A method for coupling silent breaker with hydraulic fracturing to direct rock breaking

Abstract

A kind of silent breaker and water pressure coupling directional rock breaking method, first, according to the need of directional fracturing, design the scheme of fracturing rock mass, then drill hole in rock mass;Directional cutting seam silent breaking device is placed into drill hole, and the orientation of cutting seam hole is adjusted, so that the orientation of cutting seam hole is aligned with the direction of the need of directional fracturing;The water required for the reaction of silent breaking agent is injected into drill hole by hole sealer;After water injection is completed, hole sealer is sealed, internal silent breaking agent is expanded and fractured to form directional crack;After directional crack is formed, water is injected into drill hole again, and hydraulic fracturing is carried out;After hydraulic fracturing is completed, cutting seam rate is calculated, if cutting seam rate reaches 90%, the rock breaking and fracturing of this time is completed, otherwise, rock breaking is carried out again until cutting seam rate meets the requirements.The invention controls the expansion force direction of silent breaking agent by using directional tube, forms directional crack, and on this basis, uses hydraulic fracturing technology to expand the crack range generated by silent breaking agent, realizes directional cutting seam of rock.

Description

Technical Field

[0001] This invention relates to a rock breaking method, specifically a directional rock breaking method that couples a silent fracturing agent with hydraulic fracturing, belonging to the field of directional rock breaking technology for coal and rock masses. Background Technology

[0002] Silent rock-breaking agents are a safe, simple, non-toxic, vibration-free, and long-lasting method of rock breaking, suitable for addressing engineering problems where explosive blasting is ineffective and challenging. However, silent rock-breaking agents suffer from poor control over the direction of rock fracturing and low expansion force, making it difficult to achieve the desired rock fracturing effect under certain conditions, and they are also challenging to solve engineering problems requiring directional fracturing.

[0003] Hydraulic fracturing technology is highly effective in fracturing rock masses. It can control the fracturing effect and direction according to different boreholes and water pressure output. However, the actual fracturing effect is greatly affected by in-situ stress. Furthermore, when directional fracturing is required, the borehole needs to be slotted, which is difficult to operate and has a limited range of application. Summary of the Invention

[0004] The purpose of this invention is to provide a method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing. By using a directional pipe to control the direction of the expansion force of the silent fracturing agent, directional cracks are formed. Furthermore, hydraulic fracturing technology is used to expand the range of cracks generated by the silent fracturing agent, thereby achieving directional cutting of the rock.

[0005] To achieve the above objectives, the present invention provides a method for directional rock breaking coupled with a silent fracturing agent and hydraulic fracturing, comprising the following steps:

[0006] ① Based on the requirements of directional fracturing, design a fracturing scheme for the rock mass, including parameters such as borehole size, borehole spacing, and single-hole charge amount, and then drill holes in the rock mass;

[0007] ② Insert the directional cutting silent crushing device into the borehole and adjust the orientation of the cutting hole so that it is aligned with the direction of directional cracking required.

[0008] ③ Inject the water required for the silent fracturing agent reaction into the borehole through the sealing device;

[0009] ④ After water injection is completed, the sealing device is sealed and the internal silent fracturing agent is allowed to expand and fracture to form directional cracks. Specifically, the silent fracturing agent expands in volume after reacting with water, generating expansion pressure on the surrounding rock around the borehole. Under the action of the directional tube, the compressive stress generated by the expansion and compression of the silent fracturing agent is redistributed, changing from random direction and discontinuous pressure to fixed direction and consistent compressive stress.

[0010] ⑤ After the directional fractures are formed, water is injected into the borehole again through the fracturing water injection pipe connected to the sealing device to carry out hydraulic fracturing;

[0011] ⑥ After hydraulic fracturing is completed, remove the fracturing equipment and the sealing device together, check the borehole and calculate the cutting rate. If the cutting rate reaches 90%, the rock breaking and fracturing is completed. If the cutting rate is less than 90%, repeat steps ②-⑤ to break the rock again until the cutting rate meets the requirements.

[0012] The directional cutting silent crushing device used in step ② of the present invention includes a directional tube, cutting holes, and a silent crushing agent. Two rows of cutting holes are symmetrically distributed along the axis on the tube wall of the directional tube, and the line connecting the symmetrical cutting holes passes through the center of the cross-section of the tube. The silent crushing agent is filled in the directional tube.

[0013] The silent destructive agent of the present invention can be placed in a directional tube after being moistened and wait for the reaction to begin, or it can be placed in a directional tube in a dry state and then water is injected into the directional tube to allow the silent destructive agent to react with water.

[0014] The formula for calculating the kerf ratio in this invention is as follows:

[0015] Cutting ratio = Crack length / (Length of borehole with directional pipe section × 2).

[0016] The silent fracturing agent of this invention is composed of quicklime (CaO) and inorganic compounds (SO3, Fe2O3, MgO, SiO2, Al2O3, etc.). When the silent fracturing agent reacts with water to generate calcium hydroxide, it releases a large amount of heat and increases in volume by 2-4 times. Since the drilling space is fixed, an expansion force of 30-100 MPa will be generated in the constrained space. When the stress generated exceeds the tensile strength of the rock, the rock will fracture.

[0017] The hydraulic fracturing technology in step ⑤ of this invention directly utilizes the cracks generated by the directional cutting of the silent fracturing agent as the starting point of directional hydraulic fracturing, without the need for directional cutting again; the silent fracturing agent plays the role of proppant in the hydraulic fracturing process, supporting the formation of cracks while the unreacted expansion agent continues to expand, compressing the crack surface within the directional crack.

[0018] The directional tube used in this invention has a PVC tube body.

[0019] Compared with the prior art, the directional cutting technology of the silent fracturing agent used in this invention mainly relies on the directional tube of the silent fracturing agent. By using the directional tube to control the direction of the expansion force of the silent fracturing agent, directional cracks are formed. When the silent fracturing agent reacts with water, its volume expands, generating expansion pressure on the surrounding rock of the borehole. Under the action of the directional tube, the compressive stress generated by the expansion and compression of the silent fracturing agent is redistributed, changing from random direction and discontinuous pressure to fixed direction and uniform compressive stress. When the directional pipe is subjected to expansion force, tensile stress concentration will form at the cut hole, and it will preferentially break into two symmetrical parts from this point. At this time, the directional pipe wall will be subjected to compressive stress uniformly applied to the borehole wall by the silent fracturing agent. The compressive stress direction is perpendicular to the directional direction of the cut hole, which causes tensile stress concentration in the borehole wall in the directional direction. Due to the characteristic that rock is resistant to compression but not to tension, it will first break in this direction and continue to expand under the subsequent expansion and compression of the fracturing agent, forming a large-sized crack, thus achieving directional cutting of the rock. On this basis, hydraulic fracturing technology is used to expand the range of the crack generated by the silent fracturing agent, realizing the directional expansion of the fracturing range. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the directional tube of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the directional slit-cutting silent crushing device of the present invention;

[0022] Figure 3 This is a cross-sectional view of the directional fracturing structure of the silent fracturing agent of the present invention. Figure 2 (AA cross-section view);

[0023] Figure 4 This is a schematic diagram of the directional hydraulic fracturing of the present invention.

[0024] In the diagram: 1. Directional tube, 2. Slit hole, 3. Silent fracturing agent, 4. Drill hole, 5. Sealing device, 6. Lead wire, 7. Fracturing water injection pipe, 8. Hydraulic fracturing power pump. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] A method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing includes the following steps:

[0027] ① Based on the requirements of directional fracturing, design a fracturing scheme for the rock mass, including parameters such as borehole size, borehole spacing, and single-hole charge amount, and then drill 4 holes in the rock mass;

[0028] ② Insert the directional cutting silent crushing device into the borehole 4, and adjust the orientation of the cutting hole 2 so that the orientation of the cutting hole 2 is aligned with the direction of directional cracking required;

[0029] ③ Inject the water required for the reaction of the silent fracturing agent 3 into the borehole 4 through the sealing device 5;

[0030] ④ After water injection is completed, seal the hole sealer 5 and wait for the internal silent fracturing agent to expand and fracture to form directional cracks; specifically: after the silent fracturing agent 3 reacts with water, its volume expands and generates expansion pressure on the surrounding rock of the borehole. Under the action of the directional pipe 1, the compressive stress generated by the expansion and extrusion of the silent fracturing agent is redistributed, changing from random direction and discontinuous pressure to fixed direction and consistent compressive stress.

[0031] ⑤ After the directional fracture is formed, water is injected into the borehole 4 again through the fracturing water injection pipe 7 connected to the sealing device 5. The water injection pressure is provided by the hydraulic fracturing power pump 8 to carry out hydraulic fracturing.

[0032] ⑥ After hydraulic fracturing is completed, remove the fracturing equipment and the sealing device 5 together, inspect the borehole 4 and calculate the cutting rate. The formula for calculating the cutting rate is: Cutting rate = fracture length / (length of the borehole with the directional pipe section × 2). If the cutting rate reaches 90%, the rock breaking and fracturing is completed. If the cutting rate is less than 90%, repeat steps ②-⑤ to break the rock again until the cutting rate meets the requirements.

[0033] like Figure 1 and Figure 2 As shown, the directional cutting silent crushing device of the present invention includes a directional tube 1, cutting holes 2, and a silent crushing agent 3. Two rows of cutting holes 2 are symmetrically distributed along the axis on the tube wall of the directional tube 1, and the line connecting the symmetrical cutting holes 2 passes through the center of the cross-section of the tube body. The silent crushing agent 3 is filled in the directional tube 1. The tube body of the directional tube 1 of the present invention is made of PVC material.

[0034] When the silent fracturing agent of this invention reacts with water to generate calcium hydroxide, it releases a large amount of heat and increases in volume by 2-4 times. Since the drilling space is fixed, an expansion force of 30-100 MPa will be generated in the confined space. When the stress generated exceeds the tensile strength of the rock, the rock will fracture.

[0035] The silent rock-breaking agent 3 of this invention can be placed in the directional tube 1 after being wetted and allowed to react, or it can be placed in the directional tube 1 in a dry state and then water is injected into the directional tube 1 to allow the silent rock-breaking agent to react with water. The silent rock-breaking agent of this invention is composed of quicklime (CaO) and inorganic compounds (SO3, Fe2O3, MgO, SiO2, Al2O3, etc.), which is existing technology. This invention mainly utilizes the fact that the rock-breaking principle of the silent rock-breaking agent changes substantially after reacting with water in the directional tube 1, thereby redistributing the stress. By uniformly distributing the disordered compressive stress on the wall of the directional tube, the compressive stress generated by the rock at the cut hole is concentrated, thereby preferentially causing damage and ultimately forming a two-dimensional directional crack. Specifically, after the silent rock-breaking agent 3 reacts with water, its volume expands, generating expansion pressure on the surrounding rock of the borehole 4. Under the action of the directional tube 1, the compressive stress generated by the expansion and compression of the silent rock-breaking agent 3 is redistributed, changing from random direction and discontinuous pressure to fixed direction and uniform pressure. When the directional tube 1 is subjected to expansion force, tensile stress concentration will form at the slit hole, and it will preferentially break into two symmetrical parts from this point, such as... Figure 3 As shown, at this time, the wall of the directional pipe 1 will be subjected to the compressive stress of the silent fracturing agent 3 uniformly applied to the wall of the borehole 4. At this time, the direction of the compressive stress is perpendicular to the directional direction where the cutting hole is located, so that the borehole wall will generate tensile stress concentration in the directional direction. Due to the characteristic that the rock is resistant to compression but not to tension, it will first break in this direction, and continue to expand under the subsequent expansion and compression of the fracturing agent, forming a large-sized crack, thus realizing the directional cutting of the rock.

[0036] like Figure 4 As shown, the hydraulic fracturing technology of this invention, when combined with directional cutting using a silent fracturing agent, adds two major technical features to the original technology. Firstly, it eliminates the need for further directional fracturing; the fractures generated by the directional cutting using the silent fracturing agent can be directly used as the starting point for directional hydraulic fracturing. Secondly, the expanding agent acts as a proppant during fracturing, supporting the formation of fractures while the unreacted expanding agent continues to expand, compressing the fracture surface within the directional fracture. Conventional hydraulic fracturing exhibits disordered fracture propagation, requiring pre-grooving to create stress concentration points on the borehole wall for directional fracture propagation. However, pre-grooving is difficult, costly, and has limited size, making it difficult to support large-scale directional fracturing of rock. By combining directional cutting with a silent fracturing agent, large-scale directional fracture generation can be achieved, thereby reducing the amount of grooving work and achieving better directional fracturing results. As fracturing water flows into the borehole fracture, the silent fracturing agent 3 in borehole 4 is accompanied by small particles of fracturing agent that enter the fracture along with it. As a proppant, it maintains the fracture's open state. Furthermore, the silent fracturing agent that has not yet fully reacted continues to react after entering the fracture with the fracturing water, further generating expansion pressure on the fracture, expanding the fracture's range, and achieving directional expansion of the fracturing range.

[0037] Existing single-silent fracturing agent directional cutting technology has a cutting hole spacing of 0.4-0.5m, and water pressure fracturing alone cannot control the crack direction. By using the silent fracturing agent of this invention combined with water pressure fracturing, the cutting hole spacing can reach 4-6m, which greatly improves cutting efficiency, reduces production costs, and can precisely control the crack propagation direction.

[0038] An embodiment of the present invention is given.

[0039] Taking a certain working face in a mine as an example, the coal seam in this working face is located in the middle of the Taiyuan Formation, with a vitreous luster, and is a scarce coking coal. The coal seam dip angle of the working face is 0-8°, with an average slope of 4°. The roadway cross-section is rectangular, 3.1m high, 4.6m long, and 1644m long. This roadway, after being cut off at the top, will be used as a transport roadway for the next working face. The roof lithology of the cut section above the coal seam is mudstone (0.7m) and fine sandstone (12.8m), with good roof stability; the immediate floor is sandy mudstone, which swells and softens little when exposed to water.

[0040] On the working face, field tests were conducted on top cutting using a single silent fracturing agent, top cutting using a single hydraulic fracturing agent, and top cutting using a combination of the silent fracturing agent and hydraulic fracturing agent of the present invention. Ten boreholes were drilled for each method, with a depth of 9m, an angle of 17°, and a diameter of 48mm. The borehole spacing for the top cutting test using only the silent fracturing agent was 400mm, the borehole spacing for the top cutting using only hydraulic fracturing agent was 4m, and the borehole spacing for the test using the present invention was 4.5m.

[0041] After the experiment, a borehole inspection instrument was used to observe the cracks in the borehole and calculate the cutting rate. The experimental results showed that drilling with only the silent fracturing agent produced only two cracks along the cutting line, which could achieve directional cutting, with an average cutting rate of 81%. Water pressure fracturing alone could not control the crack propagation direction and could not achieve the goal of directional cutting. The silent fracturing agent of this invention coupled with water pressure fracturing to cut the top crack along the pre-crack direction, with a superior directional cutting effect. The average cutting rate of the tested boreholes was 93%, which was 12% higher than that of using the silent fracturing agent alone. The cutting effect was better, and the borehole spacing was 11.25 times higher than that of using the silent fracturing agent alone. This greatly reduced the amount of work and operation time, lowered the cost, and improved the actual production efficiency.

Claims

1. A method for directional rock breaking coupled with a silent fracturing agent and hydraulic fracturing, characterized in that, Includes the following steps: ① Based on the requirements of directional fracturing, design a fracturing scheme for the rock mass, including borehole size, borehole spacing, and single-hole charge parameters, and then drill holes in the rock mass (4). ② Insert the directional cutting silent crushing device into the drill hole (4) and adjust the orientation of the cutting hole (2) so that the orientation of the cutting hole (2) is aligned with the direction of directional cracking required; ③ Inject the water required for the reaction of the silent destructive agent (3) into the borehole (4) through the sealing device (5); ④ After water injection is completed, the sealing device (5) is sealed and the internal silent fracturing agent is allowed to expand and fracture to form directional cracks. Specifically, the silent fracturing agent (3) expands in volume after reacting with water, generating expansion pressure on the surrounding rock around the borehole. Under the action of the directional pipe (1), the compressive stress generated by the expansion and squeezing of the silent fracturing agent is redistributed, changing from random direction and discontinuous pressure to fixed direction and consistent compressive stress. ⑤ After the directional fracture is formed, water is injected into the borehole (4) again through the fracturing water injection pipe (7) connected to the sealing device (5) to carry out hydraulic fracturing; the hydraulic fracturing technology directly uses the fracture generated by the directional cutting of the silent fracturing agent as the starting point of the directional hydraulic fracturing, without the need for grooving and directional fracturing again; the silent fracturing agent plays the role of proppant in the hydraulic fracturing process, and while supporting the formation of the fracture, the expansion agent that has not yet fully reacted will continue to expand, squeezing the fracture surface in the directional fracture; ⑥ After hydraulic fracturing is completed, the fracturing equipment and the sealing device (5) are taken out together. The borehole (4) is inspected and the cutting rate is calculated. If the cutting rate reaches 90%, the rock breaking and fracturing is completed. If the cutting rate is less than 90%, steps ②-⑤ are repeated to break the rock again until the cutting rate meets the requirements.

2. The method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing according to claim 1, characterized in that, The directional cutting silent crushing device includes a directional tube (1), cutting holes (2), and silent crushing agent (3). Two rows of cutting holes (2) are symmetrically distributed along the axis on the wall of the directional tube (1). The line connecting the symmetrical cutting holes (2) passes through the center of the cross-section of the tube body. The silent crushing agent (3) is filled in the directional tube (1).

3. The method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing according to claim 2, characterized in that, After the silent destructive agent (3) is wetted, it is placed in the directional tube (1) and the reaction is allowed to begin. Alternatively, it can be placed in the directional tube (1) in a dry state and then water is injected into the directional tube (1) to allow the silent destructive agent to react with the water.

4. The method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing according to claim 3, characterized in that, The formula for calculating the cut ratio is as follows: Cutting ratio = Crack length / (Length of borehole with directional pipe section × 2).

5. The method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing according to claim 3, characterized in that, Silent fracturing agent is composed of quicklime and inorganic compounds. When the silent fracturing agent reacts with water to produce calcium hydroxide, it releases a large amount of heat and increases in volume by 2-4 times. Since the drilling space is fixed, an expansion force of 30-100 MPa will be generated in the confined space. When the stress generated exceeds the tensile strength of the rock, the rock will fracture.

6. The method for directional rock breaking coupled with silent fracturing agent and hydraulic fracturing according to claim 3, characterized in that, The tube body of the directional tube (1) is made of PVC.

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