Ultrasonic negative pressure unblocking device for coal-bed gas well
By employing an ultrasonic negative pressure unblocking device in coalbed methane wells, the synergistic effect of ultrasonic waves and high-pressure fluid is used to peel off and extract coal powder blockages, thus solving the problem of blockage in the near-wellbore zone of coalbed methane wells, achieving efficient unblocking while avoiding reservoir damage.
Patent Information
- Application Number
- CN202511174720.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-10-17
AI Technical Summary
In the process of coalbed methane extraction, existing technologies cannot efficiently resolve the problem of coal and rock fracture zones or cleavage and crack blockage caused by coal powder production in the near-wellbore area. Conventional chemical deblocking carries the risk of pollution, and simple negative pressure powder removal has limited effect. The range of downhole physical vibration is limited and the risk is high.
The design employs coaxial inner and outer tubes, combined with an ultrasonic radiation window and a negative pressure suction port. The ultrasonic generator produces high-frequency mechanical waves that, together with the high-pressure fluid, create a transient negative pressure. This pressure works synergistically on the interface between the coal powder and the fracture, peeling off adhesive blockages and efficiently sucking up loose coal powder through the negative pressure port.
It achieves efficient unblocking of coalbed methane wells, avoids permeability damage to the reservoir caused by chemical unblocking agents, ensures 360° coverage of ultrasonic energy by rotating working head, and withstands complex downhole stresses under the support of axial reinforcing ribs, thereby improving unblocking efficiency.
Smart Images
Figure CN120798227A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of coalbed methane reservoir plugging removal, in particular to a coalbed methane well ultrasonic negative pressure plugging removal device. BACKGROUND
[0002] In the process of coalbed methane exploitation, the coal powder production leads to the plugging of the coal rock broken zone or cleat, fracture near the wellbore, which is the key problem affecting the gas production efficiency. The conventional chemical plugging removal has problems such as reservoir pollution, unstable effect, etc.; the simple negative pressure powder discharge may not effectively remove the deep and strongly adhered plugging; the conventional downhole physical vibration has limited range and high risk. The ultrasonic technology has the advantages of good directivity, strong penetration, energy concentration, etc., and has been applied to the fields of scale prevention and removal, viscosity reduction, plugging removal, etc. in the petroleum field, but there is a lack of efficient special downhole device in the coalbed methane well, especially in the combination of negative pressure and plugging removal. SUMMARY
[0003] The purpose of the present application is to overcome the problems in the prior art, provide a coalbed methane well ultrasonic negative pressure plugging removal device, which can efficiently dredge and remove the plugging of the coalbed methane well.
[0004] The present application provides a coalbed methane well ultrasonic negative pressure plugging removal device, which comprises an inner pipe and an outer pipe arranged coaxially, and further comprises a rotatable working head detachably connected to the front end of the outer pipe, a plurality of negative pressure suction holes and ultrasonic radiation windows are arranged in the side wall of the working head in an annular array; a jet pump assembly is connected to the rear end of the inner pipe, the jet pump assembly comprises a throat pipe and a high-pressure fluid inlet, the outlet of the throat pipe is connected to the rear end of the inner pipe, the working head, the inner pipe and the throat pipe form a negative pressure cavity; an ultrasonic assembly comprises an ultrasonic generator and a variable amplitude rod, the ultrasonic generator is arranged in the outer pipe, the end thereof is connected to the variable amplitude rod, and the radiation end of the variable amplitude rod penetrates into the negative pressure cavity.
[0005] Preferably, the working head comprises a conical head and a first cylindrical segment, the ultrasonic radiation windows are embedded in the conical head, and a plurality of groups of negative pressure suction units are uniformly distributed in the circumferential direction of the first cylindrical segment, each group of negative pressure suction units comprises a support block, the support block is hollow inside, three negative pressure suction holes are arranged on the surface of the support block in a distribution of 120°, and the negative pressure suction holes are in communication with the first cylindrical segment.
[0006] Preferably, the throat pipe comprises a progressive segment, a second cylindrical segment and a diffusion segment which are sequentially welded, the high-pressure fluid inlet is arranged in the side wall of the progressive segment, the diffusion segment is welded with the inner pipe, the diffusion segment is welded with the inner pipe, the high-pressure fluid inlet is connected with an external high-pressure pump, and a transient negative pressure is generated at the second cylindrical segment.
[0007] Preferably, the surface of the ultrasonic radiation window is coated with a coal-repellent coating, the negative pressure suction hole is tilted and arranged at an angle of 45° to 55° with the axis of the inner tube, and axial reinforcement ribs are arranged between adjacent support blocks.
[0008] Preferably, a delivery pipe is provided on the outside of the outer tube, the delivery pipe is connected to the pump body and the high-pressure pump, a connecting ring is provided at the bottom of the cylindrical section, the connecting ring is rotatably connected to the end of the outer tube, the end of the inner tube is sleeved with a fixing ring, the fixing ring is hollow, the connecting ring is rotatably connected to the fixing ring, a plurality of water outlet holes are circumferentially provided on the inner side wall of the fixing ring, a plurality of water inlet holes are provided on the circumferential side of the connecting ring, a plurality of injection heads are obliquely provided on the outside of the connecting ring, and the angle between the axis of the injection head and the axis of the inner tube is 65° to 70°.
[0009] Preferably, an anti-blocking grille is provided on the outside of the negative pressure suction hole.
[0010] Preferably, a drive assembly is provided in the outer tube, and the drive assembly includes a drive motor, a drive gear and a ring gear. One end of the connecting ring passes through the outer tube and is fixedly connected to the ring. The drive motor is vertically fixedly connected in the outer tube, and the rotating end is fixedly connected downward to the drive gear, and the drive gear is engaged with the ring gear.
[0011] Compared with the existing technology, the present invention has the following beneficial effects: the ultrasonic negative pressure unblocking device for coalbed methane wells of the present invention uses an ultrasonic component to directly apply high-frequency mechanical waves to the negative pressure chamber through a horn, causing a micron-level cavitation effect at the interface between coal powder and the crack, thereby peeling off adhesive blockages; a high-pressure fluid is used to form a transient negative pressure at the throat, and the loosened coal powder is efficiently sucked into the inner tube through the negative pressure hole. The two work together to greatly improve the unblocking efficiency and avoid the permeability damage to the reservoir caused by chemical unblocking agents. The annular array design of the rotating working head ensures that the ultrasonic energy covers the near-well area 360°. At the same time, the negative pressure hole, supported by the axial reinforcement ribs, withstands the complex stress of the well without deformation, thereby effectively unblocking the coalbed methane well. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 It is a schematic diagram of the overall two-dimensional structure of the present invention.
[0013] Figure 2 It is a schematic diagram of a partial three-dimensional structure of the present invention.
[0014] Figure 3 It is a schematic diagram of the fixing ring structure of the present invention.
[0015] Figure 4 It is a schematic diagram of the connecting ring structure of the present invention.
[0016] Explanation of the accompanying drawings: 1. Inner tube; 2. Outer tube; 3. Working head; 31. Conical head; 32. First cylindrical section; 4. Negative pressure suction hole; 5. Ultrasonic radiation window; 6. Ultrasonic component; 61. Ultrasonic generator; 62. Amplitude transformer; 621. First-stage cylindrical section; 622. Second-stage transition cone section; 623. Third-stage output section; 7. Jet pump assembly; 71. Throat; 711. Progressive section; 712. Second cylindrical section; 713. Diffusion section; 72. High-pressure fluid inlet; 8. Delivery pipe; 9. Connecting ring; 10. Fixed ring; 11. Water inlet; 12. Water outlet; 13. Spray head; 14. Drive assembly; 141. Drive motor; 142. Drive gear; 143. Ring gear. DETAILED DESCRIPTION
[0017] The following is combined with Figures 1-4 In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.
[0018] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects. "Inside", "outside", "upper", "lower", "far", "near", "front", "back" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. The drawings in the present invention are not drawn strictly according to the actual scale. The specific size and quantity of each structure can be determined according to actual needs. The drawings described in the present invention are only structural schematic diagrams.
[0019] The present invention provides a coalbed methane well ultrasonic negative pressure unblocking device, such as Figures 1-2As shown, it comprises coaxially arranged inner tube 1 and outer tube 2, and further comprises rotatable working head 3, which is detachably connected to the front end of outer tube 2, jet pump assembly 7, which is connected to the rear end of inner tube 1, and annular array of negative pressure suction holes 4 and ultrasonic radiation window 5 are arranged on the side wall of working head 3; jet pump assembly 7 comprises throat pipe 71 and high-pressure fluid inlet 72, the outlet of throat pipe 71 is connected to the rear end of inner tube 1, and working head 3, inner tube 1 and throat pipe 71 form a negative pressure cavity; ultrasonic assembly 6 comprises ultrasonic generator 61 and amplitude transformer 62, ultrasonic generator 61 is arranged in outer tube 2, the end of which is connected to amplitude transformer 62, and the radiation end of amplitude transformer 62 penetrates into the negative pressure cavity.
[0020] In this embodiment, the ultrasonic assembly 6 directly acts on the negative pressure cavity through the amplitude transformer 62 to produce micron-level cavitation effect on the interface between the coal powder and the crack, and to strip the adhesive blockage; the high-pressure fluid forms transient negative pressure at the throat pipe 71, and the loose coal powder is efficiently sucked into the inner tube 1 through the negative pressure hole. The two work together to greatly improve the efficiency of the blockage removal, and avoid the damage of the chemical blockage removal agent to the permeability of the reservoir. The annular array design of the rotating working head 3 ensures that the ultrasonic energy covers 360° of the near wellbore zone, and the negative pressure hole does not deform under the complex stress in the downhole under the support of the axial stiffener, thereby efficiently dredging and removing the blockage of the coalbed methane well.
[0021] Preferably, as shown in Figures 1-2 As shown, working head 3 comprises conical head 31 and first cylindrical section 32, conical head 31 is embedded with ultrasonic radiation window 5, and first cylindrical section 32 is circumferentially and uniformly distributed with several groups of negative pressure suction units, each group of negative pressure suction units comprises a support block, the inside of the support block is hollow, and three negative pressure suction holes 4 are arranged on the surface of the support block in a 120° distribution, and the negative pressure suction holes 4 are in communication with first cylindrical section 32.
[0022] In this embodiment, the conical head 31 reduces the downhole resistance, and the embedded ultrasonic radiation window 5 uses silicon nitride ceramic to improve the sound energy transmission rate. The circumferentially and uniformly distributed support block units of the first cylindrical section 32 form a triple fluid dynamics optimization, the 120° distributed negative pressure holes produce a cyclone effect, which improves the coal powder capture rate, the hollow support block constitutes a secondary booster cavity, which improves the local suction flow rate, and the axial stiffener between adjacent units improves the torsional strength of working head 3, preventing structural failure caused by coal and rock jamming.
[0023] Preferably, as shown in Figures 1-2 As shown, throat pipe 71 comprises progressive section 711, second cylindrical section 712 and diffusion section 713 which are sequentially welded, high-pressure fluid inlet 72 is arranged on the side wall of progressive section 711, diffusion section 713 is welded with inner tube 1, and high-pressure fluid inlet 72 is connected to an external high-pressure pump to generate transient negative pressure at throat pipe 71.
[0024] In this embodiment, the three-section welding structure of the gradual section 711, the second cylindrical section 712 and the diffusion section 713 of the throat pipe 71 realizes fluid energy step conversion, the gradual section 711 accelerates the fluid to the critical flow speed, the second cylindrical section 712 maintains a stable negative pressure field, and the diffusion section 713 recovers kinetic energy to restore pressure; the tangential design of the high-pressure fluid inlet 72 induces vortex flow, generates a continuous low-pressure area on the center line of the throat pipe 71, and cooperates with the downhole pressure sensor to realize dynamic adjustment of the negative pressure value, solving the pulsation problem of the traditional jet pump.
[0025] Preferably, as shown in Figures 1-2 The surface of the ultrasonic radiation window 5 is coated with a coal-repellent coating, the negative pressure suction hole 4 is obliquely arranged at an angle of 45°-55° with the axis of the inner tube 1, and axial reinforcing ribs are arranged between adjacent support blocks.
[0026] In this embodiment, the coal-repellent coating reduces the amount of coal powder adhering to the surface of the ultrasonic radiation window 5. The 45°-55° oblique design of the negative pressure suction hole generates an axial component force, improving the coal powder conveying efficiency compared to a vertical hole. The axial reinforcing ribs form flow guide grooves between the support blocks, preventing hole blockage caused by coal powder accumulation and extending the continuous operation time underground.
[0027] Preferably, as shown in Figures 1-4 The outer side of the outer tube 2 is provided with a delivery pipe 8, the delivery pipe 8 is connected with the pump body, the high-pressure pump is connected, the bottom of the cylindrical section is provided with a connecting ring 9, the connecting ring 9 is rotationally connected to the end of the outer tube 2, the end of the inner tube 1 is sleeved with a fixed ring 10, the fixed ring 10 is hollow, the connecting ring 9 is rotationally connected with the fixed ring 10, a plurality of water outlet holes 12 are circumferentially arranged on the inner side wall of the fixed ring 10, a plurality of water inlet holes 11 are arranged on the circumferential side of the connecting ring 9, a plurality of spray heads 13 are obliquely arranged on the outer side of the connecting ring 9, and the axis of the spray head 13 is at an angle of 65°-70° with the axis of the inner tube 1.
[0028] In this embodiment, the spray system realizes self-cleaning and unblocking cooperation. High-pressure fluid passes through the delivery pipe 8 to the water outlet holes 12 of the fixed ring 10, then passes through the water inlet holes 11 of the connecting ring 9, and finally sprays out from the 65°-70° inclined spray heads 13, forming a reverse spiral flow. This design realizes three functions:
[0029] The spray flow removes coal powder from the surface of the radiation window;
[0030] The rotating working head 3 covers no dead angle for unblocking;
[0031] The spray pressure assists in breaking large particles of coal and rock. The rotating sealing structure improves the pressure-bearing capacity.
[0032] Preferably, a anti-blocking grid is arranged on the outer side of the negative pressure suction hole 4.
[0033] In this embodiment, as shown in Figures 1-2As shown, the anti-blocking grid is made of zirconia ceramic material, forms a physical barrier outside the negative pressure hole, intercepts oversized coal powder particles while maintaining the flow area, and reduces the probability of hole blocking.
[0034] The ultrasonic generator 61 adopts a piezoelectric ceramic stack, and the amplitude transformer 62 adopts a three-stage stepped structure, including a first-stage cylindrical segment 621, a second-stage transition cone segment 622, and a third-stage output segment 623, the end of the third-stage output segment 623 abuts against the ultrasonic radiation window 5, and the piezoelectric ceramic stack is connected with a cable.
[0035] In this embodiment, the piezoelectric ceramic stack generates an amplitude under voltage, and the three-stage amplitude transformer 62 realizes amplitude amplification by multiple times through cross-section mutation. The rigid abutment of the output end and the radiation window reduces the sound energy loss, and the energy utilization rate is improved compared with the conventional amplitude transformer 62.
[0036] Preferably, as Figure 1 As shown, the outer tube 2 is provided with a driving assembly 14, the driving assembly 14 includes a driving motor 141, a driving gear 142 and a ring gear 143, one end of the connecting ring 9 penetrates through the outer tube 2 and is fixedly connected with the ring gear 143, the driving motor 141 is fixedly connected vertically in the outer tube 2, and the rotating end is fixedly connected with the driving gear 142 downward, and the driving gear 142 is engaged with the ring gear 143.
[0037] In this embodiment, the driving motor 141 is external to avoid damage caused by high temperature underground, the ring gear 143 has a low wear rate in the coal powder environment, the rotating speed of the working head 3 is accurately controlled, and different coal rank reservoir requirements are matched.
[0038] The use method of the coalbed methane well ultrasonic negative pressure plugging removal device is as follows:
[0039] High-pressure water flow is injected into the high-pressure fluid inlet 72 of the jet pump assembly 7 through the ground high-pressure pump, the high-speed fluid is accelerated in the gradual section 711 of the throat pipe 71, and a transient negative pressure is formed in the cylindrical section; the negative pressure is transmitted to the negative pressure cavity of the working head 3 through the inner tube 1, so that the coal powder around the wellbore enters the negative pressure suction hole 4 with an inclination angle of 45°-5° under the action of the pressure difference.
[0040] The piezoelectric ceramic stack generates high-frequency vibration under voltage excitation, and the amplitude is amplified through the three-stage amplitude transformer 62; the vibration wave penetrates the ultrasonic radiation window 5 made of silicon nitride material, generates two physical effects in the negative pressure cavity, generates micron-sized bubbles at the interface between the coal powder and the fracture, and collapses to generate a local shock wave, strips the adhesive blockage, excites the inherent frequency of the coal rock, and reduces the bonding force between the coal powder particles.
[0041] The driving motor 141 drives the working head 3 to rotate through the driving gear 142 and the ring gear 143. At the same time, the high-pressure fluid enters the water outlet 12 of the fixed ring 10 through the delivery pipe 8, passes through the water inlet 11 of the connecting ring 9, and is finally ejected from the injection head 13 with an inclination angle of 65° to 70°. The rotating flow field causes the negative pressure suction to cover the well wall, expand the unblocking radius, and the injection pressure directionally impacts the large-particle coal rock, thereby improving the crushing efficiency. The stripped coal powder enters the inner pipe 1 under the drive of the negative pressure, and is discharged from the wellbore after recovering the kinetic energy through the diffusion section 713 of the throat pipe 71.
[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.
Claims
1. An ultrasonic negative pressure unblocking device for coalbed methane wells, comprising an inner tube (1) and an outer tube (2) arranged coaxially, characterized in that: Also includes: A rotatable working head (3) is detachably connected to the front end of the outer tube (2); the front end of the inner tube (1) extends into the working head (3); and a side wall of the working head (3) is provided with an annular array of negative pressure suction holes (4) and an ultrasonic radiation window (5); a jet pump assembly (7) connected to the rear end of the inner tube (1), the jet pump assembly (7) comprising a throat (71) and a high-pressure fluid inlet (72), the throat (71) outlet being connected to the rear end of the inner tube (1), and the working head (3), the inner tube (1) and the throat (71) forming a negative pressure chamber; The ultrasonic component (6) comprises an ultrasonic generator (61) and a horn (62), wherein the ultrasonic generator (61) is arranged in the outer tube (2), and its end is connected to the horn (62), and the radiation end of the horn (62) penetrates into the negative pressure cavity.
2. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 1, characterized in that: The working head (3) includes a conical head (31) and a first cylindrical section (32), wherein the conical head (31) is embedded with the ultrasonic radiation window (5), and the first cylindrical section (32) is circumferentially distributed with a plurality of groups of negative pressure suction units, each group of the negative pressure suction units includes a support block, the interior of the support block is hollow, and the surface of the support block is provided with three negative pressure suction holes (4) distributed at 120 degrees, and the negative pressure suction holes (4) are connected to the first cylindrical section (32).
3. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 1, characterized in that: The throat pipe (71) comprises a progressive section (711), a second cylindrical section (712) and a diffuser section (713) which are welded in sequence; the side wall of the progressive section (711) is provided with the high-pressure fluid inlet (72); the diffuser section (713) is welded to the inner tube (1); the diffuser section (713) is welded to the inner tube (1); the high-pressure fluid inlet (72) is connected to an external high-pressure pump, and a transient negative pressure is generated at the second cylindrical section (712).
4. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 1, characterized in that: The surface of the ultrasonic radiation window (5) is coated with a coal-repellent coating, the negative pressure suction hole (4) is tilted and arranged at an angle of 45° to 55° with the axis of the inner tube (1), and axial reinforcement ribs are arranged between adjacent support blocks.
5. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 1, characterized in that: A delivery pipe (8) is provided on the outside of the outer tube (2), and the delivery pipe (8) is connected to the pump body. A connecting ring (9) is provided at the bottom of the second cylindrical section (712), and the connecting ring (9) is rotatably connected to the end of the outer tube (2). A fixing ring (10) is sleeved on the end of the inner tube (1), and the fixing ring (10) is hollow. The connecting ring (9) is rotatably connected to the fixing ring (10). The inner side wall of the fixing ring (10) is circumferentially provided with a plurality of water outlet holes (12), and the circumferential side of the connecting ring (9) is provided with a plurality of water inlet holes (11). A plurality of injection heads (13) are obliquely provided on the outside of the connecting ring (9), and the angle between the axis of the injection head (13) and the axis of the inner tube (1) is 65° to 70°.
6. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 1, characterized in that: An anti-blocking grille is provided on the outside of the negative pressure suction hole (4).
7. The ultrasonic negative pressure unblocking device for coalbed methane wells according to claim 5, characterized in that: A driving assembly (14) is provided in the outer tube (2), and the driving assembly (14) comprises a driving motor (141), a driving gear (142) and a ring gear (143). One end of the connecting ring (9) passes through the outer tube (2) and is fixedly connected to the ring. The driving motor (141) is vertically fixedly connected to the outer tube (2), and its rotating end is fixedly connected to the driving gear (142) downward. The driving gear (142) is meshed with the ring gear (143).