Sand control device for coal bed methane well and method of use

Abstract

The application discloses a coal bed gas well sand prevention device and a use method thereof, which comprises a pumping and swabbing pressure boosting mechanism, a flow expanding sand blocking passage, a sand setting valve and the like, the sand setting valve is provided with a lower liquid inlet and a side liquid outlet, and the opening direction of the side liquid outlet is outwardly downward. The application realizes efficient separation of liquid sand by changing the liquid flow direction and the liquid flow speed multiple times, realizes sand setting of liquid in the whole sand prevention device flowing process by arranging two-stage sand setting cavities, and plays a role of sand blocking and rapid and natural sedimentation of impurities by arranging a pressure boosting device. The device has a simple overall structure but realizes effective separation of liquid sand, and solves the technical problem of poor sand prevention effect of various sand prevention tools and restriction of efficient development of oil and gas fields.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field production technology, specifically to a sand control device for coalbed methane wells and its usage method. Background Technology

[0002] During fracturing in coalbed methane fields, severe backflow of fracturing sand and coal dust leads to frequent pump jamming operations. Due to casing diameter limitations, sand control tools have small outer diameters, making effective sand control tool structures difficult to implement downhole. While oil pumps with sand control functions and various downhole sand control devices have been designed, their field performance has been unsatisfactory. Statistics show that sand jamming and pump inspection operations caused by sand and coal dust account for over 60% of rod pump lifting operations in coalbed methane. Sand production has severely impacted normal production; therefore, there is an urgent need to develop sand control devices for coalbed methane wells to extend pump inspection cycles and reduce production costs.

[0003] Publication (Announcement) No.: CN214887022U, Publication (Announcement) Date: 2021-11-26 discloses a gas separation and sand prevention device under a pump, including an eye tube coupling, the bottom end of the eye tube coupling is connected to one end of the eye tube connecting rod, the other end of the eye tube is movably connected to one end of the upper connector, the other end of the upper connector connecting rod is movably connected to one end of the outer cylinder, the other end of the outer cylinder is movably connected to the lower connector of the connecting rod, an annular partition plate is connected to the inner wall of the eye tube near the eye tube coupling, the annular partition plate is connected to one end of the segmented central tube, the outer diameter of the segmented central tube is adapted to the inner diameter of the annular partition plate, the other end of the segmented central tube connecting rod is connected to one end of the liquid inlet eye tube, and a spiral guide plate is provided on the outside of the segmented central tube connecting rod.

[0004] Publication (Announcement) No.: CN203835688U, Publication (Announcement) Date: 2014-09-17 discloses a vortex sand-proof oil pump, including an outer cylinder, a middle cylinder, and a plunger. The outer cylinder is located outside the middle cylinder. An upstream valve cover is installed on the upper end of the plunger. A vortex generator is installed on the upper end of the outer cylinder. The vortex generator includes a vortex outer cylinder and a spiral groove on the inner wall of the vortex outer cylinder. The upper end of the plunger and the upstream valve cover both extend into the vortex sleeve. A radial hole communicating with the spiral groove is opened on the upstream valve cover. This oil pump increases the upward velocity of sand particles in crude oil, discharging the sand particles from the wellhead along with the crude oil, effectively preventing plunger wear failure caused by sand production in the oil well.

[0005] Publication (Announcement) No.: CN213331486U, Publication (Announcement) Date: 2021-06-01 discloses a novel long plunger sand control pump. It includes a sand settling outer cylinder, a coupling, and a sand settling pipe. The lower end of the connecting rod outer wall of the sand settling outer cylinder is fixedly connected to the sand settling pipe via the coupling. An oil pumping assembly is disposed inside the sand settling connecting rod outer cylinder. The oil pumping assembly includes a connecting rod long plunger, a first piston, a first oil hole, a first cross plate, a first ball connecting rod body, a short pump cylinder, a second cross plate, a second piston, a second ball, and a second connecting rod oil hole. The second ball is attached to the upper part of the second piston. This new type of long plunger sand pump features a scientifically designed and safe structure, making it convenient to use. It includes a sedimentation outer cylinder, sedimentation pipe, plug, vertical plate, vertical connecting rod cylinder, steel brush, push plate, scraper, and vertical rod. As sand particles accumulate inside the sedimentation pipe, the plug can be removed, causing the steel brush to rotate. This avoids the problem in existing technologies where removing the plug for initial cleaning is difficult, leading to a heavy subsequent cleaning burden.

[0006] Publication (Announcement) No.: CN215949787U, Publication (Announcement) Date: 2022-03-04 discloses an oil pump sand prevention device. Its connecting rod structure is that the lower end of the oil pipe is connected to a sand storage cylinder. The sand storage cylinder is bottle-shaped, that is, the outer diameter of the upper end is small and the inside is empty. The internal thread of the connecting rod at the lower end of the sand storage cylinder is connected to the external thread of the valve seat, forming an annular connecting rod space between the two. The upper part of the valve seat is provided with a thin extension cylinder. The connecting rod at the upper end of the extension cylinder is flared, and several liquid outlet connecting rod holes are opened in the upper part of the extension cylinder. The lower end of the valve seat is provided with two symmetrical wrench holes. The screw hole at the center of the connecting rod at the bottom of the valve seat is connected to the upper end of the pump cylinder. A vertically placed pull rod in the oil pipe connecting rod passes through the sand baffle cap. The large end of the sand baffle cap faces down the connecting rod. The piston and the pull rod are connected by threads and then extend into the pump cylinder.

[0007] Publication (Announcement) No.: CN214062916U, Publication (Announcement) Date: 2021-08-27 discloses a sand-prevention device for a pump, comprising a connecting rod and including: an upper connector, a lower connector, an outer tube, an inner tube, and a plug; the upper connector and the lower connector are respectively connected to the two ends of the outer tube; the inner connector and the plug are both located inside the outer tube; one end of the inner tube is connected to the lower connector of the connecting rod, and the other end is connected to the plug; the inner tube has multiple flow holes on its wall near the plug; the outer connector, the inner tube, and the lower connector together form an annular sand-prevention chamber; the channel of the upper connector of the connecting rod is connected to the channel of the lower connector in sequence through the annular sand-prevention chamber, the flow hole connecting rod, and the inner tube.

[0008] 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

[0009] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a sand control device and its usage method for coalbed methane wells. This device achieves efficient liquid-sand separation by repeatedly altering the flow direction and velocity; it incorporates a two-stage sedimentation chamber, ensuring sand settling throughout the entire flow process of the liquid within the sand control device; and it utilizes a pressurization device to prevent sand buildup and facilitate rapid natural settling of impurities. The overall structure of the device is simple yet effectively separates liquid and sand, solving the technical challenge of poor sand control performance in current sand control tools that hinders efficient oil and gas field development.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A sand control device for coalbed methane wells includes a check valve that allows only the liquid flow to ascend.

[0012] The single-flow valve is a sedimentation valve, which has a lower inlet and a side outlet, with the side outlet opening in a downward and outward direction.

[0013] The sedimentation valve includes a sedimentation valve body, a one-way valve ball, a one-way valve seat, and a closed ball cover;

[0014] The lower port of the sedimentation valve body is connected to the single-flow valve seat. The sedimentation valve body has a built-in single-flow valve ball, which sits on the upper port of the single-flow valve seat. The internal channel of the single-flow valve seat serves as the lower inlet of the sedimentation valve. The upper port of the sedimentation valve body is blocked by a closed ball cover to form a blind end.

[0015] The side wall of the sedimentation valve body has a side outlet.

[0016] The side outlet has a staggered porous structure that tilts outward and downward at an angle of 30-60 degrees.

[0017] It also includes a flow-expanding sand-blocking channel mechanism, which includes an outer pipe, an upper central pipe, and a lower central pipe;

[0018] The lower end of the upper central pipe is connected to the upper end of the sedimentation valve body, and the upper end of the lower central pipe is connected to the lower end of the single-flow valve seat; the upper central pipe is located inside the outer pipe, and the outer pipe and the upper central pipe form a sand-blocking channel; the lower central pipe is located inside the outer pipe, and the outer pipe and the lower central pipe form an outer sedimentation chamber.

[0019] The side outlet of the sedimentation valve is connected to both the sand-blocking channel and the external sedimentation chamber, wherein the sand-blocking channel is located above the side outlet and the external sedimentation chamber is located below the side outlet.

[0020] The lower ends of the outer tube and the inner central tube are simultaneously connected to the lower connector.

[0021] The lower end of the upper central tube is sealed by a closed spherical cover, which makes the inner cavity of the upper central tube form an inner sedimentation chamber. The upper central tube has a side liquid inlet, which is a side hole of the central tube. The opening direction of the side liquid inlet is inclined inward and downward.

[0022] The lateral openings of the central tube are arranged in a staggered porous structure with an inward and downward tilting angle of 30-60 degrees.

[0023] The sand-blocking channel formed between the outer pipe and the upper central pipe is equipped with at least one flow-expanding sand-blocking port. The lower end of the flow-expanding sand-blocking port is a planar opening, and the upper end of the flow-expanding sand-blocking port is a conical diffuser.

[0024] The upper central tube is also equipped with a pumping and pressurizing mechanism, which is located above the side liquid inlet and is connected to a connecting rod at its upper end. The inner wall of the upper central tube is also equipped with a baffle to prevent the pumping and pressurizing mechanism from falling. The upper ends of the outer tube and the upper central tube are both connected to an upper connector.

[0025] The pumping and pressurizing mechanism is a single-flow ball valve structure that operates actively up and down.

[0026] To achieve the above objectives, the present invention adopts the following technical solution:

[0027] A method for using a sand control device for coalbed methane wells includes the following steps:

[0028] The sedimentation valve adopts a bottom inlet and side outlet method, which effectively avoids the accumulation of sand and impurities in the sedimentation valve. At the same time, the side outlet opening direction is inclined outward and downward, which changes the flow direction and slows down the flow rate, so that most of the sand and impurities are deposited in the outer sedimentation chamber.

[0029] The bottom horizontal flow-expanding sand-blocking port effectively blocks sand and impurities near the inner wall, changes the flow direction and slows down the flow rate. At the same time, the funnel-shaped structure induces a slowdown in the flow rate, realizing the separation of sand and liquid and the sedimentation of sand and impurities during the upward process.

[0030] The upper central tube has a side inlet, which is a side hole of the central tube. The opening direction of the side inlet is inward and downward, which changes the flow direction and slows down the flow rate, so that most of the sand and impurities are deposited in the inner sedimentation chamber.

[0031] During the pumping process, the pumping pressurization mechanism generates a throttling and pressurizing effect as it descends. The pressure at the bottom of the pumping pressurization mechanism increases, instantly changing the flow state of the fluid containing sand and impurities in the flow channel from the flow-expanding sand-blocking channel to a static state. The flow direction changes, the flow velocity slows down, and the sand and impurities in the fluid containing sand and impurities are rapidly separated by gravity in a static state, further accelerating the sedimentation process of sand and impurities. That is, the pressurized liquid in the channel stops instantly during the descent of the pumping pressurization mechanism, and the setting of inner and outer two-stage sedimentation chambers ensures that the sand particles in the fluid containing sand and impurities settle fully and cannot enter the pump cylinder.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] This invention's sedimentation valve employs a bottom-inlet and side-outlet design, effectively preventing sand and impurities from accumulating within the valve. Simultaneously, the side-outlet opening slopes downwards at a 60-degree angle, ensuring that most sand and impurities settle within the outer sedimentation chamber. The horizontal, flow-expanding sand-blocking port at the bottom effectively blocks sand and impurities near the inner wall, while the funnel-shaped structure induces flow velocity changes, achieving sand-liquid separation and sand / impurity sedimentation during the upward flow. Furthermore, the flow direction of the sand- and impurity-containing fluid undergoes multiple changes as it passes through the sedimentation valve, the flow-expanding sand-blocking channel, and the pumping and pressurizing mechanism, further improving sand-liquid separation efficiency. During pumping, the downward movement of the pumping and pressurizing mechanism generates a throttling and pressurizing effect, increasing the pressure at the bottom of the mechanism. This instantaneously changes the flow state of the sand- and impurity-containing fluid in the flow channel from the flow-expanding sand-blocking channel to a static state, allowing the sand and impurities to rapidly separate by gravity in this static state, further accelerating the sedimentation process. Therefore, this invention achieves the full settling of sand particles in the fluid containing sand and impurities, preventing them from entering the pump barrel, by repeatedly changing the flow direction and flow rate, causing the pressurized liquid in the channel to stop instantly during the downward process, and by setting up two-stage sedimentation chambers (sand settling chamber and upper central pipe sedimentation chamber). This solves the problem of well lying down caused by sand burial and sand blockage in the oil pump. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a sand control device for coalbed methane wells according to the present invention.

[0035] In the diagram, the components are: connecting rod 1, upper connector 2, pressure boosting cover 3, pressure boosting ball seat 4, buoyancy ball 5, pressure boosting inlet channel 6, retaining ring 7, side hole of central tube 8, outer tube 9, upper central tube 10, flow-expanding sand-blocking port 11, inner sand settling chamber 12, closed ball cover 13, sand settling valve body 14, check valve ball 15, check valve seat 16, outer sand settling chamber 17, lower central tube 18, and lower connector 19. Detailed Implementation

[0036] 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.

[0037] Example 1:

[0038] according to Figure 1As shown, an embodiment of the present invention provides a sand control device for coalbed methane wells, including a pumping and pressurizing mechanism, a flow-expanding sand-blocking channel, a sand settling valve, etc.

[0039] The single-flow valve is a sedimentation valve, which has a lower inlet and a side outlet, with the side outlet opening in a downward and outward direction.

[0040] The sedimentation valve includes a sedimentation valve body 14, a one-way valve ball 15, a one-way valve seat 16, and a closed ball cover 13.

[0041] The lower port of the sedimentation valve body is connected to the single-flow valve seat. The sedimentation valve body has a built-in single-flow valve ball, which sits on the upper port of the single-flow valve seat. The internal channel of the single-flow valve seat serves as the lower inlet of the sedimentation valve. The upper port of the sedimentation valve body is blocked by a closed ball cover to form a blind end.

[0042] The side wall of the sedimentation valve body has a side outlet.

[0043] The side outlet has a staggered porous structure that tilts outward and downward at an angle of 30-60 degrees.

[0044] It also includes a flow-expanding sand-blocking channel mechanism, which includes an outer pipe 9, an upper central pipe 10, and a lower central pipe 18;

[0045] The lower end of the upper central pipe is connected to the upper end of the sedimentation valve body, and the upper end of the lower central pipe is connected to the lower end of the single-flow valve seat; the upper central pipe is located inside the outer pipe, and the outer pipe and the upper central pipe form a sand-blocking channel; the lower central pipe is located inside the outer pipe, and the outer pipe and the lower central pipe form an outer sedimentation chamber 17.

[0046] The side outlet of the sedimentation valve is connected to both the sand-blocking channel and the external sedimentation chamber, wherein the sand-blocking channel is located above the side outlet and the external sedimentation chamber is located below the side outlet.

[0047] The lower ends of the outer tube and the inner central tube are simultaneously connected to the lower connector 19.

[0048] The lower end of the upper central tube is blocked by a closed ball cover, so that the inner cavity of the upper central tube forms an inner sedimentation chamber 12. The upper central tube has a side liquid inlet, namely the central tube side hole 8, and the opening direction of the side liquid inlet is inclined inward and downward.

[0049] The lateral openings of the central tube are arranged in a staggered porous structure with an inward and downward tilting angle of 30-60 degrees.

[0050] The sand-blocking channel formed between the outer pipe and the upper central pipe is provided with at least one flow-expanding sand-blocking port 11. The lower end of the flow-expanding sand-blocking port is a planar opening, and the upper end of the flow-expanding sand-blocking port is a conical diffuser.

[0051] The closed ball cover 13 of the sedimentation valve is connected to the upper central tube 10, and the closed ball cover 13 and the upper central tube 10 form the inner sedimentation chamber 12; the annular space between the outer tube 9 and the lower central tube 19 forms the outer sedimentation chamber 18. The pumping and pressurizing mechanism is connected to the oil pump plunger through the connecting rod 1.

[0052] Furthermore, the outer tube 9 is connected to the lower center tube 19 via a direct-connection lower connector 20, and the outer tube 9 is connected to the upper center tube 10 via a direct-connection upper connector 2; the upper end of the lower center tube 19 is connected to the single-flow valve seat 16 via a threaded connection.

[0053] Furthermore, a retaining ring 7 is provided at the upper end of the inner side hole of the central tube, and the pumping pressurization mechanism is located in the central tube above the retaining ring;

[0054] Furthermore, a straightener can be provided on the outside of the pressure booster shroud 3 to straighten it from the upper central tube 10;

[0055] Furthermore, the buoyancy ball 5 is a high-density tetrafluoroethylene ball with a specific gravity of 0.7 to 0.8;

[0056] Working principle of the pumping and pressurizing mechanism:

[0057] The pumping and pressurizing mechanism consists of a pressurizing hood 3, a pressurizing ball seat 4, a buoyancy ball 5, and a pressurizing inlet channel 6; the pumping and pressurizing mechanism is a one-way ball valve body. The structure of this one-way ball valve is conventional in the field, equivalent to the floating valve at the bottom of an oil pump. This invention utilizes this mechanism, producing significant effects.

[0058] During descent, the pumping and pressurizing mechanism descends along with the pump plunger, driven by the connecting rod. The buoyancy ball 5 sits on the pressurizing ball seat 4, making the pumping and pressurizing mechanism a sealed solid body. Because the bottom of the upper central tube is closed, the descent of the pumping and pressurizing mechanism will compress the liquid inside its central tube. Under this compression, the pressure inside the lateral hole of the central tube is greater than the annular pressure outside the lateral hole, thus increasing the pressure at the top of the expansion-type sand-blocking channel. This forces the liquid in the expansion-type sand-blocking channel to change from an upward flowing state to a static state, making it easier for sand and impurities to settle. The pressurization principle is that the part below the lateral hole of the upper central tube is a dead cavity. When the mechanism descends, the buoyancy ball seals the ball seat, making the mechanism a solid whole, which compresses the liquid below, resulting in a pressure inside the lateral hole greater than the annular pressure outside the lateral hole. As the mechanism descends, the compression of the lower liquid causes it to rise through the gap between the central tube and the mechanism. The solid body creates a throttling effect, which accelerates the flow rate and flushes the upper plunger.

[0059] When moving upward, the pumping and pressurizing mechanism moves upward along with the oil pump plunger under the drive of the connecting rod. The buoyancy ball 5 disengages from the pressurizing ball seat 4, and the pumping and pressurizing mechanism becomes a hollow body. The liquid moves upward through the pressurizing inlet channel 6 and the gap between the pumping and pressurizing mechanism and the central tube.

[0060] Furthermore, the flow-expanding sand-blocking outlet 11 is a funnel-shaped cone with a horizontal bottom, composed of an outer pipe 9 and an upper central pipe 10.

[0061] Furthermore, the length of the outer tube 9 and the upper central tube 10 can be increased by double straight couplings, and the length of the outer tube 9 and the lower central tube 19 can be increased by double straight couplings;

[0062] Furthermore, the length of the connecting rod 1 is customized according to the stroke of the pumping unit, and the outer diameter of the connecting rod 1 is not less than 22mm and is treated with anti-corrosion.

[0063] Furthermore, the oil pump is a valveless oil pump, and the bottom of the oil pump plunger is a female thread, which is connected to the connecting rod 20 by a thread.

[0064] The method of using this invention is as follows:

[0065] Before running the tubing down the well, first remove the pumping booster mechanism from the equipment for later use. Disassemble the fixed valve assembly of the oil pump, connect the female thread of the device to the male thread at the lower end of the oil pump, and then run them into the well together. After all the tubing strings have been run, tighten the threads of the pumping booster mechanism and connecting rod, and then tighten them to the oil pump plunger. Run the tubing down the well in sequence.

[0066] The sedimentation valve adopts a bottom inlet and side outlet method, which effectively avoids the accumulation of sand and impurities in the sedimentation valve. At the same time, the side outlet opening direction is inclined outward and downward, changing the flow direction, so that most of the sand and impurities are deposited in the outer sedimentation chamber.

[0067] The horizontal lower end of the flow-expanding sand-blocking inlet plays a good role in blocking sand and impurities near the side wall. The flow channel of the flow-expanding sand-blocking inlet is cone-shaped. As the flow channel widens, the flow velocity of the liquid slows down when it passes through, thus achieving the settling of sand and impurities during the upward process.

[0068] The upper central tube has a side inlet, which is a side hole of the central tube. The opening direction of the side inlet is downward and inward, which changes the flow direction and causes the sand particles entering the central tube to be deposited in the sedimentation chamber.

[0069] During the pumping process, as the pumping booster mechanism descends along with the pump plunger driven by the connecting rod, the buoyancy ball sits on the booster ball seat, making the pumping booster mechanism a sealed solid body. Since the bottom of the upper central tube is closed, the downward movement of the pumping booster mechanism will squeeze the liquid inside its central tube. Under the squeezing action, the pressure inside the lateral hole of the central tube is greater than the annular pressure outside the lateral hole of the central tube. Therefore, the pressure in the upper part of the expansion-type sand-blocking channel increases, forcing the liquid in the expansion-type sand-blocking channel to change from an upward flowing state to a static state, thus making it easier for sand and impurities to sink.

[0070] Example 2:

[0071] Please see Figure 1 The present invention provides a technical solution: based on the technical solution of embodiment 1, the single-flow valve assembly can be one set or two sets, and if two sets are designed, threaded connection is adopted;

[0072] Furthermore, the side hole of the sedimentation valve body is a circular hole with a diameter of 10-12 mm, and the side hole 8 of the central tube is a circular hole with a diameter of 5-6 mm;

[0073] Furthermore, the pressure boosting cover 3 and pressure boosting ball seat 4 of the pumping and pressurizing mechanism, as well as the one-way valve ball 15 and one-way valve seat 16 of the sand settling valve, are all made of 20CrMo, and the surface of the one-way valve ball 15 is nickel-plated.

[0074] The minimum diameter of the flow-expanding sand-blocking inlet is greater than 10mm, and one flow-expanding sand-blocking inlet is set every 50cm.

[0075] Example 3:

[0076] Please see Figure 1 The present invention provides a technical solution: based on the technical solution of embodiment 1, the openings of the lateral holes 8 of the central tube are arranged in a staggered porous structure with an inward downward tilt of 60 degrees;

[0077] Furthermore, the lower middle part of the sedimentation valve body 14 has sedimentation side holes with a staggered arrangement of porous structures that open at a 60-degree angle outward and downward.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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 sand control device for coalbed methane wells, comprising a check valve that allows only the liquid flow to ascend; Its features are, The single-flow valve is a sand-sinking valve, which has a lower inlet and a side outlet, and the side outlet opens in an outward and downward direction. The sand-sinking valve includes a sand-sinking valve body, a one-way valve ball, a one-way valve seat, and a closed ball cover; The lower port of the grit removal valve body is connected to a flow valve seat. The grit removal valve body has a built-in flow valve ball, which sits on the upper port of the flow valve seat. The internal channel of the flow valve seat serves as the lower inlet of the grit removal valve. The upper port of the grit removal valve body is blocked by a closed ball cover to form a blind end. The side wall of the sedimentation valve body has a side liquid outlet; The side outlet has a staggered porous structure that tilts outward and downward at an angle of 30-60 degrees; It also includes a flow-expanding sand-blocking channel mechanism, which includes an outer pipe, an upper central pipe, and a lower central pipe; The lower end of the upper central tube is connected to the upper end of the sand-collecting valve body, and the upper end of the lower central tube is connected to the lower end of the single-flow valve seat; the upper central tube is located inside the outer tube, and the outer tube and the upper central tube form a sand-blocking channel; the lower central tube is located inside the outer tube, and the outer tube and the lower central tube form an outer sand-collecting cavity. The side outlet of the sand-collecting valve is connected to both the sand-blocking channel and the external sand-collecting chamber, wherein the sand-blocking channel is located above the side outlet and the external sand-collecting chamber is located below the side outlet. The lower end of the upper central tube is blocked by a closed ball cover, so that the inner cavity of the upper central tube forms an inner sand settling chamber. The upper central tube has a side liquid inlet, namely the central tube side hole, and the opening direction of the side liquid inlet is inclined inward and downward. The lower ends of the outer tube and the inner central tube are simultaneously connected to the lower connector; The lateral openings of the central tube are arranged in a staggered porous structure with an inward downward tilt of 30-60 degrees. The sand-blocking channel formed between the outer pipe and the upper central pipe is provided with at least one flow-expanding sand-blocking port. The lower end of the flow-expanding sand-blocking port is a planar opening, and the upper end of the flow-expanding sand-blocking port is a conical diffuser. The upper central tube is also equipped with a pumping and pressurizing mechanism, which is located above the side liquid inlet and is connected to a connecting rod at its upper end. The inner wall of the upper central tube is also equipped with a baffle to prevent the pumping and pressurizing mechanism from falling. The upper ends of the outer tube and the upper central tube are both connected to an upper connector. The pumping and pressurizing mechanism is a single-flow ball valve structure.

2. A method for using the sand control device for coalbed methane wells as described in claim 1, characterized in that, Includes the following steps: The grit chamber valve adopts a bottom inlet and side outlet method, which effectively avoids the accumulation of sand and impurities in the grit chamber valve. At the same time, the side outlet opening direction is inclined outward and downward, which changes the flow direction and slows down the flow rate, so that most of the sand and impurities are deposited in the outer grit chamber. The bottom horizontal flow-expanding sand-blocking port effectively blocks sand and impurities near the inner wall, changes the flow direction, and slows down the flow rate. At the same time, the funnel-shaped structure induces a slowdown in the flow rate, achieving sand-liquid separation and sedimentation of sand and impurities during the upward process. The upper central tube has a side inlet, which is a side hole of the central tube. The opening direction of the side inlet is inward and downward, which changes the flow direction and slows down the flow rate, so that most of the sand and impurities are deposited in the inner sand settling chamber. During the pumping process, the pumping pressurization mechanism generates a throttling and pressurizing effect as it descends. The pressure at the bottom of the pumping pressurization mechanism increases, thus achieving downward pressurization. This instantly changes the flow state of the fluid containing sand and impurities in the flow channel from the flow-expanding sand-blocking channel to a static state. The flow direction changes, and the flow velocity slows down. The sand and impurities in the fluid containing sand and impurities rapidly separate due to gravity in a static state, accelerating the sedimentation process of sand and impurities. In other words, the pressurized liquid in the channel becomes static during the downward process of the pumping pressurization mechanism, and the two-stage sand settling chambers inside and outside ensure that the sand particles in the fluid containing sand and impurities settle fully and cannot enter the pump cylinder. The pumping pressurization mechanism is a single-flow ball valve body. When it descends, it closes, and the liquid cannot pass through. This squeezes the liquid in the lower part, and the liquid will rise from the gap between the central tube and the mechanism. Due to the throttling effect and the reduction of the channel area, the flow velocity is accelerated, thereby flushing the upper plunger.

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