CN106894799B - Device and method for displacing coal bed gas by using supercritical carbon dioxide - Google Patents
Device and method for displacing coal bed gas by using supercritical carbon dioxide Download PDFInfo
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- CN106894799B CN106894799B CN201710283930.6A CN201710283930A CN106894799B CN 106894799 B CN106894799 B CN 106894799B CN 201710283930 A CN201710283930 A CN 201710283930A CN 106894799 B CN106894799 B CN 106894799B
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 258
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 129
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 129
- 239000003245 coal Substances 0.000 title claims abstract description 104
- 238000000034 method Methods 0.000 title claims abstract description 19
- 239000002775 capsule Substances 0.000 claims abstract description 114
- 230000005855 radiation Effects 0.000 claims abstract description 18
- 238000000605 extraction Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000005338 heat storage Methods 0.000 claims description 14
- 239000011232 storage material Substances 0.000 claims description 14
- 238000006073 displacement reaction Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000002347 injection Methods 0.000 claims description 9
- 239000007924 injection Substances 0.000 claims description 9
- 238000005065 mining Methods 0.000 claims description 9
- 238000007789 sealing Methods 0.000 claims description 9
- 238000005553 drilling Methods 0.000 claims description 7
- 238000003860 storage Methods 0.000 claims description 3
- 230000035699 permeability Effects 0.000 abstract description 7
- 238000011084 recovery Methods 0.000 abstract description 5
- 238000010276 construction Methods 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 67
- 230000009471 action Effects 0.000 description 11
- 238000001179 sorption measurement Methods 0.000 description 10
- 239000011148 porous material Substances 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 230000006872 improvement Effects 0.000 description 5
- 230000002860 competitive effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- -1 lipid organic compounds Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 239000004593 Epoxy Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000007792 gaseous phase Substances 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
- 238000007569 slipcasting Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000000194 supercritical-fluid extraction Methods 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
- 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
- E21B43/164—Injecting CO2 or carbonated water
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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
- E21B33/12—Packers; Plugs
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/70—Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells
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Abstract
The invention discloses a device and a method for displacing coal-bed gas by using supercritical carbon dioxide, which belong to the technical field of coal-bed gas exploitation and comprise a coal-bed gas displacing device body, wherein the coal-bed gas displacing device body comprises an upper capsule group and a lower capsule group, and a grouting area I is arranged in the upper capsule group; a grouting area II is arranged in the lower capsule group; the supercritical carbon dioxide radiation area is arranged between the upper capsule group and the lower capsule group, so that the supercritical carbon dioxide energy loss can be avoided, the supercritical carbon dioxide state of the finally injected coal bed is ensured, the structure is simple, the use is convenient, the construction is easy, the cost is low, the safety and the efficiency are high, the supercritical carbon dioxide gas recovery device is suitable for large-scale industrialization, the supercritical carbon dioxide gas recovery is realized, the permeability of the coal bed is improved, and the gas recovery rate of the coal bed is improved.
Description
Technical Field
The invention relates to the technical field of coalbed methane exploitation, in particular to a device and a method for displacing coalbed methane by using supercritical carbon dioxide.
Background
Coal bed gas commonly called as "gas", the main component is methane, which is the gas associated in the process of coal generation and deterioration, and the reserves are very abundant in China. The heat value of the coal seam gas is equivalent to that of the conventional natural gas, is 2 to 5 times that of the common gas, generates little pollutant after combustion, and belongs to high-quality clean gas energy. However, the coal seam in China is mostly a low-permeability coal seam, so that the gas exploitation rate is low.
The gas extraction mode commonly used at present is as follows: intensive drilling gas extraction, hydraulic fracturing extraction, hydraulic punching extraction, mining liberation layer reinforced extraction, hydraulic slotting extraction and the like. However, the prior art has little effect on improving the air permeability of the coal seam, and can not solve the problems of low coal seam permeability and low gas extraction rate of the coal seam in China.
Supercritical fluid extraction technology is a new scientific technology developed in the last three decades, and supercritical carbon dioxide is widely used in extraction processes as a good organic solvent and has good physicochemical properties. The critical density of the carbon dioxide is 0.448g/cm3, which is the highest of the common supercritical fluids, and the dissolution capacity of the supercritical fluid increases with the increase of the fluid density, which indicates that the supercritical carbon dioxide has strong extraction capacity for organic matters. In view of the specificity of supercritical carbon dioxide, various experiments are carried out on coal by vast domestic and foreign technicians, so that the conclusion that when the supercritical carbon dioxide is used as power gas for displacing coal bed gas, part of organic matters in a coal matrix can be dissolved, the porosity of the coal bed is improved, the low-permeability coal bed is improved, the gas on the micro-pore surface of the coal matrix is displaced, and the free state ratio of the coal bed gas is improved is obtained.
Although various experiments show that the effect of supercritical carbon dioxide on coal is known, the technology of preparing supercritical carbon dioxide and injecting the supercritical carbon dioxide into a coal bed still has a plurality of problems, because the supercritical carbon dioxide is prepared on the ground and then injected into the coal bed, the energy of the supercritical carbon dioxide is lost during the injection, so that the condition of the finally injected supercritical carbon dioxide in the coal bed cannot be achieved, so that a device for industrially applying the supercritical carbon dioxide to the coal bed gas exploitation in a large range is not known so far, therefore, how to avoid the energy loss of the supercritical carbon dioxide, ensure the state of the supercritical carbon dioxide finally injected into the coal bed, and ensure that the supercritical carbon dioxide is industrially, safely and efficiently applied in a large range to the coal bed gas exploitation is an important research subject in the technical field of coal bed gas exploitation at present.
Disclosure of Invention
The invention aims to solve the technical problem of providing a device and a method for displacing coal bed gas by using supercritical carbon dioxide; the invention can avoid the energy loss of the supercritical carbon dioxide, ensures the state of the supercritical carbon dioxide injected into the coal seam at last, has simple structure, easy construction, low cost, safety and high efficiency, is suitable for large-scale industrialization to apply the supercritical carbon dioxide to the coal seam gas exploitation, improves the coal seam permeability and improves the coal seam gas recovery ratio.
In order to solve the technical problems, the device for displacing coal-bed gas by using supercritical carbon dioxide provided by the invention comprises a displacement coal-bed gas device body, wherein the displacement coal-bed gas device body comprises an upper capsule group and a lower capsule group, and a grouting area I is arranged in the upper capsule group; a grouting area II is arranged in the lower capsule group; a supercritical carbon dioxide radiation area is arranged between the upper capsule group and the lower capsule group.
Further improvement, the upper capsule group comprises a capsule I and a capsule II which are sequentially arranged, and a grouting area I is arranged between the capsule I and the capsule II; the lower capsule group comprises a capsule III and a capsule IV which are sequentially arranged, and a grouting area II is arranged between the capsule III and the capsule IV; the heating device is arranged in the supercritical carbon dioxide radiation area, the design changes the traditional ground preparation supercritical carbon dioxide into underground preparation supercritical carbon dioxide, changes the conventional ground preparation supercritical carbon dioxide into the idea of reinjection into the coal bed, innovatively prepares the supercritical carbon dioxide underground and directly injects the supercritical carbon dioxide into the coal bed, avoids the energy loss of the supercritical carbon dioxide, and ensures the state of the supercritical carbon dioxide which is finally injected into the coal bed.
The heating device is further improved, the heating device is a phase-change heat storage material pipe, a supercritical carbon dioxide air cavity is arranged in the phase-change heat storage material pipe, a constant pressure relief valve is arranged on the phase-change heat storage material pipe, the phase-change heat storage material pipe is used as a heating source instead of a large heater, the heating device is low in cost, the heating device is simple in structure, space is saved, and the purpose of preparing supercritical carbon dioxide underground is achieved easily by using the phase-change heat storage material pipe; the higher the temperature is, the faster the heat loss is, the more easily the generation of supercritical carbon dioxide is affected, and experiments prove that the carbon dioxide is heated to 45-70 ℃ and is the optimal temperature for generating the supercritical carbon dioxide; when the pressure of the supercritical carbon dioxide is equal to 8MPa, the constant-pressure relief valve of the phase-change heat storage material pipe is automatically opened, the supercritical carbon dioxide is released and enters the coal bed, the pressure of the supercritical carbon dioxide which is about to enter the coal bed is determined by using the constant-pressure relief valve, and the pressure of the supercritical carbon dioxide entering the coal bed is ensured to be 8MPa.
Further improvement, the number of the constant pressure relief valves is 1-3, and the constant pressure relief valves cannot be arranged too much, so that some problems such as triggering and collision can be caused by too much.
Further improvement, the displacement coal seam gas device body is communicated with a pump, and the pump comprises a mining hole sealing grouting pump, a pneumatic booster pump and a manual water injection pump; the mining hole sealing grouting pump is communicated with the grouting area I and the grouting area II; the input port of the pneumatic booster pump is communicated with a carbon dioxide gas storage bottle, and the output port of the pneumatic booster pump is communicated with the supercritical carbon dioxide gas cavity; the manual water injection pump with capsule I, capsule II, capsule III and capsule IV are linked together, mining hole sealing slip casting pump is used for injecting into grout for this patent, and the grout is used for carrying out fixed seal to this patent and carrying out hole sealing operation to the drilling, pneumatic booster pump is used for pressurizing for carbon dioxide, manual water injection pump is used for injecting water for this patent, and water seals operation and maintains the inside atmospheric pressure of drilling to this patent.
A method of displacing coal seam gas with supercritical carbon dioxide comprising the steps of:
(1) Drilling holes in the coal seam;
(2) A lower capsule group and an upper capsule group are arranged in the drill hole, a supercritical carbon dioxide radiation area is formed by a cavity between the upper capsule group and the lower capsule group, the upper capsule group comprises a capsule I and a capsule II which are sequentially arranged, and the lower capsule group comprises a capsule III and a capsule IV which are sequentially arranged;
(3) Injecting water into the capsules I, II, III and IV; grouting between the capsule I and the capsule II, and grouting between the capsule III and the capsule IV;
(4) Conveying high-pressure carbon dioxide to a heating device in the supercritical carbon dioxide radiation area to obtain supercritical carbon dioxide, wherein the supercritical carbon dioxide is released from the supercritical carbon dioxide radiation area and enters a coal bed; the method prepares the supercritical carbon dioxide in the supercritical carbon dioxide radiation area and directly diffuses the supercritical carbon dioxide into the coal bed, so that energy loss in the process of generating the supercritical carbon dioxide on the ground and reintroducing the supercritical carbon dioxide into the coal bed is avoided;
(5) Standing to fully diffuse the supercritical carbon dioxide in the coal bed;
(6) And (5) extracting coal seam gas by using a gas extraction pipe.
Further improved, in the step (1), the diameter of the drilled hole is 60mm-113mm, the depth of the drilled hole is more than or equal to 10m, the included angle between the axis of the drilled hole and the horizontal plane is-5 degrees, and supercritical carbon dioxide is a liquid and gas coexisting material, so that the drilled hole should be horizontally or slightly inclined horizontally.
Further improved, the pressure of the water injected in the step (3) is more than or equal to 9MPa.
Further improvement, the pressure of the high-pressure carbon dioxide in the step (4) is more than 8MPa; the pressure of the supercritical carbon dioxide released in the step (4) is equal to 8MPa, and the temperature is 45-70 ℃.
According to a further improvement, the drill holes in the step (1) and the gas extraction pipes in the step (6) are alternately arranged at intervals of 2-3 meters, and according to the influence range of the invention, the drill holes and the gas extraction pipes are alternately arranged, so that the gas recovery ratio of the coal seam is improved.
The invention has the following beneficial effects:
the invention changes the traditional idea of preparing supercritical carbon dioxide on the ground and then injecting the supercritical carbon dioxide into the coal seam, innovatively prepares the supercritical carbon dioxide underground and directly injects the supercritical carbon dioxide into the coal seam, avoids the energy loss of the supercritical carbon dioxide, ensures the supercritical carbon dioxide state of the finally injected coal seam, seals and maintains the pressure of the supercritical carbon dioxide by using an upper capsule group and a lower capsule group, ensures the state of the supercritical carbon dioxide, seals and fixes the supercritical carbon dioxide by using a grouting area I and a grouting area II, ensures that the supercritical carbon dioxide is fully contacted with coal, heats the carbon dioxide to a safe temperature of 45-70 ℃ by using a phase change heat storage material pipe, avoids accidents such as spontaneous combustion of the coal body or gas explosion caused by the excessive temperature.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic view of the placement of the drill holes and gas extraction pipes according to the present invention;
the figure shows: 1-drilling holes; 2-capsule I; 3-capsule II; 4-capsule III; 5-capsule IV; 6-grouting area I; 7-supercritical carbon dioxide radiation zone; 8-grouting area II; 9-a phase change heat storage material pipe; 91-supercritical carbon dioxide air cavity; 92-constant pressure relief valve; 10-a mining hole sealing grouting pump; 101-grouting pipe; 11-a pneumatic booster pump; 12-a carbon dioxide gas cylinder; 13-manual water injection pump; 14-coal seam; 15-a gas extraction pipe.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
As shown in the figure, the device for displacing coal-bed gas by using supercritical carbon dioxide comprises a displacement coal-bed gas device body, wherein the displacement coal-bed gas device body comprises an upper capsule group and a lower capsule group, and a grouting area I6 is arranged in the upper capsule group; a grouting area II 8 is arranged in the lower capsule group; a supercritical carbon dioxide radiation area 7 is arranged between the upper capsule group and the lower capsule group, the upper capsule group comprises a capsule I2 and a capsule II 3 which are sequentially arranged, and a grouting area I6 is arranged between the capsule I2 and the capsule II 3; the lower capsule group comprises a capsule III 4 and a capsule IV 5 which are sequentially arranged, and a grouting area II 8 is arranged between the capsule III 4 and the capsule IV 5; a heating device is arranged in the supercritical carbon dioxide radiation area 7, the heating device is a phase-change heat storage material pipe 9, a supercritical carbon dioxide air cavity 91 is arranged in the phase-change heat storage material pipe 9, a constant pressure relief valve 92 is arranged on the phase-change heat storage material pipe 9, 1-3 constant pressure relief valves 92 are arranged, a displacement coal seam gas device body is communicated with pumps, and the pumps comprise a mining hole sealing grouting pump 10, a pneumatic booster pump 11 and a manual water injection pump 13; the mining hole sealing grouting pump 10 is communicated with the grouting area I6 and the grouting area II 8; the input port of the pneumatic booster pump 11 is communicated with a carbon dioxide gas storage bottle 12, and the output port of the pneumatic booster pump 11 is communicated with the supercritical carbon dioxide gas cavity 91; the manual water injection pump 13 is communicated with the capsules I2, II 3, III 4 and IV 5.
A method of displacing coal seam gas with supercritical carbon dioxide comprising the steps of:
(1) Drilling holes in the coal seam;
(2) A lower capsule group and an upper capsule group are arranged in the drill hole, a supercritical carbon dioxide radiation area is formed by a cavity between the upper capsule group and the lower capsule group, the upper capsule group comprises a capsule I and a capsule II which are sequentially arranged, and the lower capsule group comprises a capsule III and a capsule IV which are sequentially arranged;
(3) Injecting water into the capsules I, II, III and IV; grouting between the capsule I and the capsule II, and grouting between the capsule III and the capsule IV;
(4) Conveying high-pressure carbon dioxide to a heating device in the supercritical carbon dioxide radiation area to obtain supercritical carbon dioxide, wherein the supercritical carbon dioxide is released from the supercritical carbon dioxide radiation area and enters a coal bed;
(5) Standing to fully diffuse the supercritical carbon dioxide in the coal bed;
(6) And (5) extracting coal seam gas by using a gas extraction pipe.
The diameter of the drilled hole in the step (1) is 60mm-113mm, the depth of the drilled hole is more than or equal to 10m, the included angle between the axis of the drilled hole and the horizontal plane is-5 degrees, the pressure of water injected in the step (3) is more than or equal to 9MPa, and the pressure of high-pressure carbon dioxide in the step (4) is more than 8MPa; the pressure of the supercritical carbon dioxide released in the step (4) is equal to 8MPa, the temperature is 45-70 ℃, and the drill holes in the step (1) and the gas extraction pipes in the step (6) are alternately arranged at intervals of 2-3 meters.
The supercritical carbon dioxide enters the coal bed to generate extraction action, competitive adsorption displacement action, filtration adsorption displacement action, energizing driving action, fracturing action and partial pressure reduction action, so that the porosity of the coal is improved, the seepage channel of the coal bed gas is widened, the permeability of the coal bed is improved, the coal bed gas is displaced, and the coal bed gas extraction rate is improved;
1) Extraction: extracting hydrocarbon and lipoid organic compounds with lower polarity from coal by supercritical carbon dioxide;
2) Competitive adsorption displacement and filtration adsorption displacement: the adsorption capacity of coal to carbon dioxide is stronger than that of gas, and supercritical carbon dioxide and the gas on the surface of the coal matrix micropores have competitive adsorption displacement action and filtration adsorption displacement action;
3) Energizing driving action: driving gas in the coal seam pores by supercritical carbon dioxide;
4) Fracturing action: the supercritical carbon dioxide increases the porosity of the coal seam, so that the connectivity of the coal seam pores is enhanced under the action of high-pressure gas, and the seepage channels of the gas are increased, thereby achieving the fracturing effect;
5) Reducing partial pressure effect: the gas on the surface of the micropores of the coal matrix is replaced and desorbed by supercritical carbon dioxide and then diffuses into a fracture network of the pores of the coal, so that pressure difference exists between the inside and the outside of the coal matrix, and the gas in the coal matrix is continuously desorbed after gradually reducing the pressure due to the pressure difference.
The hydrocarbon and lipid organic compounds with lower polarity in the coal, such as esters, ethers, internal lipids, epoxy compounds and the like, can be extracted by supercritical carbon dioxide within the lower pressure range of 7-10 MPa, the hydrocarbon and the lipid organic compounds with lower polarity in the coal matrix or coal pore cracks are dissolved in the process, the porosity of the coal is improved, and the relationship between the permeability and the porosity is known as:
k0=n3 0/c（1-n0）2S2，
wherein k0- -permeability, D,
n0- -the porosity of the porous material,
s- -the specific surface area of the coal,
c- -dimensionless constant.
The method is characterized in that part of organic compounds in coal matrixes or coal pore gaps are extracted by supercritical carbon dioxide, the volume of the coal pore gaps is increased, the number of the coal pore gaps is increased along with the outflow of air flow from a seepage channel of coal bed gas, the seepage channel of the coal bed gas is widened, the permeability of the coal bed is improved, and the gas adsorbed on the surfaces of the micropores of the coal matrixes is converted from an adsorption state to a free state due to desorption of the pressure gradient coal bed gas.
The adsorption quantity of the coal to the carbon dioxide is 2-8 times of that of the gas, the supercritical carbon dioxide has the properties of two phases of gas and liquid, the supercritical carbon dioxide with the gaseous identity performs competitive phase adsorption with the coal bed gas, the purpose of further promoting desorption of the gas adsorbed on the surface of the micropores of the coal matrix is achieved, and the supercritical carbon dioxide flows in a seepage channel at the same time with the properties of the gaseous phase and the liquid phase, so that the coal bed gas is promoted to permeate at a faster speed.
It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.
Claims (6)
1. The method for displacing the coal-bed gas by using the supercritical carbon dioxide comprises a coal-bed gas displacing device body, wherein the coal-bed gas displacing device body comprises an upper capsule group and a lower capsule group, and a grouting area I is arranged in the upper capsule group; a grouting area II is arranged in the lower capsule group; a supercritical carbon dioxide radiation area is arranged between the upper capsule group and the lower capsule group, and a heating device is arranged in the supercritical carbon dioxide radiation area; the upper capsule group comprises a capsule I and a capsule II which are sequentially arranged, and a grouting area I is arranged between the capsule I and the capsule II; the lower capsule group comprises a capsule III and a capsule IV which are sequentially arranged, and a grouting area II is arranged between the capsule III and the capsule IV; the heating device is a phase-change heat storage material pipe, a supercritical carbon dioxide air cavity is arranged in the phase-change heat storage material pipe, and a constant pressure relief valve is arranged on the phase-change heat storage material pipe; the displacement coal seam gas device body is communicated with a pump, and the pump comprises a mining hole sealing grouting pump, a pneumatic booster pump and a manual water injection pump; the mining hole sealing grouting pump is communicated with the grouting area I and the grouting area II; the input port of the pneumatic booster pump is communicated with a carbon dioxide gas storage bottle, and the output port of the pneumatic booster pump is communicated with the supercritical carbon dioxide gas cavity; the manual water injection pump is communicated with the capsule I, the capsule II, the capsule III and the capsule IV;
the method also comprises the following steps:
(1) Drilling holes in the coal seam;
(2) A lower capsule group and an upper capsule group are arranged in the drill hole, a supercritical carbon dioxide radiation area is formed by a cavity between the upper capsule group and the lower capsule group, the upper capsule group comprises a capsule I and a capsule II which are sequentially arranged, and the lower capsule group comprises a capsule III and a capsule IV which are sequentially arranged;
(3) Injecting water into the capsules I, II, III and IV; grouting between the capsule I and the capsule II, and grouting between the capsule III and the capsule IV;
(4) Conveying high-pressure carbon dioxide to a heating device in the supercritical carbon dioxide radiation area to obtain supercritical carbon dioxide, wherein the supercritical carbon dioxide is released from the supercritical carbon dioxide radiation area and enters a coal bed;
(5) Standing to fully diffuse the supercritical carbon dioxide in the coal bed;
(6) And (5) extracting coal seam gas by using a gas extraction pipe.
2. The method of displacing coal seam gas with supercritical carbon dioxide as claimed in claim 1, wherein: the diameter of the drilled hole in the step (1) is 60-113 mm, the depth of the drilled hole is more than or equal to 10m, and the included angle between the axis of the drilled hole and the horizontal plane is-5 degrees.
3. The method of displacing coal seam gas with supercritical carbon dioxide as claimed in claim 1, wherein: and (3) the pressure of the water injected in the step (3) is more than or equal to 9MPa.
4. The method of displacing coal seam gas with supercritical carbon dioxide as claimed in claim 1, wherein: the pressure of the high-pressure carbon dioxide in the step (4) is more than 8MPa; the pressure of the supercritical carbon dioxide released in the step (4) is equal to 8MPa, and the temperature is 45-70 ℃.
5. The method of displacing coal seam gas with supercritical carbon dioxide as claimed in claim 1, wherein: the drill holes in the step (1) and the gas extraction pipes in the step (6) are alternately arranged at intervals of 2-3 meters;
6. the method of displacing coal seam gas with supercritical carbon dioxide as claimed in claim 1, wherein: the number of the constant pressure relief valves is 1-3.
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| CN107676092A (en) * | 2017-10-10 | 2018-02-09 | 山西煤炭运销集团长治有限公司 | A kind of liquid carbon dioxide phase transformation explosion rapid hole sealing device and method for sealing |
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| CN110485979B (en) * | 2019-08-19 | 2020-05-08 | 重庆大学 | Coal bed gas safe displacement extraction method based on carbon dioxide phase change fracturing device |
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| CN203476320U (en) * | 2013-09-22 | 2014-03-12 | 安徽理工大学 | Device for simultaneously determining pressure of coal bed gas through capsule grouting |
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| CN105822341B (en) * | 2016-06-12 | 2018-03-13 | 河南理工大学 | A kind of hypotonic anti-reflection system and method for coal seam supercritical carbon dioxide |
| CN106285604B (en) * | 2016-11-01 | 2019-03-01 | 中国矿业大学 | Microwave-assisted supercritical carbon dioxide cyclic fracturing system and method |
| CN206860157U (en) * | 2017-04-26 | 2018-01-09 | 华北科技学院 | A kind of device using supercritical carbon dioxide displacement coal-bed gas |
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