Water drainage and gas production lifting system for coal-bed gas well

Abstract

The invention provides a drainage and gas production lifting system for a coal-bed gas well. The drainage and gas production lifting system comprises a drum-type mechanical pumping drainage and gas production device and a mechanical pumping drainage and gas production lifting system. The output end of the drum-type mechanical pumping drainage and gas production device is connected with a bearing rope of the mechanical pumping drainage gas production lifting system; the pumping drainage gas production lifting system comprises a first oil pipe structure, an oil pumping polish rod structure and a directional flow channel plunger type gas-water separation system, the first oil pipe structure is arranged in a gas well shaft, the oil pumping polish rod structure is arranged in the first oil pipe structure, and the bottom of the oil pumping polish rod structure is connected with a continuous oil rod of the directional flow channel plunger type gas-water separation system. And the top of the directional runner plunger type gas-water separation system is detachably connected with the first oil pipe structure. According to the drainage and gas production lifting system for the coal-bed gas well, the problem that a drainage and gas production system cannot be adjusted in time due to the fact that a sucker-rod pump pumping system in the related technology cannot meet the rapid change of the stratum liquid outlet amount is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas development, and in particular relates to a drainage and gas production lifting system for coalbed methane wells. Background Art

[0002] Coalbed methane (CBM) refers to a hydrocarbon gas stored in coal seams, primarily composed of methane, adsorbed on the surface of coal particles, with some remaining free in coal pores or dissolved in coalbed water. It is an associated mineral resource with coal and is considered an unconventional natural gas. One method of extracting CBM is through surface in-situ extraction, which involves drilling drainage wells. CBM well extraction involves a process of continuous depressurization and drainage.

[0003] Currently, domestic coalbed methane (CBM) production equipment largely relies on rod pumping technology from oilfields. The development of CBM production systems and the selection of equipment are largely based on past experience, and a comprehensive and mature production technology system tailored to specific geological conditions has yet to be established. Consequently, rod pumping currently accounts for over 98% of CBM wells, but this technology presents numerous challenges.

[0004] Because the rod pumping system in related technologies cannot meet the rapid changes in formation fluid production, it is difficult to adjust the drainage system in a timely manner. It cannot meet the slow, long-term, continuous, and stable drainage requirements of coalbed methane wells in different production stages. While meeting the requirements for timely adjustment of the drainage system, it is also necessary to solve the problem of automatically controlling the drainage intensity and controlling the operation according to the requirements of the two types of drainage management systems: fixed pressure or fixed production. Traditional single-well pumping occupies a large area; there are many transmission links, short strokes, and high stroke rates, which result in low system efficiency and high energy consumption. Rod and tubing eccentric wear seriously shortens the service life of rods and tubing. Rod pump technology is relatively mature, but it is easily affected by sand and gas production, resulting in severe pump wear and reduced pump efficiency. The output of solid particles can cause the tubing pump to jam, increasing operating costs. Summary of the Invention

[0005] In view of this, the present invention aims to solve one of the related technical problems at least to a certain extent.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A drainage and gas production lifting system for coalbed methane wells, comprising a drum-type mechanical drainage and production device and a mechanical drainage and gas production lifting system;

[0008] The output end of the drum-type mechanical pumping and drainage device is connected to the load-bearing rope of the mechanical pumping and drainage and gas lifting system;

[0009] The rod-pumped drainage gas lift system includes a first tubing structure, a polished rod structure, and a directional flow channel plunger-type gas-water separation and production system. The first tubing structure is arranged in the gas wellbore. The polished rod structure is arranged inside the first tubing structure. The bottom of the polished rod structure is connected to the continuous rod of the directional flow channel plunger-type gas-water separation and production system. The top of the directional flow channel plunger-type gas-water separation and production system is detachably connected to the first tubing structure.

[0010] The polished rod structure includes a load-bearing rope, a sealing sleeve, a diversion short joint, a positioning short joint, and a dynamic sealing structure. One end of the load-bearing rope is connected to the output end of the drum-type rod-pumped drainage and production device. The other end of the load-bearing rope is connected to the dynamic sealing structure. The dynamic sealing structure is slidably arranged inside the sealing sleeve. The dynamic sealing structure is connected to the continuous rod. The diversion short joint and the positioning short joint are arranged at the bottom of the sealing sleeve. The positioning short joint is detachably connected to the bottom of the first tubing structure.

[0011] Further, the dynamic sealing structure includes a first sealing plunger and a second sealing plunger. The top of the first sealing plunger is connected to the load-bearing rope through a thimble. The second sealing plunger is arranged at the bottom of the first sealing plunger. The second sealing plunger is connected to the continuous rod.

[0012] Further, the directional flow channel plunger-type gas-water separation and production system includes a second tubing structure, a continuous rod, a connection structure, a sucker rod, a pump pull rod, a conical pump barrel, a double-closed structure plunger, a disc-type liquid-gas separator, and a self-cleaning guiding fixed valve. The top of the second tubing structure is detachably connected to the bottom of the first tubing structure. The bottom of the second tubing structure is connected to the conical pump barrel. The disc-type liquid-gas separator is arranged at the bottom of the conical pump barrel. The top of the continuous rod is connected to the second sealing plunger. The bottom of the continuous rod is connected to the sucker rod through the connection structure. The bottom of the sucker rod is connected to the double-closed structure plunger through the pump pull rod. Both the disc-type liquid-gas separator and the self-cleaning guiding fixed valve are located below the double-closed structure plunger. The self-cleaning guiding fixed valve is arranged between the disc-type liquid-gas separator and the double-closed structure plunger. Both the double-closed structure plunger and the self-cleaning guiding fixed valve are arranged inside the conical pump barrel.

[0013] Further, the side wall inclination angle of the conical pump barrel is 5°-10°.

[0014] Furthermore, the drum-type mechanical pumping and gas drainage device includes a truss support, a wellhead guiding pulley, an adjusting tie rod, a foundation base, a drum structure, a motor, a speed reducer, a rope arranging mechanism, and a moving base. The wellhead guiding pulley is arranged at the top of the truss support. The bottom of the truss support is hinged to the foundation base. One end of the adjusting tie rod is hinged to the top of the truss support, and the bottom of the adjusting tie rod is hinged to the foundation base. The moving base is connected to the foundation base through a sliding structure. The drum structure, the motor, and the speed reducer are all arranged on the moving base. The output end of the motor is connected to the input shaft of the speed reducer. The output shaft of the speed reducer is a hollow shaft. One end of the output shaft of the speed reducer is connected to the drum structure, and the other end of the output shaft of the speed reducer is threadedly connected to the threaded end of the rope arranging mechanism. The fixed end of the rope arranging mechanism is arranged on the foundation base. The load-bearing rope is wound on the drum structure. The wellhead guiding pulley is used for guiding the load-bearing rope.

[0015] Furthermore, the drum-type mechanical pumping and gas drainage device further includes a safety operation platform, and the safety operation platform is arranged on the truss support.

[0016] Furthermore, the sliding structure includes two parallel guiding slide rails. The sides of the moving base are all in sliding cooperation with the two guiding slide rails through moving rollers. Radial limiting rollers are arranged on the sides of the moving base.

[0017] Furthermore, an origin switch is arranged on the guiding slide rail, and upper dead point limit switches and lower dead point limit switches are respectively arranged at the front and rear ends of the guiding slide rail.

[0018] Furthermore, the drum structure includes a Ribas drum and two drum supports. The Ribas drum is connected to the upper end face of the moving base through the two drum supports. The Ribas drum is used for winding the load-bearing rope.

[0019] Furthermore, a jet reflux device is further included. The jet reflux device includes a suction port, a power gas source interface, and a diffuser tube. The suction port is arranged at the inlet end of the diffuser tube. The power gas source interface is arranged at the inlet end of the diffuser tube. The outlet end of the diffuser tube is connected to the gas production pipeline through a pipeline. The suction port is connected to the overflow liquid outlet of the wellhead Christmas tree cross.

[0020] Compared with the prior art, the drainage gas production lifting system for coalbed methane wells of the present invention has the following advantages:

[0021] 1. It consists of a drum-type mechanical pumping and gas-lift device, a polished rod structure adapted thereto, and a directional flow channel plunger-type gas-liquid separation system. Due to the increase in the well deviation angle, it affects the setting depth of the sucker rod pump, especially for the ultra-long stroke sucker rod pump, which can meet the requirements of the pump setting depth for drainage gas production in coalbed methane wells to the greatest extent. Adding a tail pipe reduces the utilization of the pump inlet and uses the siphon principle.

[0022] 2. The gas separation principle of the disc-type gas anchor is that the gas collection disc is used as a bubble trap. After the bubbles are gathered, the centrifugal effect during the 90° turning of the liquid flow is utilized to separate the liquid and gas. When the gas accumulates and overflows in the disc, large bubbles are formed, which float along the inner wall of the gas anchor housing to the gas cap and then reach the annulus between the tubing and the casing through the exhaust hole, while the liquid enters the pump through the suction hole into the suction pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 It is a schematic diagram of a drainage gas production lifting system for coalbed methane wells according to an embodiment of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the drum-type mechanical pumping and gas-lift device according to an embodiment of the present invention;

[0026] Figure 3 It is a top view of the structural diagram of the drum-type mechanical pumping and gas-lift device according to an embodiment of the present invention.

[0027] Description of the reference numerals:

[0028] 1. Wellhead guiding pulley; 2. Pulley bearing support; 3. Top platform; 4. Truss support; 5. Safety operation platform; 6. Pin shaft; 7. Adjusting tie rod; 8. Foundation base; 9. Lower limit slide rail; 10. Upper limit slide rail; 11. Moving base; 12. Moving roller; 13. Horizontal reversing wheel; 14. Ribas drum; 15. Drum support; 16. First coupling; 17. Reducer; 18. Rope arranging mechanism; 19. Motor; 20. Second coupling; 21. Manual-electric integrated brake; 22. Load-bearing rope; 23. Cable joint; 24. First sealing plunger; 25. Second sealing plunger; 26. Suspension seal; 27. Christmas tree cross; 28. Sealing sleeve; 29. Flow guiding stub; 30. Positioning stub; 31. Blowout preventer manual gate valve; 32. Telescopic blowout preventer pipe; 33. Jet reflux device; 34. Tubing hanger; 35. Tubing head cross; 36. First tubing structure; 37. Conical pump barrel; 38. Self-cleaning guiding fixed valve; 39. Disc type liquid-gas separator; 40. Siphon tail pipe; 41. Continuous sucker rod; 42. Safety joint; 43. Positive and negative connector; 44. Sucker rod; 45. Pump tie rod; 46. Double closed structure plunger. Detailed implementation manners

[0029] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0030] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0031] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0033] A drainage gas-lift system for a coalbed methane well, as Figure 1 , Figure 2 and Figure 3 shown, includes a drum-type mechanical pumping drainage and gas production device and a mechanical pumping drainage and gas-lift system; the output end of the drum-type mechanical pumping drainage and gas production device is connected to the load-bearing rope 22 of the mechanical pumping drainage and gas-lift system; the mechanical pumping drainage and gas-lift system includes a first tubing structure 36, a polished rod structure for pumping oil, and a directional flow channel plunger-type gas-water separation and production system. The first tubing structure 36 is arranged in the gas wellbore, the polished rod structure for pumping oil is arranged inside the first tubing structure 36, the bottom of the polished rod structure for pumping oil is connected to the continuous rod 41 of the directional flow channel plunger-type gas-water separation and production system, and the top of the directional flow channel plunger-type gas-water separation and production system is detachably connected to the first tubing structure 36;

[0034] The polished rod structure for pumping oil includes a load-bearing rope 22, a sealing sleeve 28, a diversion short joint 29, a positioning short joint 30, and a dynamic sealing structure. One end of the load-bearing rope 22 is connected to the output end of the drum-type mechanical pumping drainage and gas production device, the other end of the load-bearing rope 22 is connected to the dynamic sealing structure, the dynamic sealing structure is slidably arranged inside the sealing sleeve 28, the dynamic sealing structure is connected to the continuous rod 41, and the bottom of the sealing sleeve 28 is provided with the diversion short joint 29 and the positioning short joint 30, and the positioning short joint 30 is detachably connected to the bottom of the first tubing structure 36.

[0035] The dynamic sealing structure includes a first sealing plunger 24 and a second sealing plunger 25. The top of the first sealing plunger 24 is connected to the load-bearing rope 22 through a thimble 23, the bottom of the first sealing plunger 24 is provided with the second sealing plunger 25, and the second sealing plunger 25 is connected to the continuous rod 41.

[0036] The directional flow channel plunger type gas-liquid separation production system includes a second tubing structure, a continuous sucker rod 41, a connecting structure, a sucker rod 44, a pump draw rod 45, a conical pump barrel 37, a double-closed structure plunger 46, a disc type liquid-gas separator 39 and a self-cleaning guiding fixed valve 38. The top of the second tubing structure is detachably connected to the bottom of the first tubing structure 36, and the bottom of the second tubing structure is connected to the conical pump barrel 37. The disc type liquid-gas separator 39 is arranged at the bottom of the conical pump barrel 37. The top of the continuous sucker rod 41 is connected to the second sealing plunger 25, and the bottom of the continuous sucker rod 41 is connected to the sucker rod 44 through the connecting structure. The bottom of the sucker rod 44 is connected to the double-closed structure plunger 46 through the pump draw rod 45. Both the disc type liquid-gas separator 39 and the self-cleaning guiding fixed valve 38 are located below the double-closed structure plunger 46. The self-cleaning guiding fixed valve 38 is arranged between the disc type liquid-gas separator 39 and the double-closed structure plunger 46. Both the double-closed structure plunger 46 and the self-cleaning guiding fixed valve 38 are arranged in the conical pump barrel 37. The side wall inclination angle of the conical pump barrel 37 is 5°-10°.

[0037] The conical pump barrel 37 is composed of two parts: a conical section and an equal-diameter section. The conical section is located above the equal-diameter section of the pump barrel. Since the stroke length reaches more than 15m, during the upstroke, the plunger runs in the equal-diameter part of the pump barrel for most of the time. Once the conical section of the pump barrel is exposed from the bottom of the double-closed structure plunger 46, the gap between the double-closed structure plunger 46 and the inner wall of the pump barrel will suddenly increase and show an increasing trend as the double-closed structure plunger 46 continues to move upward. Therefore, starting from when the conical section of the pump barrel is exposed from the bottom of the plunger, the gas accumulated in the pump barrel is gradually displaced by the well fluid in the high-pressure area above the movable valve. The displacement process may continue until the plunger reaches the top dead center. The pumping unit can stay at the top dead center position for a certain time according to the actual situation to make the gas-liquid displacement more sufficient. The displacement process may also end in advance, which depends on the amount of gas accumulated in the pump barrel. At the same time, as the process of mutual displacement between the gas in the pump barrel and the well fluid in the high-pressure area above the movable valve progresses, the pressure difference between the upper and lower parts of the movable valve will gradually decrease, making the pressures above and below the movable valve in a balanced state. Therefore, during the downstroke, the movable valve of the plunger will open in time to avoid the phenomenon of delayed opening of the movable valve. The plunger adopts a double-closed structure. A closed valve cover is added between the upper opening valve cover and the plunger, and the valve ball is installed in this closed valve cover. When the valve ball opens during the upstroke, it can avoid the impact of the valve ball on the opening valve cover, effectively reducing the risk of fracture of the upper valve cover. The fixed valve assembly adopts a spring guiding structure to ensure that the fixed valve ball of the oil pump can open and close freely and the valve seat can maintain sealing when the well deviation angle ≤ 65°. There are obliquely downward holes on the self-cleaning cover of the fixed valve. When the flowing well fluid passes through these oblique holes during the upstroke, it will scour the bottom annulus of the pump downward, realizing the self-cleaning function, making it difficult for coal powder to deposit in this annulus, improving the pump efficiency, and preventing the problem of no liquid discharge due to coal powder clogging the fixed valve.

[0038] The disc-type liquid-gas separator 39 uses a gas-collecting disc to capture bubbles. After the bubbles are aggregated, the centrifugal effect during the 90° turn of the liquid flow is utilized to separate the liquid and gas. When the gas accumulates and overflows in the disc, large bubbles are formed and float upward along the inner wall of the gas anchor housing to the gas cap, and then reach the oil-casing annulus through the exhaust hole. The liquid enters the suction pipe from the suction hole and then enters the pump barrel of the sucker rod pump. The small-diameter tail pipe connected to the bottom end of the disc-type gas anchor is used to solve the problem that the increase in the well deviation angle affects the setting depth of the sucker rod pump, and it can meet the requirements of the pump setting depth for gas drainage and gas production in coalbed methane wells to the greatest extent. Adding the tail pipe uses the siphon principle to lower the pump inlet and achieve the purpose of deepening the pump setting.

[0039] The gas production wellhead is provided with a tubing head cross 35 and a Christmas tree cross 27. The upper flange at the top of the tubing head cross 35 is fixedly connected to the lower flange at the bottom of the Christmas tree cross 27. A tubing hanger 34 is arranged inside the upper flange of the tubing head cross 35, and the lower end of the tubing hanger 34 is connected to the first tubing structure 36 and the second tubing structure. An overflow liquid outlet is opened on the side of the upper flange of the Christmas tree cross 27, and the overflow liquid outlet is connected to the suction pipe of the jet reflux device 33 at the wellhead. The intake pipe of the jet reflux device 33 is connected to the outlet end of the casing gate of the tubing head cross 35, and the diffuser pipe is connected to the gas production pipeline. A blowout preventer gate is also connected to the upper flange of the Christmas tree cross 27, and a telescopic blowout preventer pipe 32 is assembled on the upper part of the blowout preventer gate.

[0040] The downhole sealing working barrel is suspended in the upper flange of the Christmas tree cross 27 through a suspension seal 26, and is concentrically and sealedly suspended with the tubing hanger 34, and is inserted into the tubing at the upper end of the downhole production string. The annular space formed between the outer wall of the sealing sleeve 28 and the inner wall of the downhole tubing is the ground drainage channel for the tubing of the mechanical pumping drainage and gas production lifting system, and this annular channel is connected to the produced liquid channel on the side of the tubing cross.

[0041] The oil-casing annulus formed between the outer wall of the downhole production string and the inner wall of the casing of the coalbed methane well is the gas production channel for the mechanical pumping drainage and gas production lifting system, and this oil-casing annulus is connected to the casing gate on the side of the casing cross.

[0042] The diversion short joint 29 at the bottom end of the sealing working barrel is communicated with the annular space formed between the outer wall of the sealing sleeve 28 and the inner wall of the downhole tubing. The first sealing plunger 24 and the second sealing plunger 25 of the wireline pumping polished rod move up and down reciprocally in the sealing working barrel driven by the drum of the mechanical pumping drainage and production device.

[0043] The lower end of the second sealing plunger 25 is connected to the downhole carbon fiber continuous sucker rod 44 hybrid string, and the bottom end of the sucker rod 44 is connected with a long-stroke sucker rod pump plunger, and the sucker rod pump plunger is arranged inside the sucker rod pump barrel.

[0044] The 44 rods of downhole sucker rods include continuous carbon fiber sucker rods 44. The bottom end of the carbon fiber sucker rod 44 is connected to the sucker rod 44 through a connection structure (safety joint 42 and positive and negative threaded joints). The sucker rod 44 is connected to the plunger of the sucker pump. A double valve ball, a valve seat and a closed valve cover are arranged inside the plunger of the sucker pump. The plunger of the sucker pump is inserted into the downhole sucker pump barrel through the sucker rod 44.

[0045] The conical pump barrel 37 is composed of a conical section and an equal-diameter section. The conical section is located at the upper part of the equal-diameter section of the pump barrel. The equal-diameter section of the conical gas-proof pump barrel is seamlessly coaxially connected by several chromium-plated or carbonitrided pump barrels. The bottom end of the pump barrel is equipped with an inclined well anti-leakage fixed valve ball assembly. The fixed valve assembly adopts a spring guiding structure. The spring is made of Monel material with good corrosion resistance. There are inclined downward holes on the self-cleaning cover of the fixed valve. The bottom end of the fixed valve assembly is sequentially connected with a disc type gas anchor and a small-diameter tail pipe.

[0046] As Figure 2-3 Shown in the figure, the drum-type mechanical pumping drainage device includes a truss support 4, a wellhead guiding pulley 1, an adjusting pull rod 7, a foundation base 8, a drum structure, a motor 19, a reducer 17, a rope arranging mechanism 18 and a moving base 11. A wellhead guiding pulley 1 is arranged at the top of the truss support 4. The bottom of the truss support 4 is hinged to the foundation base 8. One end of the adjusting pull rod 7 is hinged to the top of the truss support 4, and the bottom of the adjusting pull rod 7 is hinged to the foundation base 8. The moving base 11 is connected to the foundation base 8 through a sliding structure. The drum structure, the motor 19 and the reducer 17 are all arranged on the moving base 11. The output end of the motor 19 is connected to the input shaft of the reducer 17. The output shaft of the reducer 17 is a hollow shaft. One end of the output shaft of the reducer 17 is connected to the drum structure, and the other end of the output shaft of the reducer 17 is threadedly connected to the threaded end of the rope arranging mechanism 18. The fixed end of the rope arranging mechanism 18 is arranged on the foundation base 8. The load-bearing rope 22 is wound on the drum structure. The wellhead guiding pulley 1 is used to guide the load-bearing rope 22. The drum-type mechanical pumping drainage device also includes a safety operation platform 5, and the safety operation platform 5 is arranged on the truss support 4. The drum structure includes a Ribas drum 14 and two drum supports 15. The Ribas drum 14 is connected to the upper end surface of the moving base 11 through two drum supports 15. The Ribas drum 14 is used to wind the load-bearing rope 22.

[0047] The sliding structure includes two upper limit sliding rails 10 and a lower limit sliding rail 9. The upper limit sliding rails 10 and the lower limit sliding rail 9 are symmetrically arranged up and down. The side of the moving base 11 is slidably matched with the upper limit guiding sliding rail and the lower limit sliding rail 9 through moving rollers 12. The side of the moving base 11 is provided with radial limit rollers. The guiding sliding rail is provided with an origin switch, and upper dead point limit switches and lower dead point limit switches are respectively arranged at the front and rear ends of the guiding sliding rail.

[0048] It also includes a jet reflux device 33, which includes a suction port, a power gas source interface and a diffuser tube. The suction port is arranged at the inlet end of the diffuser tube, the power gas source interface is arranged at the inlet end of the diffuser tube, the outlet end of the diffuser tube is connected to the gas extraction pipeline through a pipeline, and the suction port is connected to the overflow liquid outlet of the production tree cross 27.

[0049] The tubing hanger 34 is installed and suspended inside the upper flange of the tubing head cross 35. The tubing hanger 34 is sequentially connected to the first tubing structure 36 and the tapered pump barrel 37 through threads. A self-cleaning guiding fixed valve 38 is arranged at the lower end of the tapered pump barrel 37. The fixed valve is sequentially connected to the disc type liquid-gas separator 39 and the siphon tail pipe 40. The oil-casing annulus formed between the outer wall of the first tubing structure 36 and the inner wall of the casing of the coalbed methane well communicates with the large cross gate of the tubing head cross 35 as the gas extraction channel of the coalbed methane well. The load-bearing rope 22 is a steel wire rope.

[0050] The lower flange of the production tree cross 27 and the upper flange of the tubing head cross 35 are fixedly connected by bolts and nuts. The hanging seal 26 is sequentially connected to the seal working cylinder, the diversion short joint 29 and the positioning short joint 30 through threads, is lowered into the combined tubing string, and is suspended inside the upper flange of the production tree cross 27 through the seal working cylinder hanging seal 26. The annular space formed between the outer wall of the seal sleeve 28 and the inner wall of the first tubing structure 36 communicates with the small cross gate of the production tree cross 27 as the produced water channel of the coalbed methane well. The lower flange of the blowout preventer manual gate valve 31 is fixedly connected to the upper flange of the production tree cross 27 by bolts. The lower flange of the telescopic blowout preventer pipe 32 is fixedly connected to the upper flange of the blowout preventer manual gate valve 31 by bolts. The suction port, the power gas source inlet and the outlet of the diffuser tube of the jet reflux device 33 are respectively connected to the reflux outlet on the upper flange of the production tree cross 27 and the surface gas extraction pipeline of the tubing head cross 35. The cable joint 23 of the load-bearing rope 22 is sequentially connected to the first sealing plunger 24 and the second sealing plunger 25, and then one end of the load-bearing rope 22 is wound and fixed on the drum.

[0051] After the above implementation is completed, the process rod string part in the directional flow channel plunger type gas-water separation and production system is implemented. The continuous carbon fiber sucker rod 41 is sequentially connected to the safety joint 42, the positive and negative connector 43, the sucker rod 44, the pump pull rod 4, the double-closed structure plunger 46 through threads. The process rod string passes through the blowout preventer manual gate valve 31, the telescopic blowout preventer pipe 32, the seal working cylinder hanging seal 26, the production tree cross 27, the seal working cylinder, the diversion short joint 29, the positioning short joint 30 in the wire rope sucker rod and seal system 2 and is installed in the first tubing structure 36 of the process tubing string part in the directional flow channel plunger type gas-water separation and production system. The double-closed structure plunger 46 is arranged in the tapered pump barrel 37. After the implementation is completed, the entire process rod string is suspended on the telescopic blowout preventer pipe 32 through a special tool.

[0052] Finally, the drum type mechanical pumping drainage and gas lift device in the mechanical pumping drainage and gas lift system is implemented;

[0053] Among them, the basic base 8 is installed at a position 1 m away from the vertical axis of the large four-way tubing head at the wellhead of the coalbed methane well. The truss support 4 and the adjusting tie rod 7 are fixedly installed on the basic base 8 through the pin shaft 6. The wellhead guiding pulley 1 is fixedly installed on the top platform 3 through the pulley bearing support 2. The safety operation platform 5 is installed on the truss support 4. The ribas drum 14 is fixedly installed on the moving base 11 by the drum bearing support. The motor 19 and the reducer 17 are fixedly installed on the moving base 11 at the same time. The ribas drum 14 is fixedly connected to the output shaft of the reducer 17 through the first coupling 16 by the drum bearing support. The output shaft is fixedly connected to the input shaft of the reducer 17 through the second coupling 20. The motor 19 drives the ribas drum 14 to rotate through the reducer 17. The moving base 11 is assembled on the lower limit track through the rollers at the bottom and the horizontal reversing wheels 13. The upper limit track is arranged on the rollers. The guiding slide rail is composed of the lower limit track and the upper limit track. The moving base 11 can move along the lower limit track. The output shaft of the reducer 17 is a hollow shaft. One end of the hollow output shaft is connected to the drum through the first coupling 16. A nut is fixedly connected to the outer end of the input shaft at the other end of the hollow output shaft. The nut is screwed on the lead screw of the wire rope arranging mechanism 18. The wire rope arranging mechanism 18 is fixedly installed on the basic base 8 through the support frame. During the rotation of the input shaft of the reducer 17, the nut and the input shaft drive the wire rope arranging mechanism 18 to move linearly along the lead screw synchronously with the rotation of the drum. The motor 19 is connected to the control system and is controlled by the control system to work.

[0054] After the no-load commissioning of the drum-type mechanical pumping drainage and gas production device is completed, the second sealing plunger 25 and the upper joint of the carbon fiber continuous sucker rod 41 are connected by threads for hanging and manual commissioning.

[0055] The working mode of this example

[0056] The first step: Design the process plan of the mechanical pumping drainage and gas production lifting system according to the geological plan design of the coalbed methane well;

[0057] The design of the process plan of the lifting system includes the pump setting depth, pump diameter, stroke, stroke frequency, combination of the carbon fiber continuous sucker rod 44 hybrid rod string, downhole process string structure, and determination of the model of the drum-type mechanical pumping drainage and gas production device.

[0058] The second step: Carry out downhole operation construction on the process string part, polished sucker rod structure, lower rod, pipe, and process rod string part in the directional flow channel plunger-type gas-water separation system in the drainage and gas production lifting system respectively according to the requirements of the process plan design.

[0059] The third step: Install the drum-type mechanical pumping drainage and gas production device;

[0060] Install the base 8 of the drum-type mechanical pumping and drainage device. Install the wellhead pulley truss support 4 and the adjustment truss support 4 on the device base 8. The workover yield adjustment pull rod 7 is installed. In this embodiment, the adjustment pull rod 7 is composed of a threaded rod and a threaded sleeve. The combination of the threaded rod and the threaded sleeve can realize the telescopic function. Install the lower limit track, place the moving base 11 on the track, install a motor 19, a reducer 17 and a Ribas drum 14 on the moving trolley, and connect the control cabinet system and the motor 19.

[0061] Step 4. Debug the drum-type mechanical pumping and drainage device

[0062] The signals of the top dead center limit switch, the origin switch, the bottom dead center limit switch, the encoder, the load sensor, the pressure transmitter, the emergency cut-off valve and the flowmeter, and the manual-electric integrated brake 21 are respectively connected to the DI, A / D and RS485 interfaces of the control core RTU34 through wires, and the control system is started through the man-machine dialogue on the display screen in the control system. First, enter the initialization screen menu to complete the initialization operation of the drum-type mechanical pumping and drainage device, and then click to enter the main menu. The manual debugging in the main menu is mainly used for on-site manual debugging.

[0063] Step 5. Connect the cable joints 23 of the load-bearing rope 22 to the first sealing plunger 24 and the second sealing plunger 25 in sequence, and then wind and fix one end of the load-bearing rope 22 on the drum. After completion, the second sealing plunger 25 and the upper joint of the carbon fiber continuous sucker rod 41 are connected by threads. Then click to enter the manual debugging in the main menu on the display screen in the control system, which is mainly used for on-site manual debugging. Detect the primary instrument signal, manually measure and adjust the minimum / maximum stroke and the anti-kickoff distance of the oil well, determine the top dead center (i.e., the origin position) and the bottom dead center limit position of the pumping and drainage device, and conduct a manual maximum stroke number test.

[0064] Step 6. Commissioning

[0065] Click to enter the "Conventional Operation" in the "Intelligent Control Mode" menu in the main menu on the display screen in the control system, and the oil well can be operated in the conventional automatic operation mode. The operation parameters are controlled according to the parameters set in the initialization; the controller will confirm the current position and direction according to the detection of the motor 19 or the rotation pulse of the drum, and decelerate and reverse after running close to the deceleration point.

[0066] Step 7. Click to enter the "Control Daily Drainage Volume" method in the "Intelligent Control Mode" menu in the main menu on the display screen in the control system. Manually preset the daily water production of the control system through man-machine dialogue. The control system searches for the pumping and lifting capacity that can meet the control target within the stroke and stroke number adjustment range of the drum-type mechanical pumping and drainage device, that is: the liquid drainage capacity of the sucker rod pump, and adjusts the pumping and drainage system in a timely manner according to the change of the bottom hole flowing pressure or liquid level.

[0067] Step 8: During the workover operation, only need to support the truss body 4, and adjust the truss body to be perpendicular to the ground foundation through the adjusting tie rod 7, then the axial distance between the pulley and the wellhead can be adjusted to be ≥ 700 cm or more.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A gas lift system for drainage gas production in coalbed methane wells, characterized in that: It includes a drum-type mechanical pumping drainage and production device and a mechanical pumping drainage and gas lift system; The output end of the drum-type mechanical pumping drainage and production device is connected to the load-bearing rope (22) of the mechanical pumping drainage and gas lift system; The mechanical pumping drainage and gas lift system includes a first tubing structure (36), a polished rod structure for pumping oil, and a directional flow channel plunger-type gas-water separation and production system. The first tubing structure (36) is arranged in the gas wellbore. The polished rod structure for pumping oil is arranged in the first tubing structure (36). The bottom of the polished rod structure for pumping oil is connected to the continuous rod (41) of the directional flow channel plunger-type gas-water separation and production system. The top of the directional flow channel plunger-type gas-water separation and production system is detachably connected to the first tubing structure (36); The polished rod structure for pumping oil includes a load-bearing rope (22), a sealing sleeve (28), a diversion nipple (29), a positioning nipple (30), and a dynamic sealing structure. One end of the load-bearing rope (22) is connected to the output end of the drum-type mechanical pumping drainage and production device. The other end of the load-bearing rope (22) is connected to the dynamic sealing structure. The dynamic sealing structure is slidably arranged inside the sealing sleeve (28). The dynamic sealing structure is connected to the continuous rod (41). The diversion nipple (29) and the positioning nipple (30) are arranged at the bottom of the sealing sleeve (28). The positioning nipple (30) is detachably connected to the bottom of the first tubing structure (36).

2. The gas lift drainage and gas production system for coalbed methane wells according to claim 1, characterized in that: The dynamic sealing structure includes a first sealing plunger (24) and a second sealing plunger (25). The top of the first sealing plunger (24) is connected to the load-bearing rope (22) through a thimble (23). The second sealing plunger (25) is arranged at the bottom of the first sealing plunger (24). The second sealing plunger (25) is connected to the continuous rod (41).

3. The gas lift system for drainage gas production in coalbed methane wells according to claim 2, wherein: The directional flow channel plunger-type gas-water separation and production system includes a second tubing structure, a continuous rod (41), a connection structure, a sucker rod (44), a pump pull rod (45), a conical pump barrel (37), a double-closed structure plunger (46), a disc-type liquid-gas separator (39), and a self-cleaning guiding fixed valve (38). The top of the second tubing structure is detachably connected to the bottom of the first tubing structure (36). The bottom of the second tubing structure is connected to the conical pump barrel (37). The disc-type liquid-gas separator (39) is arranged at the bottom of the conical pump barrel (37). The top of the continuous rod (41) is connected to the second sealing plunger (25). The bottom of the continuous rod (41) is connected to the sucker rod (44) through the connection structure. The bottom of the sucker rod (44) is connected to the double-closed structure plunger (46) through the pump pull rod (45). Both the disc-type liquid-gas separator (39) and the self-cleaning guiding fixed valve (38) are located below the double-closed structure plunger (46). The self-cleaning guiding fixed valve (38) is arranged between the disc-type liquid-gas separator (39) and the double-closed structure plunger (46). Both the double-closed structure plunger (46) and the self-cleaning guiding fixed valve (38) are arranged in the conical pump barrel (37).

4. The gas-lift drainage system for coalbed methane wells according to claim 3, wherein: The side wall inclination angle of the conical pump barrel (37) is 5°-10°.

5. A gas lift system for drainage gas production in coalbed methane wells according to any one of claims 1-4, characterized in that: The drum-type mechanical pumping and drainage device includes a truss support (4), a wellhead guiding pulley (1), an adjusting tie rod (7), a foundation base (8), a drum structure, a motor (19), a speed reducer (17), a rope arranging mechanism (18) and a moving base (11). The wellhead guiding pulley (1) is arranged at the top of the truss support (4). The bottom of the truss support (4) is hinged to the foundation base (8). One end of the adjusting tie rod (7) is hinged to the top of the truss support (4), and the bottom of the adjusting tie rod (7) is hinged to the foundation base (8). The moving base (11) is connected to the foundation base (8) through a sliding structure. The drum structure, the motor (19) and the speed reducer (17) are all arranged on the moving base (11). The output end of the motor (19) is connected to the input shaft of the speed reducer (17). The output shaft of the speed reducer (17) is a hollow shaft. One end of the output shaft of the speed reducer (17) is connected to the drum structure, and the other end of the output shaft of the speed reducer (17) is threadedly connected to the threaded end of the rope arranging mechanism (18). The fixed end of the rope arranging mechanism (18) is arranged on the foundation base (8). The load-bearing rope (22) is wound on the drum structure. The wellhead guiding pulley (1) is used to guide the load-bearing rope (22).

6. The gas-lift drainage system for coalbed methane wells according to claim 5, characterized in that: The drum-type mechanical pumping and drainage device further includes a safety operation platform (5), and the safety operation platform (5) is arranged on the truss support (4).

7. A gas lift system for drainage gas production in coalbed methane wells according to claim 5, characterized in that: The sliding structure includes two guide rails arranged in parallel. The side parts of the moving base (11) are all slidably matched with the two guide rails through moving rollers (12). The side parts of the moving base (11) are provided with radial limiting rollers.

8. A gas lift system for drainage gas production in a coalbed methane well according to claim 7, characterized in that: The guide rail is provided with a home position switch, and upper dead point limit switches and lower dead point limit switches are respectively arranged at the front and rear ends of the guide rail.

9. A gas lift system for drainage gas production in coalbed methane wells according to claim 5, characterized in that: The drum structure includes a Ribas drum (14) and two drum supports (15). The Ribas drum (14) is connected to the upper end surface of the moving base (11) through the two drum supports (15). The Ribas drum (14) is used to wind the load-bearing rope (22).

10. A gas lift system for drainage gas production in a coalbed methane well according to claim 5, characterized in that: It further includes a jet flow reflux device (33). The jet flow reflux device (33) includes a suction port, a power gas source interface and a diffuser tube. The suction port is arranged at the inlet end of the diffuser tube. The power gas source interface is arranged at the inlet end of the diffuser tube. The outlet end of the diffuser tube is connected to the gas production pipeline through a pipeline. The suction port is connected to the overflow liquid outlet of the Christmas tree cross (27).

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