Coal rock layer multi-dimensional hydraulic fracturing pressure relief device

Abstract

The utility model discloses a multidimensional hydraulic fracturing pressure relief device for a coal rock stratum. The multidimensional hydraulic fracturing pressure relief device comprises a water injection device, a three-way water distribution device, a first fracturing pipe, a second fracturing pipe and a third fracturing pipe, the first fracturing pipe, the second fracturing pipe and the third fracturing pipe are different in length, so that the first fracturing pipe, the second fracturing pipe and the third fracturing pipe extend into the drill holes with different lengths respectively, and sealed fracturing spaces with required lengths are formed in the different drill holes; meanwhile, only one water injection device is needed to inject water into the three-way water distribution device, the three-way water distribution device adjusts the opening degree of each water outlet and is combined with the length of each sealed fracturing space, hydraulic fracturing is conducted on different drill holes at the same time, and the water injection pressure and the water injection speed of hydraulic fracturing of the different drill holes can be controlled according to needs; therefore, the working efficiency of fracturing is guaranteed, the fracturing effect can be guaranteed, the occurrence possibility of rock burst is reduced as much as possible, and safe mining of a coal mine is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of coal seam fracturing and permeability enhancement and roof advance pressure relief in underground coal mines, and in particular to a coal rock stratum multi-dimensional hydraulic fracturing pressure relief device. Background Art

[0002] Most of my country's coal seams are characterized by high ground stress and low permeability. The safe and efficient mining of low-permeability coal seams is inseparable from the enhanced fracturing and permeability enhancement of coal seams and the timely collapse of the roof rock layer. If the hard roof rock layer cannot collapse in time after the coal seam is mined, a large amount of gas may accumulate in a large area of ​​suspended roof area, which is very likely to cause gas exceeding the limit in the upper corner. Therefore, hydraulic fracturing technology or deep hole blasting technology is often used to carry out advanced fracturing transformation of coal seams. Among them, hydraulic fracturing technology mainly uses high-pressure water to tensilely destroy coal seams. After the water wedge effect of high-pressure water gradually makes the pore pressure reach the tensile strength of the coal body, it is easy to form stress concentration at the tip of the crack, promote the expansion and extension of the crack, and connect with the original pore crack structure of the coal rock body to form a complex crack network, increase the permeability of the coal body, and destroy the integrity of the roof rock structure.

[0003] At present, after most mines enter deep mining, coal and rock strata all show high stress characteristics, and usually require advanced fracturing of coal and rock strata. However, the structural properties and mechanical conditions of coal and rock strata are inconsistent. If a unified fracturing scheme (i.e. the same water injection pressure and water injection volume) is adopted to hydraulically fracture coal and rock strata at the same time, it may cause waste of resources or bring potential risks of coal body pressure out, which may induce rock burst and lead to serious roof collapse events; and if the fracturing of coal and rock strata is carried out in batches, it will not only reduce work efficiency, but also be unfavorable for the interconnection of fractures.

[0004] Therefore, how to provide a device that can simultaneously fractur e coal seams and rock strata and adopt corresponding fracturing parameters according to the mechanical conditions of the coal seams and rock strata, thereby not only ensuring the working efficiency of fracturing, but also ensuring the effect of fracturing, minimizing the possibility of rock burst and ensuring safe mining of coal mines, is the research direction required by the present utility model. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the utility model provides a coal rock stratum multi-dimensional hydraulic fracturing pressure relief device, which can effectively solve the above-mentioned technical problems.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a multi-dimensional hydraulic fracturing pressure relief device for coal rock formations, including a water injection device, a three-way water distribution device, a first fracturing pipe, a second fracturing pipe and a third fracturing pipe;

[0007] The three-way water distribution device is provided with a water inlet, a first water outlet, a second water outlet and a third water outlet. The water inlet is connected to a water injection device, and water is injected into the three-way water distribution device through the water injection device. The first water outlet is connected to one end of a first fracturing pipe, the second water outlet is connected to one end of a second fracturing pipe, and the third water outlet is connected to one end of a third fracturing pipe. Each water outlet injects high-pressure water into the borehole through each fracturing pipe; pressure gauges and opening regulating valves are installed at the first water outlet, the second water outlet and the third water outlet. The pressure gauges are used to monitor the water pressure at the corresponding water outlet, and the opening regulating valves are used to adjust the water flow rate at the corresponding water outlet;

[0008] The lengths of the first fracturing pipe, the second fracturing pipe and the third fracturing pipe are different, and each fracturing pipe is equipped with a pressure-resistant sealing group, so that the first fracturing pipe, the second fracturing pipe and the third fracturing pipe extend into boreholes of different lengths respectively, and their respective pressure-resistant sealing groups seal the corresponding boreholes to form sealed fracturing spaces of different lengths, and different water pressures are used for fracturing different boreholes during water injection fracturing.

[0009] Furthermore, the opening regulating valve includes a check valve, a measuring rod, an arc-shaped valve and a spring. The arc-shaped valve is installed in the water outlet, and one end of it is hinged to the inner wall of the water outlet, so that the arc-shaped valve can rotate around this end to open or close; the check valve is installed outside the water outlet, and its control rod is threadedly connected to the side wall of the water outlet. By rotating the check valve, the length of one end of the control rod extending into the water outlet can be adjusted. One end of the measuring rod is fixedly connected to the arc-shaped valve, and the other end is in contact with one end of the control rod in the water outlet. Both ends of the spring are connected to the arc-shaped valve and the inner wall of the water outlet respectively. When the length of one end of the control rod extending into the water outlet increases, it can drive the arc-shaped valve to close by pressing on the other end of the measuring rod, and the spring increases the deformation restoring force during the closing process; when the length of one end of the control rod extending into the water outlet decreases, the arc-shaped valve is opened by the deformation restoring force of the spring. Using this structure can ensure the precise control of the water injection flow rate.

[0010] Furthermore, each water outlet of the three-way water distribution device is connected to one end of each fracturing pipe through a high-pressure rubber hose. By setting the high-pressure rubber hose, which is made of flexible material, it is convenient to adjust the angle at which the fracturing pipe extends into the borehole.

[0011] Furthermore, the pressure-resistant sealing group includes two packers and a high-pressure bladder. The high-pressure bladder is located between the two packers, and the maximum pressure resistance of the pressure-resistant sealing group is 5 MPa.

[0012] Furthermore, the water injection device is a high-pressure water injection pump.

[0013] Compared with the prior art, the utility model adopts a water injection device, a three-way water distribution device, a first fracturing tube, a second fracturing tube and a third fracturing tube in combination. Through the different lengths of the first fracturing tube, the second fracturing tube and the third fracturing tube, the first fracturing tube, the second fracturing tube and the third fracturing tube are respectively extended into boreholes of different lengths, and sealed fracturing spaces of required lengths are formed in different boreholes; different boreholes are respectively arranged in different coal and rock formations, and only one water injection device is required to inject water into the three-way water distribution device. The three-way water distribution device adjusts the opening of each water outlet and combines with the length of each sealed fracturing space to achieve hydraulic fracturing of different boreholes at the same time, and can control the water injection pressure and water injection speed of hydraulic fracturing of different boreholes as needed. Therefore, the utility model can adopt corresponding water injection speed and water injection pressure according to the mechanical conditions of the coal seam or rock formation where the borehole is located, thereby not only ensuring the working efficiency of fracturing, but also ensuring the effect of fracturing, reducing the possibility of rock burst as much as possible, and ensuring safe mining of coal mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a construction schematic diagram of the utility model;

[0015] Figure 2 It is a structural schematic diagram of the three-way water distribution device of the utility model when each opening regulating valve is not opened;

[0016] Figure 3 It is a structural schematic diagram of each opening regulating valve in the three-way water distribution device of the utility model when it is partially opened.

[0017] In the figure: 1-coal seam; 2-roof rock layer; 3-bottom rock tunnel; 4-high-pressure water injection pump; 5-three-way water distribution device; 5-1, arc valve, 5-2, meter rod, 5-3, spring, 5-4, check valve, 6-short borehole; 7-medium borehole, 8-long borehole; 9-high-pressure hose; 10-first fracturing pipe; 11-pressure-resistant isolation group. DETAILED DESCRIPTION

[0018] The utility model will be further described below.

[0019] like Figure 1 As shown, the utility model includes a water injection device, a three-way water distribution device 5, a first fracturing pipe 10, a second fracturing pipe and a third fracturing pipe;

[0020] The three-way water distribution device 5 is provided with a water inlet, a first water outlet, a second water outlet and a third water outlet. The water inlet is connected to a water injection device, and water is injected into the three-way water distribution device 5 through the water injection device. The first water outlet is connected to one end of the first fracturing pipe 10, the second water outlet is connected to one end of the second fracturing pipe, and the third water outlet is connected to one end of the third fracturing pipe. Each water outlet injects high-pressure water into the borehole through each fracturing pipe; pressure gauges and opening regulating valves are installed at the first water outlet, the second water outlet and the third water outlet. The pressure gauges are used to monitor the water pressure at the corresponding water outlet, and the opening regulating valves are used to adjust the water flow rate at the corresponding water outlet; each water outlet of the three-way water distribution device is connected to one end of each fracturing pipe through a high-pressure rubber hose 9. By providing the high-pressure rubber hose 9, which is made of a flexible material, it is convenient to adjust the fracturing pipe to extend into boreholes at different angles. The pressure-resistant packer group 11 includes two packers and a high-pressure bladder. The high-pressure bladder is located between the two packers. The maximum pressure resistance of the pressure-resistant packer group 11 is 5 MPa. The water injection device is a high-pressure water injection pump 4.

[0021] The lengths of the first fracturing pipe 10, the second fracturing pipe and the third fracturing pipe are different, and a pressure-resistant packer group 11 is installed on each fracturing pipe. Among them, the first pressure pipe 10 is the shortest and the third fracturing pipe is the longest, so that the first fracturing pipe 10, the second fracturing pipe and the third fracturing pipe extend into boreholes of different lengths respectively. Their respective pressure-resistant packer groups 11 seal the corresponding boreholes to form sealed fracturing spaces of different lengths, and different water pressures are used for fracturing in different boreholes during water injection fracturing.

[0022] As an improvement of the present invention, as Figure 2 and 3 shown, the opening regulating valve includes a check valve 5-4, a counter rod 5-2, an arc-shaped valve 5-1 and a spring 5-3. The arc-shaped valve 5-1 is installed in the water outlet, and one end of it is hinged to the inner wall of the water outlet, so that the arc-shaped valve 5-1 can rotate around this end to open or close; the check valve 5-4 is installed outside the water outlet, and its control rod is threadedly connected to the side wall of the water outlet. By rotating the check valve 5-4, the length of one end of the control rod extending into the water outlet can be adjusted. One end of the counter rod 5-2 is fixedly connected to the arc-shaped valve 5-1, and the other end is in contact with one end of the control rod in the water outlet. Both ends of the spring 5-3 are respectively connected to the arc-shaped valve 5-1 and the inner wall of the water outlet. When the length of one end of the control rod extending into the water outlet increases, it can drive the arc-shaped valve 5-1 to close by pressing on the other end of the counter rod 5-2, and the spring 5-3 increases the deformation restoring force during the closing process; when the length of one end of the control rod extending into the water outlet decreases, the arc-shaped valve 5-1 is opened by the deformation restoring force of the spring 5-3. Using this structure can ensure the accurate control of the water injection flow rate.

[0023] During operation, first install the water injection device and the three-way water distribution device 5 of the present utility model in the floor rock roadway 3, and complete the assembly of each component. Then, drill three holes with different lengths in the required fracturing area. Among them, the short hole 6 is drilled into the coal seam 1, the medium hole 7 is drilled to the coal-rock interface, and the long hole 8 is drilled into the roof rock stratum 2. Then, the first fracturing pipe 10, the second fracturing pipe, and the third fracturing pipe are respectively inserted into the short hole 6, the medium hole 7, and the long hole 8. Then, seal each hole through the corresponding pressure-resistant sealing group 11, so that the sealed fracturing space formed in the short hole 6 is within the coal seam 1, the sealed fracturing space formed in the medium hole 7 is at the coal-rock interface, and the sealed fracturing space formed in the long hole 8 is within the roof rock stratum 2. Then, start the water injection device to inject high-pressure water into the three-way water distribution device 5, and control the opening of the regulating valve at each water outlet to inject different flow rates of water into different holes, thereby realizing the control of the water injection pressure and water injection speed in different holes at the same time. Subsequently, by checking the reading changes of each pressure gauge, the corresponding opening can be adjusted accordingly, so as to realize hydraulic fracturing at different positions at the same time, and the water injection pressure and water injection speed of the hydraulic fracturing at different positions can be controlled according to needs, and finally achieve the fracturing effect required by the coal mine.

[0024] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model.

Claims

1. A multi-dimensional hydraulic fracturing pressure relief device for coal rock formations, characterized in that: It includes a water injection device, a three-way water distribution device, a first fracturing pipe, a second fracturing pipe and a third fracturing pipe; The three-way water distribution device is provided with a water inlet, a first water outlet, a second water outlet and a third water outlet, the water inlet is connected to a water injection device, water is injected into the three-way water distribution device through the water injection device, the first water outlet is connected to one end of the first fracturing pipe, the second water outlet is connected to one end of the second fracturing pipe, the third water outlet is connected to one end of the third fracturing pipe, and each water outlet injects high-pressure water into the borehole through each fracturing pipe; the first water outlet, the second water outlet and the third water outlet are all equipped with a pressure gauge and an opening regulating valve, the pressure gauge is used to monitor the water pressure of the water outlet, and the opening regulating valve is used to adjust the water outlet flow rate of the water outlet; The first fracturing tube, the second fracturing tube and the third fracturing tube have different lengths, and each fracturing tube is equipped with a pressure-resistant sealing group, so that the first fracturing tube, the second fracturing tube and the third fracturing tube are respectively extended into boreholes of different lengths, and each pressure-resistant sealing group seals the borehole in which it is located to form sealed fracturing spaces of different lengths, so that different boreholes can be fractured with different water pressures during water injection fracturing.

2. The coal-rock stratum multi-dimensional hydraulic fracturing pressure relief device according to claim 1 is characterized in that: The opening regulating valve comprises a check valve, a meter rod, an arc valve and a spring. The arc valve is installed in the water outlet, and one end of the arc valve is hinged to the inner wall of the water outlet so that the arc valve can be rotated around the end to open or close. The check valve is installed outside the water outlet, and its control rod is threadedly connected to the side wall of the water outlet. The length of one end of the control rod extending into the water outlet can be adjusted by rotating the check valve. One end of the meter rod is fixedly connected to the arc valve, and the other end contacts one end of the control rod in the water outlet. Two ends of the spring are respectively connected to the arc valve and the inner wall of the water outlet. When the length of one end of the control rod extending into the water outlet increases, it can drive the arc valve to close by applying pressure to the other end of the meter rod, and the spring increases the deformation restoring force during the closing process. When the length of one end of the control rod extending into the water outlet decreases, the arc valve is opened by the deformation restoring force of the spring.

3. The coal-rock stratum multi-dimensional hydraulic fracturing pressure relief device according to claim 1 is characterized in that: Each water outlet of the three-way water distribution device is connected to one end of each fracturing pipe through a high-pressure hose.

4. The coal-rock stratum multi-dimensional hydraulic fracturing pressure relief device according to claim 1, characterized in that: The pressure-resistant sealing group includes two packers and a high-pressure bladder, and the high-pressure bladder is located between the two packers. The maximum pressure resistance strength of the pressure-resistant sealing group is 5 MPa.

5. The coal-rock stratum multi-dimensional hydraulic fracturing pressure relief device according to claim 1, characterized in that: The water injection device is a high-pressure water injection pump.

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