Coal bed methane downhole gas lift stimulation device and method of use

Abstract

The application discloses a kind of coal bed gas downhole gas lift stimulation equipment and use method, it is related to coal bed gas mining technical field.The application includes gas pressure supply device, casing, gas return pipe, preliminary separation device, cyclone separation device, gas pressure supply device is connected casing, casing is inserted into coal seam, gas return pipe is placed in casing and is connected with preliminary separation device, preliminary separation device is connected cyclone separation device;Gas return pipe contains multiple section pipes, section pipe has mixed flow channel, top is provided with booster gas lift nozzle, channel is equipped with spoiler and flow cutting ring, nozzle is provided with pressure sensing module, spoiler has main channel, ring position channel and special-shaped channel, copper foil sheet is arranged in flow cutting ring.When using, mixed flow is formed by high-pressure gas flow, pressurized by nozzle, mixed flow by spoiler, particle aggregation is suppressed by flow cutting ring, pressure sensing monitors and intelligently clears blockage, and finally separates coal bed gas.The application can improve the uniformity of mixed flow, suppress particle aggregation and blockage, realize intelligent unblocking, and ensure stable and efficient operation of the equipment.

Description

Technical Field

[0001] This invention relates to the field of coalbed methane extraction technology, and in particular to a coalbed methane downhole gas lift production enhancement device and its usage method. Background Technology

[0002] In the field of coalbed methane extraction, the gas lift method, as a production enhancement technology that drives downhole fluids upward by injecting high-pressure gas, is widely used in the development of low-permeability, high-liquid-content coal seams due to its strong applicability and minimal damage to the coal seam. Its core principle is to inject high-pressure gas into the downhole casing using a gas supply device, causing the coalbed methane, interstitial fluids (such as formation water and fracturing flowback fluid), and solid particles (such as coal dust and rock cuttings) in the coal seam to form a three-phase mixture. This mixture is then transported to the surface separation system through a return gas pipe, ultimately achieving the extraction and recovery of coalbed methane.

[0003] However, in practical applications, existing gas lift production enhancement equipment is limited by complex downhole conditions and structural design flaws, and generally faces the technical challenge of solid particle aggregation and blockage of key components in mixed flow, which seriously restricts production efficiency and equipment stability. The specific problems can be summarized in the following three aspects:

[0004] I. Polymerization of solid particles leads to frequent failure of booster nozzles

[0005] As the core channel of mixed-flow conveying, the return gas pipe contains pressurized air-lift nozzles, which are crucial components for maintaining the upward momentum of the mixed flow. However, during the mixed-flow ascent, solid particles (mostly 0.1-5 mm in diameter) produced from the coal seam are easily attracted to each other and agglomerate into larger aggregate particles (some of which can reach over 20 mm in diameter) due to the influence of fluid viscosity, interparticle adsorption forces (such as van der Waals forces), and turbulent flow disturbances. When these aggregate particles flow through the pressurized air-lift nozzles, they are prone to getting stuck at the nozzle inlet (usually 10-15 mm in diameter) or outlet (usually 8-12 mm in diameter), causing blockage of the nozzle pressurization channel.

[0006] Once the nozzle becomes clogged, it will not only lose its pressurization function for mixing, but also disrupt the pressure balance in the return pipe, resulting in insufficient mixing and conveying power in the downstream pipe section, and even causing a "flow interruption" phenomenon.

[0007] II. Poor flow uniformity exacerbates the risk of localized blockage.

[0008] Existing return gas pipes mostly have a single, straight-through channel structure. During the transport of gas-liquid-solid three-phase mixtures, a "stratification" phenomenon easily occurs: the denser liquid and solid particles flow along the inner wall of the channel, while the less dense coalbed methane concentrates in the central area of ​​the channel, forming a non-uniform flow state of "gas core-liquid-solid ring". This stratified flow not only leads to uneven distribution of the overall kinetic energy of the mixture, but also causes solid particles to accumulate in local areas of the channel (such as bends and diameter changes).

[0009] At the same time, a single channel cannot effectively disturb the mixed flow, and the tendency of particles to aggregate is difficult to suppress, which further increases the probability of the formation of aggregated particles.

[0010] Current gas lift equipment fault monitoring relies heavily on indirect assessments from surface pressure gauges. This means that only when an abnormally high total pressure in the return gas pipe is detected on the surface can a potential blockage be suspected downhole. However, the location of the blockage (such as the flow-cutting ring or nozzle of a specific pipe section) cannot be precisely pinpointed, nor can the extent of the blockage be determined. This "lagging monitoring" necessitates that workers disassemble and inspect the return gas pipe section by section, which is not only time-consuming and labor-intensive but may also cause secondary damage to the equipment due to blind operation (such as stripped bolts or damaged seals).

[0011] Furthermore, existing unblocking methods mainly rely on the traditional "shutdown-disassembly-manual cleaning" model, lacking intelligent unblocking methods that can be implemented without shutting down the machine. Even when some equipment attempts to "impact unblock" by increasing the overall airflow pressure, the lack of precise pressure control for the blocked area can easily lead to overload damage to the nozzles of normal pipe sections, and may also disturb the original structure of the coal seam, causing safety hazards such as well wall collapse.

[0012] In summary, existing coalbed methane downhole gas lift enhancement equipment has significant technical shortcomings in three aspects: "inhibiting particle aggregation," "improving flow uniformity," and "real-time monitoring and intelligent unblocking," resulting in high equipment failure rates, low operating efficiency, and high maintenance costs. Therefore, how to develop gas lift enhancement equipment that inhibits solid particle aggregation at the source, monitors blockage risks in real time, and achieves intelligent unblocking has become a technical problem that needs to be solved in the efficient extraction of coalbed methane. Summary of the Invention

[0013] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0014] This invention provides a coalbed methane downhole gas lift production enhancement device, including a gas pressure supply device, a casing, a return gas pipe, a preliminary separation device, and a cyclone separation device. The gas pressure supply device is connected to the casing, which is inserted into the coal seam. The return gas pipe is placed inside the casing and is connected to the preliminary separation device. The preliminary separation device is connected to the cyclone separation device. The return gas pipe is equipped with multiple vertically connected sections, and the inside of each section is a mixing channel. A pressurized gas lift nozzle is fixedly installed on the inner circumference of the top of each section. Multiple turbulence cylinders are configured in the mixing channel, and a flow-cutting ring is installed above each turbulence cylinder. The pressurized gas lift nozzle includes an inlet on the bottom side and an outlet on the top side.

[0015] A low-level cavity is formed between the turbulence tube at the lowest position of the tube and the pressurized air-lift nozzle at the top of the lower tube, and between the turbulence tube at the non-lowest position and the adjacent shroud ring below it. A mixing cavity is formed between the turbulence tube and the adjacent shroud ring above it.

[0016] The booster air lift nozzle ring is equipped with a high-level pressure sensing module for monitoring the pressure of the mixed fluid in the top region of the lower mixing channel and a low-level pressure sensing module for monitoring the pressure of the mixed fluid in the bottom region of the upper mixing channel.

[0017] The turbulence-inducing ring has a vertically continuous main channel, multiple annular channels distributed around the main channel, and multiple irregularly shaped channels interspersed with the annular channels. Multiple copper foil sheets are arranged inside the flow-cutting ring.

[0018] As a preferred technical solution of the air-lift production enhancement device of the present invention: a recessed inner fixing ring is provided on the inner circumference of the top of the tube, and a mounting ring is provided on the ring side of the pressurized air-lift nozzle. The mounting ring is fastened to the upper part of the inner fixing ring by bolts. A sealing ring is provided between the mounting ring and the inner fixing ring.

[0019] As a preferred technical solution of the air lift production enhancement device of the present invention: a connection port is provided at the bottom of the tube, the inner wall of the connection port is provided with an internal thread, the outer periphery of the top of the tube is provided with an external thread that matches the internal thread, and the top of the lower tube is screwed to the connection port position at the bottom of the upper tube.

[0020] As a preferred technical solution of the gas lift production enhancement equipment of the present invention: a cone-shaped bolt for fastening the baffle and the flow-cutting ring is embedded on the side of the tube ring, and a conical sealing ring is provided at the connection position between the cone-shaped bolt and the tube ring side. The baffle and the flow-cutting ring are provided with threaded blind holes that mate with the cone-shaped bolt.

[0021] As a preferred technical solution of the air lift production enhancement equipment of the present invention: both the main channel and the annular channel adopt a cylindrical through-hole structure, the diameter of the annular channel is smaller than the diameter of the main channel, the radial length of the irregular channel is larger than the diameter of the annular channel, and the maximum circumferential width of the irregular channel is smaller than the diameter of the annular channel.

[0022] As a preferred technical solution of the air lift production enhancement equipment of the present invention: the horizontal cross-section of the irregular channel can be any kind of curved surface structure or any kind of polygonal structure.

[0023] As a preferred technical solution of the air lift production enhancement equipment of the present invention: the horizontal cross-sectional areas of the main channel, the annular channel, and the irregular channel are all different, and the sum of the horizontal cross-sectional areas of the main channel, the annular channel, and the irregular channel is not less than half of the horizontal cross-sectional area of ​​the mixed flow channel.

[0024] This invention provides a method for using a downhole gas lift enhancement device for coalbed methane production, the details of which are as follows:

[0025] Step 1: Turn on the air pressure supply device and inject high-pressure airflow steadily into the casing through the preset gas pipeline.

[0026] Step 2: Under the action of high-pressure airflow, coalbed methane, interstitial liquid and solid particles in the coal seam form a gas-liquid-solid mixture. Driven by the pressure difference, this mixture gradually enters the return gas pipe placed inside the casing.

[0027] In step three, after the gas-liquid-solid mixed flow enters the return gas pipe, it flows through the pressurized air-lift nozzle fixedly configured on the inner circumference of the top of the section pipe and is discharged upward into the mixing channel of the upper section pipe.

[0028] Step 4: After being pressurized, the mixed flow continues to rise and enters the low-level cavity inside the tube, and then continues to rise into the turbulence tube.

[0029] Step 5: Fluids with outlet deviations from the various channels of the turbulence tube are discharged together into the mixing chamber formed by the turbulence tube and the adjacent tangential ring above it. Inside the mixing chamber, multiple fluid streams collide and mix, ensuring thorough mixing of the gas, liquid, and solid phases and improving the overall uniformity of the mixing.

[0030] Step Six: After being thoroughly mixed, the mixed flow continues to rise and enters the tangential flow ring. Multiple copper foil sheets arranged inside the tangential flow ring physically separate the solid particles that are about to be adsorbed and polymerized in the mixed flow, thus disrupting the polymerization trend of the solid particles.

[0031] Step 7: Within the same pipe section, the high-level pressure sensing module monitors the mixed fluid pressure Pn in the top region of the mixing channel, while the low-level pressure sensing module monitors the mixed fluid pressure Pm in the bottom region of the mixing channel. If Pn < (1-λ)Pm, it is determined that there is a pressure difference abnormality in the current mixing channel, where λ is the pressure attenuation coefficient of the rising mixing pressure, which is related to the pipe section length, inner wall material, turbulence cylinder, and shear ring distribution. When a pressure difference abnormality exists, the two booster air-lift nozzles at the bottom and top of the pipe section are synchronously adjusted. By increasing the nozzle power or making the nozzle generate a pulsed booster jet, the flow intensity of the mixed fluid in the mixing channel is increased, impacting any blockages that may exist in the gaps of the copper foil sheets in the shear ring, until the pressure parameter satisfies Pn ≥ (1-λ)Pm, restoring the normal conveying state of the mixed fluid.

[0032] Compared with existing technologies, the beneficial effects of this invention are:

[0033] In this invention, the main channel, annular channel, and irregular channel of the turbulence tube create a significant difference in the position of the inlet and outlet when the mixed flow passes through different channels. After multiple mixed flows enter the mixing chamber from the turbulence tube, they collide and merge with each other, allowing the gas, liquid, and solid three-phase substances to be fully mixed and improving the overall uniformity of the mixed flow.

[0034] In this invention, multiple copper foil sheets arranged around the inner circumference of the flow-cutting ring can physically separate the solid particles that are about to be adsorbed and polymerized in the mixed flow, directly destroying the polymerization trend of the solid particles and preventing small particles from forming large-volume polymerized particles (large polymerized particles are easy to get stuck in the inlet and outlet of the pressurized air-lift nozzle, causing the nozzle to fail). This reduces the risk of blockage from the source and ensures continuous and stable pressurization of the nozzle.

[0035] This invention incorporates a pressure sensor and nozzle adjustment system to intelligently clear potential blockages: A high / low pressure sensor module on the side of the booster air-lift nozzle ring monitors the top and bottom pressures of the mixing channel within the same pipe section in real time. Based on a judgment standard, it identifies abnormal blockages in the gaps between the copper foil sheets of the flow-cutting ring. When an abnormal pressure difference occurs, the parameters of the booster air-lift nozzles at the bottom and top of the pipe section are adjusted simultaneously (increasing power or generating pulsed jets) to enhance the mixing flow intensity, impacting the blockage until the pressure returns to normal. This clearing process can be completed without shutdown and disassembly, reducing operational downtime.

[0036] In summary, this invention solves the key problem of "mixed-flow agglomerating particles clogging the pressurized airlift nozzle" in the prior art through a dual mechanism of "physical segmentation to suppress blockage + pressure monitoring to clear blockage". Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the distribution structure of the air lift production enhancement equipment in this invention.

[0038] Figure 2 This is a schematic diagram of the continuous installation of the tube sections in this invention.

[0039] Figure 3 for Figure 2 A magnified structural diagram of part A in the middle.

[0040] Figure 4 for Figure 2 A magnified structural diagram of section B in the middle.

[0041] Figure 5 This is a schematic diagram of the horizontal cross-sectional structure of the turbulence-disrupting cylinder in this invention.

[0042] Figure 6 This is a schematic diagram of the horizontal cross-sectional structure of the flow-cutting ring in this invention.

[0043] Wherein: 1-Air pressure supply device; 2-Casing; 3-Coal seam; 4-Return gas pipe; 401-Section pipe; 402-Mixed flow channel; 402a-Low-position cavity; 402b-Mixed flow cavity; 403-Inner fixing ring; 404-Connecting port; 4041-Internal thread; 405-External thread; 5-Pressurized air lift nozzle; 501-Inlet; 502-Outlet; 503-Mounting ring; 504-High-position pressure sensing module; 505-Low-position pressure sensing module; 6-Sealing ring; 7-Bolt; 8-Break current cylinder; 801-Main channel; 802-Ring position channel; 803-Irregular channel; 9-Flow cutting ring; 901-Copper foil sheet; 10-Conical cap bolt; 11-Conical sealing ring; 12-Preliminary separation device; 13-Cyclone separation device. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] Example 1: This invention designs a downhole gas lift enhancement device for coalbed methane, with the following specific structural configuration:

[0046] I. Core functional components and their connections (e.g.) Figure 1 , Figure 2 )

[0047] Air pressure supply device 1: As a high-pressure airflow output source, it is connected to the sleeve 2 through a preset gas pipeline, and can stably inject high-pressure airflow into the sleeve 2, providing a power basis for the formation and rise of gas-liquid-solid mixed flow.

[0048] Casing 2: It has a vertical tubular structure and is inserted into the coal seam 3 at the bottom. The return gas pipe 4 is installed inside the casing 2. Its internal space provides a channel for the high-pressure airflow to act on the coal seam 3 and for the initial collection of mixed flow.

[0049] Return gas pipe 4: The main body is composed of multiple vertically connected sections 401, placed inside the casing 2, and the top is connected to the preliminary separation device 12. It is used to transport the gas-liquid-solid mixed flow formed in the coal seam 3. The inside of the return gas pipe 4 is the mixed flow channel 402, which is the core space for the mixed flow within the return gas pipe 4.

[0050] Preliminary separation device 12: One end is connected to the return gas pipe 4, and the other end is connected to the cyclone separation device 13. After receiving the mixed flow transported by the return gas pipe 4, it first performs preliminary separation of the gas, liquid and solid three-phase substances to prepare for subsequent fine separation.

[0051] Cyclone Separator 13: Connected to the preliminary separation device 12, it uses the cyclone separation principle to perform fine separation on the mixed flow after preliminary separation, and finally achieves efficient separation of coalbed methane from liquid and solid impurities to obtain qualified coalbed methane products.

[0052] II. Pipe joint and supporting structures (such as...) Figure 1 , Figure 2 , Figure 3 , Figure 4 )

[0053] Section pipe 401: The basic component of return pipe 4. The interior of a single section pipe 401 is a mixing channel 402. A pressurized air lift nozzle 5 is fixedly configured on the inner circumference of the top of section pipe 401. Multiple turbulence cylinders 8 are arranged vertically inside the mixing channel 402, and a flow cutting ring 9 is installed above each turbulence cylinder 8.

[0054] Inner fixing ring 403: It has a ring structure and a recessed design. It is fixedly installed on the inner circumference of the top of the tube 401 to support and fix the booster air lift nozzle 5. The inner fixing ring 403 is connected to the mounting ring 503 of the booster air lift nozzle 5 by bolts 7, and a sealing ring 6 is arranged between the two to achieve a seal.

[0055] Connection port 404: Located at the bottom of the tube 401, the inner wall of the connection port 404 has an internal thread 4041, which cooperates with the external thread 405 on the outer periphery of the top of the upper tube 401. The vertical connection of multiple tubes 401 is achieved by screwing, ensuring the overall sealing and structural stability of the return air pipe 4.

[0056] External thread 405: Machined on the top periphery of the section tube 401, matching the internal thread 4041 of the bottom connection port 404 of the adjacent lower section tube 401. It is a key structure for the detachable connection between the section tubes 401, facilitating equipment installation, maintenance and replacement.

[0057] Mixed flow channel 402: Located inside the joint tube 401, it is a channel for mixed upward flow, forming two functional chambers inside:

[0058] The low-position cavity 402a is formed by two types of structures: one is the space between the turbulence tube 8 at the lowest position of the section tube 401 and the pressurized air-lift nozzle 5 at the top of the lower section tube 401, and the other is the space between the turbulence tube 8 at the non-lowest position and the adjacent tangential ring 9 below it, which is used for temporary storage of mixed flow and transition of flow state.

[0059] Mixing chamber 402b: It is formed by the turbulence cylinder 8 and the adjacent tangential ring 9 above it. It is a region where multiple streams from different outlet positions collide and merge, so as to achieve full mixing of gas, liquid and solid three-phase substances and improve the uniformity of mixing.

[0060] III. Boosting airlift nozzle and monitoring structure (e.g.) Figure 2 , Figure 3 )

[0061] The booster air lift nozzle 5 is fixed to the top inner circumference of the tube 401 and is the core component for mixed-flow pressurization. It has an inlet 501 at the bottom and an outlet 502 at the top. The mixed flow enters through the inlet 501, is pressurized by the internal structure, and is discharged from the outlet 502 into the mixed-flow channel 402 of the upper tube 401. The booster air lift nozzle 5 is equipped with a mounting ring 503, a high-level pressure sensing module 504, and a low-level pressure sensing module 505 on its circumferential side.

[0062] Inlet 501: Located on the bottom side of the pressurized air-lift nozzle 5, it is the inlet for the mixed flow to enter the nozzle. Its size is matched with the mixed flow rate to ensure that the mixed flow enters the nozzle stably for pressurization.

[0063] Drain 502: Located on the top side of the pressurized air-lift nozzle 5, it is the outlet of the mixed flow nozzle after pressurization. Through the outlet size design and matching with the internal flow channel, it achieves stable output after mixed flow pressurization and provides kinetic energy for mixed flow rise.

[0064] Mounting ring 503: A ring structure, fixed on the ring side of the booster air lift nozzle 5, and fastened above the inner fixing ring 403 by bolts 7. It is a transition structure connecting the booster air lift nozzle 5 and the inner fixing ring 403 of the tube 401, ensuring the firmness of the nozzle installation.

[0065] High-position pressure sensing module 504: Installed on the ring side of the booster air lift nozzle 5, it is used to monitor the pressure of the mixed fluid in the top area of ​​the mixing channel 402 below in real time, and provide top pressure data for judging pressure difference abnormalities.

[0066] Low-position pressure sensing module 505: Also installed on the ring side of the booster air lift nozzle 5, it is used to monitor the pressure of the mixed fluid in the bottom area of ​​the upper mixing channel 402 in real time. In conjunction with the high-position pressure sensing module 504, it can realize the synchronous monitoring of the top and bottom pressures of the mixing channel 402 in the same section pipe 401.

[0067] Sealing ring 6: Located between mounting ring 503 and inner fixing ring 403, made of high pressure resistant and corrosion resistant material, used to seal the connection gap between the two to prevent mixed flow from leaking from the connection part and ensure stable internal pressure of return pipe 4.

[0068] Bolt 7: Used to fasten the mounting ring 503 and the inner fixing ring 403. It is made of high-strength alloy material, which has good fatigue resistance and corrosion resistance, ensuring that the booster gas lift nozzle 5 is firmly installed under high pressure and complex working conditions downhole and does not loosen.

[0069] IV. Baffle tube and supporting channel structure (such as...) Figure 2 , Figure 4 , Figure 5 )

[0070] The turbulence-dispersing tube 8 has a cylindrical structure and is installed in the mixing channel 402 of the section tube 401. It is fixed to the section tube 401 by the cone cap bolt 10. The turbulence-dispersing tube 8 has a main channel 801, annular channel 802 and irregular channel 803, which are used to split the mixed flow into multiple streams of fluid with different outlet positions, laying the foundation for subsequent mixing.

[0071] Main channel 801: Vertically opened at the center of the turbulence cylinder 8, it adopts a cylindrical through-hole structure and is the main channel for mixed flow through the turbulence cylinder 8. Its diameter is the largest, and the flow rate of mixed flow in this channel is relatively stable.

[0072] Circular channels 802: There are multiple channels, which are distributed in a ring around the main channel 801. They all adopt a cylindrical through-hole structure and the diameter is smaller than the diameter of the main channel 801.

[0073] Irregularly shaped channels 803: There are multiple such channels, which are distributed alternately with annular channels 802 on the baffle tube 8. The radial length of the irregularly shaped channel 803 is greater than the diameter of the annular channel 802, and the maximum circumferential width is less than the diameter of the annular channel 802. The horizontal cross-section of the irregularly shaped channel 803 can be any curved surface structure (such as arc or wave) or any polygonal structure (such as triangle or pentagon). The upward discharge outlet position of the fluid is different from that of the main channel 801 and the annular channel 802, which further increases the degree of mixing when the fluid is discharged upward.

[0074] Conical nut bolt 10: It is embedded in the ring side of the tube 401 and is used to fasten the turbulence cylinder 8 and the flow cutting ring 9. The bolt head has a conical structure and a conical sealing ring 11 is provided at the connection position with the ring side of the tube 401 to ensure sealing performance. The ring side of the turbulence cylinder 8 and the flow cutting ring 9 is provided with a threaded blind hole structure that matches the conical nut bolt 10 to ensure a firm installation.

[0075] Conical sealing ring 11: It is set at the connection position between the conical cap bolt 10 and the ring side of the tube 401. It is made of elastic and wear-resistant material. Its conical structure fits tightly with the head of the conical cap bolt 10 and the mounting hole of the tube 401, effectively preventing mixed flow from leaking from the bolt installation gap, while enhancing the stability of the bolt connection.

[0076] V. Flow-cutting ring and anti-polymerization structure (such as...) Figure 2 , Figure 4 , Figure 6 )

[0077] Flow-cutting ring 9: A ring structure, installed above the turbulence-spreading cylinder 8, together with the turbulence-spreading cylinder 8 forming a mixing chamber 402b, and fixed to the section tube 401 by the cone cap bolt 10; the inner circumference of the flow-cutting ring 9 is provided with multiple copper foil sheets 901, the core function of which is to physically separate the solid particles in the mixing and inhibit particle aggregation.

[0078] Copper foil sheets 901: There are multiple sheets, evenly distributed inside the flow-cutting ring 9. They are made of thin copper foil material and have a certain degree of flexibility and strength. When the mixed flow passes through the flow-cutting ring 9, the copper foil sheets 901 can physically separate the solid particles that are about to be adsorbed and polymerized, destroy the adsorption force and polymerization tendency between particles, avoid the formation of large-volume polymerized particles, and reduce the risk of blockage from the source.

[0079] Example 2: This invention designs a method for using a coalbed methane downhole gas lift production enhancement device, the specific method is as follows:

[0080] Step 1: Start the air pressure supply system: Turn on the air pressure supply device 1 and inject high-pressure airflow steadily into the casing 2 through the preset gas pipeline to ensure that the high-pressure airflow can continuously act on the coal seam 3 area along the casing 2 channel, providing the power basis for the subsequent collection of coalbed methane, interstitial liquid and particulate matter.

[0081] Step 2: Guiding the gas-liquid-solid mixture into the return gas pipe: Under the action of high-pressure airflow, coalbed gas, interstitial liquid and solid particles in coal seam 3 form a gas-liquid-solid mixture. Driven by the pressure difference, this mixture gradually enters the return gas pipe 4 placed inside the casing 2, realizing the initial collection and guidance of the target fluid.

[0082] Step 3: Preliminary pressurization treatment by the pressurizing airlift nozzle: After the gas-liquid-solid mixed flow enters the return gas pipe 4, it first flows through the pressurizing airlift nozzle 5, which is fixedly configured on the inner circumference of the top of the section pipe 401. The mixed flow enters from the inlet 501 on the bottom side of the pressurizing airlift nozzle 5, and after being pressurized by the internal structure of the nozzle, it is discharged upward from the outlet 502 on the top side into the mixing channel 402 of the upper section pipe 401, providing kinetic energy for the subsequent transport of the mixed flow.

[0083] Step 4: Mixed Flow Enters Low-Level Cavity for Temporary Storage and Transition: After pressurization, the mixed flow continues to rise and enters the low-level cavity 402a formed by the turbulence-inducing cylinder 8 inside the section tube 401 and the structure below. Specifically, the low-level cavity 402a is formed between the lowest-positioned turbulence-inducing cylinder 8 and the pressurized air-lift nozzle 5 at the top of the lower section tube 401, and also between the non-lowest-positioned turbulence-inducing cylinder 8 and its adjacent lower shear ring 9. Within the low-level cavity 402a, the mixed flow achieves temporary storage and a smooth transition between different flow states.

[0084] Step 5: Multi-channel Differentiated Flow Guidance in the Baffle Cylinder: The mixed flow temporarily stored in the low-level cavity 402a continues to rise and enters the interior of the baffle cylinder 8. The mixed flow passes through the vertically penetrating main channel 801 opened in the baffle cylinder 8, multiple annular channels 802 distributed around the sides, and irregularly shaped channels 803 interspersed with the annular channels 802. Due to the differences in the structural dimensions and positions of each channel, the movement state of the mixed flow in different channels forms obvious differences, creating conditions for the secondary fusion and mixing of the subsequent mixed flow.

[0085] Step Six: Mixing of Multiple Fluid Streams in the Mixing Chamber: Multiple fluid streams flowing from various channels of the turbulence cylinder 8, with varying outlet positions, converge into the mixing chamber 402b, formed by the turbulence cylinder 8 and its adjacent tangential ring 9. Within the mixing chamber 402b, the multiple fluid streams collide and mix, ensuring thorough mixing of the gas, liquid, and solid phases and enhancing the overall uniformity of the mixture.

[0086] Step 7: Copper Foil Sheets in the Flow-Cutting Ring Segment Solid Particles: After homogenization, the mixed flow continues to rise and enters the region of the Flow-Cutting Ring 9. Multiple copper foil sheets 901 arranged inside the Flow-Cutting Ring 9 physically segment the solid particles that are about to be adsorbed and polymerized in the mixed flow, disrupting the polymerization trend of the solid particles, avoiding the formation of large polymer particles, and ensuring the smooth flow of the subsequent mixed flow transport channel.

[0087] Step 8: Real-time pressure monitoring by the pressure sensing module: During the mixed flow process, the high-level pressure sensing module 504 and the low-level pressure sensing module 505, configured on the annular side of the booster air-lift nozzle 5, continuously operate. Within the same pipe section 401, the high-level pressure sensing module 504 monitors the mixed fluid pressure Pn in the top region of the mixed flow channel 402, while the low-level pressure sensing module 505 monitors the mixed fluid pressure Pm in the bottom region of the mixed flow channel 402.

[0088] Step Nine: Pressure Parameter Comparison and Anomaly Judgment: (Within the same pipe section 401) Compare the pressure parameter Pn detected by the high-level pressure sensing module 504 with the pressure parameter Pm detected by the low-level pressure sensing module 505 to determine whether the pressure condition Pn ≥ (1-λ)Pm is met (where λ is the mixing flow rising pressure attenuation coefficient, which is related to the length of the pipe section 401, the inner wall material, the distribution of the baffle 8 and the flow-cutting ring 9. The longer the length of the pipe section 401, the rougher the inner wall material, and the greater the resistance generated by the distribution of the baffle 8 and the flow-cutting ring 9, the larger λ will be, and the greater the pressure difference between the top and bottom of the mixing channel 402 in the same pipe section 401 will be). If Pn < (1-λ)Pm, it is determined that there is a pressure difference anomaly in the current mixing channel 402.

[0089] Step 10: Adjustment of the parameters of the booster air lift nozzle: When an abnormal pressure difference is determined, the parameters of the two booster air lift nozzles 5 at the bottom and top of the section pipe 401 are adjusted synchronously. By increasing the nozzle power or making the nozzle generate a pulsed booster jet, the flow intensity of the mixed flow in the mixed flow channel 402 is increased, and the blockage that may exist in the gap of the copper foil sheet 901 of the flow cutting ring 9 is impacted until the pressure parameter meets Pn≥(1-λ)Pm, and the normal conveying state of the mixed flow is restored.

[0090] Step 11: Mixed Flow Enters the Preliminary Separation Device: The gas-liquid-solid mixed flow after the above treatment is continuously transported along the return gas pipe 4 to the preliminary separation device 12, which is connected to the return gas pipe 4. The preliminary separation of the gas, liquid and solid three-phase substances is completed in the preliminary separation device 12, laying the foundation for subsequent fine separation.

[0091] Step 12: Mixed Flow Enters Cyclone Separator for Fine Separation: The mixed flow that has completed the initial separation enters the cyclone separator 13, which is connected to the initial separation device 12. The cyclone separation principle is used to perform fine separation of the mixed flow, so as to achieve efficient separation of coalbed methane from other impurities and finally obtain coalbed methane products that meet the requirements.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coalbed methane downhole gas lift production enhancement device, comprising a gas pressure supply device (1), a casing (2), a return gas pipe (4), a preliminary separation device (12), and a cyclone separation device (13), wherein the gas pressure supply device (1) is connected to the casing (2), the casing (2) is inserted into the coal seam (3), the return gas pipe (4) is placed inside the casing (2), the return gas pipe (4) is connected to the preliminary separation device (12), and the preliminary separation device (12) is connected to the cyclone separation device (13), characterized in that: The return pipe (4) is equipped with multiple vertically connected section pipes (401). The inside of the section pipe (401) is a mixing channel (402). A pressurizing air lift nozzle (5) is fixedly arranged on the inner circumference of the top of each section pipe (401). Multiple turbulence cylinders (8) are arranged in the mixing channel (402), and a flow cutting ring (9) is installed above each turbulence cylinder (8). The pressurizing air lift nozzle (5) includes an inlet (501) on the bottom side and an outlet (502) on the top side. The inner circumference of the top of the tube section (401) is provided with a recessed inner fixing ring (403), and the ring side of the booster air lift nozzle (5) is provided with an installation ring (503). The installation ring (503) is fastened to the inner fixing ring (403) by bolts (7). A sealing ring (6) is provided between the installation ring (503) and the inner fixing ring (403). The lowest position of the baffle tube (8) of the segment tube (401) and the top pressurizing air lift nozzle (5) of the lower segment tube (401) form a low-position cavity (402a), and the non-lowest position of the baffle tube (8) and the adjacent tangential ring (9) below it form a mixing cavity (402b). The baffle tube (8) and the adjacent tangential ring (9) above it form a mixing cavity (402b). The pressurizing air lift nozzle (5) is provided with a high-position pressure sensing module (504) for monitoring the pressure of the mixed fluid in the top region of the lower mixing channel (402) and a low-position pressure sensing module (505) for monitoring the pressure of the mixed fluid in the bottom region of the upper mixing channel (402). The turbulence tube (8) has a vertically penetrating main channel (801), multiple annular channels (802) distributed on the circumferential side of the main channel (801), and multiple irregularly shaped channels (803) interspersed with the annular channels (802). Multiple copper foil sheets (901) are arranged around the inner circumference of the flow-cutting ring (9). Both the main channel (801) and the annular channel (802) adopt a cylindrical through-hole structure. The diameter of the annular channel (802) is smaller than that of the main channel (801). The radial length of the irregular channel (803) is greater than that of the annular channel (802). The maximum circumferential width of the irregular channel (803) is smaller than that of the annular channel (802).

2. The coalbed methane downhole gas lift production enhancement device according to claim 1, characterized in that: The bottom of the tube segment (401) is provided with a connection port (404), the inner wall of the connection port (404) is provided with an internal thread (4041), the top periphery of the tube segment (401) is provided with an external thread (405) that matches the internal thread (4041), and the top of the lower tube segment (401) is screwed to the connection port (404) at the bottom of the upper tube segment (401).

3. The coalbed methane downhole gas lift production enhancement device according to claim 1, characterized in that: The section tube (401) is fitted with a cone-shaped nut bolt (10) for fastening the baffle (8) and the flow-cutting ring (9) on the circumferential side. A cone-shaped sealing ring (11) is provided at the connection position between the cone-shaped nut bolt (10) and the section tube (401). The turbulence cylinder (8) and the flow-cutting ring (9) are provided with threaded blind hole structures that cooperate with the cone cap bolt (10) on the ring side.

4. The coalbed methane downhole gas lift production enhancement device according to claim 1, characterized in that: The horizontal cross-section of the irregular channel (803) can be any curved surface structure or any polygonal structure.

5. The coalbed methane downhole gas lift production enhancement device according to claim 1, characterized in that: The horizontal cross-sectional areas of the main channel (801), the annular channel (802), and the irregular channel (803) are all different, and the sum of the horizontal cross-sectional areas of the main channel (801), the annular channel (802), and the irregular channel (803) is not less than half of the horizontal cross-sectional area of ​​the mixed flow channel (402).

6. The coalbed methane downhole gas lift production enhancement device according to claim 1, characterized in that, It also includes instructions on how to use the air-lift production enhancement equipment, as follows: Step 1: Turn on the air pressure supply device (1) and inject high-pressure airflow into the casing (2) through the preset gas pipeline; Step 2: Under the action of high-pressure airflow, coalbed gas, interstitial liquid and solid particles in coal seam (3) form gas-liquid-solid mixed flow. Driven by pressure difference, this mixed flow gradually enters the return gas pipe (4) placed inside the casing (2). Step 3: After the gas-liquid-solid mixture enters the return gas pipe (4), it flows through the pressurized air lift nozzle (5) fixedly configured on the inner circumference of the top of the section pipe (401) and is discharged upward into the mixing channel (402) of the upper section pipe (401). Step 4: After being pressurized, the mixed flow continues to rise and enters the low-level cavity (402a) in the joint tube (401), and continues to rise into the interior of the turbulence tube (8); Step 5: The mixed flow that has a discharge position deviation from each channel of the turbulence tube (8) is discharged into the mixing cavity (402b) formed by the turbulence tube (8) and the adjacent tangential ring (9) above it; Inside the mixing chamber (402b), multiple fluids collide and mix with each other, enabling the gas, liquid, and solid three-phase substances to be fully mixed in the mixing chamber (402b), thereby improving the overall uniformity of the mixing. Step 6: After being mixed evenly, the mixed flow continues to rise and enters the tangential ring (9). Multiple copper foil sheets (901) arranged inside the tangential ring (9) physically separate the solid particles that are about to be adsorbed and polymerized in the mixed flow, thereby destroying the polymerization trend of the solid particles. Section 7. Within the same pipe section (401), the high-level pressure sensing module (504) monitors the mixed fluid pressure Pn in the top area of ​​the mixing channel (402), and the low-level pressure sensing module (505) monitors the mixed fluid pressure Pm in the bottom area of ​​the mixing channel (402). If Pn < (1-λ)Pm, then it is determined that there is a pressure difference abnormality in the current mixing channel (402), where λ is the pressure attenuation coefficient of the mixing rise, which is related to the length of the tube (401), the inner wall material, the distribution of the turbulence tube (8) and the flow shear ring (9); When there is a pressure difference, the two booster air lift nozzles (5) at the bottom and top of the section pipe (401) are synchronously adjusted. By increasing the nozzle power or making the nozzle generate a pulse booster jet, the flow intensity of the mixed flow in the mixed flow channel (402) is increased, and the blockage that may exist in the gap of the copper foil sheet (901) of the flow shear ring (9) is impacted until the pressure parameter satisfies Pn≥(1-λ)Pm, and the normal conveying state of the mixed flow is restored.

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