CN111472832B - Coal bed gas self-circulation gas injection yield increasing method - Google Patents

Coal bed gas self-circulation gas injection yield increasing method Download PDF

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CN111472832B
CN111472832B CN202010273790.6A CN202010273790A CN111472832B CN 111472832 B CN111472832 B CN 111472832B CN 202010273790 A CN202010273790 A CN 202010273790A CN 111472832 B CN111472832 B CN 111472832B
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gas
extraction
valve
gas extraction
pipe
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CN111472832A (en
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刘厅
林柏泉
赵洋
朱传杰
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China University of Mining and Technology CUMT
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    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21FSAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
    • E21F7/00Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/166Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
    • E21B43/168Injecting a gaseous medium

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  • 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)
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  • Solid Fuels And Fuel-Associated Substances (AREA)

Abstract

The invention discloses a coal seam gas self-circulation gas injection yield-increasing method which is suitable for underground coal mine gas extraction.A gas injection drill hole and a gas extraction drill hole are constructed in a coal seam at first, then a gas extraction pipe and a gas injection pipe are respectively placed into the gas extraction drill hole and the gas injection drill hole and then sealed, and a coal seam gas self-circulation gas injection yield-increasing system is formed through the serial work of a gas extraction pump, a filtering device, a gas storage tank, a gas mixing chamber, a gas booster pump and a valve; the alternating reinforced gas extraction method is formed by combining the gas extraction systems connected in parallel, and is simple to operate, low in cost, high in safety, good in extraction effect and wide in application range.

Description

Coal bed gas self-circulation gas injection yield increasing method
Technical Field
The invention relates to the field of coal seam gas extraction, in particular to a coal seam gas self-circulation gas injection yield-increasing method.
Background
With the gradual exhaustion of shallow coal resources, the coal resource exploitation will gradually enter deep coal resources in the future. And the deep coal seam has the characteristics of high gas content, high pressure and the like, and seriously threatens the safe mining and generation of coal mines. Because coal bed gas is not only a clean energy source but also a strong greenhouse gas. According to statistics, the coal bed gas resource amount buried deep between 1000-2000 m in China accounts for 61.2% of the total coal bed gas resource amount in China, and the coal bed gas resource mining method has extremely high mining value. Therefore, the realization of the efficient exploitation of the coal bed gas has important significance for improving the coal mine safety exploitation, realizing the resource utilization and protecting the environment.
Most coal bed gas extraction modes in China at present mainly comprise: (1) directly connecting the coal ash into an extraction system for extraction through an extraction pump; (2) firstly, performing fracturing and permeability increasing on a coal seam through measures such as hydraulic fracturing, hydraulic slotting, loosening blasting and the like, and then pumping in a pumping system; (3) and injecting gases such as nitrogen, carbon dioxide and the like through a high-pressure pump to perform displacement extraction on the coal seam gas. However, the measures have the defects of high cost, low extraction efficiency, high construction risk and the like. Therefore, in order to improve the efficient extraction effect and the extraction concentration of the coal seam gas, a brand new extraction mode and method are urgently needed to meet the requirement of efficient extraction of the coal mine underground gas.
Disclosure of Invention
Aiming at the technical defects, the invention aims to provide a coal bed gas self-circulation gas injection yield increasing method which is simple to operate, low in cost, high in safety and good in extraction effect.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a coal bed gas self-circulation gas injection production increasing method, which specifically comprises the following steps:
s1: firstly, respectively constructing two gas extraction drill holes and one gas injection drill hole from a roadway drill site to a coal seam, then respectively placing a gas extraction pipe I, a gas extraction pipe II and a gas injection pipe into the gas extraction drill holes and the gas injection drill holes, and then sealing the holes;
s2: connecting the first gas extraction pipe and the second gas extraction pipe with a gas suction port of a gas extraction pump through pipelines, and connecting a gas injection pipe with a gas outlet of a gas booster pump through a pipeline;
s3: the gas outlet of the gas extraction pump is divided into two paths, one path is connected with the gas extraction system, the other path is connected with the filtering device, a fourth valve and a first valve are respectively arranged on pipelines among the gas extraction system, the filtering device and the gas extraction pump, the gas outlet of the filtering device is sequentially connected with the gas storage tank, the gas mixing chamber and the gas booster pump through pipelines, and a second valve and a third valve are respectively arranged on pipelines among the gas storage tank, the gas booster pump and the gas mixing chamber;
s4: closing a valve IV, opening a gas extraction pump and a valve I, starting gas extraction of the coal seam, filtering waste residues and waste water generated in the extraction process of the extracted gas through a filtering device, then entering a gas storage tank, and then opening a valve II and controlling the opening degree of the valve II to enable the gas to enter a gas mixing chamber according to a certain flow;
s5: the method comprises the following steps of firstly detecting the concentration of gas flowing in a gas mixing chamber through the gas concentration detection function of the gas mixing chamber, and reducing the gas concentration to be outside an explosion limit range through injecting dry air for mixing if the gas concentration is within the gas explosion limit; then opening a valve III and a gas booster pump, and injecting the mixed gas into the coal bed through a gas injection pipe for displacement operation after the mixed gas is boosted to a set critical value through the gas booster pump;
s6: after the displacement is carried out for a certain time, closing the valve I, the valve II, the valve III and the gas booster pump;
s7: opening the valve IV, and connecting the gas extraction pipe I and the gas extraction pipe II into a gas extraction system through a gas extraction pump to perform extraction operation;
s8: and when the gas concentration in the gas extraction system is reduced to be below a set critical value, repeating the steps S4-S7 until the extraction operation is finished.
Preferably, in step S1, the gas injection borehole is located at a middle position between the two gas extraction boreholes.
Preferably, in step S8, the gas concentration critical value in the gas extraction system is set to 20%.
Preferably, in step S5, the critical value of the pressurization of the mixed gas by the gas booster pump is set to 10 Mpa.
Preferably, the displacement time is set to be hours in step S6.
The invention has the beneficial effects that: according to the self-displacement method for the coal bed gas, the self-displacement method for the coal bed gas is formed through the self-circulation system for the coal bed gas, so that a large amount of external gas is prevented from being mixed into the coal bed, the displacement cost is saved, and the displacement risk is reduced; meanwhile, the coal seam gas is circularly displaced by the extracted gas, so that the gas displacement effect is improved, and an alternating reinforced gas extraction method is formed by combining the gas extraction systems connected in parallel.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a diagram of a connection system of components in a coal bed gas self-circulation gas injection stimulation method according to an embodiment of the present invention.
Description of the drawings: 1-a drill site, 2-a gas injection pipe, 3-a gas extraction pipe I, 4-a gas extraction pipe II, 5-a coal bed, 6-a gas extraction pump, 7-a valve I, 8-a filtering device, 9-a gas storage tank, 10-a valve II, 11-a gas mixing chamber, 12-a valve III, 13-a gas booster pump, 14-a valve IV and 15-a gas extraction system.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a coal bed gas self-circulation gas injection production increasing method specifically comprises the following steps:
s1: firstly, respectively constructing two gas extraction drill holes and a gas injection drill hole from a roadway drill site 1 to a coal seam 5, wherein the gas injection drill hole is positioned in the middle position between the two gas extraction drill holes, and then respectively placing a gas extraction pipe I3, a gas extraction pipe II 4 and a gas injection pipe 2 into the gas extraction drill hole and the gas injection drill hole, and then sealing the holes;
s2: connecting the first gas extraction pipe 3 and the second gas extraction pipe 4 with an air suction port of a gas extraction pump 6 through pipelines, and connecting the gas injection pipe 2 with a gas outlet of a gas booster pump 13 through a pipeline;
s3: the gas outlet of the gas extraction pump (6) is divided into two paths, one path is connected with the gas extraction system 15, the other path is connected with the filtering device 8, the pipelines among the gas extraction system 15, the filtering device 8 and the gas extraction pump 6 are respectively provided with a valve IV 14 and a valve I7, the gas outlet of the filtering device 8 is sequentially connected with the gas storage tank 9, the gas mixing chamber 11 and the gas booster pump 13 through pipelines, and the pipelines among the gas storage tank 9, the gas booster pump 13 and the gas mixing chamber 11 are respectively provided with a valve II 10 and a valve III 12;
s4: closing a fourth valve 14, opening a gas extraction pump 6 and a first valve 7, starting gas extraction of the coal seam 5, filtering waste residues and waste water generated in the extraction process by using an extracted gas through a filtering device 8, then entering a gas storage tank 9, and then opening a second valve 10 and controlling the opening degree of the second valve 10 to enable the gas to enter a gas mixing chamber 11 according to a certain flow rate;
s5: the concentration of the gas flowing in the gas mixing chamber 11 is detected through the gas concentration detection function of the gas mixing chamber, and if the concentration of the gas is within the gas explosion limit, the concentration of the gas is reduced to be outside the explosion limit range through injecting dry air for mixing; then opening a third valve 12 and a gas booster pump 13, boosting the mixed gas to 10Mpa by the gas booster pump 13, and injecting the gas into the coal seam 5 through a gas injection pipe 2 for displacement operation;
s6: after the displacement is carried out for 24 hours, closing the first valve 7, the second valve 10, the third valve 12 and the gas booster pump 13;
s7: opening a fourth valve 14, and connecting the first gas extraction pipe 3 and the second gas extraction pipe 4 into a gas extraction system 15 through a gas extraction pump 6 for extraction;
s8: and when the gas concentration in the gas extraction system 15 is reduced to be below 20%, repeating the steps S4-S7 until the extraction operation is finished.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (5)

1. A coal bed gas self-circulation gas injection production increasing method is characterized by comprising the following steps:
s1: firstly, respectively constructing two gas extraction drill holes and a gas injection drill hole from a roadway drill site (1) to a coal seam (5), then respectively placing a gas extraction pipe I (3), a gas extraction pipe II (4) and a gas injection pipe (2) into the gas extraction drill holes and the gas injection drill holes, and then sealing the holes;
s2: connecting a first gas extraction pipe (3) and a second gas extraction pipe (4) with an air suction port of a gas extraction pump (6) through a pipeline, and connecting a gas injection pipe (2) with a gas outlet of a gas booster pump (13) through a pipeline;
s3: the gas outlet of the gas extraction pump (6) is divided into two paths, one path is connected with the gas extraction system (15), the other path is connected with the filtering device (8), pipelines among the gas extraction system (15), the filtering device (8) and the gas extraction pump (6) are respectively provided with a valve IV (14) and a valve I (7), the gas outlet of the filtering device (8) is sequentially connected with the gas storage tank (9), the gas mixing chamber (11) and the gas booster pump (13) through pipelines, and pipelines among the gas storage tank (9), the gas booster pump (13) and the gas mixing chamber (11) are respectively provided with a valve II (10) and a valve III (12);
s4: closing a fourth valve (14), opening a gas extraction pump (6) and a first valve (7), starting gas extraction of the coal seam (5), filtering waste residues and waste water generated in the extraction process by using the extracted gas through a filtering device (8), then entering a gas storage tank (9), and then opening a second valve (10) and controlling the opening degree of the second valve (10) to enable the gas to enter a gas mixing chamber (11) according to a certain flow rate;
s5: the concentration of the gas flowing in the gas mixing chamber (11) is detected through the gas concentration detection function of the gas mixing chamber, and if the concentration of the gas is within the gas explosion limit, the concentration of the gas is reduced to be outside the explosion limit range through injecting dry air for mixing; then opening a valve III (12) and a gas booster pump (13), and after the mixed gas is boosted to a set critical value through the gas booster pump (13), injecting the gas into the coal seam (5) through a gas injection pipe (2) for displacement operation;
s6: after a certain time of displacement, closing the valve I (7), the valve II (10), the valve III (12) and the gas booster pump (13);
s7: opening a fourth valve (14), and connecting the first gas extraction pipe (3) and the second gas extraction pipe (4) into a gas extraction system (15) through a gas extraction pump (6) to perform extraction operation;
s8: and when the gas concentration in the gas extraction system (15) is reduced to be below the set critical value, repeating the steps S4-S7 until the extraction operation is finished.
2. The coal seam gas self-circulation gas injection stimulation method of claim 1, wherein in the step S1, the gas injection drill hole is located in the middle position between the two gas extraction drill holes.
3. The coal seam gas self-circulation gas injection stimulation method as claimed in claim 1, wherein in the step S8, the gas concentration critical value in the gas extraction system (15) is set to be 20%.
4. The coal seam gas self-circulation gas injection production increasing method of claim 1, wherein in step S5, the critical value of the pressure increase of the mixed gas through the gas booster pump (13) is set to 10 Mpa.
5. The self-circulation gas injection stimulation method for coal bed gas as claimed in claim 1, wherein the displacement time is set to 24 hours in step S6.
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CN112696177B (en) * 2020-12-30 2022-04-01 太原理工大学 Application method of coal bed gas pressure device based on compressed air system
CN112761586B (en) * 2021-01-22 2022-04-12 中国矿业大学 Drilling methane self-circulation blasting fracturing enhanced extraction method
CN113217079B (en) * 2021-03-01 2023-07-14 柴兆喜 Pressure equalizing circulation mine gas extraction coal hole
CN112780334A (en) * 2021-03-18 2021-05-11 柴兆喜 Shaft for extracting pure gas
CN113565470A (en) * 2021-06-18 2021-10-29 煤炭科学技术研究院有限公司 Gas injection displacement pneumatic pressurization system and method for promoting coal seam gas extraction
CN113404471A (en) * 2021-07-06 2021-09-17 煤炭科学技术研究院有限公司 Gas injection displacement coal seam gas extraction promoting coal seam gas drilling arrangement method
CN114320259A (en) * 2021-12-28 2022-04-12 徐州工程学院 Method and system for improving gas extraction effect through linkage of ground drilling groups
CN114320257B (en) * 2021-12-30 2023-11-03 中国矿业大学 Closed loop system and method for enhanced extraction of coal seam after burning of underground coal mine gas
CN115467703B (en) * 2022-09-23 2024-07-30 湖南科技大学 Auxiliary directional long-borehole gas extraction method and system

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