Coal bed gas well tail pipe sand discharge device and process string and use method thereof

Abstract

The application discloses a coal bed gas well tail pipe sand discharging device, a process pipe column and a use method thereof, and comprises an outer shell, a one-way valve, a valve core action limiting mechanism and a valve core. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The one-way valve is arranged in the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and the outer shell. The valve core action limiting mechanism is arranged between the valve core and

Description

Technical Field

[0001] This invention relates to the technical field of gas well sand removal devices, specifically a coalbed methane well tailpipe sand removal device, its process tubing, and its usage method. Background Technology

[0002] With the increasing scale of effective fracturing in the Yanchuan South coalbed methane project, a large amount of coal lumps are generated after fracturing, making it impossible to effectively support the fracturing sand, resulting in severe sand backflow during production. While the under-pump sand control technology has achieved some sand control, it only blocks sand particles with a certain median size or larger, leaving a large amount of smaller sand particles inside and depositing in the tailpipe. This large amount of sand (especially in the early stages of fracturing) entering the tailpipe will clog the fluid inlet channel, necessitating sand removal and pump inspection operations in the tailpipe.

[0003] Publication (Announcement) No.: CN217176572U discloses a hydraulically convertible oil well drainage and sand control / sand settling tubing string. The tail pipe (10) is connected to the sand settling bridge plug (9), hydraulic switch (8), sand filter pipe (6), packer (4), and oil pump (3) in sequence from bottom to top to form a production tubing string. The production tubing string is located inside the oil well casing (11) and above the artificial well bottom (12). The sucker rod (2) is connected to the piston of the oil pump (3) and is lowered from the tubing (1) to make the piston reach the pump barrel of the oil pump (3). The hydraulic switch (8) is connected to the fixed valve of the oil pump (3) through the sand filter pipe (6) via the tightly inserted central tube (7). An upper annulus (S) is provided between the tightly inserted central tube (7) and the central screen of the sand filter pipe (6). This existing technology is used to extract crude oil from muddy fine sandstone reservoirs in oil wells, improving the development effect on thin poor layers with high mud content, poor oil layer development but high remaining oil saturation, and high muddy sections at the top of thick oil layers, thereby increasing crude oil production.

[0004] The existing sand control and sand settling tubing has packers. Because the packers block the annulus of the oil casing, gas cannot be discharged from the annulus, so it is not suitable for use in gas producing wells.

[0005] Publication No. CN208777954U discloses a backwashing sand setter, which can settle sand and dirt generated during the backwashing process of oil and water wells in the petroleum industry, preventing well blockage. The sand setter includes an upper connector, a lower connector, and a sealing ball. Externally, from top to bottom, the sand setter is connected to the upper connector, outer cylinder, diversion body, and lower connector. Internally, from top to bottom, the sand setter is connected to a back cap, flow pipe, sealing body, and the central blind cavity and blind plug of the diversion body. The blind plug and sealing body are connected by shear pins. A valve spring and sealing ball are installed between the back cap and the blind plug. The flow pipe has a through hole. The body outside the central blind cavity of the diversion body has a sand settling channel, and the radial flow hole communicates with the central blind cavity of the diversion body. The annular space formed between the sealing body, flow pipe, back cap, and outer cylinder connected above the central blind cavity of the diversion body communicates with the sand settling channel. This effectively shortens the construction period and avoids various drawbacks caused by well blockage.

[0006] The existing technology requires backwashing to remove sand from the tailpipe. Since coalbed methane wells extract gas through drainage, the drainage formation is severely depleted. Therefore, using the well-washing method will result in a large amount of well-washing water entering the coal seam. Draining the well-washing water takes a long time, and sand will be generated in the tailpipe during the drainage process, causing the drainage and well-washing process to be repeated, which will affect gas production.

[0007] Publication No. CN209129585U discloses a well-washing coalbed methane drainage and production string, comprising a tubing string, a pump barrel, and a tail structure connected in sequence; it also includes a hollow sucker rod string and a piston, which are connected and both inserted into the tubing string. The sucker rod string can drive the piston to move, causing the piston to extend into or exit the pump barrel. An axially extending flow channel is formed inside the sucker rod string, and the flow channel communicates with the inner cavity of the piston. A first switching valve is provided inside the piston. When open, liquid in the pump barrel and / or the tubing string can be introduced into the inner cavity of the piston. A second switching valve is provided between the tail structure and the pump barrel. When open, liquid in the tail structure can be introduced into the pump barrel. The well-washing coalbed methane drainage and production string provided by this prior art can perform well-washing operations without leakage of washing fluid into the coal seam, thus avoiding coal seam contamination and not increasing the drainage burden.

[0008] The existing sand discharge channel is prone to frequent opening and closing, leading to ineffective sand discharge.

[0009] In summary, the technical solutions, technical problems to be solved, and beneficial effects of the above-disclosed technologies are all different from those of the present invention. For more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the Invention

[0010] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a tailpipe sand discharge device for coalbed methane wells, its process tubing, and its usage method. By using the tailpipe sand discharge device and process tubing, when the sand surface in the tailpipe reaches a certain height, the sand discharge channel automatically opens to quickly discharge the sand from the tailpipe to the bottom of the well, thereby preventing the continuous deposition of sand and blockage of the fluid inlet channel.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A tailpipe sand removal device for a coalbed methane well includes an outer shell and a one-way valve, wherein the one-way valve is disposed within the outer shell and a valve core movement limiting mechanism is also included.

[0013] The one-way valve is provided with a valve core, and the valve core movement limiting mechanism is disposed between the valve core and the outer shell.

[0014] The one-way valve includes an inner cylinder, a valve body spring, and a valve core;

[0015] The inner wall of the outer shell is provided with a boss, and the upper outer wall of the inner cylinder is connected to the boss.

[0016] A support plate is provided on the lower inner wall of the inner cylinder, the valve body spring is mounted on the support plate, and the valve core is mounted on the valve body spring.

[0017] The inner cylinder is a sand discharge channel. The upper end of the inner cylinder is open. A sealing protrusion ring is provided on the inner side of the upper end of the inner cylinder. The upper end of the inner wall of the sealing protrusion ring is provided with an upper conical surface and the lower end is provided with a lower conical surface.

[0018] The valve core is rod-shaped, and a sealing body is provided at the top of the valve core; the cone can fit into the sealing body;

[0019] A straightening rod is provided at the center of the upper end face of the support plate; the valve body spring is provided on the straightening rod; the support plate is provided with through holes or the support plate is a spoked wheel structure, so that gravel can pass through the support plate.

[0020] The upper conical surface is the first outer conical surface, and the lower conical surface is the first inner conical surface;

[0021] The sealing body is a cone; the cone can fit against the lower conical surface;

[0022] The upper surface of the protrusion is provided with a flow guide cone surface, which is flush with the upper cone surface;

[0023] The upper end face of the support plate is provided with a conical surface that converges towards the through hole.

[0024] The valve core movement limiting mechanism includes a movable cylinder limiting mechanism, a movable cylinder, and a movable base plate;

[0025] The movable cylinder limiting mechanism is disposed on the inner wall of the outer shell;

[0026] The inner cylinder wall is provided with at least two track grooves; the movable base plate includes a central connecting block, the outer wall of the central connecting block is provided with at least two spokes, the number of spokes is the same as the number of track grooves, the spokes pass through the track grooves, so that the movable base plate can slide up and down;

[0027] The lower end of the valve core is connected to the central connecting block; the central connecting block is provided with a through hole for sand and gravel to pass through;

[0028] The movable cylinder is disposed between the inner cylinder and the outer shell, and the lower end of the movable cylinder is connected to the spokes; a limit protrusion ring is provided on the upper outer wall of the movable cylinder;

[0029] The limiting protrusion ring and the movable cylinder limiting mechanism jointly control the up and down movement of the movable cylinder.

[0030] At least two of the movable cylinder limiting mechanisms are evenly arranged circumferentially on the inner wall of the outer shell.

[0031] In one embodiment of the present invention, the movable cylinder limiting mechanism is a protrusion;

[0032] The protrusion of the bump is provided with a first starting surface and a first resetting surface, and the first starting surface is located above the first resetting surface;

[0033] The movable cylinder is made of an elastic material.

[0034] The first starting surface is a second outer conical surface, and the first resetting surface is a second inner conical surface; the protruding shape of the limiting ring is semi-circular or triangular;

[0035] The upper plane of the triangular limiting protrusion is parallel to the first reset surface, and the lower plane is parallel to the first starting surface; the initial position of the limiting protrusion of the movable cylinder is on the starting surface.

[0036] In one embodiment of the present invention, the movable cylinder limiting mechanism includes a pressure block spring, a pressure block, and a groove;

[0037] The groove is provided on the inner wall of the outer shell, and a pressure spring is provided in the groove, with a pressure block provided on the pressure spring;

[0038] The protruding surface of the pressure block is provided with a second starting surface and a second resetting surface, and the second starting surface is located above the second resetting surface;

[0039] The movable cylinder is made of a rigid material.

[0040] The second starting surface is the third outer conical surface, and the second resetting surface is the third inner conical surface; the protruding shape of the limiting ring is semi-circular or triangular;

[0041] The upper plane of the triangular limiting protrusion is parallel to the second reset surface, and the lower plane is parallel to the second starting surface; the initial position of the limiting protrusion of the movable cylinder is above the second starting surface.

[0042] The upper and lower ends of the pressure block are provided with limiting protrusions, and the upper and lower ends of the groove opening are provided with anti-detachment protrusions. The limiting protrusions and the anti-detachment protrusions together prevent the pressure block from detaching from the groove.

[0043] The upper end of the outer shell is a female snap-on connector, and the lower end of the outer shell is a male snap-on connector.

[0044] A process tubing string for a tailpipe sand removal device in a coalbed methane well includes a tailpipe, a sand-proof gas anchor, an oil pump, and a tailpipe sand removal device for a coalbed methane well.

[0045] The tailpipe sand removal device for coalbed methane wells is connected to the tailpipe at the lower end and to the sand control gas anchor at the upper end. The upper end of the sand control gas anchor is connected to the oil pump, and the upper end of the oil pump is connected to the completion tubing.

[0046] A method for using a sand removal device for the tailpipe of a coalbed methane well includes the following steps.

[0047] S0. Assemble the tailpipe sand discharge device for coalbed methane wells, and install the limiting protrusion of the movable cylinder above the limiting mechanism of the movable cylinder; so that the valve body spring is in a compressed state after the support device is assembled.

[0048] S1. Install the tailpipe sand discharge device of the coalbed methane well onto the tubing string and lower it into the well. When lowering it into the well, the valve core and the sealing convex ring are in a sealed state under the action of the valve body spring.

[0049] S2. During the production process, the sand particles entering the tailpipe accumulate at the top of the valve core. When the accumulated sand in the tailpipe overcomes the sum of the elastic force of the valve body spring and the resistance of the moving cylinder limiting mechanism, the moving cylinder moves downward, the valve core separates from the inner cylinder, and the sand particles flow from the top of the valve core into the sand discharge channel of the inner cylinder and are discharged to the bottom of the well.

[0050] S3. Because the limiting protrusion is located below the moving cylinder limiting mechanism, the moving cylinder limiting mechanism hinders the moving cylinder from moving upward, the valve core and the inner cylinder are in a separated state, and sand particles will continue to be discharged.

[0051] S4. After the sand particles above the valve core are discharged, the upward elastic force of the valve body spring overcomes the resistance between the moving cylinder limit mechanism, the moving cylinder moves upward, the valve core re-blocks the sealing ring, and the sand particles are deposited above the valve core; the cycle of intermittent sand discharge begins.

[0052] In one embodiment of the present invention, the movable cylinder limiting mechanism is a protrusion, and the movable cylinder is made of an elastic material.

[0053] In S0, the limiting protrusion of the movable cylinder is located above the protrusion;

[0054] In S2, when the sand accumulation in the tailpipe reaches a level that can overcome the sum of the elastic force of the valve body spring, the elastic force of the movable cylinder, and the frictional resistance between the limiting convex ring and the first starting surface, the limiting convex ring contracts, the movable cylinder moves downward, and the valve core separates from the inner cylinder the instant the limiting convex ring passes the first starting surface.

[0055] In S3, the first reset surface obstructs the upward movement of the movable cylinder;

[0056] In S4, the upward elastic force of the valve body spring overcomes the elastic force of the movable cylinder and the friction between the limiting convex ring and the first reset surface. The limiting convex ring contracts, the movable cylinder moves upward, and the limiting convex ring passes through the second reset surface. Since the movable cylinder and the valve core move synchronously, the valve core re-blocks the sealing convex ring.

[0057] In one embodiment of the present invention, the movable cylinder limiting mechanism comprises a pressure block, a pressure block spring, and a groove, wherein the movable cylinder is made of a rigid material.

[0058] In S0, the limiting protrusion of the movable cylinder is located above the pressure block;

[0059] In S2, when the sand accumulation in the tailpipe reaches a level that can overcome the sum of the elastic force of the valve body spring, the elastic force of the pressure block spring, and the frictional resistance between the limiting convex ring and the first starting surface, the movable cylinder moves downward and squeezes the pressure block into the outer shell. When the limiting convex ring passes through the second starting surface, the valve core separates from the inner cylinder.

[0060] In S3, the second reset surface obstructs the upward movement of the movable cylinder;

[0061] In S4, the upward elastic force of the valve body spring overcomes the elastic force of the pressure block spring and the friction between the limiting convex ring and the first reset surface. After the movable cylinder squeezes the pressure block into the outer shell, the movable cylinder moves upward and the limiting convex ring passes through the second reset surface. Since the movable cylinder and the valve core move synchronously, the valve core re-blocks the sealing convex ring.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] This invention utilizes the gravity of accumulated sand in the tailpipe to overcome the elastic force of the valve body spring and the frictional force of the elastomer to open the sand discharge channel in the inner cylinder. Through the cooperation of the elastomer and the movable cylinder, the sand discharge channel can completely discharge the accumulated sand in the tailpipe, avoiding ineffective sand discharge caused by frequent opening and closing of the sand discharge channel, thereby effectively extending the pump inspection cycle of the coalbed methane drainage pump. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the sand discharge channel of a coalbed methane well tailpipe sand discharge device in the open state according to the present invention;

[0065] Figure 2 This is a schematic diagram of the sand discharge channel of a coalbed methane well tailpipe sand discharge device in the closed state according to the present invention;

[0066] Figure 3 This is a schematic diagram of the structure of the sand discharge production pipe column of the present invention;

[0067] In the diagram: 1. Upper connector; 2. Sealing ring; 3. Inner cylinder; 4. Valve core; 5. Pressure block; 6. Pressure block spring; 7. Outer shell; 8. Movable cylinder; 9. Movable base plate; 10. Valve body spring; 11. Straightening rod; 12. Support plate; 13. Lower connector;

[0068] 001. Oil pump; 002. Sand-proof gas anchor; 003. A sand removal device for tailpipe of a coalbed methane well. Detailed Implementation

[0069] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0070] Please see Figures 1 to 2 The present invention provides a tailpipe sand discharge device for coalbed methane wells, comprising an outer shell 7, a one-way valve, and a valve core action limiting mechanism;

[0071] The one-way valve is disposed inside the housing 7, and the valve core action limiting mechanism is disposed between the one-way valve and the housing 7.

[0072] The one-way valve includes an inner cylinder 3, a valve body spring 10, and a valve core 4;

[0073] The inner wall of the outer shell 7 is provided with a boss, and the upper outer wall of the inner cylinder 3 is connected to the boss.

[0074] The inner cylinder 3 is a sand discharge channel. The upper end of the inner cylinder 3 is open. A sealing ring 2 is provided on the inner side of the upper end of the inner cylinder 3. The upper end of the inner wall of the sealing ring 2 has an upper conical surface and the lower end has a lower conical surface. The upper conical surface is the first outer conical surface and the lower conical surface is the first inner conical surface. A support plate 12 is provided on the inner wall of the lower end of the inner cylinder 3. A straightening rod 11 is provided at the center of the upper end surface of the support plate 12. The valve body spring 10 is provided on the straightening rod 11. The valve core 4 is provided on the valve body spring 10.

[0075] The valve core 4 is rod-shaped, and a sealing body is provided at the top of the valve core 4; the sealing body is a cone; the cone can fit against the lower conical surface;

[0076] The upper surface of the protrusion is provided with a flow guide cone surface, which is flush with the upper cone surface;

[0077] The support plate 12 is provided with through holes, or the support plate 12 is a spoked structure, so that gravel can pass through the support plate 12.

[0078] The upper end face of the support plate 12 is provided with a conical surface that converges toward the through hole;

[0079] The upper end of the outer shell 7 is a female upper connector 1, and the lower end of the outer shell 7 is a male lower connector 1;

[0080] The outer shell 7, upper connector 1, and lower connector 13 are made of 45 steel and are treated with anti-corrosion measures.

[0081] Example 1:

[0082] Please see Figures 1 to 2 The valve core movement limiting mechanism includes a protrusion, a movable cylinder 8, and a movable base plate 9;

[0083] The protrusion is disposed on the inner wall of the outer shell 7. The convex surface of the protrusion is provided with a first starting surface and a first resetting surface. The first starting surface is disposed above the first resetting surface. The first starting surface is a second outer conical surface and the first resetting surface is a second inner conical surface.

[0084] The inner cylinder 3 has at least two track grooves on its wall; the movable base plate 9 includes a central connecting block, the outer wall of which has at least two spokes, the number of which is the same as the number of track grooves, and the spokes pass through the track grooves, allowing the movable base plate 9 to slide up and down; the lower end of the valve core 4 is connected to the central connecting block; the central connecting block has a through hole for allowing sand and gravel to pass through.

[0085] The movable cylinder 8 is disposed between the inner cylinder 3 and the outer shell 7, and the lower end of the movable cylinder 8 is connected to the spokes; a limiting protrusion ring is provided on the upper outer wall of the movable cylinder 8, and the protrusion of the limiting protrusion ring is circular or triangular; the upper plane of the triangle is parallel to the first reset surface, and the lower plane of the triangle is parallel to the first start surface;

[0086] At least two protrusions are evenly and circumferentially arranged on the inner wall of the outer shell 7.

[0087] The movable cylinder 8 is made of elastic material. The initial position of the limiting protrusion of the movable cylinder 8 is on the starting surface. When the sand and gravel at the upper end of the sealing body accumulate to the point that the cylinder wall of the movable cylinder 8 undergoes elastic deformation, the limiting protrusion passes through the starting surface and the sand and gravel passes through the sealing body. After the sand and gravel are discharged, the valve body spring 10 pushes the valve core 4, the movable base plate 9, and the movable cylinder 8 upward, so that the limiting protrusion passes through the protrusion.

[0088] The inner cylinder 3, valve core 4, movable base plate 9, and support plate 12 are made of high-density polyethylene.

[0089] How to use this embodiment:

[0090] S1. When the tailpipe sand discharge process string of the coalbed methane well is run down the well, the limiting convex ring of the movable cylinder 8 of the tailpipe sand discharge device of the coalbed methane well is located above the convex block, and the valve core 4 and the upper end of the inner cylinder 3 are in a sealed state under the action of the valve body spring 10.

[0091] S2. During the production process, the sand particles entering the tailpipe accumulate on the upper part of the valve core 4. When the accumulated sand in the tailpipe reaches the sum of the elastic force of the valve body spring 10, the elastic force of the movable cylinder, and the frictional resistance between the limiting convex ring and the first starting surface, the limiting convex ring contracts, the movable cylinder 8 moves downward, and when the limiting convex ring 8 passes the first starting surface, the valve core 4 separates from the inner cylinder 3, and the sand particles flow from the top of the valve core 4 into the sand discharge channel of the inner cylinder 3 and are discharged to the bottom of the well.

[0092] S3. Since the limiting protrusion is located below the protrusion, the first reset surface hinders the upward movement of the movable cylinder 8. Therefore, the valve core 4 and the inner cylinder 3 are in a separated state, and sand particles will continue to be discharged through the gap between them.

[0093] S4. After the sand particles above the valve core 4 are discharged, the upward elastic force of the valve body spring 10 overcomes the elastic force of the movable cylinder and the pressure between the limiting convex ring and the first reset surface. The limiting convex ring contracts, the movable cylinder 8 moves upward, and the limiting convex ring passes through the second reset surface. Since the movable cylinder 8 and the valve core 4 move synchronously, the valve core 4 re-blocks the sealing convex ring 2, and the sand particles are deposited above the valve core 4; the intermittent sand discharge cycle begins.

[0094] Example 2:

[0095] Please see Figures 1 to 2 The valve core movement limiting mechanism includes a pressure block 5, a pressure block spring 6, a movable cylinder 8, and a movable base plate 9;

[0096] The inner wall of the outer casing 7 is provided with a groove, in which a pressure spring 6 is provided, and a pressure block 5 is provided on the pressure spring 6. The upper and lower ends of the pressure block 5 are provided with limiting protrusions, and the upper and lower ends of the groove opening are provided with anti-detachment protrusions. The limiting protrusions and the anti-detachment protrusions together prevent the pressure block 5 from detaching from the groove. The protruding surface of the pressure block is provided with a second starting surface and a second resetting surface. The second starting surface is located above the second resetting surface. The second starting surface is a third outer conical surface, and the second resetting surface is a third inner conical surface. The contact surface between the pressure block 5 and the pressure spring 6 is provided with a valve body spring limiting countersunk hole. The pressure block 5, the pressure spring 6, and the groove are a group, and at least two groups are evenly provided circumferentially on the inner wall of the outer casing 7.

[0097] The inner cylinder 3 has at least two track grooves on its wall; the movable base plate 9 includes a central connecting block, the outer wall of which has at least two spokes, the number of which is the same as the number of track grooves, and the spokes pass through the track grooves, allowing the movable base plate 9 to slide up and down; the lower end of the valve core 4 is connected to the central connecting block; the central connecting block has a through hole for allowing sand and gravel to pass through.

[0098] The movable cylinder 8 is disposed between the inner cylinder 3 and the outer shell 7, and the lower end of the movable cylinder 8 is connected to the spokes; a limiting protrusion ring is provided on the upper outer wall of the movable cylinder 8, and the protrusion shape of the limiting protrusion ring is circular or triangular; the upper plane of the triangle is parallel to the second reset surface, and the lower plane of the triangle is parallel to the second start surface;

[0099] The movable cylinder 8 is made of rigid material. The initial position of the limiting protrusion of the movable cylinder 8 is on the starting surface. When the sand and gravel at the upper end of the sealing body accumulate to the point that the cylinder wall of the movable cylinder 8 undergoes elastic deformation, the limiting protrusion passes through the starting surface and the sand and gravel passes through the sealing body. After the sand and gravel are discharged, the valve body spring 10 pushes the valve core 4, the movable base plate 9, and the movable cylinder 8 upward, so that the limiting protrusion passes through the protrusion.

[0100] The movable cylinder is made of rigid material. After the movable cylinder 8 is assembled, its limiting protrusion is located above the pressure block 5. After the support device is assembled, the valve body spring 10 is in a compressed state.

[0101] The inner cylinder 3, valve core 4, movable base plate 9, and support plate 12 are made of high-density polyethylene.

[0102] The working principle of this embodiment:

[0103] S1. When the tailpipe sand discharge process string of the coalbed methane well is lowered into the well, the limiting protrusion ring of the movable cylinder 8 of the tailpipe sand discharge device of the coalbed methane well is located above the pressure block 5. Under the action of the valve body spring 10, the valve core 4 and the upper end of the inner cylinder 3 are in a sealed state.

[0104] S2. During the production process, the sand particles entering the tailpipe accumulate on the upper part of the valve core 4. When the accumulated sand in the tailpipe reaches the sum of the elastic force of the valve body spring 10, the elastic force of the pressure block spring, and the frictional resistance between the limiting convex ring and the second starting surface, the movable cylinder 8 moves down and squeezes the pressure block 5 into the outer shell 7. When the limiting convex ring 8 passes through the second starting surface, the valve core 4 separates from the inner cylinder 3, and the sand particles flow from the top of the valve core 4 into the sand discharge channel of the inner cylinder 3 and are discharged to the bottom of the well.

[0105] S3. Since the limiting protrusion ring is located below the pressure block 5, the second reset surface hinders the upward movement of the movable cylinder 8. Therefore, the valve core 4 and the inner cylinder 3 are in a separated state, and sand particles will continue to be discharged through the gap between them.

[0106] S4. After the sand particles above the valve core 4 are discharged, the upward elastic force of the valve body spring 10 overcomes the elastic force of the pressure block spring and the pressure between the limiting convex ring and the second reset surface. After the movable cylinder 8 squeezes the pressure block 5 into the outer shell 7, the movable cylinder 8 moves upward and the limiting convex ring passes through the second reset surface. Since the movable cylinder 8 and the valve core 4 move synchronously, the valve core 4 re-blocks the sealing convex ring 2, and the sand particles are deposited above the valve core 4; the intermittent sand discharge cycle begins.

[0107] The two embodiments above enable the periodic discharge of sand accumulated in the tailpipe to the bottom of the well, effectively extending the pump inspection cycle of the coalbed methane drainage well.

[0108] Example 3:

[0109] Based on Embodiment 1 or 2, this embodiment provides a tailpipe sand removal process string for coalbed methane wells, including a tailpipe sand removal device 003; the lower end of the tailpipe sand removal device is connected to a tailpipe, and the upper end is connected to a sand control gas anchor 002. The upper end of the sand control gas anchor is connected to an oil pump 001, and the upper end of the oil pump 001 is connected to a completion string.

[0110] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0111] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0112] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0113] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tailpipe sand removal device for coalbed methane wells, comprising an outer casing and a one-way valve, wherein the one-way valve is disposed within the outer casing, characterized in that... It also includes a valve core movement limiting mechanism; The one-way valve is provided with a valve core, and the valve core movement limiting mechanism is disposed between the valve core and the outer shell. The valve core movement limiting mechanism is used to control the opening and closing of the one-way valve. The one-way valve includes an inner cylinder, a valve body spring, and a valve core; The inner wall of the outer shell is provided with a boss, and the upper outer wall of the inner cylinder is connected to the boss. A support plate is provided on the lower inner wall of the inner cylinder, the valve body spring is provided on the support plate, and the valve core is provided on the valve body spring; The inner cylinder is a sand discharge channel. The upper end of the inner cylinder is open. A sealing protrusion ring is provided on the inner side of the upper end of the inner cylinder. The upper end of the inner wall of the sealing protrusion ring is provided with an upper conical surface and the lower end is provided with a lower conical surface. The valve core is rod-shaped, and a sealing body is provided at the top of the valve core; the sealing body is a cone; the cone can fit against the lower conical surface; A straightening rod is provided at the center of the upper end face of the support plate; the valve body spring is provided on the straightening rod; the support plate is provided with through holes or the support plate is a spoked wheel structure so that gravel can pass through the support plate; The valve core movement limiting mechanism includes a movable cylinder limiting mechanism, a movable cylinder, and a movable base plate; The movable cylinder limiting mechanism is disposed on the inner wall of the outer shell; The inner cylinder wall is provided with at least two track grooves; the movable base plate includes a central connecting block, the outer wall of the central connecting block is provided with at least two spokes, the number of spokes is the same as the number of track grooves, the spokes pass through the track grooves, so that the movable base plate can slide up and down; The lower end of the valve core is connected to the central connecting block; the central connecting block is provided with a through hole for sand and gravel to pass through; The movable cylinder is disposed between the inner cylinder and the outer shell, and the lower end of the movable cylinder is connected to the spokes; a limit protrusion ring is provided on the upper outer wall of the movable cylinder; The limiting protrusion ring and the movable cylinder limiting mechanism jointly control the up and down movement of the movable cylinder; The movable cylinder limiting mechanism includes a pressure block spring, a pressure block, and a groove; The groove is provided on the inner wall of the outer shell, and a pressure spring is provided in the groove, with a pressure block provided on the pressure spring; The protruding surface of the pressure block is provided with a second starting surface and a second resetting surface, and the second starting surface is located above the second resetting surface; The movable cylinder is made of a rigid material.

2. The sand removal device for the tailpipe of a coalbed methane well according to claim 1, characterized in that, The upper conical surface is the first outer conical surface, and the lower conical surface is the first inner conical surface; The upper surface of the protrusion is provided with a flow guide cone surface, which is flush with the upper cone surface; The upper end face of the support plate is provided with a conical surface that converges towards the through hole.

3. The sand removal device for the tailpipe of a coalbed methane well according to claim 1, characterized in that, At least two of the movable cylinder limiting mechanisms are evenly arranged circumferentially on the inner wall of the outer shell.

4. A sand removal device for a coalbed methane well tailpipe according to claim 1, characterized in that, The second starting surface is the third outer conical surface, and the second resetting surface is the third inner conical surface; the protruding shape of the limiting ring is semi-circular or triangular; The upper plane of the triangular limiting protrusion is parallel to the second reset surface, and the lower plane is parallel to the second starting surface; the initial position of the limiting protrusion of the movable cylinder is above the second starting surface.

5. A sand removal device for a coalbed methane well tailpipe according to claim 1, characterized in that, The upper and lower ends of the pressure block are provided with limiting protrusions, and the upper and lower ends of the groove opening are provided with anti-detachment protrusions. The limiting protrusions and the anti-detachment protrusions together prevent the pressure block from detaching from the groove.

6. A sand removal device for the tailpipe of a coalbed methane well according to any one of claims 1-5, characterized in that, The upper end of the outer shell is a female snap-on connector, and the lower end of the outer shell is a male snap-on connector.

7. A process tubing string for a coalbed methane well tailpipe sand removal device, comprising a tailpipe, a sand-control gas anchor, and a pumping unit, characterized in that, It also includes a coalbed methane well tailpipe sand removal device as described in any one of claims 1-5; The tailpipe sand removal device for coalbed methane wells is connected to the tailpipe at the lower end and to the sand control gas anchor at the upper end. The upper end of the sand control gas anchor is connected to the oil pump, and the upper end of the oil pump is connected to the completion tubing.

8. A method of using a sand removal device for the tailpipe of a coalbed methane well, characterized in that, Using the tailpipe sand removal device of any one of claims 1-5, the method includes the following steps: S0. Assemble the tailpipe sand discharge device for coalbed methane wells, and install the limiting protrusion of the movable cylinder above the limiting mechanism of the movable cylinder; so that the valve body spring is in a compressed state after the support device is assembled. S1. Install the tailpipe sand discharge device of the coalbed methane well onto the tubing string and lower it into the well. When lowering it into the well, the valve core and the sealing convex ring are in a sealed state under the action of the valve body spring. S2. During the production process, the sand particles entering the tailpipe accumulate at the top of the valve core. When the accumulated sand in the tailpipe overcomes the sum of the elastic force of the valve body spring and the resistance of the moving cylinder limiting mechanism, the moving cylinder moves downward, the valve core separates from the inner cylinder, and the sand particles flow from the top of the valve core into the sand discharge channel of the inner cylinder and are discharged to the bottom of the well. S3. Because the limiting protrusion is located below the moving cylinder limiting mechanism, the moving cylinder limiting mechanism hinders the moving cylinder from moving upward, the valve core and the inner cylinder are in a separated state, and sand particles will continue to be discharged. S4. After the sand particles above the valve core are discharged, the upward elastic force of the valve body spring overcomes the resistance between the moving cylinder limit mechanism, the moving cylinder moves upward, the valve core re-blocks the sealing ring, and the sand particles are deposited above the valve core; the cycle of intermittent sand discharge begins.

9. The method of using a coalbed methane well tailpipe sand removal device according to claim 8, characterized in that, The movable cylinder limiting mechanism consists of a pressure block, a pressure block spring, and a groove, and the movable cylinder is made of a rigid material. In S0, the limiting protrusion of the movable cylinder is located above the pressure block; In S2, when the sand accumulation in the tailpipe reaches a level that can overcome the sum of the elastic force of the valve body spring, the elastic force of the pressure block spring, and the frictional resistance between the limiting convex ring and the first starting surface, the movable cylinder moves downward and squeezes the pressure block into the outer shell. When the limiting convex ring passes through the second starting surface, the valve core separates from the inner cylinder. In S3, the second reset surface obstructs the upward movement of the movable cylinder; In S4, the upward elastic force of the valve body spring overcomes the elastic force of the pressure block spring and the friction between the limiting convex ring and the first reset surface. After the movable cylinder squeezes the pressure block into the outer shell, the movable cylinder moves upward and the limiting convex ring passes through the second reset surface. Since the movable cylinder and the valve core move synchronously, the valve core re-blocks the sealing convex ring.

Images