A splitting-injection integrated hydraulic transformation system and process for low-permeability coal seams

Abstract

The present invention discloses a splitting-injection integrated hydraulic transformation system and process for low-permeability coal seams, and relates to the technical field of water injection for low-permeability coal seams. The system includes a first sleeve, a second sleeve, a transmission system, a splitting system, and a water injection system. The splitting system includes a fixed seat, a central wedge, an outer wedge, a splitting blade, and a spring returner. The central wedge is located below the fixed seat, and the transmission system is used to provide power to the central wedge and apply downward extrusion force; the outer wedges are provided in four groups, evenly spaced and distributed on the periphery of the central wedge, and a splitting blade is provided on the circumference of each outer wedge. When the outer wedges and their splitting blades expand outward, the splitting blades can fit tightly with the coal body to complete the splitting of the coal body. After the splitting is completed, water injection is completed through the water injection system, achieving splitting-water injection integration and improving water injection efficiency. The present invention effectively alleviates technical problems such as low coal seam permeability and low gas extraction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of water injection into low-permeability coal seams, and in particular to a splitting-injection integrated hydraulic transformation system and process applied to low-permeability coal seams. Background Art

[0002] Coal seam water injection is an important measure for coal mine safety production. It has multiple functions, such as reducing dust generation, preventing gas and coal dust explosions, improving coal mining efficiency, inhibiting coal oxidation, reducing gas outbursts, and improving the physical and mechanical properties of coal. It can effectively prevent mine disasters and improve coal mine production efficiency and safety. Existing technologies use hydraulic fracturing technology, which involves injecting liquid into the coal seam using a high-pressure pump. When the injection rate exceeds the absorption rate of the formation, the high pressure generated causes the coal seam to break and form cracks. The cracks are then filled with proppant to increase the permeability of the coal seam. However, the low porosity and low permeability, high ground stress, and complex pore-crack structure of low-permeability coal seams make it easy for them to form a certain thickness of plastic deformation zone on both sides of the fracture during fracturing. This increases the crack propagation pressure and makes it difficult to extend the fracture to a distance. As a result, the fracture is short and wide, making it difficult to achieve the desired production increase.

[0003] The current existing technology mainly focuses on the research of efficient water injection technology for low permeability coal seams. For example, application No. 201810255594.9 discloses an efficient water injection method for low permeability coal seams, whose main steps are: step 1, measuring the mechanical properties of the coal body; step 2, determining the maximum injection pressure of high-pressure gas injection; step 3, drilling the coal body; step 4, uncoupling charging; step 5, reserving a high-pressure pipeline in the borehole; step 6, sealing the borehole; step 7, injecting high-pressure gas; step 8, detonating explosives for pre-cracking and permeability enhancement; step 9, injecting water into the coal seam.

[0004] The above-mentioned prior art solves the technical problems existing in the prior art through the water injection process. In order to solve the problems existing in the current prior art, the present invention intends to provide an integrated splitting-injection hydraulic transformation system, and further limit the transformation process of the system to achieve the effects of improving the permeability and air permeability of the coal seam, improving the gas extraction efficiency, improving the gas flow state, and improving the production efficiency of coal mines. Summary of the Invention

[0005] One of the purposes of the present invention is to provide an integrated splitting-injection hydraulic transformation system for low-permeability coal seams. Through the mutual cooperation of a first sleeve, a second sleeve, a transmission system, a splitting system and a water injection system, water injection can be carried out after splitting is completed. In other words, splitting and water injection can be completed using one set of systems, which is more efficient and improves the water injection efficiency, effectively alleviating technical problems such as low coal seam permeability and low gas extraction efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A splitting-injection integrated hydraulic transformation system for low-permeability coal seams includes a first sleeve, a second sleeve, a transmission system, a splitting system, and a water injection system. The cross-section of the first sleeve is concave, and the second sleeve is located in the concave portion of the first sleeve.

[0008] The transmission system is located in the second sleeve and is connected to an oil pipeline. A pressure indicator is provided on the inner wall of the second sleeve. Four grooves are evenly spaced in an annular direction on the outer wall of the second sleeve, and a fixed lock is provided in each groove.

[0009] The splitting system is located below the concave portion of the first sleeve, and the splitting system includes a fixed seat, a central wedge, an outer wedge, a splitting blade and a spring returner, the fixed seat is located at the bottom of the second sleeve, and the central wedge is located below the fixed seat, and the transmission system is used to provide power to the central wedge and apply a downward extrusion force; the outer wedges are provided with four groups, which are evenly distributed on the periphery of the central wedge, and a splitting blade is provided on the circumference of each outer wedge, the top of each splitting blade is slidably connected to the fixed seat, and the bottom of each splitting blade is connected to the spring returner, and the splitting blade expanded outward is retracted by the spring returner. When the transmission system provides downward extrusion force to the central wedge, the central wedge squeezes the outer wedges around and drives the splitting blades to move outward, and a cavity for expanding the splitting blades outward is provided on the first sleeve corresponding to each splitting blade and opposite to the position of each splitting blade;

[0010] Four ejector pins are provided on the inner wall of the concave portion of the first sleeve, and the four ejector pins are respectively engaged with the fixed lock buckles in the four grooves and locked together;

[0011] The water injection system includes a water injection branch and a water injection pipe column. After the splitting system completes the splitting, the water injection branch is adjusted to a position close to the coal seam, and water is injected through the water injection pipe column.

[0012] The above-mentioned integrated splitting-injection hydraulic transformation system applied to low-permeability coal seams, the transmission system includes a piston and a connecting rod, and the connecting rod is connected to the central wedge block through a perforation in the fixing seat to complete power transmission.

[0013] In the above-mentioned splitting-injection integrated hydraulic transformation system applied to low-permeability coal seams, an oil outlet pipe is provided on the other side of the oil pipeline. When the pressure indicator reading increases significantly, the hydraulic oil is withdrawn through the oil outlet pipe.

[0014] The above-mentioned integrated splitting-injection hydraulic transformation system applied to low-permeability coal seams, the water injection system also includes a water pressure regulator and a protective groove, the protective groove is arranged on the outer wall of the first sleeve, the protective groove is used to place the water injection branch, and the water injection pressure is adjusted by the water pressure regulator.

[0015] In the above-mentioned splitting-injection integrated hydraulic transformation system applied to low-permeability coal seams, each splitting blade is elliptical in shape.

[0016] The above-mentioned splitting-injection integrated hydraulic transformation system applied to low-permeability coal seams is provided with a button on the first sleeve, and the four ejector pins and the four fixed locks are separated by pressing the button.

[0017] Another object of the present invention is to provide a splitting-injection integrated hydraulic reconstruction process for low permeability coal seams, comprising the following steps:

[0018] a. Drill a hole in a coal seam to be split, vertically place the splitting-injection integrated hydraulic transformation system for low-permeability coal seams on the coal body to be split in the hole, and lock the four ejector pins on the first sleeve with the four fixed lock buckles on the second sleeve to complete the placement and seal the hole;

[0019] b. Hydraulic oil is supplied to the transmission system through the oil filling pipeline. The connecting rod of the transmission system presses the central wedge downward, and the central wedge presses the outer wedges toward the surrounding areas, driving the splitting blades to move outward, causing the splitting blades to squeeze the coal seam and thus split the coal body. When the pressure indicator reading increases significantly, indicating that the splitting blades have completely entered the coal body, the hydraulic oil is withdrawn through the oil outlet pipe. The splitting blades are retracted by the spring return device.

[0020] c. After the splitting is completed, place the water injection branch close to the coal seam in the protection groove, inject water through the water injection pipe column, and adjust the water flow through the water pressure regulator;

[0021] d. After the water injection is completed, a splitting-injection integrated hydraulic transformation system applied to low permeability coal seams is retrieved.

[0022] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0023] The present invention proposes an integrated splitting-injection hydraulic reconstruction system for low-permeability coal seams. The system comprises a first sleeve, a second sleeve, a transmission system, a splitting system, and a water injection system. In the splitting system, the interaction between a central wedge, outer wedges, splitting blades, and a spring returner—that is, the transmission force of the transmission system—causes the central wedge to squeeze outward. The outer wedges and their splitting blades then expand outward until the splitting blades tightly adhere to the coal, completing the splitting of the coal. After splitting is complete, water is injected through the water injection system, achieving an integrated splitting-water injection system and improving water injection efficiency.

[0024] The splitting blade is retracted after splitting by a spring returner, which facilitates the subsequent water injection step. The present invention provides an elliptical splitting blade on the outer wedge block, which can achieve efficient splitting of the coal body. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings:

[0026] Figure 1 This is a cross-sectional view of a splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to the present invention;

[0027] In the picture:

[0028] 1. Oil pipeline, 2. Oil outlet pipe, 3. Water injection column, 4. Button, 5. Pressure indicator, 6. Water pressure regulator, 7. Ejector pin, 8. Contraction spring, 9. Groove, 10. Center spring, 11. Piston, 12. Connecting rod, 13. Fixed seat, 14. Water injection branch, 15. Center wedge, 16. Guard groove, 17. Outer wedge, 18. Splitting blade, 19. Spring returner, 20. Curved housing. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0030] It is understood that the connection relationships described in this application refer to direct or indirect connections. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B via one or more other electrical components. For example, A and C can be directly connected, and C can be directly connected to B, so that A and B are connected through C. It is also understood that the description of "A connecting to B" in this application can be a direct connection between A and B or an indirect connection between A and B via one or more other electrical components.

[0031] In the description of this application, unless otherwise specified, " / " means "or". For example, A / B can mean A or B. "And / or" in this document is simply a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0032] In the description of this application, words such as "first" and "second" are used only to distinguish different objects and do not limit the quantity or execution order. In addition, words such as "first" and "second" do not necessarily mean different. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0033] The technical solution of the present application is further described in detail below with reference to the accompanying drawings.

[0034] To address the problem of plastic deformation zones of a certain thickness forming on both sides of the fracture during hydraulic fracturing in low-permeability coal seams, which increases the fracture propagation pressure and makes it difficult to extend the fracture further, resulting in short and wide fractures and difficulty in achieving desired production increases, and to improve water injection effects, the present invention provides an integrated splitting-injection hydraulic reconstruction system for low-permeability coal seams, comprising a first sleeve, a second sleeve, a transmission system, a splitting system, and a water injection system.

[0035] like Figure 1 As shown, the cross section of the first sleeve is in a concave shape, and the second sleeve is located in the concave portion of the first sleeve.

[0036] The second sleeve is mainly used to install the pressure indicator 5 and the transmission system. Specifically: the transmission system is located in the second sleeve, and the transmission system is connected to an oil pipeline 1, through which hydraulic oil is supplied to the transmission system, so that the transmission system works; a pressure indicator 5 is provided on the inner wall of the second sleeve, and the pressure of the system can be measured by the pressure indicator to know whether the splitting of the coal body is completed. Four grooves 9 are evenly spaced in the annular direction of the outer wall of the second sleeve, and a fixed lock is provided in each groove. The fixed lock adopts the press-type spring lock in the prior art, including a contraction spring 8. When the ejector pin 7 is inserted into the fixed lock in each groove, the other end of the ejector pin is inserted into the coal body, and the placement and sealing operation are completed. A button 4 is provided on the first sleeve, and the four ejector pins and the four fixed locks are separated by pressing the button.

[0037] The transmission system includes a piston 11 and a connecting rod 12. The connecting rod is connected to the center wedge block through the through-hole in the fixed seat 13 to complete power transmission. The connecting rod is connected to the center wedge block 15 through the through-hole in the fixed seat to achieve the function of power transmission. A center spring 10 is provided above the piston 11. The oil outlet pipe 2 is connected to the piston, and the hydraulic oil is recovered through the oil outlet pipe 2.

[0038] The first sleeve is composed of an arc-shaped outer shell 20, and the splitting system is located in the first sleeve. The splitting system includes a central wedge 15, four outer wedges 17, an attached elliptical splitting blade 18, and a spring returner 19. The central wedge 15 is placed below the fixed seat 13, and a connecting rod 12 is assembled on its top. The connecting rod 12 passes through the through hole and is connected to the bottom of the piston 11. The four elliptical splitting blades 18 are respectively located around the outer wedge 17, and their upper ends are slidably connected to the fixed seat 13 through a sliding assembly. During operation, first, the four fixed ejectors 7 above the first sleeve are aligned with the four cylindrical grooves 9 with compression springs on the second sleeve, so that the ejectors pass through the grooves and are fixed in the coal body, completing the placement and sealing the hole. Then, the hydraulic oil is transmitted to the upper part of the piston 11 through the oil pipe 1 via the transmission system to provide power, squeezing the piston 11 and controlling the center spring 10, and making the piston 11 pull the connecting rod 12 downward to squeeze the center wedge 15, and the center wedge 15 then squeezes the outer wedges 17 to both sides, so that the outer wedges 17 drive the elliptical splitting blades 18 to squeeze the coal seam to achieve the splitting effect. When the oil pressure rises rapidly, it means that the splitting blades have completely entered the coal body, the oil pressure flow increases, and there is no filling space in the cavity, causing the pressure to increase rapidly. Afterwards, the hydraulic oil is withdrawn through the oil outlet pipe 2, and the splitting blades 18 are withdrawn under the action of the spring returner 19.

[0039] The water injection system includes a water injection pipe column 3, a water pressure regulator 6, a water injection branch 14, and its corresponding protective groove 16. The water injection branch 14 is connected to the fixed seat 13. After the splitting is completed, the upper end of the water injection branch 14 is pressed along the protective groove 16 through the fixed seat 13 to the outer wedge 17, so that the water injection branch 14 is close to the cracked coal seam. Then the water injection pipe column 3 is injected with water. The water flows through the water pressure regulator 6 to adjust the injection pressure, forming a low-pressure, small-flow steady flow water injection, which effectively improves the desorption efficiency of coal seam gas and improves the coal seam gas extraction effect. After the water injection branch is injected, the water injection branch 14 is retracted, and the button 4 above the first sleeve is pressed to activate the retraction spring 8, causing the first sleeve's ejector pin 7 to retract, ending the fixation and retracting the splitting-injection integrated hydraulic transformation system.

[0040] As a preferred embodiment of the present invention, the four groups of outer wedges are evenly spaced and distributed around the periphery of the central wedge. The evenly spaced splitting blades can split the coal body with maximum efficiency.

[0041] In conjunction with the above system, the present invention provides a detailed description of a splitting-injection integrated hydraulic transformation process for low-permeability coal seams, which specifically includes the following steps:

[0042] Step 1: Drill a hole in the coal seam that needs to be split, place the splitting-injection integrated hydraulic transformation system vertically on the coal body that needs to be split, and align the four ejector pins 7 above the first sleeve with the four cylindrical grooves 9 with compression springs on the second sleeve, so that the ejector pins just pass through the grooves and are fixed in the coal body, completing the placement and sealing the hole.

[0043] Step 2: Start the oil filling pipeline. First, the hydraulic oil is introduced into the upper part of the piston 11 through the transmission system through the oil pipe 1 to provide power, squeeze the piston 11 and control the center spring 10, and make the piston 11 pull the connecting rod 12 downward to squeeze the center wedge 15. The center wedge 15 then squeezes the outer wedges 17 around and drives the elliptical splitting blade 18, so that the elliptical splitting blade 18 squeezes the coal seam to achieve the splitting effect. When the number on the pressure indicator 5 continues to rise, it means that the splitting blade 18 has completely entered the coal body, the oil pressure flow increases, and there is no filling space in the cavity, causing the pressure to increase rapidly. The splitting process ends, and the hydraulic oil is withdrawn through the oil outlet pipe 2. The splitting blade 18 is retracted under the action of the spring returner 19;

[0044] Step 3: After the splitting is completed, the water injection branch 14 at the upper end is pressed along the groove through the fixed seat to the outer wedge block, so that the water injection branch 14 is close to the cracked coal seam, and then the water injection pipe column 3 is used to inject water. The water flows through the water pressure regulator 6 to adjust the injection pressure to form a low-pressure, small-flow steady-flow water injection, so as to effectively improve the coal seam gas desorption efficiency and improve the coal seam methane extraction effect.

[0045] Step 4: After the water injection branch 14 is completed, retract the water injection branch 14 and press the button 4 above the first sleeve to activate the contraction spring 8 to retract the ejector pin 7 of the first sleeve, ending the fixation and retracting the splitting-injection integrated hydraulic transformation system.

[0046] Parts not described in the present invention can be implemented by referring to the existing technology.

[0047] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A splitting-injection integrated hydraulic transformation system for low-permeability coal seams, comprising a first sleeve, a second sleeve, a transmission system, a splitting system, and a water injection system, characterized in that: The cross section of the first sleeve is in a concave shape, and the second sleeve is located in the concave portion of the first sleeve; The transmission system is located in the second sleeve and is connected to an oil pipeline. A pressure indicator is provided on the inner wall of the second sleeve. Four grooves are evenly spaced in an annular direction on the outer wall of the second sleeve, and a fixed lock is provided in each groove. The splitting system is located below the concave portion of the first sleeve, and the splitting system includes a fixed seat, a central wedge, an outer wedge, a splitting blade and a spring returner, the fixed seat is located at the bottom of the second sleeve, and the central wedge is located below the fixed seat, and the transmission system is used to provide power to the central wedge and apply a downward extrusion force; the outer wedges are provided with four groups, which are evenly distributed on the periphery of the central wedge, and a splitting blade is provided on the circumference of each outer wedge, the top of each splitting blade is slidably connected to the fixed seat, and the bottom of each splitting blade is connected to the spring returner, and the splitting blade expanded outward is retracted by the spring returner. When the transmission system provides downward extrusion force to the central wedge, the central wedge squeezes the outer wedges around and drives the splitting blades to move outward, and a cavity for expanding the splitting blades outward is provided on the first sleeve corresponding to each splitting blade and opposite to the position of each splitting blade; Four ejector pins are provided on the inner wall of the concave portion of the first sleeve, and the four ejector pins are respectively engaged with the fixed lock buckles in the four grooves and locked together; The water injection system includes a water injection branch and a water injection pipe column. After the splitting system completes the splitting, the water injection branch is adjusted to a position close to the coal seam, and water is injected through the water injection pipe column.

2. The splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to claim 1 is characterized by: The transmission system includes a piston and a connecting rod, and the connecting rod is connected to the central wedge block through a through hole in the fixing seat to complete power transmission.

3. The splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to claim 1 is characterized by: An oil outlet pipe is provided on the other side of the oil pipeline. When the pressure indicator reading increases obviously, the hydraulic oil is withdrawn through the oil outlet pipe.

4. The splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to claim 1 is characterized by: The water injection system also includes a water pressure regulator and a protective groove. The protective groove is arranged on the outer wall of the first sleeve. The water injection branch is placed in the protective groove. The water injection pressure is adjusted by the water pressure regulator.

5. The splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to claim 1 is characterized in that: Each splitting blade is oval in shape.

6. The splitting-injection integrated hydraulic transformation system for low-permeability coal seams according to claim 1 is characterized by: A button is provided on the first sleeve, and the four ejector pins and the four fixing locks are separated by pressing the button.

7. A splitting-injection integrated hydraulic transformation process for low permeability coal seams, characterized in that: It adopts the splitting-injection integrated hydraulic transformation system for low-permeability coal seams as described in any one of claims 1 to 6, and the transformation process includes the following steps: a. Drill a hole in a coal seam to be split, vertically place the splitting-injection integrated hydraulic transformation system for low-permeability coal seams on the coal body to be split in the hole, and lock the four ejector pins on the first sleeve with the four fixed lock buckles on the second sleeve to complete the placement and seal the hole; b. Hydraulic oil is supplied to the transmission system through the oil filling pipeline. The connecting rod of the transmission system presses the central wedge downward, and the central wedge presses the outer wedges toward the surrounding areas and drives the splitting blades to move outward, so that the splitting blades squeeze the coal seam and then split the coal body. When the pressure indicator reading increases significantly, it indicates that the oil pressure flow has increased and the splitting blades have completely entered the coal body, leaving no filling space in the cavity. The splitting process is completed and the hydraulic oil is withdrawn through the oil outlet pipe. The splitting blades are retracted by the spring returner. c. After the splitting is completed, place the water injection branch close to the coal seam in the protection groove, inject water through the water injection pipe column, and adjust the water flow through the water pressure regulator; d. After the water injection is completed, a splitting-injection integrated hydraulic transformation system applied to low permeability coal seams is retrieved.

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