Hydraulic pre-fracturing soundless cracking agent rock breaking method

Abstract

The invention discloses a hydraulic pre-fracturing soundless cracking agent rock breaking method. The method comprises the steps that pre-fracturing drill holes are arranged; a hole packer injects water to seal holes; checking the sealing state of the debugging pipeline; performing water injection pre-fracturing and seam opening; pre-splitting drilling and draining; injecting a soundless cracking agent; waiting for the soundless crushing agent to break the rock; and the hole packer drains water and relieves pressure, and the next cycle is carried out. Presplitting control of the working face roof can be accurately achieved, it is ensured that safe and efficient natural collapse of the goaf roof is achieved, and potential safety hazards caused by goaf roof suspension are effectively weakened. The technical scheme is especially suitable for coping with complex geological conditions that the gate roadway roof rock stratum is hard and the goaf roof is difficult to naturally collapse, and has wide application prospects in roof management in the field of coal mining.

Description

Technical Field

[0001] The present invention relates to the technical field of weakening hard roof and unloading pressure of surrounding rock of high-stress tunnel, and specifically to a hydraulic pre-fracturing soundless crushing agent rock breaking method, which is especially suitable for coping with complex geological conditions in which the rock layer of the top of the drift is highly hard and the top of the goaf is difficult to collapse naturally. Background Art

[0002] In view of the lack of mature experience and cases for safe mining of working faces with water accumulation on both sides, the traditional solutions to the problem of the difficulty of natural collapse of the roof in the initial mining stage of the working face mainly include forced roof caving by blasting before or after mining, water injection weakening method and hydraulic fracturing method. Among them, the blasting method aims to reduce the strength of the roof along the crack direction by pre-constructing a three-dimensional crack network composed of multiple cracks in the target rock layer of the roof, thereby weakening the overall strength of the hard roof and promoting its collapse. Although the blasting method is simple to construct, the current approval process for pyrotechnics is cumbersome, the project volume is large, the cost is high and the safety risk is high. The water injection weakening method is limited in effect and scope of application due to the low solubility of hard rocks such as sandstone and conglomerate, and it is difficult to control accurately. The hydraulic fracturing technology that combines directional long drilling and conventional short drilling to weaken the hard roof also faces many challenges in actual operation, such as high permeability requirements of rocks and serious water pollution problems, which limit the widespread application of hydraulic fracturing technology. Therefore, exploring a new, safe and efficient roof pre-splitting technology has become a key problem that needs to be overcome urgently in the field of coal mining, and it is of great significance to promote the sustainable development of the coal industry. Summary of the invention

[0003] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a hydraulic pre-fracturing soundless cracking agent rock breaking method, which uses the principle of hydraulic fracturing to induce cracks in the roof rock layer in advance, and then injects a soundless cracking agent into the prefabricated cracks to perform secondary rock breaking and cracking on the roof, so that when the mining operation is advanced, the roof cantilever is forced and naturally cut off, effectively pre-cracked the working face roof. Ensure that the goaf roof can collapse smoothly, and significantly reduce the safety risks caused by the suspended roof in the goaf. The entire operation process is simple and easy, providing a strong safety guarantee for advanced pre-cracking operations.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a hydraulic pre-fracturing soundless cracking agent rock breaking method, comprising the following steps:

[0006] 1) Arrangement of pre-splitting drilling holes: construct pre-splitting holes, determine the drilling azimuth, drilling slope and final hole depth, and the final hole faces the Laotang side;

[0007] 2) Double-end sealing of the borehole sealer by water injection; the sealer is arranged at the target fracturing layer, and water is injected to expand the sealer to seal the borehole;

[0008] 3) Check the sealing status of the debugging pipeline; check the grouting pump and pipelines required for grouting;

[0009] 4) Water injection pre-fracturing: Inject high-pressure water into the pre-fractured borehole that has been installed with a sealer and successfully sealed, and use the principle of hydraulic fracturing technology to induce and expand prefabricated cracks in the target rock formation to achieve the expected rock formation fracturing effect;

[0010] 5) Pre-crack drilling and drainage: Perform crack drainage operations to completely remove the high-pressure water remaining inside the prefabricated cracks to ensure that the cracks are in a suitable state for subsequent treatment;

[0011] 6) Prepare the high pressure of the soundless crushing agent; mix the BC-high efficiency soundless crushing agent and water in a ratio of 3:1 and stir to obtain a fluid paste-like slurry;

[0012] 7) injecting a soundless cracking agent and waiting for it to expand and break the rock; injecting the paste-like slurry obtained in step 4) into the pre-splitting borehole and waiting for the soundless cracking agent to expand and break the rock;

[0013] 8) The sealer is depressurized and the next cycle is carried out. After the construction is completed, the sealer is drained and depressurized, and the discharged water flow stops flowing, that is, after the sealer is completely depressurized, the next layer is fracturing and the next cycle begins.

[0014] Preferably, in step 6), 25 kg of BC-high efficiency soundless crushing agent and 8.5 kg of water are poured into a stirring container and stirred evenly to obtain a fluid paste-like slurry.

[0015] Preferably, in step 7), water and the soundless breaker react after 30 minutes after being mixed, so the waiting time for the soundless breaker to react is greater than 30 minutes, and the grouting time requirement must be completed within 30 minutes.

[0016] Preferably, in step 7), when filling the silent crushing agent, it is required to fill in alternate holes, fill one borehole at a time, and do not operate simultaneously. After the borehole protection is filled, the next borehole can be constructed. If a punching hole occurs in a nearby borehole within 10m, the operation will be stopped immediately.

[0017] Preferably, within 5 hours after the soundless crushing agent is loaded into the pre-splitting borehole, protective facilities must be installed at the pre-splitting borehole, and people are not allowed to stay near the hole mouth or look up at the hole mouth to prevent the hole from breaking and injuring people.

[0018] The beneficial effects of the present invention are:

[0019] The present invention is particularly suitable for working faces with hard rock formations on the top of the drift and cantilevered top of the goaf that are not prone to collapse. The present invention requires less water and has ideal viscosity and sand-carrying performance; there is no water lock, no polymer residue, and no clay expansion. After the fracturing operation, only the proppant remains in the formation, causing minimal damage to the formation; compared with other fracturing technologies, this method of pre-hydraulic fracturing and then injecting a silent crushing agent produces longer cracks; after fracturing, no backflow is required and it can be put into production directly. Compared with the existing technology, it has great advantages in both construction and safety, and the crushing agent of the present invention does not belong to dangerous goods. The crushing agent can be mixed with water and injected into the prefabricated borehole through a sealer, without the need for professional work. The present invention is non-toxic, odorless, silent, and vibration-free, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A side view, a front view and a top view of the pre-splitting drilling arrangement of a mining face provided by an embodiment of the present invention;

[0022] Figure 2 Cross-sectional view of drilling and sealing holes for rail transport chute and belt transport chute;

[0023] Figure 3 A diagram of a hydraulic pre-fracturing soundless breaker rock breaking system provided in an embodiment of the present invention.

[0024] Description of reference numerals:

[0025] 1-silent crushing agent filling area; 2-long tube hole sealer injection pipe; 3-hole sealer; 4-short tube hole sealer water injection pipe; 5-transportation chute; 6-mining working face; 7-direct top; 8-basic top; 9-pressure gauge; 10-flow meter; 11-four-way valve; 12-three-way valve; 13-high-pressure pipeline; 14-water tank; 15-silent crushing agent mixing box; 16-high-pressure pump. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] This embodiment provides a hydraulic pre-fracturing soundless cracking agent rock breaking method, comprising the following steps:

[0028] 1) Arrangement of pre-splitting drilling holes: construct a row of pre-splitting holes at a certain distance from the coal wall on the side of the protective coal pillar in the drift, name the drilling hole number S, determine the drilling azimuth and drilling slope according to the actual situation on site, and determine the final hole depth according to the depth of the rock layer and the width of the roadway to ensure that it can penetrate to the basic top, and the final hole faces the old pond side;

[0029] 2) Double-end sealing of the borehole sealer with water injection; before using the high-efficiency silent cracking agent, the borehole should be sealed in advance, and the sealer should be used. It can be placed in the target fracturing layer and then water can be injected to expand the sealer, thereby achieving the purpose of plugging the borehole;

[0030] 3) Check the sealing status of the debugging pipeline; turn on the grouting pump and inject clean water to check the sealing status of the debugging pipeline, and check to make sure that the grouting pump and grouting pipeline are sealed intact without leakage;

[0031] 4) Water injection pre-fracturing;

[0032] High-pressure water is injected into the pre-cracked borehole that has been installed with a sealer and successfully sealed. The principle of hydraulic fracturing technology is used to induce and expand prefabricated cracks in the target rock formation to achieve the expected rock formation fracture effect.

[0033] 5) Pre-splitting drilling drainage;

[0034] Perform crack drainage operations to completely remove the high-pressure water remaining inside the prefabricated cracks and ensure that the cracks are in a suitable state for subsequent processing.

[0035] 6) Prepare high pressure of silent crushing agent; Divide into two groups, one group is responsible for making the proportion of BC-high-efficiency silent crushing agent, pour a whole bag of BC-high-efficiency silent crushing agent (25kg) into the mixing container, and quickly stir about 8.5kg of water (8.5kg of water is weighed in a container on the ground, and the water level of the container is measured. The same container is used to measure the water of the same height underground.) and BC-high-efficiency silent crushing agent in a ratio of 1:3, and stir evenly into a fluid paste-like slurry; The other group is responsible for the perfect docking and debugging of the grouting pump; Because BC-high-efficiency silent crushing agent is corrosive, construction personnel must wear protective glasses and rubber gloves when operating;

[0036] 7) Inject the silent cracking agent and wait for it to expand and break the rock; inject the paste-like slurry obtained in step 4) into the pre-splitting borehole, and wait for the silent cracking agent to expand and break the rock in the silent cracking agent filling area 1; the filling must be completed within 30 minutes, otherwise its fluidity and expansion and cracking effect will be significantly reduced. (Note: If the slurry is stored in the mixing container for too long after adding water for more than 30 minutes, it will spray).

[0037] 8) The sealer is depressurized and the next cycle is carried out. After the construction is completed, the sealer is drained and depressurized, and the discharged water flow stops flowing, that is, after the sealer is completely depressurized, the next layer is fracturing and the next cycle begins.

[0038] Reference Figure 1-Figure 2 , using the above method, combined with the mining face 6 of Henan Energy 110503 as an example, in order to ensure that the suspended roof of the goaf area of ​​the 110503 mining face does not exceed the regulations, it is necessary to construct pre-splitting drilling holes in the 110503 transport chute 5 (belt transport chute, rail transport chute), fill BC-high-efficiency silent crushing agent, weaken the roof, and create cracks in the rock layer of the roof of the transport chute. When the mining is advanced, the cantilever of the roof is cut off by force to achieve the effect of pre-splitting the roof of the working face and ensure that the roof of the goaf collapses smoothly.

[0039] In the pre-splitting drilling arrangement, the top plate pre-splitting holes are constructed using a ZYWL-1200 crawler drilling rig, the drill rod model is Φ42×800mm, and the drill bit is Φ50mm.

[0040] Pre-splitting holes in rail transport drift: A row of pre-splitting holes is constructed at the direct top 7 position 1m (±0.2m) away from the coal wall on the side of the protective coal pillar in the rail transport drift. The first borehole (numbered S) has a borehole azimuth of 272°, a borehole slope of 80°, and a final hole depth of 19m. It must reach the basic top 8, and the final hole faces the Laotang side. From the inside to the outside, a borehole is constructed every 500m, and the azimuth, slope, and final hole depth of each borehole are the same as those of the borehole (numbered S).

[0041] Pre-splitting holes in belt conveyor drift: A row of pre-splitting holes is constructed at the direct top 7 position 1.5m (±0.2m) away from the coal wall on the side of the protective coal pillar in the belt conveyor drift. If the local protective coal pillar is irregular, the drilling holes are kept in a straight line. The first one (numbered X) has a drilling azimuth of 272°, a drilling slope of 80°, and a final hole depth of 19m. It must reach the basic top 8, and the final hole faces the old pond side. From the inside to the outside, a drilling hole is constructed every 300mm-500mm, and the azimuth, slope, and final hole depth of each drilling hole are the same as the drilling hole (numbered X).

[0042] Carry out drilling plugging operation, use the plug to reach the target layer, inject water to expand the plug and plug the pre-fractured borehole. During the water injection fracturing operation, it is necessary to open the main water source switch and the water inlet valve, wait for water to seep out from the top of the rock formation and observe the pressure gauge and flow meter, and after confirming that the fracturing is completed, close the main water pipe switch and open the water release valve to realize the prefabricated fracture water release operation.

[0043] Before the water in the cracks flows out, the silent crushing agent and other materials need to be transported to the work site for mixing. Pour a whole bag of BC-high-efficiency silent crushing agent (25kg) into the mixing container, and quickly mix about 8.5kg of water (8.5kg of water is weighed in a container on the ground, and the water level of the container is measured. The same container is used to measure water at the same height underground.) and BC-high-efficiency silent crushing agent in a ratio of 1:3. After the mixture is evenly mixed into a fluid paste-like slurry, there must be a person in charge on site to direct the operation, and the entire process from mixing the slurry to grouting must be supervised.

[0044] After the pre-splitting drill hole is injected with silent crushing agent, 12# iron wire is used to fix the four corners of the old belt on the top plate steel bar mesh at the pre-splitting drill hole of the top plate for auxiliary protection to prevent the hole from hurting people. The protection time shall not be less than 5 hours, and warning signs shall be hung on site to prohibit personnel from staying in this section. When filling the silent crushing agent, it is required to fill the holes one by one, and do not operate at the same time. After the drill hole protection is filled, the next drill hole can be constructed. If a punching hole occurs in the nearby drill hole within 10m, the operation shall be stopped immediately.

[0045] like Figure 3 As shown, this embodiment also provides a hydraulic pre-fracturing soundless cracking agent rock breaking system, including two high-pressure water pumps 16, the two high-pressure water pumps 16 are respectively connected to the water tank 14 and the soundless cracking agent mixing tank 15;

[0046] The outlets of the water tank 14 and the silent breaker mixing tank 15 are respectively connected to valve ② and valve ① of the four-way valve 11 through the high-pressure pipeline 13. The valve ③ of the four-way valve 11 is connected to the long tube water injection pipe 2 of the hole sealer 3 through the high-pressure pipeline, and the high-pressure pipeline is provided with a pressure gauge 9 and a flow meter 10;

[0047] The last valve of the four-way valve 11 is connected to one of the valves of the three-way valve 12. The other two valves of the three-way valve 12 are valve ④ and valve ⑤. Valve ④ is connected to the short tube water injection pipe 4 of the hole sealer 3 through a high-pressure pipeline, and a pressure gauge 9 and a flow meter 10 are provided on the high-pressure pipeline. Valve ⑤ is connected to the drain pipe through a pipeline.

[0048] This embodiment also provides a method for using a hydraulic pre-fracturing silent breaker rock breaking system, and the specific method is: during the sealing operation, the sealing device 3 is placed at a designated position of the rock formation through a high-pressure steel pipe, the water source is turned on, valves ①, ③, and ⑤ are closed, valves ② and ④ are opened, and the pressure gauge 9 and the flow meter 10 are observed;

[0049] When the pressure increases to the specified pressure, first turn off the main water source switch, then close valve ④, so that the hole sealer 3 can seal the hole normally and complete the sealing operation;

[0050] When entering the hydraulic fracturing phase, the water source main switch and valve ③ need to be reopened, and at the same time, observe whether there is water seepage around the top plate of the rock formation, and continuously monitor the readings of the pressure gauge [9] and flow meter

[10] . After confirming that the fracturing operation is completed, close the water pipe main switch and valve ②, and then open valve ⑤ to release water;

[0051] During high-pressure rock breaking operation with the addition of silent crushing agent 15, it is necessary to open the main water source switch, open valves ① and ③, close valves ②, ④ and ⑤, and observe the pressure gauge 9. When the pressure increases and stabilizes, turn off the main water source switch, close valve ③, wait for the silent crushing agent 15 to act, and observe the effect;

[0052] After the above operation is completed, the water in the hole sealer 3 is released and the hole sealer 3 is withdrawn. During the withdrawal operation, valves ①, ② and ③ need to be closed, and valves ④ and ⑤ need to be opened. When no water flows out of the pipeline at valve ⑤, the hole sealer 3 is withdrawn and the next cycle is carried out.

[0053] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A hydraulic pre-fracturing soundless cracking agent rock breaking method, characterized in that: The following steps are involved: 1) Pre-splitting drilling arrangement; Construct pre-splitting holes, determine the drilling azimuth, drilling slope and final hole depth, and the final hole should face the old pond side; 2) Double-end sealing of the borehole sealer by water injection; the sealer is arranged at the target fracturing layer, and water is injected to expand the sealer to seal the borehole; 3) Check the sealing status of the debugging pipeline; check the grouting pump and pipelines required for grouting; 4) Water injection pre-fracturing: Inject high-pressure water into the pre-fractured borehole that has been installed with a sealer and successfully sealed, and use the principle of hydraulic fracturing technology to induce and expand prefabricated cracks in the target rock formation to achieve the expected rock formation fracturing effect; 5) Pre-crack drilling and drainage: Perform crack drainage operations to completely remove the high-pressure water remaining inside the prefabricated cracks to ensure that the cracks are in a suitable state for subsequent treatment; 6) Prepare the high pressure of the soundless crushing agent; mix the BC-high efficiency soundless crushing agent and water in a ratio of 3:1 and stir to obtain a fluid paste-like slurry; 7) injecting a soundless cracking agent and waiting for it to expand and break the rock; injecting the paste-like slurry obtained in step 4) into the pre-splitting borehole and waiting for the soundless cracking agent to expand and break the rock; 8) The sealer is depressurized and the next cycle is carried out. After the construction is completed, the sealer is drained and depressurized, and the discharged water flow stops flowing, that is, after the sealer is completely depressurized, the next layer is fracturing and the next cycle begins.

2. The method according to claim 1, characterized in that In step 6), 25 kg of BC-high efficiency soundless crushing agent and 8.5 kg of water are poured into a stirring container and stirred evenly to obtain a fluid paste-like slurry.

3. The method according to claim 2, characterized in that In step 7), water and the silent breaker react after 30 minutes after being mixed, so the waiting time for the silent breaker to react is greater than 30 minutes, and the grouting time requirement must be filled within 30 minutes.

4. The method according to claim 3, characterized in that In step 7), when filling the silent crushing agent, it is required to fill the holes in alternate holes, fill one hole at a time, and do not operate at the same time. After the drilling hole protection is filled, the next drilling hole can be constructed. If a punching hole occurs in the drilling hole within 10m nearby, the operation will be stopped immediately.

5. A double-injection double-sealed silent cracking agent high-pressure rock breaking method as claimed in claim 4, characterized in that: Within 5 hours after the silent crushing agent is loaded into the pre-splitting drill hole, protective facilities must be set up at the pre-splitting drill hole. People are not allowed to stay near the hole mouth or look up at the hole mouth to prevent the hole from bursting and injuring people.

6. A hydraulic pre-fracturing soundless cracking agent rock breaking system, characterized in that: It includes two high-pressure water pumps 16, which are respectively connected to the water tank 14 and the silent crushing agent mixing tank 15; The outlets of the water tank 14 and the silent breaker mixing tank 15 are respectively connected to valve ② and valve ① of the four-way valve 11 through the high-pressure pipeline 13. The valve ③ of the four-way valve 11 is connected to the long tube water injection pipe 2 of the hole sealer 3 through the high-pressure pipeline, and the high-pressure pipeline is provided with a pressure gauge 9 and a flow meter 10; The last valve of the four-way valve 11 is connected to one of the valves of the three-way valve 12. The other two valves of the three-way valve 12 are valve ④ and valve ⑤. Valve ④ is connected to the short tube water injection pipe 4 of the hole sealer 3 through a high-pressure pipeline, and a pressure gauge 9 and a flow meter 10 are provided on the high-pressure pipeline. Valve ⑤ is connected to the drain pipe through a pipeline.

7. A method for using the hydraulic pre-fracturing soundless cracking agent rock breaking system as described in claim 6, characterized in that: The specific method is as follows: during the sealing operation, the sealing device 3 is placed at the designated position of the rock formation through a high-pressure steel pipe, the water source is turned on, valves ①, ③, and ⑤ are closed, valves ② and ④ are opened, and the pressure gauge 9 and the flow meter 10 are observed; When the pressure increases to the specified pressure, first turn off the main water source switch, then close valve ④, so that the hole sealer 3 can seal the hole normally and complete the sealing operation; When entering the hydraulic fracturing phase, the water source main switch and valve ③ need to be reopened, and at the same time, observe whether there is water seepage around the top plate of the rock formation, and continuously monitor the readings of the pressure gauge [9] and flow meter [10]. After confirming that the fracturing operation is completed, close the water pipe main switch and valve ②, and then open valve ⑤ to release water; During high-pressure rock breaking operation with the addition of silent crushing agent 15, it is necessary to open the main water source switch, open valves ① and ③, close valves ②, ④ and ⑤, and observe the pressure gauge 9. When the pressure increases and stabilizes, turn off the main water source switch, close valve ③, wait for the silent crushing agent 15 to act, and observe the effect; After the above operation is completed, the water in the hole sealer 3 is released and the hole sealer 3 is withdrawn. During the withdrawal operation, valves ①, ② and ③ need to be closed, and valves ④ and ⑤ need to be opened. When no water flows out of the pipeline at valve ⑤, the hole sealer 3 is withdrawn and the next cycle is carried out.

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