Adjustable staged hydraulic fracturing device applied to coal mine

Abstract

The invention provides an adjustable staged hydraulic fracturing device applied to a coal mine, and particularly relates to the technical field of underground hydraulic fracturing of coal mines. The device comprises an inclined guide part, a one-way valve, a throttling element and a water injection tubular column, an inlet of the water injection tubular column is connected with water supply equipment through a water pump, and an outlet of the water injection tubular column is connected with an inlet of the throttling element through the rear-end packer; an outlet of the throttling element is connected with an inlet of the one-way valve through the front-end packer, and an outlet of the one-way valve is connected with an inlet of the guide slope. The throttling element at least comprises a unit throttler or the unit throttler and a plurality of detachable throttlers connected with the unit throttler in series. The device is simple in structure and convenient to mount and dismount, and the problem that the hole sealing effect is prone to being affected by various errors during punching is solved by arranging the packer to seal a drilled hole; and by arranging the throttling piece with the adjustable length, different drilling depths can be better adapted.

Description

Technical Field

[0001] The invention patent relates to the technical field of hydraulic fracturing in coal mines, and specifically to an adjustable segmented hydraulic fracturing device used in coal mines. Background Art

[0002] In the process of coal and oil mining, advanced segmented high-pressure hydraulic fracturing technology is often used to force coal seams to rupture, weaken the strength of the fractured coal seams, and prevent impact ground pressure accidents. In addition, water penetrates into the coal seams through new fracture networks, which also has a significant effect on preventing coal and gas outbursts and softening coal seams, thereby achieving the purpose of displacing gas and reducing the concentration of coal dust on the working face, realizing safe and efficient mining of coal mines, and ultimately achieving the maximum economic and social benefits of the coalfield.

[0003] There are many problems in the process of staged high-pressure hydraulic fracturing, especially in the underground coal mine fracturing process, the main problems are in two aspects: one is the sealing problem. The diameter of some boreholes does not meet the design requirements, which seriously affects the sealing quality; the depth of some boreholes does not meet the design requirements, resulting in insufficient sealing and prone to water leakage; the other is the length of the fracturing section. The length of the fracturing section of the existing hydraulic fracturing technology is uncontrollable. If special circumstances occur underground and it is difficult to control the length of the fracturing section, the distance of the fracturing section cannot be adjusted, resulting in poor fracturing effect and inability to effectively fracture the coal seam, which is not conducive to the adjustment and control of the coal mine production site.

[0004] Therefore, it is urgent to solve the problem of how to ensure the sealing quality and the length of the fracturing section are not consistent with the actual situation of the coal mine. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides an adjustable staged hydraulic fracturing device for use in coal mines, and the specific technical scheme is as follows:

[0006] An adjustable segmented hydraulic fracturing device used in coal mines, comprising a guide pipe, a one-way valve, a throttling device and a water injection pipe column; the inlet of the water injection pipe column is connected to a water supply device through a water pump, and the outlet of the water injection pipe column is connected to the inlet of the throttling device through a rear end packer; the outlet of the throttling device is connected to the inlet of the one-way valve through a front end packer, and the outlet of the one-way valve is connected to the inlet of the guide pipe; the throttling device at least comprises a unit throttle or a unit throttle and a plurality of detachable throttles connected in series therewith.

[0007] Preferably, the unit throttle and the detachable throttle have the same structure but different lengths, and both include an upper joint, a core tube, a piston and a lower joint; the inlet of the core tube is connected to the outlet of the lower joint, and the outlet of the core tube is connected to the inlet of the upper joint; the inlet of the lower joint is connected to the outlet of the water injection pipe column or the outlet of the upper joint of an adjacent detachable throttle; the outlet of the upper joint is connected to the inlet of a one-way valve or the inlet of the lower joint of the unit throttle or the inlet of the lower joint of an adjacent detachable throttle; the piston is sleeved on the surface of the core tube near the lower joint, and a water outlet is provided on the side wall of the core tube corresponding to the position of the piston; a spring is sleeved on the outer surface of the core tube, one end of the spring is fixedly connected to the bottom of the upper joint, and the other end of the spring is fixedly connected to the piston; the unit throttle is arranged on the side close to the inclination.

[0008] Preferably, the length of the unit throttle is 0.485m; the length of a plurality of the detachable throttles is 0.1m.

[0009] Preferably, the front-end packer and the rear-end packer have the same structure, both comprising an upper port, a rubber cylinder, a center tube and a lower port; an overflow port is provided on the side wall of the center tube; the inlet of the center tube is connected with the outlet of the lower port, and the outlet of the center tube is connected with the inlet of the upper port; the rubber cylinder is arranged between the upper port and the lower port and wrapped around the outside of the center tube; the two ends of the rubber cylinder are fixedly connected to the upper port and the lower port by clamps.

[0010] Preferably, a plurality of pressure relief holes are provided on the outer surface of the guide bevel; the outer diameter of the guide bevel is larger than the outer diameters of the throttling member and the water injection pipe column.

[0011] Also preferably, the one-way valve is sealed by a steel ball to achieve the opening and closing of the one-way valve.

[0012] Also preferably, sealing rings are provided at the connections between the unit throttle and the plurality of detachable throttles.

[0013] Further preferably, the rubber cylinder has three layers in total, and each layer is made of a rubber-coated stainless steel belt frame.

[0014] Still further preferably, the pressure bearing range of the rubber cylinder is 2-3 MPa.

[0015] More preferably, the number of the detachable throttles is determined according to the actual situation of the coal mine.

[0016] The beneficial effects of the present invention are:

[0017] 1. The present invention has a simple structure and is easy to disassemble and assemble; by setting a throttle with adjustable length, the length of the fracturing section can be adjusted according to the actual coal mine conditions;

[0018] 2. The purpose of sealing the hole is achieved by arranging packers at both ends of the throttling member of the present invention, and the sealing of the hole is not affected by the operation error during drilling;

[0019] 3. Each component in the present invention is made of pressure-resistant and corrosion-resistant materials, which can well withstand the high-pressure water pressure and the corrosion of underground gas, ensuring the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting the specification of this application are used to provide further understanding of this application and do not constitute improper limitations on this application.

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the unit throttle in the present invention;

[0023] Figure 3 is a schematic diagram of a throttling device;

[0024] Figure 4 is a schematic diagram of the structure of the packer;

[0025] In the figure, 1-pipe guide; 2-check valve; 3-front end packer; 4-throttling device; 5-rear end packer; 6-water injection string; 7-upper joint; 8-core tube; 9-spring; 10-water outlet; 11-lower joint; 12-upper port; 13-rubber cylinder; 14-overflow port; 15-center tube; 16-lower port. DETAILED DESCRIPTION

[0026] The specific implementation of an adjustable staged hydraulic fracturing device applied to a coal mine provided by the present invention is further described in conjunction with the accompanying drawings and embodiments.

[0027] like Figure 1 As shown, an adjustable staged hydraulic fracturing device for coal mines includes a deflector 1, a one-way valve 2, a throttling device and a water injection string 6. The inlet of the water injection string 6 is connected to a water supply device through a water pump, the outlet of the water injection string 6 is connected to the inlet of the throttling device 4 through a rear end packer 5, the outlet of the throttling device 4 is connected to the inlet of the one-way valve 2 through a front end packer 3, and the outlet of the one-way valve 2 is connected to the inlet of the deflector 1.

[0028] It is worth noting here that, in order to adapt to high-pressure hydraulic fracturing of different borehole sizes, the throttling device 4 in the present invention includes at least one unit throttling device, or is composed of a unit throttling device and a plurality of detachable throttling devices connected to the unit throttling device in sequence (in this case, the unit throttling device is arranged on a side close to the guide angle 1), such as Figure 3 shown.

[0029] like Figure 2 As shown, the unit throttle and the detachable throttle have the same structure but different lengths, specifically, they include an upper joint 7, a core tube 8, a piston and a lower joint 11; the inlet of the core tube 8 is connected to the outlet of the lower joint 11, and the outlet of the core tube 8 is connected to the inlet of the upper joint 7; the inlet of the lower joint 11 is connected to the outlet of the water injection column 6 or the outlet of the upper joint 7 of the adjacent detachable throttle; the outlet of the upper joint 7 is connected to the inlet of the one-way valve 2 or the inlet of the lower joint 11 of the unit throttle or the inlet of the lower joint 11 of the adjacent detachable throttle. The piston is sleeved on the surface of the core tube 8 near the lower joint 11, and the side wall of the core tube 8 is provided with a water outlet 10 for high-pressure water spraying corresponding to the position of the piston; the outer surface of the core tube 8 is also sleeved with a spring 9, one end of the spring 9 is fixedly connected to the bottom of the upper joint 7, and the other end is fixedly connected to the piston.

[0030] Preferably, the length of the unit throttle is 0.485m; the length of a plurality of the detachable throttles is 0.1m.

[0031] like Figure 4 As shown, the front packer 3 and the rear packer 5 have the same structure, and both include an upper port 12, a rubber tube 13, a central tube 15, and a lower port 16. Specifically, an overflow port 14 is provided on the side wall of the central tube 15; the inlet of the central tube 15 is connected to the outlet of the lower port 16, and the outlet of the central tube 15 is connected to the inlet of the upper port 12; the rubber tube 12 is arranged between the upper port 12 and the lower port 16 and wrapped around the outside of the central tube 15; and the two ends of the rubber tube 13 are fixedly connected to the upper port 12 and the lower port 16 through clamps.

[0032] Preferably, the outer surface of the guide ramp 1 is provided with a plurality of pressure relief holes.

[0033] Further preferably, the outer diameter of the guide bevel 1 is larger than the outer diameters of the throttling device and the water injection pipe column 6. This design of the guide bevel 1 can guide other components when lowering the pipe, and can also prevent the water injection pipe column 6 and other components from scraping against the hole wall, so that the pipeline can be smoothly lowered to the bottom of the hole.

[0034] Further preferably, in order to ensure the sealing of the entire device, sealing rings are provided at the connections between the unit throttle and the plurality of detachable throttles.

[0035] More preferably, the pressure-bearing range of the rubber cylinder 13 is 2-3 MPa; wherein the rubber cylinder 13 has three layers, and each layer is made of a rubber-coated stainless steel belt frame.

[0036] It is worth noting that the components in the present invention are made of pressure-resistant and corrosion-resistant materials, which can well withstand the high-pressure water pressure and the corrosion of underground gas, ensuring the service life of the device. In addition, the connection of the components in the present invention includes but is not limited to other detachable connection methods such as thread connection and threaded connection, and the specific connection relationship is not used as a further limitation of the present invention.

[0037] When in use, first, calculate whether it is necessary to add detachable throttles and the number of detachable throttles required according to the actual size of the coal mine borehole; then, combine the components and push one end of the guide into the borehole until the throttling device is sent to the area to be hydraulically fractured; then, turn on the high-pressure water pump, and pump high-pressure water into the device through the water injection pipe column, and the high-pressure water pushes the steel ball in the one-way valve to the valve outlet for holding the pressure; after that, when the high-pressure water flows through the front and rear end packers, the overflow port on the surface of the central tube discharges water, so that the rubber cylinder is filled with water until the outer wall of the rubber cylinder fits tightly with the hole wall, completing the plugging of the borehole; finally, the piston mounted on the unit throttle or the detachable throttle will drive the piston to move along the flow direction of the high-pressure water and compress the spring due to the water outlet set on the core tube below it. After the water outlet is completely leaked out, the high-pressure water in the device is sprayed onto the hole wall through the water outlet, completing the hydraulic fracturing of the hole wall.

[0038] After the hydraulic fracturing test is completed, the water pump is turned off to release the pressure of the water flow in the device. The steel ball in the one-way valve is detached from its outlet. At the same time, air enters the device from several pressure relief holes on the inclined surface to assist in rapid pressure relief. After the pressure relief is completed, the device can be recovered.

[0039] The present invention has a simple structure and is convenient to install and disassemble. On the one hand, it effectively solves the problem that the sealing effect is easily affected by various errors during drilling, and on the other hand, it can better adapt to different drilling depths.

[0040] In the present invention, the orientation or position relationship indicated by terms such as "upper", "lower", "bottom", "top", etc. is based on the orientation or position relationship shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationship of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limitations on the present invention. Terms such as "connected" and "connected" should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances, and they cannot be understood as limitations on the present invention.

[0041] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An adjustable staged hydraulic fracturing device for coal mines, characterized in that: It includes a guide pipe, a one-way valve, a throttling piece and a water injection string; The inlet of the water injection string is connected to the water supply equipment through a water pump, and the outlet of the water injection string is connected to the inlet of the throttling device through a rear end packer; the outlet of the throttling device is connected to the inlet of the one-way valve through a front end packer, and the outlet of the one-way valve is connected to the inlet of the guide; The throttling device at least includes a unit throttle or a unit throttle and a plurality of detachable throttles connected in series therewith.

2. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: The unit throttle and the detachable throttle have the same structure but different lengths, and both include an upper joint, a core tube, a piston and a lower joint; The inlet of the core tube is connected to the outlet of the lower joint, and the outlet of the core tube is connected to the inlet of the upper joint; The inlet of the lower joint is connected to the outlet of the water injection pipe column or the outlet of the upper joint of the adjacent detachable throttle; The outlet of the upper joint is connected to the inlet of the one-way valve or the inlet of the lower joint of the unit throttle or the inlet of the lower joint of the adjacent detachable throttle; The piston sleeve is arranged on the surface of the core tube near the lower joint, and a water outlet is opened on the side wall of the core tube corresponding to the position of the piston; A spring is sleeved on the outer surface of the core tube, one end of the spring is fixedly connected to the bottom of the upper joint, and the other end of the spring is fixedly connected to the piston; The unit throttle is arranged on a side close to the inclination.

3. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: The length of the unit throttle is 0.485m; the length of some of the detachable throttles is 0.1m.

4. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: The front-end packer and the rear-end packer have the same structure, and both include an upper port, a rubber tube, a central tube and a lower port; An overflow port is provided on the side wall of the central tube; the inlet of the central tube is connected to the outlet of the lower port, and the outlet of the central tube is connected to the inlet of the upper port; The rubber tube is arranged between the upper port and the lower port and wrapped around the outside of the central tube; the two ends of the rubber tube are fixedly connected with the upper port and the lower port through clamps.

5. The adjustable staged hydraulic fracturing device for coal mines according to claim 2, characterized in that: The outer surface of the guide is provided with a plurality of pressure relief holes; The outer diameter of the guide is larger than the outer diameters of the throttling piece and the water injection pipe column.

6. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: The one-way valve is sealed by a steel ball to realize the opening and closing of the one-way valve.

7. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: Sealing rings are arranged at the connection points between the unit throttle and a plurality of detachable throttles.

8. The adjustable staged hydraulic fracturing device for coal mines according to claim 4, characterized in that: The rubber cylinder has three layers in total, and each layer is made of a stainless steel belt frame covered with rubber.

9. The adjustable staged hydraulic fracturing device for coal mines according to claim 8, characterized in that: The pressure bearing range of the rubber cylinder is 2-3Mpa.

10. The adjustable staged hydraulic fracturing device for coal mines according to claim 1, characterized in that: The number of the detachable throttles is determined according to the actual situation of the coal mine.

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