump 5 is connected to the rodless pump 1 via a wellhead device 2 and a tubing string 3, driving the power fluid into the rodless pump 1 to control its operation. The waste power fluid inlet of the reservoir 4 is connected to the waste power fluid outlet of the rodless pump 1 to receive waste power fluid from the rodless pump 1.

[0048] The storage tank 4 is used to store the power fluid, and it is equipped with a power fluid outlet and a waste power fluid inlet. The power fluid is water. A heater 12 is installed on the storage tank 4 to heat the power fluid and prevent freezing. A filter 29 is also installed on the storage tank 4 to filter coal dust from the produced fluid discharged along with the waste power fluid.

[0049] like Figure 3 As shown, the power pump 5 is a double telescopic mud pump, including a cylinder assembly 6, two hydraulic cylinders 10 disposed on both sides of the cylinder assembly 6, and a piston 7 slidably disposed in the cylinder assembly 6 and the two hydraulic cylinders 10.

[0050] Each of the two hydraulic cylinders 10 has a pump head 8 at the end furthest from the cylinder assembly 6; these are a left pump head 801 and a right pump head 802, respectively, with identical structures. Each pump head 8 is connected to its corresponding hydraulic cylinder 10. Figure 4 As shown, the pump head 8 includes a one-way valve 9 with a drain port and a liquid inlet at both ends of the pump head 8; the liquid inlets of the left pump head 801 and the right pump head 802 are both connected to the power fluid outlet of the liquid storage tank 4, and the drain ports of the left pump head 801 and the right pump head 802 are respectively connected to the central pipeline and the annular pipeline 202 of the oil tubing string 3.

[0051] All of the above connections are made via pipes.

[0052] like Figure 5 As shown, the one-way valve 9 includes a valve seat 901, a valve core 902, a valve cover 903, a spring 904, a valve disc 905, and a process port 906. The specific structure of the one-way valve 9 is existing technology; for details, please refer to the second edition of *Introduction to Petroleum Drilling and Production Machinery*, edited by Li Jizhi and published by China University of Petroleum Press in July 2015. The spring 904 only opens when the lower pressure is greater than the upper pressure, ensuring that the hydraulic fluid in the inner cavity does not return to the reservoir 4, and that the hydraulic fluid discharged from the valve cavity does not return to the cavity.

[0053] like Figure 3 As shown, the piston 7 consists of a piston rod 702 that runs through the cylinder assembly 6 and a piston body 701 located at both ends of the piston rod 702.

[0054] The piston rod 702 passes through the hydraulic cylinder assembly 6. The portion of the piston rod 702 near both ends has a smaller diameter than the middle portion and is used to mount the piston body 701.

[0055] The hydraulic cylinder assembly 6 is sealed by guide sleeves, support rings, and Glyd rings fixedly mounted on the inner sides of both ends of the hydraulic cylinder assembly 6 and sleeved on the piston rod 702, preventing the liquid inside the hydraulic cylinder assembly 6 from flowing out, while the piston rod 702 can move back and forth. A hydraulic cylinder piston is installed inside the hydraulic cylinder assembly 6, and the hydraulic cylinder piston is fixedly sleeved on the piston rod 702 and can move with the piston rod 702 inside the hydraulic cylinder assembly 6.

[0056] like Figure 6 As shown, the piston body 701 consists of a piston core 701A, a rubber sleeve 701B, a sealing ring 701E, a baffle 701C, and a retaining ring 701D, which are sequentially fitted together. The piston core 701A is fixedly fitted onto the end of the piston rod 702. The rubber sleeve 701B is connected to the piston core 701A and positioned on the outer side of the piston core 701A near the end of the piston rod 702. The sealing ring 701E is positioned on the outer side of the rubber sleeve 701B. The baffle 701C is abutted against the sealing ring 701E to prevent movement of the piston core 701A, rubber sleeve 701B, and sealing ring 701E. The retaining ring 701D is fixedly connected to the piston core 701A and contacts the baffle 701C to prevent movement of the baffle 701C. The piston body 701 is made of rubber material. The sealing ring 701E is made of polyurethane or nitrile rubber.

[0057] Specifically, the piston rod 702 may consist of two short rods at the ends and a long rod in the middle, with the piston body 701 located at the ends of the two short rods away from the long rod. A fitting such as... is sleeved at the connection between the short rods and the long rod. Figure 7The clamp 703 shown securely connects the short rod and the long rod. The clamp 703 is located inside the hydraulic cylinder 10, inside the piston body 701, and sleeved on the piston rod 702. The clamp 703 consists of a threaded left clamp lobe 703A, a spring washer 703B, a screw 703C, and a right clamp lobe 703D. The left clamp lobe 703A and the right clamp lobe 703D are threaded together by the screw 703C. The spring washer 703B is placed on the right clamp lobe 703D, and the screw 703C passes through the spring washer 703B, which prevents the screw 703C from loosening. The clamp 703 has a groove 703E. The design of the groove 703E makes the connection between the short rod and the long rod of the piston rod stable and secure, and can more effectively prevent the problem of falling off during operation. In one specific embodiment, the screw 703C is an M12 socket head cap screw. The clamp 703 and the segmented design of the piston rod 702 facilitate the replacement of the piston body 701. When the piston body 701 needs to be replaced, the short rod at the end of the piston rod 702, together with the piston body 701, can be removed through the clamp 703, and then the new piston body 701 can be reinstalled to complete the replacement of the piston body 701. This solves the problems of the long time required to disassemble the power pump when replacing the piston, which also affects the accuracy of the power pump.

[0058] like Figure 3 As shown, oil ports are respectively opened on both sides of the hydraulic cylinder assembly 6; there are two oil ports, namely the first oil port 601 and the second oil port 602. The first oil port 601 is close to the left pump head 801, and the second oil port 602 is close to the right pump head 802.

[0059] After the piston 7 inside the power pump 5 moves, it pushes the drain port on one of the pump heads 8 to open, discharging the power fluid and closing the inlet port. At the same time, the inlet port on the other pump head 8 opens, drawing in the power fluid and closing the drain port. The power fluid is discharged from the power pump 5 through the open drain port, passes through the wellhead device 2 and the tubing string 3, and enters the rodless pump 1, pushing the plunger of the rodless pump 1 to move and discharge the spent power fluid. During the back-and-forth movement of the piston 7 inside the power pump 5, the two spent power fluid outlets of the rodless pump 1 alternately discharge the spent power fluid. For example, when the piston 7 inside the power pump 5 moves to the right pump head 802, the drain port of the left pump head 801 closes and the inlet port opens, drawing in the power fluid from the reservoir 4; the inlet port of the right pump head 802 closes and the drain port opens. The power fluid in the right pump head 802 is discharged through the drain port and enters the core of the rodless pump 1 through the annular pipe 202, pushing the plunger of the rodless pump 1 downward from the upper end of the plunger.

[0060] like Figure 8 As shown, the power pump 5 is also equipped with an accumulator 11 to ensure that the internal pressure of the entire power pump 5 is within the normal range.

[0061] like Figure 9As shown, the closed-loop hydraulic station includes an oil tank 19 and a piston pump 20 connected to the oil tank 19. The piston pump 20 is equipped with a drive motor 21 and is driven by the drive motor 21. The drive motor 21 is an explosion-proof motor. The piston pump 20 is a closed-loop piston pump. The oil tank 19 has two oil tank outlets, namely a first oil tank outlet 1901 and a second oil tank outlet 1902. The first oil tank outlet 1901 and the second oil tank outlet 1902 are respectively connected to the first oil port 601 and the second oil port 602 of the power pump 5 through pipelines. The closed-loop hydraulic station also includes a radiator 22, which is located on one side of the oil tank 19 and is used to cool the oil inside the oil tank 19 when the temperature is too high. The closed-loop hydraulic station is also equipped with an oil tank heater 30, which is used to heat the oil tank 19 when the temperature is too low and improve the fluidity of the oil at low temperatures.

[0062] The closed-loop hydraulic station is used to drive the movement of piston 7 of power pump 5. When drive motor 21 drives plunger pump 20 to bring oil from oil tank 19 into cylinder assembly 6 through first oil tank outlet 1901 and first oil port 601, it pushes cylinder piston to move towards second oil port 602, thereby pushing piston 7 to move towards right pump head 802. At this time, the oil on the side of cylinder piston inside cylinder assembly 6 that is close to second oil port 602 is discharged from second oil port 602 and returned to oil tank 19 through second oil tank outlet 1902 for recycling. Conversely, when drive motor 21 drives plunger pump 20 to bring oil from oil tank 19 into cylinder assembly 6 through second oil tank outlet 1902 and second oil port 602, piston 7 moves towards left pump head 801. At this time, the oil on the side of cylinder piston inside cylinder assembly 6 that is close to first oil port 601 is discharged from first oil port 601 and returned to oil tank 19 through first oil tank outlet 1901 for recycling.

[0063] The plunger pump 20 is a closed-loop plunger pump. The plunger moves back and forth within the hydraulic cylinder of the plunger pump 20, driving oil in the tank to enter the power pump 5 from different tank outlets. This, in turn, moves the piston 7 of the power pump 5, discharging the power fluid from one pump head 8 into the wellhead device 2. The power fluid then enters the downhole rodless pump 1 through the wellhead device 2, driving the plunger of the rodless pump 1. Meanwhile, the waste power fluid flows out from the pipe connected to the wellhead device 2 on the other side of the pump head 8 and enters the reservoir 4 through the waste power fluid inlet for recycling. The closed-loop plunger pump provides better sealing and reduces the risk of oil contamination. The sealing design of the closed-loop plunger pump improves efficiency and allows for better control of the pumped fluid flow and pressure.

[0064] Based on the aforementioned natural gas and deep coalbed methane drainage and gas extraction device, this invention provides a control system for the drainage and gas extraction device, used to control the drainage process of the rodless pump 1 during natural gas or deep coalbed methane drainage and extraction. For example... Figure 1 , 11As shown in Figure 13, it includes an electromagnetic directional valve 13, an electromagnetic ranging displacement sensor 18, a one-way valve 9, a pressure sensor 15, an automatic exhaust valve 16, an electromagnetic safety valve 17, a control cabinet 14, etc.

[0065] The electromagnetic distance measuring displacement sensor 18 is installed on the power pump 5 to monitor the movement of the piston 7 in the power pump 5 and to position the piston 7 to obtain its position in the power pump 5. When the piston 7 moves to the set position, the control cabinet 14 receives the signal transmitted by the electromagnetic distance measuring displacement sensor 18 and decelerates the piston 7. At the same time, the data measured by the electromagnetic distance measuring displacement sensor 18 can also effectively determine whether the power pump 5 is working properly.

[0066] The control cabinet 14 receives signals from the electromagnetic ranging displacement sensor 18 and controls the opening and closing of the electromagnetic reversing valve 13 and the plunger pump 20, thereby controlling the piston 7 of the power pump 5 to move in the corresponding direction within the power pump 5 and discharge the power fluid in the power pump 5 from the drain port of the pump head 8. The power fluid enters the rodless pump 1, pushes the plunger of the rodless pump 1 to move, and drives the rodless pump 1 to discharge the waste power fluid. The waste power fluid flows into the storage tank 4 through the electromagnetic reversing valve 13, realizing the upward or downward movement of the plunger of the rodless pump 1.

[0067] Specifically, after receiving the signal transmitted by the electromagnetic ranging displacement sensor 18, the control cabinet 14 sends a signal to the plunger pump 20, controlling the opening and flow direction of the plunger pump 20 while simultaneously controlling the opening and closing of the electromagnetic directional valve 13. The plunger pump 20 controls the oil tank 19 to enter the cylinder assembly 6 of the power pump 5 through the oil tank outlet and the corresponding oil port, pushing the piston 7 of the power pump 5 to move. When the piston 7 reaches the set position, the electromagnetic ranging displacement sensor 18 will transmit a signal to the control cabinet 14 that deceleration is required. At this time, the control cabinet 14 sends a signal to the plunger pump 20 to slowly reduce the opening, causing the oil tank 19 to inject less oil into the power pump 5, and the piston 7 of the power pump 5 to slowly decelerate until it stops. When the piston 7 of the power pump 5 stops, and the result measured by the electromagnetic ranging displacement sensor 18 shows that no position change has occurred, the control cabinet 14 receives the signal transmitted by the electromagnetic ranging displacement sensor 18 and sends a signal to the plunger pump 20 and the electromagnetic directional valve 13, causing the oil tank 19 to inject oil through another oil tank outlet and its corresponding oil port, and then repeats the above actions.

[0068] The control cabinet 14 receives signals from the electromagnetic ranging displacement sensor 18 and controls the opening of the plunger pump 20 to gradually reduce the input to the oil tank 19 until the piston 7 stops, which can prevent cylinder collision and extend the life of the power pump 5.

[0069] The electromagnetic reversing valve 13 is located between the rodless pump 1 and the storage tank 4, and is connected to the power pump 5. The electromagnetic reversing valve 13 controls the input of the power fluid from the power pump 5 into the rodless pump 1 and returns the waste power fluid discharged from the rodless pump 1 to the storage tank 4.

[0070] like Figure 11 As shown, the electromagnetic directional valve 13 is a two-position two-way directional valve, and there are two of them: a first electromagnetic directional valve 1301 and a second electromagnetic directional valve 1302. The inlets of the two two-position two-way directional valves are respectively connected to the annular pipeline 202 and the central pipeline, and the outlets of both are connected to the waste fluid inlet of the storage tank 4. The inlet of the first electromagnetic directional valve 1301 is also connected to the drain port on the right pump head 802, and the inlet of the second electromagnetic directional valve 1302 is also connected to the drain port on the left pump head 801; or, the electromagnetic directional valve 13 can be a two-position three-way directional valve, such as... Figure 13 As shown, the first input port B is connected to the drain port of the right pump head 802 and the annular pipeline 202, the second input port C is connected to the drain port of the left pump head 801 and the central pipeline, and the output port A is connected to the depleted power fluid inlet of the storage tank 4.

[0071] A one-way valve 9 is installed between the liquid storage tank 4 and the rodless pump 1 to ensure that the power fluid enters the rodless pump 1 in one direction and cannot return to the liquid storage tank 4. Specifically, the one-way valve 9 is installed at the drain port and the inlet port of the power pump 5, serving as the drain valve and the inlet valve of the power pump 5.

[0072] The control cabinet 14 receives signals from various sensors in the system and controls the opening and closing of various valves, including controlling the reversing of the plunger pump 20 and the amount of oil flowing out of the oil tank 19, and controlling the solenoid reversing valve 13 to realize the plunger reversing of the rodless pump 1.

[0073] Pressure sensor 15 is installed on wellhead device 2 of the drainage gas extraction device to monitor the pressure in the pipeline of wellhead device 2 and transmit the signal to the control cabinet 14.

[0074] like Figure 1 and Figure 11 As shown, there are two pressure sensors 15, located on the central tubing 201 and the main tubing 301 of the wellhead device 2, respectively, to monitor the pressure in the central tubing and the annulus tubing 202.

[0075] An automatic venting valve 16 is installed on the annulus line 202 of the wellhead device 2 to release the gas in the annulus line 202 of the wellhead device 2.

[0076] The automatic air vent valve 16 is equipped with an electromagnetic safety valve 17 to protect the safety of the automatic air vent valve 16 and ensure its normal operation; the set pressure of the electromagnetic safety valve 17 is 1.0 to 2.5 MPa.

[0077] The maximum working pressure of the automatic air vent valve 16 is 2.5 MPa. Exceeding this pressure will damage the float mechanism. Therefore, when the automatic air vent valve 16 is connected to the annular pipeline 202, an electromagnetic safety valve 17 (set pressure 1.0~2.5 MPa) needs to be installed at its front end to protect the safety of the automatic air vent valve 16 and ensure that the automatic air vent valve 16 works normally.

[0078] The control cabinet 14 adjusts the electromagnetic safety valve 17 according to the data transmitted back by the pressure sensor 15, and controls the opening of the electromagnetic safety valve 17 so that the automatic exhaust valve 16 can normally discharge the gas separated from the liquid in the pipeline, thereby improving the working efficiency and stability of the system.

[0079] like Figure 11 As shown, the control system also includes: two flow sensors 23; one flow sensor 23 is located between the storage tank 4 and the power pump 5 to monitor the power fluid flowing out of the storage tank 4; the other flow sensor 23 is located between the storage tank 4 and the solenoid directional valve 13 to monitor the flow rate of the waste power fluid entering the storage tank 4; a temperature sensor and a water level sensor are located on the storage tank 4 to monitor the temperature and water level inside the storage tank 4 and provide real-time feedback on the parameters of the power fluid inside the storage tank 4; two sets of spring-reset safety valves 26 and diaphragm pressure gauges 27 are located between the two drain ports of the power pump 5 and the solenoid directional valve 13, and both spring-reset safety valves 26 are connected to the storage tank 4 to monitor the pressure of the drain ports and ensure the one-way opening and closing of the drain ports. Figure 10 and 12 As shown, a level gauge 31 is installed on the oil tank 19 to monitor the liquid level inside the oil tank 19, and a ball valve 32 is installed on the plunger pump 20 to control the flow and shut-off of oil between the oil tank 19 and the plunger pump 20. Figure 9 and 12 As shown, the level gauge 31 is connected to the temperature transmitter 33, and outputs the detection result of the level gauge 31 to the control cabinet 14.

[0080] like Figure 11 As shown, both drain ports of the power pump 5 are equipped with vent valves 28 to discharge the gas extracted from the circulating power fluid. When the pressure detected by the diaphragm pressure gauge 27 is lower than the pressure that the vent valve 28 can withstand, the control cabinet 14 receives a signal and adjusts the vent valve 28 to open and discharge the gas.

[0081] The control cabinet 14 receives signals from the sensors, monitors the stable operation of the deep coalbed methane drainage and gas extraction device, and controls the upward and downward movement of the rodless pump 1 in the deep coalbed methane drainage and gas extraction device by adjusting the plunger pump 20 and the electromagnetic reversing valve 13, thereby realizing the automatic drainage and gas extraction process of the drainage and gas extraction device.

[0082] The above-mentioned control system can realize the control of the drainage and gas production device. The control method is as follows: the drive motor 21 is turned on, the control cabinet 14 receives the signal from the electromagnetic ranging displacement sensor 18, and controls the opening and closing of the electromagnetic reversing valve 13 according to the movement of the plunger pump 20. According to the set parameters, the drive motor 21 drives the plunger pump 20 to inject the oil in the oil tank 19 into the power pump 5, pushes the piston 7 in the power pump 5 to move in the set direction in the power pump 5 and opens the drain port check valve 9 to discharge the power fluid in the power pump 5. The power fluid enters the rodless pump 1 through the wellhead device 2 and the tubing string 3, pushes the plunger of the rodless pump 1 to move, and drives the rodless pump 1 to discharge the exhausted power fluid.

[0083] In this method, the flow path of the power fluid includes direction A1, direction B1, liquid circuit A2, and liquid circuit B2.

[0084] In direction A1, the power fluid flows out from the drain port check valve 9 of the left pump head 801 and enters the pipeline. At this time, the second electromagnetic reversing valve 1302 is closed, and the power fluid enters the central oil pipe 201 through the pipeline and enters the annular space of the downhole rodless pump 1, pushing the plunger of the downhole rodless pump 1 to move upward.

[0085] In direction B1, the power fluid flows out from the drain port check valve 9 of the right pump head 802 and enters the pipeline. At this time, the first electromagnetic reversing valve 1301 is closed, and the power fluid enters the annulus pipeline 202 through the pipeline and enters the upper end of the plunger of the rodless pump 1, pushing the plunger of the downhole rodless pump 1 to move downward.

[0086] Liquid circuit A2 opens the inlet of the second electromagnetic directional valve 1302, and the waste fluid returns to the storage tank 4 through the central oil pipe 201.

[0087] Liquid circuit B2 opens the inlet of the first electromagnetic reversing valve 1301, and the waste fluid and produced fluid return to the storage tank 4 through the annular pipeline 202.

[0088] The above methods specifically include the following working conditions:

[0089] System self-check cycle: The system self-circulation process is a self-check procedure designed to verify the correctness of system pipeline connections and ensure safe system operation. This process is limited to use during the initial system operation. The specific operation of the system self-circulation process shown is controlled by control cabinet 14, keeping liquid circuits A2 and B2 constantly connected to perform a complete liquid return process. At this time, all solenoid directional valves 13 are open, and the power fluid discharged from power pump 5 returns directly to the storage tank 4 through pipelines and solenoid directional valves 13. The power fluid does not enter the downhole rodless pump 1 but returns directly to the storage tank 4 through solenoid directional valves 13, circulating only within the system.

[0090] System Pump Start-up Cycle: The system pump start-up procedure is a process designed to raise the plunger of the downhole rodless pump 1. Its purpose is to check whether the rodless pump 1 can start and operate, and whether drainage operations can be performed. The system pump start-up procedure is similar to the upstroke operation. The specific operating method of the system pump start-up procedure is as follows: keep the fluid circuit A2 disconnected at all times, preventing fluid return; keep the fluid circuit B2 connected at all times, allowing fluid return; when the pressure of the power fluid in the central tubing 201 of the system is higher than the upstroke set pressure, connect the fluid circuit A2 to release pressure, and the pump start-up procedure ends. After running the pump start-up procedure, the system zeroing procedure must be run first to prepare for starting the normal operation procedure.

[0091] System Zeroing Cycle: The system zeroing process is essentially to push the plunger of the downhole rodless pump 1 to the bottom of the well, and then retract piston 7 to the position at the beginning of the upstroke. This ensures that piston 7 is aligned with the plunger of the downhole rodless pump 1 when the system starts normal operation. The specific operating method for the system zeroing process is as follows: Liquid circuit B2 is always disconnected, preventing fluid return; liquid circuit A2 is always connected, allowing fluid return; when the dynamic hydraulic pressure in the annulus line 202 is higher than the downstroke set pressure, liquid circuit B2 is connected to relieve pressure, ending the zeroing process. Simultaneously, the surface piston 7 is moved to the position at the beginning of the upstroke to prepare for starting the normal operating procedure. Generally, after system zeroing, the normal operating procedure should start automatically.

[0092] Upstroke: The drive motor 21, controlled by the control cabinet 14, drives the plunger pump 20 to inject oil from the oil tank 19 into the second oil port 602 of the power pump 5, thereby pushing the piston 7 to move to the left pump head 801. At this time, the inlet check valve 9 of the right pump head 802 opens and the outlet check valve 9 closes, drawing power fluid from the storage tank 4. The inlet check valve 9 of the left pump head 801 closes and the outlet check valve 9 opens, allowing the power fluid to flow in the A1 direction. The power fluid enters the pipeline through the outlet of the left pump head 801, then enters the annular space of the rodless pump 1 through the central oil pipe 201, and enters the lower end of the plunger of the rodless pump 1 from the annular space of the rodless pump 1, pushing the plunger of the downhole rodless pump 1 to move upward. The liquid circuit A2 is disconnected, and there is no return of liquid. The liquid circuit B2 is connected, and normal return of liquid occurs. The spent power fluid and produced fluid return to the storage tank 4 through the annular pipe 202.

[0093] Downstroke: The drive motor 21, controlled by the control cabinet 14, drives the plunger pump 20 to inject oil from the oil tank 19 into the first oil port 601 of the power pump 5, thereby pushing the piston 7 to move to the right pump head 802. At this time, the inlet check valve 9 of the left pump head 801 is opened and the outlet check valve 9 is closed, drawing power fluid from the storage tank 4. The inlet check valve 9 of the right pump head 802 is closed and the outlet check valve 9 is opened, allowing the power fluid to flow along direction B1. The power fluid enters the pipeline through the outlet of the right pump head 802 and enters the upper end of the plunger of the rodless pump 1 through the annular pipeline 202, pushing the plunger of the downhole rodless pump 1 to move downward. The liquid circuit B2 is disconnected, and there is no return of liquid. The liquid circuit A2 is connected, and normal return of liquid occurs. The spent power fluid returns to the storage tank 4 through the central oil pipe 201.

[0094] After the upstroke is completed, the electromagnetic reversing valve 13 is controlled to switch the system to perform the downstroke, and the entire drainage and gas extraction process is completed by repeating the cycle.

Claims

1. A surface device for a drainage gas extraction apparatus, used to control the drainage process of a rodless pump (1) during deep coalbed methane drainage, wherein the surface device is connected to the rodless pump (1) and is used to drive the plunger of the rodless pump (1) to move, thereby realizing the drainage process of the rodless pump (1); characterized in that: It includes a control system, a wellhead device (2), and a surface power system; the surface power system is connected to the rodless pump (1) through the wellhead device (2); The ground power system includes a reservoir (4) for storing power fluid, a power pump (5) connected to the reservoir (4), and a closed hydraulic station connected to the power pump (5); The power pump (5) includes a cylinder assembly (6), two hydraulic cylinders (10) disposed on both sides of the cylinder assembly (6), a piston (7) slidably disposed in the cylinder assembly (6) and the two hydraulic cylinders (10), and a pump head (8) disposed at both ends of the power pump (5); the cylinder assembly (6) is provided with a cylinder piston inside, and two oil ports are opened on the sides at both ends; the pump head (8) includes a one-way valve (9) disposed at its discharge port and inlet port respectively; the inlet port is connected to the power fluid outlet of the storage tank (4), and the discharge port is connected to the rodless pump (1) through the wellhead device (2); The closed hydraulic station includes an oil tank (19) and a plunger pump (20) connected to the oil tank (19); the plunger pump (20) is equipped with a drive motor (21), and the oil tank (19) is provided with two oil tank outlets, which are respectively connected to the two oil ports of the power pump (5). The control system includes: An electromagnetic reversing valve (13) is installed between the storage tank (4) of the drainage gas extraction device and the rodless pump (1), and is connected to the power pump (5) of the drainage gas extraction device. The electromagnetic reversing valve (13) is used to control the return of the waste power fluid and extracted fluid discharged by the rodless pump (1) to the storage tank (4). The electromagnetic reversing valve (13) is two two-position two-way reversing valves. The inlets of the two two-position two-way reversing valves are respectively connected to the two waste power fluid outlets of the rodless pump (1), and the outlets are both connected to the waste power fluid inlet of the storage tank (4). Alternatively, the electromagnetic reversing valve (13) is a two-position three-way reversing valve, wherein the two inlets are respectively connected to the two waste power fluid outlets of the rodless pump (1), and the outlet is connected to the waste power fluid inlet of the storage tank (4). An electromagnetic ranging displacement sensor (18) is installed on the power pump (5) to monitor the movement position of the piston (7) inside the power pump (5); The control cabinet (14) is used to receive signals from various sensors in the pipeline and control the opening and closing of the electromagnetic directional valve (13) based on the signal transmitted by the electromagnetic ranging displacement sensor (18).

2. The control system according to claim 1, characterized in that: It also includes a one-way valve (9), which is set between the power fluid outlet of the liquid storage tank (4) and the power fluid inlet of the rodless pump (1) to ensure that the power fluid enters the rodless pump (1) from the liquid storage tank (4) in one direction and cannot return to the liquid storage tank (4) through the power fluid outlet of the liquid storage tank (4).

3. The ground device according to claim 2, characterized in that: The one-way valve (9) is installed on the drain port and inlet port of the power pump (5).

4. The ground device according to claim 1, characterized in that: The control system further includes: A pressure sensor (15) is installed on the pipeline between the power pump (5) and the rodless pump (1) to monitor the pressure in the pipeline and transmit the signal to the control cabinet (14); An automatic vent valve (16) is installed on the wellhead device (2) of the drainage and gas extraction device to vent the gas in the annular pipeline inside the wellhead device (2); the automatic vent valve (16) is equipped with an electromagnetic safety valve (17) to protect the automatic vent valve (16) and ensure that the automatic vent valve (16) works normally; the set pressure of the electromagnetic safety valve (17) is 1.0 to 2.5 MPa.

5. The ground device according to any one of claims 1 to 4, characterized in that: The electromagnetic ranging displacement sensor (18) transmits the monitoring result signal to the control cabinet (14), which controls the opening of the plunger pump (20) to adjust the oil flow rate and outflow direction, thereby controlling the reversing movement of the piston (7) in the power pump (5).

6. The ground device according to claim 1, characterized in that: The piston (7) includes a piston rod (702) and piston bodies (701) located at both ends of the piston rod (702); the cylinder piston is fixedly sleeved on the piston rod (702); the piston rod (702) is composed of a long rod and short rods located at both ends of the long rod, and the piston bodies (701) are provided at the ends of the two short rods away from the long rod; a clamp (703) is sleeved at the connection between the short rod and the long rod to fix the short rod and the long rod of the piston rod (702) in place.

7. A control method for the ground device according to claim 1, characterized in that: Includes the following steps: The control cabinet (14) receives signals from the electromagnetic ranging displacement sensor (18) and controls the opening of the plunger pump (20) to adjust the oil flow rate and outflow direction and control the opening and closing of the electromagnetic reversing valve (13), thereby controlling the piston (7) of the power pump (5) to move in the corresponding direction in the power pump (5) and discharge the power fluid in the power pump (5). The power fluid enters the rodless pump (1), pushes the plunger of the rodless pump (1) to move, and drives the rodless pump (1) to discharge the waste power fluid. The waste power fluid returns to the storage tank (4) through the electromagnetic reversing valve (13), realizing the upward or downward movement of the plunger of the rodless pump (1), thereby realizing the discharge process of the rodless pump (1).

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