CN110056355B - Safe and efficient cross-cut coal uncovering method for increasing permeability and promoting pumping through freeze-thaw cycle - Google Patents
Safe and efficient cross-cut coal uncovering method for increasing permeability and promoting pumping through freeze-thaw cycle Download PDFInfo
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- CN110056355B CN110056355B CN201910332864.6A CN201910332864A CN110056355B CN 110056355 B CN110056355 B CN 110056355B CN 201910332864 A CN201910332864 A CN 201910332864A CN 110056355 B CN110056355 B CN 110056355B
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- 239000003245 coal Substances 0.000 title claims abstract description 161
- 238000000034 method Methods 0.000 title claims abstract description 43
- 230000035699 permeability Effects 0.000 title claims abstract description 13
- 238000005086 pumping Methods 0.000 title description 6
- 230000001737 promoting effect Effects 0.000 title description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 154
- 238000002347 injection Methods 0.000 claims abstract description 118
- 239000007924 injection Substances 0.000 claims abstract description 118
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 113
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 77
- 238000007710 freezing Methods 0.000 claims abstract description 70
- 230000008014 freezing Effects 0.000 claims abstract description 70
- 238000007789 sealing Methods 0.000 claims abstract description 65
- 239000007789 gas Substances 0.000 claims abstract description 39
- 239000011435 rock Substances 0.000 claims abstract description 29
- 239000007788 liquid Substances 0.000 claims abstract description 26
- 230000008569 process Effects 0.000 claims abstract description 21
- 238000000605 extraction Methods 0.000 claims abstract description 16
- 238000005553 drilling Methods 0.000 claims abstract description 8
- 238000010276 construction Methods 0.000 claims abstract description 7
- 239000002775 capsule Substances 0.000 claims description 32
- 239000012774 insulation material Substances 0.000 claims description 12
- 230000000903 blocking effect Effects 0.000 claims description 9
- 239000011810 insulating material Substances 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000005422 blasting Methods 0.000 claims description 4
- 239000011440 grout Substances 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000005336 cracking Methods 0.000 claims description 2
- 238000009423 ventilation Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 7
- 230000001976 improved effect Effects 0.000 abstract description 7
- 230000006872 improvement Effects 0.000 description 4
- 230000002787 reinforcement Effects 0.000 description 4
- 239000011083 cement mortar Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
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- 239000000243 solution Substances 0.000 description 1
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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
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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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
- E21B43/006—Production of coal-bed methane
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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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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- 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
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
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- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- E—FIXED CONSTRUCTIONS
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- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
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Abstract
A freeze-thaw cycle anti-reflection pumping-promoting safe and efficient cross-cut coal uncovering method comprises the following steps: (1) measuring the influence radius phi of high-pressure water injection of the coal seam; (2) drilling to a coal seam roof or a coal seam floor in a construction drill site; (3) the drill holes are divided into water injection holes and freezing holes which are alternately arranged; (4) sealing the water injection hole and the freezing hole; (5) injecting water into the water injection hole, injecting liquid nitrogen into the freezing hole to freeze the coal around the water injection hole, injecting hot nitrogen into the freezing hole after a period of time to unfreeze and melt the frozen coal around the water injection hole, and gasifying the liquid nitrogen; (6) extracting gas discharged from the water injection hole; (7) repeating the step (5) 48 hours after gas extraction; (8) and carrying out rock cross-cut coal uncovering operation. According to the invention, through the coal body freezing-heat injection process, the air permeability of the coal bed is effectively increased, the gas extraction effect of the coal bed can be greatly improved, the gas pressure of the coal bed is reduced, and the outburst danger of the coal bed is eliminated.
Description
Technical Field
The invention belongs to the technical field of coal mine safety production, and particularly relates to a safe and efficient cross-cut coal uncovering method for freeze-thaw cycle permeability improvement and pumping promotion.
Background
Coal and gas outburst is one of main disasters threatening the safety production of coal mines, and especially has the maximum outburst strength and the highest danger when a cross-cut coal seam is uncovered. The stress state of the coal rock in front of the rock cross-cut coal uncovering working face is easy to change suddenly, and the elastic potential of the rock and the coal bed and the gas energy are released in large quantity to generate high-strength outburst. More than 80% of oversize protrusions occur in the rock cross-cut coal uncovering process, and the average protruding strength of the protrusions is more than 6 times of that of other various roadways. Due to the particularity of the rock cross-cut coal uncovering construction process, the whole process of uncovering the outburst coal seam is dangerous, continuous outburst, delay outburst and self-uncovering outburst can occur, and the control difficulty is higher than that of the outburst of the common type.
At present, the cross cut coal uncovering method of the high gas outburst coal seam is mainly implemented from two aspects of pressure relief and permeability increase of the coal seam and coal body reinforcement. Measures such as hydraulic punching, loosening blasting, hydraulic slotting and the like are mainly implemented in the aspect of pressure relief and permeability increase of the coal seam, so that the effects of fully relieving the pressure of the coal seam and reducing the ground stress and the gas pressure are achieved; but at the same time, the integrity of the coal seam is damaged, the outburst resistance is reduced, and the outburst prevention work is also not favorable. In the aspect of coal body reinforcement, measures such as metal frameworks, coal body grouting reinforcement and the like are mainly adopted, so that the purposes of increasing the coal body strength and increasing the outburst resistance are achieved, and the danger and the outburst strength of gas outburst are reduced; however, in the coal body reinforcing process, cement mortar can only permeate and diffuse in the cracks, and due to the fact that the size of the cracks of the coal layer is very small, the cement mortar diffusion range is limited, the strength of the coal layer in the coal uncovering area can only be improved in a small range, regional reinforcement cannot be achieved, the gas pressure cannot be effectively reduced, the coal layer in the rock cross-cut coal uncovering area still has higher ground stress and gas pressure, and the outburst risk of the coal body is still high. Therefore, the safe and efficient rock cross-cut coal uncovering method is urgently needed, and not only can meet the requirements of pressure relief and permeability improvement, efficient coal seam gas extraction and effective reduction of gas pressure, but also can strengthen and reinforce the coal body strength of a coal uncovering area, and realizes safe and rapid coal uncovering of a rock cross-cut coal uncovering working face.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a freeze-thaw cycle permeability-increasing pumping-promoting safe and efficient rock cross-cut coal uncovering method which has the characteristics of scientific principle, convenience and quickness in construction, effective improvement of coal seam gas extraction effect, improvement of coal body strength in a coal uncovering area, and high coal uncovering efficiency and high safety.
In order to solve the technical problems, the invention adopts the following technical scheme: a safe and efficient cross-cut coal uncovering method for improving permeability and pumping by freeze-thaw cycling comprises the following steps,
(1) measuring the influence radius phi of high-pressure water injection of a coal seam near a cross-cut coal uncovering place of a roadway;
(2) arranging a drill site at the minimum normal distance of 5-7 m from the cross-cut coal uncovering working face to the coal seam, and drilling holes in the drill site to the top plate or the bottom plate of the coal seam;
(3) in the drilling construction process, firstly constructing water injection holes, and then constructing freezing holes in the range that the two sides of the water injection holes are smaller than phi, so that the water injection holes and the freezing holes are alternately arranged, the constructed water injection holes and the freezing holes completely cover the working face area of the rock cross-cut coal uncovering, and the arrangement parameters of the water injection holes and the freezing holes meet the related design requirements;
(4) sealing all the water injection holes by using a conventional hole sealing machine, and sealing all the freezing holes by using a special hole sealing machine;
(5) injecting water into the water injection hole through a conventional hole packer, injecting liquid nitrogen into the freezing hole through a special hole packer to freeze coal bodies around the water injection hole, injecting hot nitrogen into the freezing hole through the special hole packer after a period of time to unfreeze and melt the frozen coal bodies around the water injection hole, and gasifying the liquid nitrogen;
(6) connecting the conventional hole packer with a gas extraction system, extracting gas discharged from the water injection hole, and further reducing the gas pressure of the coal seam;
(7) after gas extraction is carried out for 48 hours, repeating the step (5) until the outburst danger of the coal body in the working face area of the rock cross-cut coal uncovering is eliminated;
(8) and (3) disassembling the extraction system, injecting water into the water injection hole through a conventional hole packer, then injecting liquid nitrogen into the coal bed through the freezing hole, and performing cross-cut coal uncovering work by adopting methods such as remote blasting and the like after the coal around the cross-cut coal uncovering working face is completely frozen, so as to uncover the cross-cut safely.
The special hole packer comprises a central tube, a grouting pump and a nitrogen injection pump, wherein a cylindrical heat insulation material layer is fixedly arranged on the outer circumference of the central tube in the axial direction, a hole sealing capsule is fixedly arranged on the outer circumference of the heat insulation material layer in the axial direction, a blocking plate is fixedly arranged at the outer end of the central tube, the blocking plate is connected with the outlet of the nitrogen injection pump through a nitrogen injection pipe, the outlet of the nitrogen injection pipe extends into the central tube, the outlet of the grouting pump is connected with the outer end part of the hole sealing capsule through a grouting pipe, a grouting valve is arranged on the grouting pipe, and a nitrogen injection valve is arranged on the.
The hole sealing capsule is of a cylindrical structure, and a spiral sealing strip is arranged on the outer circumferential surface of the hole sealing capsule along the axial direction of the central tube.
The inner end of the conventional hole packer is provided with a temperature sensor.
The specific working steps of the step (5) are,
A. high-pressure water is injected into the water injection hole through a conventional hole packer by using a high-pressure pump, and water is injected in a pulsating mode in the water injection process, wherein the pulsating mode is a pulsating mode of low pressure → high pressure → low pressure → high pressure circulation mode, so that the coal body is promoted to produce cracks, and the air permeability of a coal bed is increased; stopping water injection when water seepage occurs on the coal wall around the water injection hole, or water is discharged from the adjacent drill hole, or the water injection pressure is suddenly reduced, or the continuous water injection pressure has no obvious change; after stopping injecting water for half an hour, measuring the temperature in the water injection hole by a temperature sensor extending into the water injection hole;
B. the method comprises the following steps of sealing a freezing hole by using a special hole sealing device, injecting liquid nitrogen into the freezing hole by using the special hole sealing device in a high-pressure injection mode, freezing and cracking the coal around the freezing hole, loosening and ventilating the coal around the freezing hole, increasing the ventilation property of the coal, and facilitating later-stage gas extraction work;
C. monitoring the temperature in the water injection hole in real time through a temperature sensor, and determining that coal bodies around the water injection hole and the freezing hole are frozen when the temperature in the water injection hole is lower than 0 ℃;
D. stopping production and keeping the current situation for more than 8 hours after the coal around the water injection hole is frozen, so that the coal and the water around the freezing hole are fully frozen; after 8 hours, injecting hot nitrogen into the freezing hole through a special hole packer to melt the water body in the freezing area and gasify liquid nitrogen; gasified nitrogen and steam generated at high temperature drive coal bed gas to be discharged from cracks around the water injection hole and the freezing hole, so that the coal bed gas pressure is reduced, and the outburst danger is reduced.
The hole sealing process of the special hole sealing device comprises the steps of integrally inserting the central pipe, the heat insulation material layer and the hole sealing capsule into the freezing hole, connecting the grouting pipe with the hole sealing capsule, starting the grouting pump, injecting the grout into the hole sealing capsule by the grouting pump, expanding the hole sealing capsule, pressing the outer wall of the hole sealing capsule and the spiral sealing strip against the wall of the freezing hole, and closing the grouting valve so as to seal the freezing hole.
The nitrogen injection process of the special hole packer comprises the steps of connecting a nitrogen injection pipe with a blocking plate, connecting an inlet of a nitrogen injection pump with a liquid nitrogen source or a hot nitrogen source, starting the nitrogen injection pump, enabling liquid nitrogen or hot nitrogen to enter a central pipe through the nitrogen injection pipe, and enabling the liquid nitrogen or hot nitrogen to enter a freezing hole inwards along the axial direction of the central pipe.
The outer circles of the two ends of the inner and outer ends of the central tube are coaxially and fixedly provided with an inner limiting disc and an outer limiting disc, the inner end and the outer end of the heat-insulating material layer are respectively contacted with the inner limiting disc and the outer limiting disc, and the diameters of the inner limiting disc and the outer limiting disc are larger than the diameter of the heat-insulating material layer and smaller than the diameter of the expanded hole sealing capsule.
A guide cylinder with a thin inner part and a thick outer part and in a conical shape is arranged between the inner side of the outer circumference of the inner limiting disc and the outer circle of the inner end head of the central tube
By adopting the technical scheme, the invention has the following technical effects:
(1) by the coal freezing-heat injection process (i.e. the freeze-thaw cycle permeability-increasing and pumping-promoting process), the air permeability of the coal seam is effectively increased, the gas pumping effect of the coal seam can be greatly improved, the gas pressure of the coal seam is reduced, and the outburst risk of the coal seam is eliminated.
(2) By injecting water into the coal seam at high pressure, the water content of the coal body in the working face area of the cross cut coal uncovering is increased, the freeze-thaw cycle permeability-increasing and pumping-promoting effect of the coal body is improved, the air permeability of the coal body is effectively increased, and the gas pumping effect is improved.
(3) After the outburst danger of the coal body in the working face area of the rock cross-cut coal uncovering is eliminated, water is injected into the coal body, the coal body is frozen, the coal body is changed into a hard coal-ice block body from a loose body, the strength of the coal body is greatly improved, the resistance of gas outburst is increased, and safe coal uncovering is ensured.
(4) The invention can effectively reduce the drilling engineering amount, accelerate the coal uncovering process of the rock cross-cut coal uncovering working face and realize high-efficiency coal uncovering.
(5) The inner limiting disc and the outer limiting disc play a role in limiting the axial positions of the heat insulation material layer and the hole sealing capsule, so that the central pipe, the limited heat insulation material layer and the hole sealing capsule shaft keep axial stability during hole sealing.
(6) The inner limiting disc also provides a positioning and supporting effect for the outer end part of the guide cylinder; when the special hole packer extends into the drilled hole, the guide cylinder plays a role in guiding, and the situation that the special hole packer is blocked by local hole collapse is avoided.
Drawings
FIG. 1 is a plan view of the borehole arrangement of the present invention during construction operations;
fig. 2 is a schematic structural diagram of the special hole packer in the invention.
Detailed Description
As shown in fig. 1 and fig. 2, the freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method comprises the following steps,
(1) measuring the high-pressure water injection influence radius phi of the coal seam 2 near a cross-cut coal uncovering place of the roadway 1;
(2) arranging a drill site 3 at the minimum normal distance of 5-7 m from the cross-cut coal uncovering working face to the coal seam 2, and drilling a hole in the drill site 3 to the top plate or the bottom plate of the coal seam 2;
(3) in the drilling construction process, firstly constructing a water injection hole 4, then constructing a freezing hole 5 in a range that two sides of the water injection hole 4 are smaller than phi, so that the water injection hole 4 and the freezing hole 5 are alternately arranged, the constructed water injection hole 4 and the freezing hole 5 completely cover a rock cross-cut coal uncovering working face area, and the arrangement parameters of the water injection hole 4 and the freezing hole 5 meet the related design requirements (the existing conventional technology);
(4) sealing all the water injection holes 4 by using a conventional hole sealing machine (the conventional technology is adopted, and the detailed structure is not described any more), and sealing all the freezing holes 5 by using a special hole sealing machine;
(5) injecting water into the water injection hole 4 through a conventional hole packer, injecting liquid nitrogen into the freezing hole 5 through a special hole packer to freeze coal around the water injection hole 4, and injecting hot nitrogen into the freezing hole 5 through the special hole packer to unfreeze and melt the frozen coal around the water injection hole 4 after a period of time, so that the liquid nitrogen is gasified;
(6) connecting the conventional hole packer with a gas extraction system, extracting gas discharged from the water injection hole 4, and further reducing the gas pressure of the coal seam 2;
(7) after gas extraction is carried out for 48 hours, repeating the step (5) until the outburst danger of the coal body in the area of the rock cross-cut coal uncovering working face 6 is eliminated;
(8) and (3) disassembling the extraction system, injecting water into the water injection hole 4 through a conventional hole packer, then injecting liquid nitrogen into the coal bed 2 through the freezing hole 5, and after the coal bodies around the rock cross-cut coal uncovering working face 6 are completely frozen, performing rock cross-cut coal uncovering work by adopting methods such as remote blasting and the like to safely uncover the rock cross.
The special hole packer comprises a central pipe 7, a grouting pump 8 and a nitrogen injection pump 9, a cylindrical heat insulation material layer 10 is coaxially and fixedly arranged on the outer circumference of the central pipe 7, a hole sealing capsule 11 is coaxially and fixedly arranged on the outer circumference of the heat insulation material layer 10, a blocking plate 12 is fixedly arranged at the outer end of the central pipe 7, the blocking plate 12 is connected with the outlet of the nitrogen injection pump 9 through a nitrogen injection pipe 13, the outlet of the nitrogen injection pipe 13 extends into the central pipe 7, the outlet of the grouting pump 8 is connected with the outer end of the hole sealing capsule 11 through a grouting pipe 14, a grouting valve 15 is arranged on the grouting pipe 14, and a nitrogen injection valve 16 is arranged on the nitrogen injection pipe 13.
The hole sealing capsule 11 is a cylindrical structure, and a spiral sealing strip 17 is arranged on the outer circumferential surface of the hole sealing capsule 11 along the axial direction of the central tube 7.
The inner end of the conventional hole packer is provided with a temperature sensor.
The specific working steps of the step (5) are as follows:
A. high-pressure water is injected into the water injection hole 4 through a conventional hole packer by using a high-pressure pump, water is injected in a pulsating mode in the water injection process, the pulsating mode water injection is a pulsating mode of low pressure → high pressure → low pressure → high pressure circulation mode, so that the coal body is promoted to produce cracks, and the air permeability of the coal bed 2 is increased; stopping water injection when water seepage occurs on the coal wall around the water injection hole 4, or water is discharged from the adjacent drill hole, or the water injection pressure is suddenly reduced, or the continuous water injection pressure has no obvious change; after stopping injecting water for half an hour, measuring the temperature in the water injection hole 4 by a temperature sensor extending into the water injection hole 4;
B. the special hole packer is used for sealing the freezing hole 5, liquid nitrogen is injected into the freezing hole 5 through the special hole packer in a high-pressure injection mode, and coal bodies around the freezing hole 5 are frozen and fractured, so that the coal bodies around the freezing hole become loose and breathable, the breathability of the coal bodies is increased, and the later-stage gas extraction work is facilitated;
C. monitoring the temperature in the water injection hole 4 in real time through a temperature sensor, and determining that the coal bodies around the water injection hole 4 and the freezing hole 5 are frozen when the temperature in the water injection hole 4 is lower than 0 ℃;
D. stopping production and keeping the current situation for more than 8 hours after the coal around the water injection hole 4 is frozen, so that the coal and the water around the freezing hole 5 are fully frozen; after 8 hours, injecting hot nitrogen into the freezing holes 5 through a special hole packer to melt the water body in the freezing area and gasify liquid nitrogen; gasified nitrogen and steam generated at high temperature drive gas in the coal seam 2 to be discharged from cracks around the water injection hole 4 and the freezing hole 5, so that the gas pressure of the coal seam 2 is reduced, and the outburst danger is reduced.
The hole sealing process of the special hole sealing device comprises the steps of integrally inserting the central pipe 7, the heat insulation material layer 10 and the hole sealing capsule 11 into the freezing hole 5, connecting the grouting pipe 14 with the hole sealing capsule 11, starting the grouting pump 8, injecting the grout into the hole sealing capsule 11 by the grouting pump 8, expanding the hole sealing capsule 11, pressing the outer wall of the hole sealing capsule 11 and the spiral sealing strip 17 against the wall of the freezing hole 5, and closing the grouting valve 15 to seal the freezing hole 5.
The nitrogen injection process of the special hole packer is that, the nitrogen injection pipe 13 is connected with the blocking plate 12, the inlet of the nitrogen injection pump 9 is connected with the liquid nitrogen source or the hot nitrogen source, the nitrogen injection pump 9 is started, liquid nitrogen or hot nitrogen enters the central pipe 7 through the nitrogen injection pipe 13, the inside freezing hole 5 along the axial direction of the central pipe 7 enters, in the process of injecting the liquid nitrogen source or the hot nitrogen source, the heat insulation material layer 10 plays a role in reducing heat conduction, and the heat exchange efficiency is improved.
The outer circles of the inner end and the outer end of the central tube 7 are coaxially and fixedly provided with an inner limiting disc 18 and an outer limiting disc 19, the inner end and the outer end of the heat-insulating material layer 10 are respectively in contact with the inner limiting disc 18 and the outer limiting disc 19, and the diameters of the inner limiting disc 18 and the outer limiting disc 19 are larger than the diameter of the heat-insulating material layer 10 and smaller than the diameter of the expanded hole sealing capsule 11.
A guide cylinder 20 which is thin in inside and thick in outside and is conical is arranged between the inner side of the outer circumference of the inner limiting disc 18 and the outer circle of the inner end head of the central tube 7.
The hot nitrogen injected by the invention can be replaced by hot steam.
The present embodiment is not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (8)
1. A freeze-thaw cycle anti-reflection pumping-promoting safe and efficient cross-cut coal uncovering method is characterized by comprising the following steps: comprises the following steps of (a) carrying out,
(1) measuring the influence radius phi of high-pressure water injection of a coal seam near a cross-cut coal uncovering place of a roadway;
(2) arranging a drill site at the minimum normal distance of 5-7 m from the cross-cut coal uncovering working face to the coal seam, and drilling holes in the drill site to the top plate or the bottom plate of the coal seam;
(3) in the drilling construction process, firstly constructing water injection holes, and then constructing freezing holes in the range that the two sides of the water injection holes are smaller than phi, so that the water injection holes and the freezing holes are alternately arranged, the constructed water injection holes and the freezing holes completely cover the working face area of the rock cross-cut coal uncovering, and the arrangement parameters of the water injection holes and the freezing holes meet the related design requirements;
(4) sealing all the water injection holes by using a conventional hole sealing machine, and sealing all the freezing holes by using a special hole sealing machine;
(5) injecting water into the water injection hole through a conventional hole packer, injecting liquid nitrogen into the freezing hole through a special hole packer to freeze coal bodies around the water injection hole, injecting hot nitrogen into the freezing hole through the special hole packer after a period of time to unfreeze and melt the frozen coal bodies around the freezing hole, and gasifying the liquid nitrogen;
(6) connecting the conventional hole packer with a gas extraction system, extracting gas discharged from the water injection hole, and further reducing the gas pressure of the coal seam;
(7) after gas extraction is carried out for 48 hours, repeating the step (5) until the outburst danger of the coal body in the working face area of the rock cross-cut coal uncovering is eliminated;
(8) disassembling an extraction system, injecting water into the water injection hole through a conventional hole packer, then injecting liquid nitrogen into the coal bed through the freezing hole, and performing cross-cut coal uncovering work by adopting a remote blasting method after coal bodies around a cross-cut coal uncovering working face are completely frozen so as to uncover a cross-cut safely;
the special hole packer comprises a central tube, a grouting pump and a nitrogen injection pump, wherein a cylindrical heat insulation material layer is fixedly arranged on the outer circumference of the central tube in the axial direction, a hole sealing capsule is fixedly arranged on the outer circumference of the heat insulation material layer in the axial direction, a blocking plate is fixedly arranged at the outer end of the central tube, the blocking plate is connected with the outlet of the nitrogen injection pump through a nitrogen injection pipe, the outlet of the nitrogen injection pipe extends into the central tube, the outlet of the grouting pump is connected with the outer end part of the hole sealing capsule through a grouting pipe, a grouting valve is arranged on the grouting pipe, and a nitrogen injection valve is arranged on the.
2. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 1, characterized in that: the hole sealing capsule is of a cylindrical structure, and a spiral sealing strip is arranged on the outer circumferential surface of the hole sealing capsule along the axial direction of the central tube.
3. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 2, characterized in that: the inner end of the conventional hole packer is provided with a temperature sensor.
4. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 3, characterized in that: the specific working steps of the step (5) are,
A. high-pressure water is injected into the water injection hole through a conventional hole packer by using a high-pressure pump, and water is injected in a pulsating mode in the water injection process, wherein the pulsating mode is a pulsating mode of low pressure → high pressure → low pressure → high pressure circulation mode, so that the coal body is promoted to produce cracks, and the air permeability of a coal bed is increased; stopping water injection when water seepage occurs on the coal wall around the water injection hole, or water is discharged from the adjacent drill hole, or the water injection pressure is suddenly reduced, or the continuous water injection pressure has no obvious change; after stopping injecting water for half an hour, measuring the temperature in the water injection hole by a temperature sensor extending into the water injection hole;
B. the method comprises the following steps of sealing a freezing hole by using a special hole sealing device, injecting liquid nitrogen into the freezing hole by using the special hole sealing device in a high-pressure injection mode, freezing and cracking the coal around the freezing hole, loosening and ventilating the coal around the freezing hole, increasing the ventilation property of the coal, and facilitating later-stage gas extraction work;
C. monitoring the temperature in the water injection hole in real time through a temperature sensor, and determining that coal bodies around the water injection hole and the freezing hole are frozen when the temperature in the water injection hole is lower than 0 ℃;
D. stopping production and keeping the current situation for more than 8 hours after the coal around the water injection hole is frozen, so that the coal and the water around the freezing hole are fully frozen; after 8 hours, injecting hot nitrogen into the freezing hole through a special hole packer to melt the water body in the freezing area and gasify liquid nitrogen; gasified nitrogen and steam generated at high temperature drive coal bed gas to be discharged from cracks around the water injection hole and the freezing hole, so that the coal bed gas pressure is reduced, and the outburst danger is reduced.
5. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 4, characterized in that: the hole sealing process of the special hole sealing device comprises the steps of integrally inserting the central pipe, the heat insulation material layer and the hole sealing capsule into the freezing hole, connecting the grouting pipe with the hole sealing capsule, starting the grouting pump, injecting the grout into the hole sealing capsule by the grouting pump, expanding the hole sealing capsule, pressing the outer wall of the hole sealing capsule and the spiral sealing strip against the wall of the freezing hole, and closing the grouting valve so as to seal the freezing hole.
6. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 5, characterized in that: the nitrogen injection process of the special hole packer comprises the steps of connecting a nitrogen injection pipe with a blocking plate, connecting an inlet of a nitrogen injection pump with a liquid nitrogen source or a hot nitrogen source, starting the nitrogen injection pump, enabling liquid nitrogen or hot nitrogen to enter a central pipe through the nitrogen injection pipe, and enabling the liquid nitrogen or hot nitrogen to enter a freezing hole inwards along the axial direction of the central pipe.
7. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 2, characterized in that: the outer circles of the two ends of the inner and outer ends of the central tube are coaxially and fixedly provided with an inner limiting disc and an outer limiting disc, the inner end and the outer end of the heat-insulating material layer are respectively contacted with the inner limiting disc and the outer limiting disc, and the diameters of the inner limiting disc and the outer limiting disc are larger than the diameter of the heat-insulating material layer and smaller than the diameter of the expanded hole sealing capsule.
8. The freeze-thaw cycle anti-reflection pumping-promoting safe and efficient rock cross-cut coal uncovering method according to claim 7, characterized in that: a guide cylinder with a thin inner part and a thick outer part and a conical shape is arranged between the inner side of the outer circumference of the inner limiting disc and the outer circle of the inner end head of the central tube.
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| CN112412421B (en) * | 2020-11-05 | 2022-12-02 | 河南理工大学 | Method for strengthening pumping promotion by heat injection and hydraulic punching in layer-crossing drilling |
| CN112412417B (en) * | 2020-11-05 | 2022-11-18 | 河南理工大学 | Method for promoting pumping of coal seam by combining hydraulic cave building with drilling, heat injection, permeability increase |
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| CN112412415B (en) * | 2020-11-05 | 2022-11-04 | 河南理工大学 | Hydraulic punching, freezing fracturing and heat injection stimulation synergistic permeability-increasing pumping-promoting method |
| CN112412416B (en) * | 2020-11-05 | 2022-11-11 | 河南理工大学 | Freezing fracturing and heat injection stimulation combined fracturing coal body permeability increasing and pumping promoting method |
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