Mining double-liquid cooperative pressure injection permeability increasing method

Abstract

The invention belongs to the technical field of coal mine safety, and particularly relates to a mining double-liquid cooperation pressure injection permeability increasing method which comprises the following steps of drill hole arrangement, medicament preparation and device installation, acidification pressure injection permeability increasing, carbon dioxide phase change blasting permeability increasing, circulating construction and hole sealing extraction. According to the method, a retreating type construction and partitioned pressure injection mode is adopted, and double-liquid cooperative pressure injection is sequentially carried out on all sections in the direction from the hole bottom to the hole opening. And along with advancing of the working face, the construction process is repeated on all the areas in sequence, and a circulating treatment mode of advanced liquid injection, advancing and advanced liquid injection again is formed. Gas concentration monitoring points are arranged on the working face, the average gas concentration change of the working face before and after liquid injection is investigated in real time, and the anti-reflection effect is evaluated. Aiming at the problem of high use risk of CO2 phase change blasting, the technology adopts a scheme of compounding the acidizing anti-reflection agent and the surfactant, is green and environment-friendly, has a remarkable coal permeability transformation effect, is widely applied to mines, and verifies the safety and effectiveness of the coal permeability improvement agent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal mine safety, and particularly relates to a mine dual-liquid synergistic pressure injection permeability improvement method. BACKGROUND

[0002] Gas efficient extraction is a key means to ensure safety production in underground coal mines and to utilize coalbed methane resources. With the gradual deepening of coal mining, the problem of poor permeability has occurred in most mines. Based on the existing conditions, the mining enterprises mostly apply hydraulic permeability improvement measures such as hydraulic punching, hydraulic slotting, hydraulic cavitation and hydraulic fracturing. However, after the coal seam is subjected to the hydraulic permeability improvement measures and the water is discharged, the residual water will adhere to the capillary pores in the coal body and block the desorption of gas in the coal, that is, the water lock effect, which results in that the gas extraction effect is good in the early stage after the hydraulic pressure relief and permeability improvement, but the gas extraction is seriously attenuated in the middle and late stages due to the closure of the cracks in the coal, which affects the exploitation and utilization of coalbed methane. Meanwhile, for the coal seam extraction boreholes with a depth of more than 100 m, the boreholes are simply divided into one permeability improvement section for implementing the permeability improvement measures such as hydraulic fracturing once, and the effect is not obvious, but the implementation of the permeability improvement measures multiple times has the disadvantages of frequent hole sealing, complicated on-site construction, long cycle and the like.

[0003] In view of this, the present application provides a mine dual-liquid synergistic pressure injection permeability improvement method to solve the above problems. SUMMARY

[0004] In order to solve the above problems in the prior art, the present application provides a mine dual-liquid synergistic pressure injection permeability improvement method, which comprises the following steps: S1, borehole arrangement: a plurality of dual-liquid synergistic pressure injection permeability improvement boreholes are drilled along the haulage roadway and the track roadway, the hole spacing is 4 m, and two ordinary extraction holes are arranged between each dual-liquid synergistic pressure injection permeability improvement borehole, and the effective section in the dual-liquid synergistic pressure injection permeability improvement borehole is divided into a plurality of sections, and the length of each section is 10-30 m.

[0005] S2, preparation of medicament and installation of device: an acidification permeability improvement agent is prepared, and a packer assembly is pushed into the bottom of the dual-liquid synergistic pressure injection permeability improvement borehole.

[0006] S3, acidification pressure injection permeability improvement: the position of the packer assembly is adjusted, the acidification fracturing section of the packer assembly is matched with the first section of the dual-liquid synergistic pressure injection permeability improvement borehole, a high-pressure pulse pump is started, and the acidification permeability improvement agent is pressure injected into the first section, so that the coal seam is subjected to acidification pressure injection permeability improvement.

[0007] S4, carbon dioxide phase change blasting permeability improvement: the packer assembly is retreated backward, the carbon dioxide phase change blasting section of the packer assembly is matched with the first section, and carbon dioxide phase change blasting permeability improvement is implemented to further strengthen the permeability improvement effect.

[0008] S5, cyclic construction and hole sealing and extraction: repeat steps S3-S4 to complete the double-liquid synergistic pressure injection of the remaining sections; after the construction is completed, the water in the double-liquid synergistic pressure injection hole is emptied, the hole is quickly sealed and pumped, and the gas concentration and flow rate during pumping are monitored and recorded.

[0009] Preferably, in step S1, after the hole is formed, the orifice 15m and the hole bottom 15m are not subjected to pressure injection to prevent the hole from collapsing due to the permeability improvement measures.

[0010] Preferably, in step S1, the drilling depth is 100-150m, and the hole diameter is 73-113mm.

[0011] Preferably, in step S2, the acidizing permeability enhancer is prepared by mixing and stirring the following raw materials in the proportions by weight: 5% sulfamic acid, 2.5% ammonium hydrogen fluoride, 2% acetic acid, 1% octadecyl trimethyl ammonium chloride, and the rest water.

[0012] Specifically, the sulfamic acid and ammonium hydrogen fluoride can undergo ion exchange to generate hydrofluoric acid, and both the sulfamic acid and the generated hydrofluoric acid can slowly react with the minerals in the coal and are not easy to damage the pores and fissures formed by fracturing, effectively reducing secondary precipitation. In addition, the acidizing permeability enhancer is environmentally friendly and will not cause discomfort to the human body. The organic acid and inorganic acid compound delay the acid etching reaction, and the cationic quaternary ammonium salt surfactant that is effective in acidic solution enhances the wetting effect of the acid solution in the coal body, making the acid solution effectively penetrate into the coal body. It is widely used in the market and has been proven to be harmless to humans and the environment.

[0013] Preferably, in step S2, the packer assembly includes three front, middle, and rear spaced expansion sealing bags and a liquid injection device arranged between the three expansion sealing bags. The section between the two expansion sealing bags located at the front and middle positions is set as a carbon dioxide phase change blasting section, and the section between the two expansion sealing bags located at the middle and rear positions is set as an acidizing fracturing section. The rear end of the packer assembly is connected with a high-pressure sealed water tail.

[0014] Preferably, in step S3, when the water pressure reaches 3MPa, the expansion sealing bag expands to seal the fracturing section of the hole; when the water pressure continues to rise to 5MPa, the liquid injection hole of the liquid injection device opens, and as the water pressure continues to rise to the cracking stage and the crack propagation stage, the pump pressure is maintained between 10MPa and 15MPa, and the fracturing time is maintained for 30min. The high pressure formed by the fracturing section continues to act on the surrounding coal body to cause fracturing damage, and the formed fracture network continuously expands and extends to form a fracture network, thereby realizing acidizing pressure injection permeability improvement.

[0015] Preferably, in step S3, when the water pressure reaches 3MPa, the expansion sealing bag expands and is fixed at the preset position, and after the pressure relief valve is opened, it can move backward to realize continuous construction in the backward direction.

[0016] Preferably, in step S4, the implementation process of the carbon dioxide phase change blasting permeability improvement is as follows: a blasting rod filled with liquid carbon dioxide is inserted into the position of the first section, and the blasting rod at the first section is detonated by increasing the water pressure; during the implementation process, the pressure relief valve is closed, and high-pressure water is pressed into the position of the second section to serve as a temporary hole sealing, preventing carbon dioxide leakage from affecting the permeability improvement effect, and utilizing the displacement displacement effect and phase change blasting of carbon dioxide gas on methane gas to transfer energy radially to the hole wall.

[0017] Specifically, the blasting rod is filled with liquid carbon dioxide, the rod body head is inserted into the hole towards the hole, and the blasting port is preset around the rod body. After the blasting rod is put in, the water pressure in the carbon dioxide phase change blasting section is increased to more than 5MPa, the blasting rod is detonated by increasing the water pressure, and the shock wave and gaseous gas generated by the carbon dioxide phase change are diffused radially around the hole wall in the drilling section. At the same time, the whole section is filled with aqueous solution. The shock wave generated by carbon dioxide blasting is propagated to the surrounding of the hole wall through the aqueous solution as the transmission medium, and the effect is better than that of air medium blasting.

[0018] Preferably, in step S5, the hole sealing is completed by using a two-plugging and one-injection hole sealing device, and the hole sealing length is 15m.

[0019] The beneficial effects of the present application are: (1) Significant permeability improvement effect: chemical acidizing and fracturing and physical phase change blasting cooperate to not only expand the pore by dissolving the coal body mineral with acid liquid, but also promote the crack penetration by phase change shock wave, and cooperate with carbon dioxide gas displacement to significantly improve the coal seam permeability and gas extraction efficiency.

[0020] (2) Solve the "water lock effect": the gas pressure generated by the carbon dioxide phase change accelerates the fracturing fluid to drain water, and the gas displacement effect reduces the water residue, effectively alleviates the "water lock effect", and prolongs the stable period of extraction.

[0021] (3) High construction efficiency: the backward construction does not need to seal the hole frequently, and the multi-section permeability improvement is completed at one time, thereby shortening the construction period.

[0022] (4) Safety and environmental protection: the acidizing fracturing fluid is green and non-toxic, and harmless to human body and environment; the temporary hole sealing by high-pressure water reduces the risk of carbon dioxide leakage and improves the safety of construction.

[0023] (5) Wide application range: suitable for coal seam extraction drilling with a depth of 100m~150m and a hole diameter of 73mm~113mm, especially suitable for deep low-permeability coal seams. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below in conjunction with the drawings and examples.

[0025] Fig. 1A schematic diagram of the mine double-liquid synergistic pressure injection permeability improvement method provided by the present application in specific implementation.

[0026] Fig. 2 A schematic diagram of the mine double-liquid synergistic pressure injection permeability improvement method provided by the present application in implementation of the back-off construction.

[0027] Fig. 3 A planar layout of the drilling position in the present application.

[0028] In the figure: 1. double-liquid synergistic pressure injection permeability improvement drilling, 2. blasting rod, 3. expansion sealing bag, 4. liquid injection hole, 5. pressure relief valve, 6. flow meter, 7. valve, 8. pressure gauge, 9. pulse high-pressure water pump truck. DETAILED DESCRIPTION

[0029] The present application will be clearly described below in combination with the drawings and specific embodiments in the embodiments of the present application, and the description herein is only used to explain the present application, but not as a limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor, any modification, equivalent replacement, improvement, etc. should be included in the protection scope of the present application.

[0030] Embodiment 1 In combination Figs. 1-3 As shown in the figure, the present application provides a mine double-liquid synergistic pressure injection permeability improvement method, which specifically includes the following steps: (1) Drilling arrangement: a plurality of double-liquid synergistic pressure injection permeability improvement drillings 1 are drilled along the transportation roadway and the track roadway, the hole spacing is 4 m, the drilling depth is 100 m~150 m, the hole diameter is 73 mm~113 mm, and each double-liquid synergistic pressure injection permeability improvement drilling is spaced apart from two ordinary extraction holes, the effective section in the double-liquid synergistic pressure injection permeability improvement drilling is divided into a plurality of sections, and the length of each section is 10~30 m; after the drilling is completed, in order to prevent the drilling collapse caused by the permeability improvement measure, the 15 m range around the hole mouth and the hole bottom is not subjected to the pressure injection permeability improvement.

[0031] (2) Preparation of medicament and installation of device: prepare the acidification permeability improvement agent, the acidification permeability improvement agent is prepared by mixing and stirring the following raw materials in proportion by weight: 5% of sulfamic acid, 2.5% of ammonium hydrogen fluoride, 2% of acetic acid, 1% of octadecyl trimethyl ammonium chloride, and the rest is water; then push the packer assembly to the hole bottom of the double-liquid synergistic pressure injection permeability improvement drilling, the packer assembly includes three expansion sealing bags 3 arranged in front, middle and rear intervals, and a liquid injection device arranged between the three expansion sealing bags, the section between the two expansion sealing bags located at the front and middle positions is set as a carbon dioxide phase change blasting section, the section between the two expansion sealing bags located at the middle and rear positions is set as an acidification fracturing section, and the rear end of the packer assembly is connected with a high-pressure sealed water tail.

[0032] It can be understood that the aminosulfonic acid and ammonium hydrogen fluoride can be ion exchanged to generate hydrofluoric acid, and both the aminosulfonic acid and the generated hydrofluoric acid can slowly react with the minerals in the coal and are not easy to destroy the pores and fractures formed by fracturing, thereby effectively reducing the secondary precipitation. In addition, the acidizing permeability enhancer is green and environmentally friendly, does not cause discomfort to the human body, the organic acid and the inorganic acid are compounded to delay the acid corrosion reaction, the cationic quaternary ammonium salt surfactant which is good in the acidic solution is preferably selected to enhance the wetting effect of the acid solution in the coal body, so that the acid solution is effectively immersed into the coal body, and the acid solution is widely used in the market and has been proved to have no harm to the human body and the environment.

[0033] (3) Acidizing and pressure injection of permeability enhancement: adjust the position of the packer assembly, so that the acidizing and fracturing section of the packer assembly corresponds to the first section of the double-liquid synergistic pressure injection and permeability enhancement borehole, start the high-pressure pulse pump, and inject the acidizing and permeability enhancer into the first section. When the water pressure reaches 3 MPa, the inflatable sealing bag expands to seal the fracturing section of the borehole. When the water pressure continues to rise to 5 MPa, the injection hole 4 of the injection device opens. As the water pressure continues to rise to the cracking stage and the crack propagation stage, the pump pressure is maintained between 10 MPa and 15 MPa, and the fracturing time is maintained for 30 min. The high pressure formed by the fracturing section continues to act on the surrounding coal body to cause fracturing damage, and the fracture network formed continues to expand and extend, thereby realizing acidizing and pressure injection of permeability enhancement in the coal seam. When the water pressure reaches 3 MPa, the inflatable sealing bag expands and is fixed at the preset position. After the pressure relief valve is opened, it can move backward, providing convenience for subsequent continuous construction.

[0034] (4) Carbon dioxide phase change blasting for permeability enhancement: back the packer assembly, so that the carbon dioxide phase change blasting section of the packer assembly corresponds to the first section, and insert the blasting rod 2 filled with liquid carbon dioxide into the first section, and increase the water pressure to detonate the blasting rod at the first section. During the implementation process, the pressure relief valve is closed, and high-pressure water is injected into the second section to temporarily seal the hole and prevent carbon dioxide leakage from affecting the permeability enhancement effect. The displacement and displacement effect of carbon dioxide gas on methane gas and the radial energy transfer of phase change blasting to the hole wall further enhance the permeability enhancement effect.

[0035] It can be understood that the blasting rod is filled with liquid carbon dioxide, the head of the rod body is inserted into the hole with the hole mouth, and the blasting port is preset around the rod body. After the blasting rod is inserted, the water pressure in the carbon dioxide phase change blasting section is increased to more than 5 MPa. After the water pressure is increased to detonate the blasting rod, the shock wave and gaseous gas generated by the carbon dioxide phase change diffuse radially around the hole wall in the section. At the same time, the entire section is filled with an aqueous solution. The shock wave generated by carbon dioxide blasting is transmitted to the surrounding hole wall through the aqueous solution as a transmission medium, and the blasting effect is better than that of air medium.

[0036] (5) Cyclic construction and hole sealing and extraction: repeat steps 3~4 to complete the double-liquid synergistic pressure injection permeability improvement in the remaining sections; after the construction is completed, the water in the double-liquid synergistic pressure injection permeability improvement borehole is emptied, and rapid hole sealing and extraction are performed; the hole sealing is completed by using a two-plugging-and-one-annular-sealing packer, the hole sealing length is 15 m, and then the gas extraction concentration and flow rate are monitored and recorded.

[0037] Example 2 The coal seam extraction borehole depth of a certain deep coal mine is 120 m, and the borehole diameter is 94 mm, and the method is used for permeability improvement: (1) Borehole arrangement: the double-liquid synergistic pressure injection permeability improvement boreholes are arranged at an interval of two ordinary extraction boreholes, the borehole spacing is 4 m, the 15 m at the borehole mouth and the 15 m at the borehole bottom are non-permeability improvement sections, and the middle 90 m is divided into three permeability improvement sections according to 30 m; (2) Acidizing permeability improvement agent preparation and device installation: 5% aminosulfonic acid, 2.5% ammonium hydrogen fluoride, 2% acetic acid, 1% octadecyl trimethyl ammonium chloride and 89.5% water are mixed and stirred according to the weight ratio to prepare an acidizing permeability improvement agent; (3) Device installation: the packer assembly is pushed into the borehole bottom, and the pressure relief valve 5, the flowmeter 6, the valve 7, the pressure gauge 8 and the high-pressure pulse pump are connected, wherein the high-pressure pulse pump is arranged on the pulse high-pressure water pump vehicle 9; (4) First section acidizing pressure injection permeability improvement: the high-pressure pulse pump is started, the water pressure is raised to 3 MPa, the inflatable sealing bag is inflated and sealed, the liquid injection hole is opened at 5 MPa, the pump pressure is maintained at 12 MPa for 30 min, and a fracture network is formed; (5) First section carbon dioxide phase change blasting permeability improvement: the packer assembly is retracted backward, the liquid carbon dioxide blasting rod is inserted, the pressure relief valve is closed, the high-pressure water temporary hole sealing is pressed into the first section, the water pressure of the first section is raised to 6 MPa for detonation, and the shock wave is transmitted through the water solution to strengthen the fracture effect; (6) Repeat steps 4~5 to complete the permeability improvement of the second section and the third section in turn; (7) Hole sealing and extraction: the borehole water is emptied, the two-plugging-and-one-annular-sealing packer is used to complete the 15 m hole sealing, and after the extraction is connected, the monitoring shows that the gas extraction concentration is increased from the original 15% to 42%, the flow rate is stabilized at 0.8 m³ / min, and the stable extraction period is extended by 6 months.

[0038] Example 3 The coal seam extraction borehole depth of a certain mine is 150 m, the borehole diameter is 113 mm, the coal seam contains a large amount of pyrite and carbonate minerals, and the method is used for permeability improvement: (1) The middle effective section 120 m is divided into six permeability improvement sections according to 20 m; (2) The acidizing fracturing pump pressure is maintained at 15 MPa, and the CO2 blasting water pressure is raised to 7 MPa; (3) After construction, the gas extraction concentration is increased from 12% to 38%, the flow is increased from 0.5m 3 / min to 0.9m 3 / min, and there is no extraction attenuation phenomenon caused by "water lock effect".

[0039] In summary, the permeability improvement measure uses physical fracturing and chemical agent injection to improve permeability. High-pressure liquid fractures the coal body, and at the same time, uses acid solution and carbonate minerals in coal, as well as pyrite, hematite, quartz, albite and montmorillonite to react to generate water-soluble inorganic salts to discharge from the coal body. The generated gas, such as carbon dioxide, can replace the gas in the coal. In order to further strengthen the displacement effect of gas on the gas in the coal and reduce the "water lock effect" after fracturing, a carbon dioxide blasting rod is inserted into the borehole after acidizing and fracturing, and water pressure is used to detonate. Liquid carbon dioxide is phase changed into gas to promote the secondary development of the fractures generated by fracturing. In combination with the carbon dioxide generated by the reaction of acidizing fracturing fluid and cementing material in the coal to strengthen the displacement of methane gas in the coal, the excess fracturing fluid is promoted to drain from the coal, and the gas extraction effect is improved.

[0040] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for enhancing permeability through dual-liquid synergistic injection in mining, characterized in that: Includes the following steps: S1, Drilling layout: Drill multiple dual-liquid synergistic injection permeability enhancement boreholes along the transport roadway and track roadway, with each dual-liquid synergistic injection permeability enhancement borehole spaced apart by two ordinary extraction holes. The effective section of the dual-liquid synergistic injection permeability enhancement borehole is divided into several sections, each section being 10~30m in length. S2, Reagent preparation and equipment installation: Prepare acidification and permeability enhancement agent, and push the packer assembly into the bottom of the two-liquid synergistic injection permeability enhancement borehole; S3, Acidizing and Injecting Permeability Enhancement: Adjust the position of the packer assembly so that the acidizing and fracturing section of the packer assembly corresponds to the first section of the dual-liquid synergistic injection permeability enhancement borehole. Start the high-pressure pulse pump to inject acidizing and permeability enhancement agent into the first section to achieve acidizing and injection permeability enhancement of the coal seam. S4, Carbon dioxide phase change blasting penetration enhancement: The packer assembly is retracted so that the carbon dioxide phase change blasting section of the packer assembly corresponds to the first section, and carbon dioxide phase change blasting penetration enhancement is implemented to further enhance the penetration enhancement effect. S5, Cyclic construction and borehole sealing and extraction: Repeat steps S3~S4 to complete the dual-liquid synergistic injection permeability enhancement in the remaining sections; after construction, drain the water inside the dual-liquid synergistic injection permeability enhancement borehole, quickly seal the borehole and start extraction, and monitor and record the extraction gas concentration and flow rate.

2. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S1, after drilling, to prevent the borehole from collapsing due to the permeability enhancement measures, no pressure injection permeability enhancement is performed within 15m of the borehole opening and 15m of the borehole bottom.

3. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S1, the drilling depth is 100m~150m and the hole diameter is 73mm~113mm.

4. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S2, the acidification and penetration enhancer is prepared by mixing and stirring the following raw materials in the following weight ratio: 5% aminosulfonic acid, 2.5% ammonium bifluoride, 2% acetic acid, 1% octadecyltrimethylammonium chloride, and the remainder is water.

5. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S2, the packer assembly includes three expansion sealing bags arranged at intervals in the front, middle and rear, and a liquid injection device disposed between the three expansion sealing bags. The section between the two expansion sealing bags located in the front and middle positions is designated as the carbon dioxide phase change explosion section, and the section between the two expansion sealing bags located in the middle and rear positions is designated as the acid fracturing section. The rear end of the packer assembly is connected to a high-pressure sealing water tail.

6. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S3, when the water pressure reaches 3MPa, the expansion sealing bag expands and seals the fracturing section of the borehole; when the water pressure continues to rise to 5MPa, the injection hole of the injection device is opened. As the water pressure continues to rise to the fracturing initiation stage and the fracture propagation stage, the pump pressure is maintained between 10MPa and 15MPa, and the fracturing time is maintained at 30min. The high pressure formed in the fracturing section continues to act on the surrounding coal body to fracture and destroy it. The resulting fracture network continues to expand, extend and connect, thereby realizing the coal seam acidizing injection permeability enhancement.

7. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 6, characterized in that: In step S3, when the water pressure reaches 3MPa, the expansion sealing bag expands and is fixed in the preset position. After the pressure relief valve is opened, it can be moved backward to realize the backward continuous construction.

8. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S4, the carbon dioxide phase change blasting penetration enhancement process is as follows: a blasting rod filled with liquid carbon dioxide is inserted into the first section, and the water pressure is increased to detonate the blasting rod in the first section; during the process, the pressure relief valve is closed, and high-pressure water is injected into the second section as a temporary seal to prevent carbon dioxide leakage from affecting the penetration enhancement effect. The displacement effect of carbon dioxide gas on methane gas and the phase change blasting transfer energy radially to the borehole wall are utilized.

9. The method for enhancing permeability in mines using dual-liquid synergistic injection according to claim 1, characterized in that: In step S5, the hole is sealed using a two-plug-one-injection hole sealer, with a sealing length of 15m.

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