Forced pull rod type well-flushing drainage and mining pump for coal bed gas

Abstract

The utility model discloses a coal bed gas forced pull rod type well-flushing drainage pump. The device comprises a pump upper joint, a drainage pump lower joint and a bridge pipe, a pump cylinder is arranged in the bridge pipe, a plunger, a plunger upper joint and a plunger lower joint are arranged in the pump cylinder, and a hollow pull rod is arranged in the plunger; the upper portion of the hollow pull rod is connected with a hollow sucker rod connector, the upper portion of the hollow sucker rod connector is connected with a hollow sucker rod, the lower portion of the hollow pull rod is connected with a traveling valve ball and a pressing cap, and the hollow sucker rod, the hollow pull rod, the traveling valve ball and the pressing cap are provided with through well washing channels. And a through normal production channel is arranged among the plunger, the plunger lower joint and the hollow pull rod. The utility model has the advantages that not only can the production requirement be met, but also the requirements of well washing and pulverized coal discharging can be met, the purposes of discharging pulverized coal from the pump cylinder without lifting a tubular column, preventing the pulverized coal from blocking the pump and prolonging the pump inspection period can be achieved, and the pollution of well washing fluid to stratums is avoided. And the'airlock 'phenomenon during the down stroke of the pump is effectively prevented.

Description

Technical Field

[0001] This utility model relates to a downhole tool for coalbed methane extraction, and in particular to a coalbed methane forced pull rod type well-washing and drainage pump that simultaneously has the functions of drainage, well washing, and gas prevention. Background Technology

[0002] Currently, the fracturing and drainage methods in coalbed methane extraction have changed. They have evolved from conventional hydraulic fracturing with controlled drainage to volumetric fracturing with large fluid and sand volumes. The amount of fracturing fluid used has increased significantly from 500-1000 m³ to 6000-7000 m³, and the drainage system has also changed from continuous, slow, and stable to rapid return drainage.

[0003] The significantly increased flowback rate has led to severe sand and coal dust production in the gas wells. As the production of coalbed methane wells decreases, conventional tubular pumps are unable to discharge the coal dust to the surface. The coal dust accumulates at the fixed valve, causing blockage and making pump jamming unavoidable. Under normal circumstances, resolving these issues requires removing the production tubing for pump inspection, making continuous production impossible. Furthermore, these operations easily cause coal seam contamination, reducing reservoir permeability and drastically decreasing gas production. Through on-site analysis, the main reasons for the short pump inspection cycle of drainage wells are as follows: (1) Coal powder and sand enter the gap of the pump barrel, causing pump jamming; (2) Due to the reduced discharge volume of some drainage wells of coalbed methane, conventional tubular pumps cannot discharge coal powder to the ground. Coal powder falls on the fixed valve, causing blockage of the fixed valve, making it impossible to achieve continuous drainage of coalbed methane wells; (3) When conventional production tubing is used for well washing, the well washing fluid enters the formation, causing formation pollution; (4) Gas lock is easy to occur after gas enters the pump barrel. Later, some drainage pumps that can wash wells gradually appeared on the market, but their structural design is complex, their reliability is poor, and the product cost is also very high. In addition, due to unreasonable structural design, there is also a problem of easy failure, and the product maintenance cost is also very high. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide a coalbed methane forced tie rod type washable well drainage pump that can not only meet the normal drainage needs, but also realize the operation of washing the well to remove coal powder without the tubing string, avoid coal powder blocking the pump, and extend the pump inspection cycle.

[0005] To solve the above-mentioned technical problems, the present invention provides a coalbed methane forced tie rod type washable well drainage pump, including an upper pump connector, a lower drainage pump connector, and a bridge pipe connecting the upper pump connector and the lower drainage pump connector. A pump barrel is installed inside the bridge pipe, and a plunger, an upper plunger connector connected to the upper part of the plunger, and a lower plunger connector connected to the lower part of the plunger are installed inside the pump barrel. A hollow tie rod is installed inside the plunger. A hollow sucker rod connector is connected to the upper part of the hollow tie rod, and a hollow sucker rod is connected to the upper part of the hollow sucker rod connector. A floating valve ball and a pressure cap are connected to the lower part of the hollow tie rod. A through-flow well-washing channel is provided between the hollow sucker rod, the hollow tie rod, the floating valve ball, and the pressure cap. A through-flow normal production channel is provided between the plunger, the lower plunger connector, and the hollow tie rod.

[0006] The bottom end of the plunger lower connector is provided with a lower annular sealing surface. During the upward stroke, the sealing surface of the plunger lower connector and the sealing surface of the floating valve ball form an effective seal.

[0007] The top surface of the movable valve ball is provided with a sealing surface that mates with the lower plunger connector. During the downstroke or well washing operation, the sealing surface between the lower plunger connector and the movable valve ball is forcibly opened, and the gap between the movable valve ball and the lower plunger connector becomes a flow channel for formation fluid or well washing fluid.

[0008] The hollow tie rod passes through the movable valve ball and the pressure cap, and the pressure cap is connected to the hollow tie rod by a thread.

[0009] The movable valve ball has a forced pull rod structure and can be forcibly opened and closed by driving the hollow pull rod up and down through the hollow sucker rod.

[0010] The plunger is provided with a drain hole, which forms a gap channel between the drain hole, the hollow sucker rod connector, and the pump barrel for draining.

[0011] A check valve is installed inside the hollow sucker rod connector.

[0012] The lower end of the bridge pipe is connected to the lower connector of the bridge pipe.

[0013] The advantages of this utility model are:

[0014] (1) A dual-channel structure for normal drainage and gas production and well washing and coal powder discharge was designed; it can meet both production needs and well washing and coal powder discharge needs. It can achieve the purpose of discharging coal powder from the pump barrel without the pipe string, avoiding coal powder jamming the pump and extending the pump inspection cycle. At the same time, it avoids the well washing fluid from entering the formation during well washing and avoids the well washing fluid from polluting the formation.

[0015] (2) The floating valve ball is designed as a forced pull rod type opening and closing structure. The floating valve ball is forced to open and close by driving the hollow pull rod up and down through the hollow sucker rod; effectively preventing the occurrence of "air lock" during the pump downstroke. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view of the coalbed methane forced tie rod type washable well drainage pump of this utility model;

[0017] Figure 2 for Figure 1 A magnified structural diagram at point A. Detailed Implementation

[0018] The following detailed description of the coalbed methane forced tie rod type washable well drainage pump of this utility model, in conjunction with the accompanying drawings and specific embodiments, will be provided in further detail.

[0019] like Figure 1 As shown, the coalbed methane forced tie rod type washable well drainage pump of this utility model includes a hollow sucker rod connector 1, a hollow tie rod 6 connected to the bottom end of the hollow sucker rod connector 1, a pump upper connector 2 set outside the hollow sucker rod connector 1, a pump barrel 3 connected to the inner thread of the pump upper connector, a crossover pipe 4 connected to the outer thread of the pump upper connector 2, a crossover pipe lower connector 10 connected to the lower part of the crossover pipe 4, and a drainage pump lower connector 13 connected to the bottom of the crossover pipe lower connector 10. A plunger 7 is provided on the outside of the hollow tie rod 6, and a plunger lower connector 8 is connected to the bottom end of the plunger 7. A moving valve ball 9 is provided at the bottom end of the hollow tie rod 6 to seal with the plunger lower connector 8. The lower part of the moving valve ball 9 is connected to the pressure cap 14 through threads. The hollow tie rod 6, the plunger lower connector 8, the moving valve ball 9, and the pressure cap 14 constitute a moving valve assembly. The fixed valve cover 11 is connected to the lower connector 10 of the bridge pipe, and the fixed valve 12 is placed inside the fixed valve cover 11. The above components are connected to form a fixed valve assembly. The hollow tie rod 6 is provided with an upper connector 5, a plunger 7, and a lower connector 8 connected to the top of the plunger. The upper connector 5, the plunger 7, and the lower connector 8 form a plunger assembly.

[0020] The lower connector 13 of the drainage pump and the lower connector 10 of the bridge pipe have interconnected central channels. The upper connector 5 of the plunger is provided with a drain hole. A gap channel is formed between the hollow sucker rod connector 1 and the pump barrel 3, which is connected to the drain hole. The annulus between the hollow tie rod 6 and the plunger 7, the annulus between the hollow sucker rod connector 1 and the pump barrel 3, and the annulus between the hollow sucker rod and the tubing are designed to provide liquid discharge channels. This ensures that the well washing fluid will not enter the formation, avoiding the contamination of the formation caused by the well washing fluid of conventional coalbed methane production tubing entering the formation.

[0021] It can be seen that the hollow sucker rod, hollow tie rod, floating valve ball, and pressure cap are equipped with a through well washing channel; the lower part of the upper plunger connector is connected to the plunger, the lower part of the plunger is connected to the lower plunger connector, and a through normal production channel is provided between the plunger, the lower plunger connector and the hollow tie rod.

[0022] Furthermore, the hollow pull rod 6 passes through the floating valve ball 9 and the pressure cap 14, and the pressure cap 14 is connected to the hollow pull rod 6 by threads. The bottom end of the plunger lower connector 8 is provided with a lower annular conical surface, and the top surface of the floating valve ball 9 is provided with a spherical sealing surface that mates with the lower annular conical surface.

[0023] Before the production pump needs to be flushed, the floating valve ball 9 and the pressure cap 14 are lowered to the "pump-touching" position. The lower plunger connector 8 is removed from the sealing surface of the floating valve ball 9, opening the flushing channel between the floating valve ball 9 and the lower plunger connector 8. The floating valve ball is connected to the hollow tie rod. The hollow sucker rod drives the hollow tie rod to move up and down, thereby forcibly opening and closing the floating valve ball, thus preventing "gas lock" in the production pump.

[0024] Furthermore, a check valve is installed inside the hollow sucker rod joint. It is closed during normal production to prevent formation fluid from entering the hollow sucker rod and affecting pump efficiency. It is opened during well cleaning to achieve the connection of the well cleaning channel of the hollow sucker rod joint.

[0025] The internal fluid flow is as follows:

[0026] Normal production: Gas produced from the coal seam is produced through the tubing and casing annulus. During the upstroke, the plunger drives the hollow tie rod upward through the hollow sucker rod, opening the fixed valve. Formation fluid enters the pump chamber through the central channel of the lower joint of the drainage pump, the fixed valve, and the central channel of the lower joint of the bridge pipe. During the downstroke, the plunger drives the hollow tie rod downward through the hollow sucker rod, causing the floating valve ball to leave the sealing surface of the lower joint of the plunger. Formation fluid enters the gap channel between the hollow tie rod and the plunger, the drain hole of the upper joint of the plunger, the gap channel between the upper joint of the plunger and the pump barrel, the gap channel between the hollow sucker rod joint and the upper joint of the pump, and the annulus channel between the hollow sucker rod and the tubing, and is discharged to the surface.

[0027] Well washing operation: First, lower the floating valve ball and pressure cap to the "pump-touching" position, allowing the floating valve ball to move away from the sealing surface of the lower plunger connector, thus opening the well washing channel between the floating valve ball and the lower plunger connector. Inject well washing fluid through the hollow sucker rod using a surface pump truck. The well washing fluid passes through the annular channel between the hollow sucker rod and tubing, the hollow sucker rod connector, the hollow tie rod, the central channel of the floating valve ball, the gap channel between the hollow tie rod and the plunger, the drain hole of the upper plunger connector, the gap channel between the upper plunger connector and the pump barrel, the gap channel between the hollow sucker rod connector and the upper pump connector, and the annular channel between the hollow sucker rod and tubing before being discharged to the surface.

[0028] Of course, the above description is not intended to limit the present utility model, and the present utility model is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present utility model should also fall within the protection scope of the present utility model.

Claims

1. A coalbed methane forced tie rod type washable well drainage pump, characterized in that: The system includes an upper pump connector (2), a lower pump connector (13), and a bridge pipe (4) connecting the upper pump connector (2) and the lower pump connector (13). A pump cylinder (3) is installed inside the bridge pipe (4). A plunger (7), an upper plunger connector (5) connected to the upper part of the plunger, and a lower plunger connector (8) connected to the lower part of the plunger are installed inside the pump cylinder (3). A hollow tie rod (6) is installed inside the plunger (7). The upper part is connected to a hollow sucker rod connector (1), the upper part of which is connected to a hollow sucker rod. The lower part of the hollow pull rod (6) is connected to a floating valve ball (9) and a pressure cap (14). The hollow sucker rod, hollow pull rod (6), floating valve ball (9), and pressure cap (14) are provided with a through well washing channel. A through normal production channel is provided between the plunger (7), the plunger lower connector (8), and the hollow pull rod (6).

2. The forced-rod type washable well drainage pump according to claim 1, characterized in that: The top surface of the movable valve ball (9) is provided with a sealing surface that mates with the lower plunger connector (8). During the downstroke or well washing operation, the sealing surface between the lower plunger connector (8) and the movable valve ball (9) is forcibly opened, and the gap between the lower plunger connector (8) and the movable valve ball (9) becomes a flow channel for formation fluid or well washing fluid.

3. The coalbed methane forced tie rod type washable well drainage pump according to claim 1 or 2, characterized in that: The hollow pull rod (6) passes through the movable valve ball (9) and the pressure cap (14), and the pressure cap (14) is connected to the hollow pull rod (6) by a thread.

4. The coalbed methane forced tie rod type washable well drainage pump according to claim 2, characterized in that: The bottom end of the plunger lower connector (8) is provided with a lower annular sealing surface. During the upward stroke, the sealing surface of the plunger lower connector (8) and the sealing surface of the floating valve ball (9) form an effective sealing surface.

5. The coalbed methane forced tie rod type washable well drainage pump according to claim 1, 2 or 4, characterized in that: The movable valve ball (9) is a forced pull rod structure and can be forcibly opened and closed by driving the hollow pull rod up and down through the hollow sucker rod.

6. The coalbed methane forced tie rod type washable well drainage pump according to claim 5, characterized in that: The plunger connector (5) is provided with a drain hole, and a gap channel for draining is formed between the drain hole and the hollow sucker rod connector (1) and the pump barrel (3).

7. The coalbed methane forced tie rod type washable well drainage pump according to claim 6, characterized in that: A check valve is installed inside the hollow sucker rod connector (1).

8. The coalbed methane forced tie rod type washable well drainage pump according to claim 7, characterized in that: The lower end of the bridge pipe (4) is connected to the lower connector (10) of the bridge pipe.

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