WO2021120701A1 - Coal seam permeability increasing method utilizing cyclic damage of liquid nitrogen cold impact and phase change gas - Google Patents
Coal seam permeability increasing method utilizing cyclic damage of liquid nitrogen cold impact and phase change gas Download PDFInfo
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- WO2021120701A1 WO2021120701A1 PCT/CN2020/113351 CN2020113351W WO2021120701A1 WO 2021120701 A1 WO2021120701 A1 WO 2021120701A1 CN 2020113351 W CN2020113351 W CN 2020113351W WO 2021120701 A1 WO2021120701 A1 WO 2021120701A1
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- liquid nitrogen
- borehole
- gas
- coal seam
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 206
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 101
- 239000007788 liquid Substances 0.000 title claims abstract description 90
- 239000007789 gas Substances 0.000 title claims abstract description 75
- 239000003245 coal Substances 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 16
- 230000008859 change Effects 0.000 title claims abstract description 15
- 230000035699 permeability Effects 0.000 title abstract description 5
- 230000001965 increasing effect Effects 0.000 title abstract description 4
- 125000004122 cyclic group Chemical group 0.000 title abstract 2
- 238000002347 injection Methods 0.000 claims abstract description 31
- 239000007924 injection Substances 0.000 claims abstract description 31
- 239000011435 rock Substances 0.000 claims abstract description 8
- 230000035515 penetration Effects 0.000 claims description 47
- 238000005553 drilling Methods 0.000 claims description 9
- 238000005336 cracking Methods 0.000 claims description 8
- 230000035939 shock Effects 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 4
- 238000001028 reflection method Methods 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 9
- 238000002309 gasification Methods 0.000 description 6
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/06—Valve arrangements for boreholes or wells in wells
- E21B34/08—Valve arrangements for boreholes or wells in wells responsive to flow or pressure of the fluid obtained
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
Definitions
- the invention relates to a coal seam anti-reflection method, in particular to a coal seam anti-reflection method using liquid nitrogen cold shock and phase change gas circulation damage.
- High gas coal seams in my country's coal mines account for 50% to 70%. With the continuous increase of mining depth, coal seam pressure and gas pressure are constantly increasing. The gas problem is becoming more and more serious. Gas explosion and gas outburst have become urgent problems to be solved in mine safety production. .
- the coal seams in my country are mostly high gas and low gas permeability coal seams.
- the existing hydraulic fracturing, hydraulic slitting and pre-splitting blasting methods are not enough to overcome the problems of high gas adsorption and low permeability of coal seams, which makes the current concentration of gas drainage Low, small drainage volume, unsatisfactory drainage effect.
- liquid nitrogen injection has attracted wide attention due to its multiple mechanisms of cold shock, phase change gas expansion force, and water ice phase change frost heave force.
- the existing liquid nitrogen injection methods and patents all have the following significant problems: due to the severe gasification problem in the liquid nitrogen injection process, the liquid nitrogen gas will be expanded to pure nitrogen at 21°C.
- the volume has an expansion rate of 696 times, which means that in the initial stage of liquid nitrogen injection, when the liquid nitrogen has not flowed to the position of the coal body, the borehole has been filled with heated gasified nitrogen and the pressure continues to rise. The pressure in the borehole is very high.
- liquid nitrogen cannot be injected into the borehole quickly and in large quantities. It can only be injected into the borehole at a very small flow rate.
- advantages of liquid nitrogen cannot be used in this way (that is, the impact of the volume expansion during liquid nitrogen gasification and the impact of liquid nitrogen).
- the present invention provides a method for anti-reflection of coal seam using liquid nitrogen cold impact and phase change gas circulation damage, which can ensure the rapid and continuous injection of liquid nitrogen into the through-bed borehole while using liquid nitrogen.
- the cold shock, the expansion pressure of the phase change gas and the frost heave pressure of the moisture in the crack crack the coal, effectively ensuring the anti-reflection effect.
- the technical solution adopted by the present invention is: a coal seam anti-reflection method using liquid nitrogen cold shock and phase change gas circulation damage, the specific steps are:
- A. Set up at least one through-layer borehole in the roadway, which penetrates the rock layer and extends into the coal seam;
- the gas expansion force cracks until the air pressure in the penetration borehole exceeds the set opening threshold, the safety valve is opened to relieve the pressure, and the cycle is repeated, and the coal body is cracked by the gas expansion force for many times until the penetration borehole. After the liquid nitrogen is completely vaporized, the safety valve will no longer be opened; the cracking and anti-reflection process of the penetration drilling is completed;
- the outer surface of the liquid nitrogen injection pipe is wrapped with a heat insulation layer. Reduce the degree of gasification of liquid nitrogen when it is injected through the liquid nitrogen injection pipe into the penetration borehole, and ensure the amount of liquid nitrogen entering the penetration borehole, thereby improving its cracking effect.
- the opening threshold of the safety valve is 30 MPa.
- the present invention firstly drills through the rock layer into the coal seam in the roadway, and uses hydraulic slitting equipment to cut the coal seam at equal intervals and perpendicular to the through-layer borehole. Extend the liquid nitrogen injection pipe and exhaust pipe into the penetration borehole, and seal the rock section of the penetration borehole.
- the exhaust pipe outside the penetration borehole is equipped with a three-way pipe.
- the other two ports of the pipe are respectively connected to two gas pipelines, and the two gas pipelines are respectively equipped with a safety valve and a spherical valve.
- the spherical valve switches and controls the discharge of nitrogen gas when liquid nitrogen is injected into the penetration borehole, so as to control the speed of liquid nitrogen injection into the penetration borehole; when the spherical valve is closed, the threshold value of the safety valve is set, so that the safety valve crosses the hole. The pressure in the borehole is controlled. When the air pressure in the borehole exceeds the threshold, the safety valve is opened to discharge the internal nitrogen to relieve the pressure, and the safety valve is automatically closed after the pressure is relieved.
- This method makes full use of the cold impact of liquid nitrogen, the expansion pressure of the phase change gas, and the frost heave pressure of the residual moisture in the cracks to crack the coal.
- the effective fracture area is wide, especially the expansion pressure of the phase change gas increases with the liquid
- the continuous gasification of nitrogen and the multiple opening of the safety valve enable the air pressure inside the borehole to repeatedly reach the threshold of the safety valve, so that the coal can be repeatedly expanded and damaged, and the fracture network of the coal can be enlarged.
- two gas drainage boreholes were drilled in the surrounding area for gas drainage.
- the invention can ensure the rapid and continuous injection of liquid nitrogen into the penetration borehole, and at the same time use the cold impact of liquid nitrogen, the expansion pressure of the phase change gas and the frost heave pressure of the moisture in the cracks to crack the coal, effectively ensuring the anti-reflection effect .
- Fig. 1 is a schematic diagram of the construction cloth erected body of the present invention.
- Two drill holes 8 are drilled in the roadway, and the two drill holes penetrate the rock layer 3 into the coal seam 1;
- liquid nitrogen injection pipe 6 Connect the other end of the liquid nitrogen injection pipe 6 to the liquid nitrogen pump, start the liquid nitrogen pump and open the spherical valve 4, the liquid nitrogen is injected through the liquid nitrogen injection pipe 6 into the penetration borehole 8 and enters each disc-shaped crack 2 ,
- the heat absorption of liquid nitrogen gas makes the temperature of the coal body drop rapidly, the moisture in the coal body freezes and expands to impose icing expansion force on the coal body to crack; at the same time, the rapid expansion of the gasified nitrogen volume exerts gas expansion force on the coal body to crack.
- the air pressure in the penetration borehole 8 increases rapidly, and the nitrogen gas is discharged from the gas pipeline where the spherical valve 4 is located through the exhaust pipe 9 to the penetration borehole 8, thereby reducing the pressure in the penetration borehole 8 to make the liquid nitrogen continue injection;
- the outer surface of the liquid nitrogen injection pipe 6 is wrapped with a heat insulation layer.
- the degree of gasification of liquid nitrogen when it is injected into the penetration borehole through the liquid nitrogen injection pipe 6 is reduced, and the amount of liquid nitrogen entering the penetration borehole 8 is ensured, thereby improving its cracking effect.
- the opening threshold of the safety valve 5 is 30 MPa.
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
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- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
Disclosed is a coal seam permeability increasing method utilizing cyclic damage of liquid nitrogen cold impact and phase change gas. According to the method, a through-layer borehole (8) running through a rock layer to a coal seam (1) is first drilled in a tunnel; a plurality of cracks perpendicular to the through-layer borehole (8) are cut from the coal seam (1) in the through-layer borehole (8); a liquid nitrogen injection pipe (6) and an exhaust pipe (9) are inserted into the through-layer borehole (8); the exhaust pipe (9) is connected to two gas pipelines respectively provided with a safety valve (5) and a ball valve (4); the ball valve (4) as a switch controls the discharge of nitrogen when liquid nitrogen is injected into the through-layer borehole (8); after the ball valve (4) is closed, a threshold of the safety valve (5) is set so that the safety valve (5) controls the pressure in the through-layer borehole (8); when air pressure in the through-layer borehole (8) exceeds the threshold, the safety valve is opened so that the internal nitrogen is discharged for pressure relief, and the safety valve (5) is automatically closed after pressure relief. The method can ensure rapid and continuous injection of liquid nitrogen into the through-layer borehole (8); moreover, the cold impact of liquid nitrogen, the expansion pressure of phase change gas, and the frost heaving pressure of moisture in the cracks are utilized to crack the coal seam, and the permeability increasing effect is effectively ensured.
Description
本发明涉及一种煤层增透方法，具体是一种利用液氮冷冲击及相变气体循环损伤的煤层增透方法。The invention relates to a coal seam anti-reflection method, in particular to a coal seam anti-reflection method using liquid nitrogen cold shock and phase change gas circulation damage.
我国煤矿高瓦斯煤层占50％～70％，随着开采深度的不断增加，煤层压力及瓦斯压力都在不断地增大，瓦斯问题日趋严重，瓦斯***和瓦斯突出成为矿井安全生产亟待解决的难题。我国煤层又多为高瓦斯低透气性煤层，现有的水力压裂、水力割缝和预裂***等方法已不足以克服煤层瓦斯高吸附、低渗透性的问题，使得目前瓦斯抽采的浓度低、抽放量小，抽采效果不理想。目前液氮注井的方式因其冷冲击、相变气体膨胀力及水冰相变冻胀力的多重作用机制被广泛关注。但实际试验中发现，现有液氮注井方法及专利，均存在以下显著问题：由于液氮注井过程中存在剧烈的气化问题，液氮气化膨胀为21℃的纯氮气后会使其体积具有696倍的膨胀率，这就意味着在液氮注井初期，液氮还未流动到煤***置处时钻孔已被升温气化的氮气充满且气压不断上升，钻孔内气压很快便达到几十个MPa，而液氮因其稳定性差又导致注井泵所能提供的有效压力和流速不高，与钻孔内生成的气体膨胀压相比相差了10倍以上，最终导致液氮无法大量快速的注入钻孔，只能以极小的流量将液氮注入钻孔，但是这样就无法发挥液氮增透的优点(即利用液氮气化时体积膨胀的冲击力及液氮温度低对煤体冻结效果相叠加，而一旦液氮小流量的注入，则会失去快速膨胀差生的冲击力)；同时会大大增加煤层增透所需的时间及无法保证增透效果。High gas coal seams in my country's coal mines account for 50% to 70%. With the continuous increase of mining depth, coal seam pressure and gas pressure are constantly increasing. The gas problem is becoming more and more serious. Gas explosion and gas outburst have become urgent problems to be solved in mine safety production. . The coal seams in my country are mostly high gas and low gas permeability coal seams. The existing hydraulic fracturing, hydraulic slitting and pre-splitting blasting methods are not enough to overcome the problems of high gas adsorption and low permeability of coal seams, which makes the current concentration of gas drainage Low, small drainage volume, unsatisfactory drainage effect. At present, the method of liquid nitrogen injection has attracted wide attention due to its multiple mechanisms of cold shock, phase change gas expansion force, and water ice phase change frost heave force. However, in actual tests, it was found that the existing liquid nitrogen injection methods and patents all have the following significant problems: due to the severe gasification problem in the liquid nitrogen injection process, the liquid nitrogen gas will be expanded to pure nitrogen at 21°C. The volume has an expansion rate of 696 times, which means that in the initial stage of liquid nitrogen injection, when the liquid nitrogen has not flowed to the position of the coal body, the borehole has been filled with heated gasified nitrogen and the pressure continues to rise. The pressure in the borehole is very high. It quickly reaches dozens of MPa, and because of its poor stability, the effective pressure and flow rate provided by the injection pump are not high due to the poor stability of liquid nitrogen, which is more than 10 times different from the expansion pressure of the gas generated in the borehole. Liquid nitrogen cannot be injected into the borehole quickly and in large quantities. It can only be injected into the borehole at a very small flow rate. However, the advantages of liquid nitrogen cannot be used in this way (that is, the impact of the volume expansion during liquid nitrogen gasification and the impact of liquid nitrogen). Low temperature has superimposed effects on coal freezing, and once the small flow of liquid nitrogen is injected, it will lose the impact of rapid expansion and differential generation); at the same time, it will greatly increase the time required for coal seam anti-reflection and cannot guarantee the anti-reflection effect.
发明内容Summary of the invention
针对上述现有技术存在的问题，本发明提供一种利用液氮冷冲击及相变气体循环损伤的煤层增透方法，能保证液氮快速、持续注入穿层钻孔内，同时利用液氮的冷冲击、相变气体的膨胀压力以及裂缝内水分的冻胀压力对煤体进行致裂，有效保证增透效果。In view of the above-mentioned problems in the prior art, the present invention provides a method for anti-reflection of coal seam using liquid nitrogen cold impact and phase change gas circulation damage, which can ensure the rapid and continuous injection of liquid nitrogen into the through-bed borehole while using liquid nitrogen. The cold shock, the expansion pressure of the phase change gas and the frost heave pressure of the moisture in the crack crack the coal, effectively ensuring the anti-reflection effect.
为了实现上述目的，本发明采用的技术方案是：一种利用液氮冷冲击及相变气体循环损伤的煤层增透方法，具体步骤为：In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a coal seam anti-reflection method using liquid nitrogen cold shock and phase change gas circulation damage, the specific steps are:
A、在巷道内打设至少一个穿层钻孔，该钻孔穿过岩层伸入煤层内；A. Set up at least one through-layer borehole in the roadway, which penetrates the rock layer and extends into the coal seam;
B、采用水力割缝设备伸入穿层钻孔达到煤层内，以穿层钻孔为中心沿垂直于穿层钻孔的方向在煤层中等间距的割出多个圆盘形裂缝；用于使液氮注入后与煤体的充分接触，实现更好的致裂增透效果；B. Use hydraulic slitting equipment to penetrate the through-bed drilling to reach the coal seam, and cut multiple disc-shaped cracks in the coal seam at equal intervals in the direction perpendicular to the through-bed drilling centered on the through-bed drilling; Full contact with the coal body after liquid nitrogen injection to achieve better cracking and anti-reflection effects;
C、将液氮注入管一端和排气管一端伸入穿层钻孔达到煤层内，然后对液氮注入管和排气管 与穿层钻孔岩层段进行密封；排气管另一端连通三通管，三通管另外两口分别连接两个气体管路；两个气体管路上分别装有安全阀和球形阀门；C. Extend one end of the liquid nitrogen injection pipe and one end of the exhaust pipe into the penetration borehole to reach the coal seam, and then seal the liquid nitrogen injection pipe and the exhaust pipe with the strata section of the penetration borehole; the other end of the exhaust pipe is connected to three Through pipe, the other two ports of the three-way pipe are respectively connected to two gas pipelines; the two gas pipelines are respectively equipped with safety valves and spherical valves;
D、将液氮注入管另一端与液氮泵连接，启动液氮泵并开启球形阀门，液氮经过液氮注入管注入穿层钻孔，并进入各个圆盘形裂缝内，液氮气化吸热使煤体温度快速降低，煤体内的水分结冰膨胀对煤体施加结冰膨胀力致裂；同时气化后的氮气体积快速膨胀对煤体施加气体膨胀力致裂，穿层钻孔内的气压快速增大，氮气经过排气管从球形阀门所处的气体管路排出穿层钻孔，从而降低穿层钻孔内的气压使液氮内持续注入；D. Connect the other end of the liquid nitrogen injection pipe to the liquid nitrogen pump, start the liquid nitrogen pump and open the spherical valve. The liquid nitrogen is injected into the through-layer borehole through the liquid nitrogen injection pipe, and enters the disc-shaped cracks, and the liquid nitrogen is absorbed. The heat causes the temperature of the coal body to decrease rapidly, and the water in the coal body freezes and expands to impose icing expansion force on the coal body to crack; at the same time, the gasified nitrogen volume rapidly expands to impose gas expansion force on the coal body to crack, and penetrate the borehole. The air pressure increases rapidly, and nitrogen is discharged from the gas pipeline where the spherical valve is located through the exhaust pipe to the penetration borehole, thereby reducing the air pressure in the penetration borehole so that the liquid nitrogen is continuously injected;
E、液氮持续注入至球形阀门所处的气体管路有液氮流出时，停止液氮泵并关闭球形阀门，设定安全阀的开启阈值，液氮在穿层钻孔内持续气化膨胀，对煤体施加气体膨胀力致裂，当穿层钻孔内的气压超过设定的开启阈值，则安全阀开启，此时穿层钻孔内的氮气从安全阀所处的气体管路排出穿层钻孔，从而使穿层钻孔内部的气压降低，当气压低于设定的开启阈值后安全阀关闭，此时液氮在穿层钻孔内持续气化膨胀，对煤体再次施加气体膨胀力致裂，直至穿层钻孔内的气压超过设定的开启阈值，则安全阀开启卸压，如此循环重复，对煤体多次进行气体膨胀力致裂，直至穿层钻孔内的液氮完全气化后安全阀不再开启；完成穿层钻孔的致裂增透过程；E. When liquid nitrogen is continuously injected into the gas pipeline where the spherical valve is located, when liquid nitrogen flows out, stop the liquid nitrogen pump and close the spherical valve, set the opening threshold of the safety valve, and the liquid nitrogen continues to vaporize and expand in the borehole. , Apply gas expansion force to the coal to crack. When the air pressure in the borehole exceeds the set opening threshold, the safety valve opens. At this time, the nitrogen in the borehole is discharged from the gas pipeline where the safety valve is located. Drill through the strata to reduce the air pressure inside the borehole. When the air pressure is lower than the set opening threshold, the safety valve will be closed. At this time, the liquid nitrogen will continue to gasify and expand in the drill through the strata, and apply again to the coal. The gas expansion force cracks until the air pressure in the penetration borehole exceeds the set opening threshold, the safety valve is opened to relieve the pressure, and the cycle is repeated, and the coal body is cracked by the gas expansion force for many times until the penetration borehole. After the liquid nitrogen is completely vaporized, the safety valve will no longer be opened; the cracking and anti-reflection process of the penetration drilling is completed;
F、在穿层钻孔两侧向煤层打设两个瓦斯抽采钻孔、且两个瓦斯抽采钻孔均穿过各个圆盘形裂缝；最后通过两个瓦斯抽采钻孔对煤层进行瓦斯抽采；F. Two gas drainage boreholes are drilled into the coal seam on both sides of the penetration borehole, and the two gas drainage boreholes pass through each disc-shaped crack; finally, the coal seam is carried out through two gas drainage boreholes Gas drainage
G、完成该处的瓦斯抽采后，间隔一定距离在巷道另一位置重复步骤A至F，进行该位置的煤层增透及瓦斯抽采，如此循环，直至完成整个巷道的煤层增透及瓦斯抽采。G. After completing the gas drainage at this location, repeat steps A to F at another location in the roadway at a certain distance to perform the coal seam penetration enhancement and gas drainage at this location, and so on, until the entire roadway is completed. Drain.
进一步，所述液氮注入管的外表面包裹隔热层。降低液氮在经过液氮注入管注入穿层钻孔时的气化程度，保证进入穿层钻孔内的液氮量，从而提高其致裂效果。Further, the outer surface of the liquid nitrogen injection pipe is wrapped with a heat insulation layer. Reduce the degree of gasification of liquid nitrogen when it is injected through the liquid nitrogen injection pipe into the penetration borehole, and ensure the amount of liquid nitrogen entering the penetration borehole, thereby improving its cracking effect.
进一步，所述安全阀的开启阈值为30MPa。Further, the opening threshold of the safety valve is 30 MPa.
与现有技术相比，本发明首先在巷道中穿过岩石层向煤层打设一个穿层钻孔，利用水力割缝设备在穿层钻孔内将煤层等间距割出垂直于穿层钻孔的多个裂缝，将液氮注入管和排气管伸入穿层钻孔，并对穿层钻孔的岩层段进行封口，处于穿层钻孔外部的排气管装有三通管，三通管另外两口分别连接两个气体管路，两个气体管路上分别装有安全阀和球形阀门。其中球形阀门对液氮注入穿层钻孔时排放氮气进行开关控制，从而能控制液氮注入穿层钻孔的速度；当球形阀门关闭后，设定安全阀的阈值，从而使安全阀对穿层钻孔内的压力进行控制，每当穿层钻孔内的气压超过阈值后则安全阀开启，使内部的氮气排出卸压，并且卸压后安全阀自动关闭。该方法充分利用了液氮的冷冲击、相变气体的膨胀压力以及裂缝内残留水分的冻胀压力对煤体进行致裂，有效致裂面积广，尤其是相变气体的膨胀压力随着液氮的持续气化及安全阀的多次开启，使得穿层钻孔 内部的气压能够反复达到安全阀的阈值，因此可以对煤体进行反复地膨胀损伤，扩大煤体的裂隙网络。致裂结束时，在周边打两个瓦斯抽采钻孔进行瓦斯抽采。本发明能保证液氮快速、持续注入穿层钻孔内，同时利用液氮的冷冲击、相变气体的膨胀压力以及裂缝内水分的冻胀压力对煤体进行致裂，有效保证增透效果。Compared with the prior art, the present invention firstly drills through the rock layer into the coal seam in the roadway, and uses hydraulic slitting equipment to cut the coal seam at equal intervals and perpendicular to the through-layer borehole. Extend the liquid nitrogen injection pipe and exhaust pipe into the penetration borehole, and seal the rock section of the penetration borehole. The exhaust pipe outside the penetration borehole is equipped with a three-way pipe. The other two ports of the pipe are respectively connected to two gas pipelines, and the two gas pipelines are respectively equipped with a safety valve and a spherical valve. Among them, the spherical valve switches and controls the discharge of nitrogen gas when liquid nitrogen is injected into the penetration borehole, so as to control the speed of liquid nitrogen injection into the penetration borehole; when the spherical valve is closed, the threshold value of the safety valve is set, so that the safety valve crosses the hole. The pressure in the borehole is controlled. When the air pressure in the borehole exceeds the threshold, the safety valve is opened to discharge the internal nitrogen to relieve the pressure, and the safety valve is automatically closed after the pressure is relieved. This method makes full use of the cold impact of liquid nitrogen, the expansion pressure of the phase change gas, and the frost heave pressure of the residual moisture in the cracks to crack the coal. The effective fracture area is wide, especially the expansion pressure of the phase change gas increases with the liquid The continuous gasification of nitrogen and the multiple opening of the safety valve enable the air pressure inside the borehole to repeatedly reach the threshold of the safety valve, so that the coal can be repeatedly expanded and damaged, and the fracture network of the coal can be enlarged. At the end of the fracture, two gas drainage boreholes were drilled in the surrounding area for gas drainage. The invention can ensure the rapid and continuous injection of liquid nitrogen into the penetration borehole, and at the same time use the cold impact of liquid nitrogen, the expansion pressure of the phase change gas and the frost heave pressure of the moisture in the cracks to crack the coal, effectively ensuring the anti-reflection effect .
图1是本发明的施工布设立体示意图。Fig. 1 is a schematic diagram of the construction cloth erected body of the present invention.
图中：1、煤层，2、圆盘形裂缝，3、岩层，4、球形阀门，5、安全阀，6、液氮注入管，7、瓦斯抽采孔，8、穿层钻孔，9、排气管。In the picture: 1. Coal seam, 2. Disc-shaped crack, 3. Rock formation, 4. Spherical valve, 5. Safety valve, 6. Liquid nitrogen injection pipe, 7. Gas drainage hole, 8. Cross-layer drilling, 9. ,exhaust pipe.
下面将对本发明作进一步说明。The present invention will be further explained below.
如图1所示，本发明的具体步骤为：As shown in Figure 1, the specific steps of the present invention are:
A、在巷道内打设两个穿层钻孔8，两个钻孔穿过岩层3伸入煤层1内；A. Two drill holes 8 are drilled in the roadway, and the two drill holes penetrate the rock layer 3 into the coal seam 1;
B、采用水力割缝设备伸入穿层钻孔8达到煤层1内，以穿层钻孔8为中心沿垂直于穿层钻孔8的方向在煤层1中等间距的割出多个圆盘形裂缝2；用于使液氮注入后与煤体的充分接触，实现更好的致裂增透效果；B. Use hydraulic slitting equipment to extend the penetration borehole 8 into the coal seam 1, and cut out a plurality of discs in the coal seam 1 at medium intervals in the direction perpendicular to the penetration borehole 8 with the penetration borehole 8 as the center. Crack 2; it is used to make full contact with the coal body after the liquid nitrogen is injected, so as to achieve a better effect of cracking and anti-reflection;
C、将液氮注入管6一端和排气管9一端伸入穿层钻孔8达到煤层内，然后对液氮注入管和排气管9与穿层钻孔8岩层段进行密封；排气管9另一端连通三通管，三通管另外两口分别连接两个气体管路；两个气体管路上分别装有安全阀5和球形阀门4；C. Extend one end of the liquid nitrogen injection pipe 6 and the exhaust pipe 9 into the penetration borehole 8 to reach the coal seam, and then seal the rock interval between the liquid nitrogen injection pipe and the exhaust pipe 9 and the penetration borehole 8; The other end of the pipe 9 is connected to a three-way pipe, and the other two ports of the three-way pipe are respectively connected to two gas pipelines; the two gas pipelines are respectively equipped with a safety valve 5 and a spherical valve 4;
D、将液氮注入管6另一端与液氮泵连接，启动液氮泵并开启球形阀门4，液氮经过液氮注入管6注入穿层钻孔8，并进入各个圆盘形裂缝2内，液氮气化吸热使煤体温度快速降低，煤体内的水分结冰膨胀对煤体施加结冰膨胀力致裂；同时气化后的氮气体积快速膨胀对煤体施加气体膨胀力致裂，穿层钻孔8内的气压快速增大，氮气经过排气管9从球形阀门4所处的气体管路排出穿层钻孔8，从而降低穿层钻孔8内的气压使液氮内持续注入；D. Connect the other end of the liquid nitrogen injection pipe 6 to the liquid nitrogen pump, start the liquid nitrogen pump and open the spherical valve 4, the liquid nitrogen is injected through the liquid nitrogen injection pipe 6 into the penetration borehole 8 and enters each disc-shaped crack 2 , The heat absorption of liquid nitrogen gas makes the temperature of the coal body drop rapidly, the moisture in the coal body freezes and expands to impose icing expansion force on the coal body to crack; at the same time, the rapid expansion of the gasified nitrogen volume exerts gas expansion force on the coal body to crack. The air pressure in the penetration borehole 8 increases rapidly, and the nitrogen gas is discharged from the gas pipeline where the spherical valve 4 is located through the exhaust pipe 9 to the penetration borehole 8, thereby reducing the pressure in the penetration borehole 8 to make the liquid nitrogen continue injection;
E、液氮持续注入至球形阀门4所处的气体管路有液氮流出时，停止液氮泵并关闭球形阀门4，设定安全阀5的开启阈值，液氮在穿层钻孔8内持续气化膨胀，对煤体施加气体膨胀力致裂，当穿层钻孔8内的气压超过设定的开启阈值，则安全阀5开启，此时穿层钻孔8内的氮气从安全阀5所处的气体管路排出穿层钻孔8，从而使穿层钻孔8内部的气压降低，当气压低于设定的开启阈值后安全阀5关闭，此时液氮在穿层钻孔8内持续气化膨胀，对煤体再次施加气体膨胀力致裂，直至穿层钻孔8内的气压超过设定的开启阈值，则安全阀5开启卸压，如此循环重复，对煤体多次进行气体膨胀力致裂，直至穿层钻孔8内的液氮完全气化后安全阀5不再开启；完成穿层 钻孔8的致裂增透过程；E. When liquid nitrogen is continuously injected into the gas pipeline where the spherical valve 4 is located, when liquid nitrogen flows out, stop the liquid nitrogen pump and close the spherical valve 4, set the opening threshold of the safety valve 5, and the liquid nitrogen is in the penetration hole 8 Continue to gasify and expand, and apply gas expansion force to the coal to crack. When the air pressure in the penetration borehole 8 exceeds the set opening threshold, the safety valve 5 opens. At this time, the nitrogen in the penetration borehole 8 flows from the safety valve The gas pipeline where 5 is located is discharged from the penetration borehole 8, so that the air pressure inside the penetration borehole 8 is reduced. When the pressure is lower than the set opening threshold, the safety valve 5 is closed. At this time, the liquid nitrogen is in the penetration borehole. Gasification and expansion continues in 8, and gas expansion force is applied again to the coal to crack until the air pressure in the borehole 8 exceeds the set opening threshold, and the safety valve 5 is opened to relieve the pressure. This cycle is repeated, and the coal is more Perform gas expansion force cracking again until the liquid nitrogen in the penetration borehole 8 is completely vaporized and the safety valve 5 no longer opens; complete the cracking and antireflection process of the penetration borehole 8;
F、在穿层钻孔8两侧向煤层1打设两个瓦斯抽采钻孔7、且两个瓦斯抽采钻孔7均穿过各个圆盘形裂缝2；最后通过两个瓦斯抽采钻孔7对煤层进行瓦斯抽采；F. Drill two gas drainage boreholes 7 toward coal seam 1 on both sides of the penetration borehole 8, and both gas drainage boreholes 7 pass through each disc-shaped crack 2; finally pass through two gas drainage Drill hole 7 for gas drainage in the coal seam;
G、完成该处的瓦斯抽采后，间隔一定距离在巷道另一位置重复步骤A至F，进行该位置的煤层增透及瓦斯抽采，如此循环，直至完成整个巷道的煤层增透及瓦斯抽采。G. After completing the gas drainage at this location, repeat steps A to F at another location in the roadway at a certain distance to perform the coal seam penetration enhancement and gas drainage at this location, and so on, until the entire roadway is completed. Drain.
进一步，所述液氮注入管6的外表面包裹隔热层。降低液氮在经过液氮注入管6注入穿层钻孔时的气化程度，保证进入穿层钻孔8内的液氮量，从而提高其致裂效果。Further, the outer surface of the liquid nitrogen injection pipe 6 is wrapped with a heat insulation layer. The degree of gasification of liquid nitrogen when it is injected into the penetration borehole through the liquid nitrogen injection pipe 6 is reduced, and the amount of liquid nitrogen entering the penetration borehole 8 is ensured, thereby improving its cracking effect.
进一步，所述安全阀5的开启阈值为30MPa。Further, the opening threshold of the safety valve 5 is 30 MPa.
Claims (3)
- 一种利用液氮冷冲击及相变气体循环损伤的煤层增透方法，其特征在于，具体步骤为：A coal seam anti-reflection method using liquid nitrogen cold shock and phase change gas cycle damage is characterized in that the specific steps are:A、在巷道内打设至少一个穿层钻孔，该钻孔穿过岩层伸入煤层内；A. Set up at least one through-layer borehole in the roadway, which penetrates the rock layer and extends into the coal seam;B、采用水力割缝设备伸入穿层钻孔达到煤层内，以穿层钻孔为中心沿垂直于穿层钻孔的方向在煤层中等间距的割出多个圆盘形裂缝；B. Use hydraulic slitting equipment to penetrate the through-bed drilling to reach the coal seam, and cut multiple disc-shaped cracks in the coal seam at equal intervals in the direction perpendicular to the through-bed drilling centered on the through-bed drilling;C、将液氮注入管一端和排气管一端伸入穿层钻孔达到煤层内，然后对液氮注入管和排气管与穿层钻孔岩层段进行密封；排气管另一端连通三通管，三通管另外两口分别连接两个气体管路；两个气体管路上分别装有安全阀和球形阀门；C. Extend one end of the liquid nitrogen injection pipe and one end of the exhaust pipe into the penetration borehole to reach the coal seam, and then seal the liquid nitrogen injection pipe and the exhaust pipe with the strata section of the penetration borehole; the other end of the exhaust pipe is connected to three Through pipe, the other two ports of the three-way pipe are respectively connected to two gas pipelines; the two gas pipelines are respectively equipped with safety valves and spherical valves;D、将液氮注入管另一端与液氮泵连接，启动液氮泵并开启球形阀门，液氮经过液氮注入管注入穿层钻孔，并进入各个圆盘形裂缝内，液氮气化吸热使煤体温度快速降低，煤体内的水分结冰膨胀对煤体施加结冰膨胀力致裂；同时气化后的氮气体积快速膨胀对煤体施加气体膨胀力致裂，穿层钻孔内的气压快速增大，氮气经过排气管从球形阀门所处的气体管路排出穿层钻孔，从而降低穿层钻孔内的气压使液氮能持续注入；D. Connect the other end of the liquid nitrogen injection pipe to the liquid nitrogen pump, start the liquid nitrogen pump and open the spherical valve. The liquid nitrogen is injected into the through-layer borehole through the liquid nitrogen injection pipe, and enters the disc-shaped cracks, and the liquid nitrogen is absorbed. The heat causes the temperature of the coal body to decrease rapidly, and the water in the coal body freezes and expands to impose icing expansion force on the coal body to crack; at the same time, the gasified nitrogen volume rapidly expands to impose gas expansion force on the coal body to crack, and penetrate the borehole. The air pressure increases rapidly, and nitrogen is discharged from the gas pipeline where the spherical valve is located through the exhaust pipe to the penetration borehole, thereby reducing the air pressure in the penetration borehole so that the liquid nitrogen can be continuously injected;E、液氮持续注入至球形阀门所处的气体管路有液氮流出时，停止液氮泵并关闭球形阀门，设定安全阀的开启阈值，液氮在穿层钻孔内持续气化膨胀，对煤体施加气体膨胀力致裂，当穿层钻孔内的气压超过设定的开启阈值，则安全阀开启，此时穿层钻孔内的氮气从安全阀所处的气体管路排出穿层钻孔，从而使穿层钻孔内部的气压降低，当气压低于设定的开启阈值后安全阀关闭，此时液氮在穿层钻孔内持续气化膨胀，对煤体再次施加气体膨胀力致裂，直至穿层钻孔内的气压超过设定的开启阈值，则安全阀开启卸压，如此循环重复，对煤体多次进行气体膨胀力致裂，直至穿层钻孔内的液氮完全气化后安全阀不再开启；完成穿层钻孔的致裂增透过程；E. When liquid nitrogen is continuously injected into the gas pipeline where the spherical valve is located, when liquid nitrogen flows out, stop the liquid nitrogen pump and close the spherical valve, set the opening threshold of the safety valve, and the liquid nitrogen continues to vaporize and expand in the borehole. , Apply gas expansion force to the coal to crack. When the air pressure in the borehole exceeds the set opening threshold, the safety valve opens. At this time, the nitrogen in the borehole is discharged from the gas pipeline where the safety valve is located. Drill through the strata to reduce the air pressure inside the borehole. When the air pressure is lower than the set opening threshold, the safety valve will be closed. At this time, the liquid nitrogen will continue to gasify and expand in the drill through the strata, and apply again to the coal. The gas expansion force cracks until the air pressure in the penetration borehole exceeds the set opening threshold, the safety valve is opened to relieve the pressure, and the cycle is repeated, and the coal body is cracked by the gas expansion force for many times until the penetration borehole. After the liquid nitrogen is completely vaporized, the safety valve will no longer be opened; the cracking and anti-reflection process of the penetration drilling is completed;F、在穿层钻孔两侧向煤层打设两个瓦斯抽采钻孔、且两个瓦斯抽采钻孔均穿过各个圆盘形裂缝；最后通过两个瓦斯抽采钻孔对煤层进行瓦斯抽采；F. Two gas drainage boreholes were drilled into the coal seam on both sides of the penetration borehole, and the two gas drainage boreholes passed through each disc-shaped crack; finally, the coal seam was carried out through two gas drainage boreholes. Gas drainageG、完成该处的瓦斯抽采后，间隔一定距离在巷道另一位置重复步骤A至F，进行该位置的煤层增透及瓦斯抽采，如此循环，直至完成整个巷道的煤层增透及瓦斯抽采。G. After completing the gas drainage at this location, repeat steps A to F at another location in the roadway at a certain distance to perform the coal seam penetration enhancement and gas drainage at this location, and so on, until the entire roadway is completed. Drain.
- 根据权利要求1所述利用液氮冷冲击及相变气体循环损伤的煤层增透方法，其特征在于，所述液氮注入管的外表面包裹隔热层。The method for anti-reflection of coal seam using liquid nitrogen cold shock and phase change gas circulation damage according to claim 1, wherein the outer surface of the liquid nitrogen injection pipe is wrapped with a heat insulation layer.
- 根据权利要求1所述利用液氮冷冲击及相变气体循环损伤的煤层增透方法，其特征在于，所述安全阀的开启阈值为30MPa。The method for anti-reflection of coal seam using liquid nitrogen cold shock and phase change gas circulation damage according to claim 1, wherein the opening threshold of the safety valve is 30 MPa.
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| CN111119829B (en) | 2021-07-23 |
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