CN111058891B - Method for replacing and extracting coal seam gas in underground and aboveground modes - Google Patents
Method for replacing and extracting coal seam gas in underground and aboveground modes Download PDFInfo
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- CN111058891B CN111058891B CN201911262514.3A CN201911262514A CN111058891B CN 111058891 B CN111058891 B CN 111058891B CN 201911262514 A CN201911262514 A CN 201911262514A CN 111058891 B CN111058891 B CN 111058891B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
Abstract
The invention relates to a wellThe method for alternatively extracting coal seam gas from underground includes such steps as drilling a row of vertical wells at the position of working surface corresponding to ground surface, and sequentially hydraulic fracturing and supercritical CO2After fracturing, extracting coal bed gas from a ground well; constructing a plurality of rows of bedding drill holes in a working face, removing ground gas extraction equipment when the ground well gas extraction enters a failure period, connecting a ground well gas injection system, intermittently injecting gas, performing coal seam gas over-well gas injection displacement, and extracting the bedding drill holes under the coal seam until the coal seam reaches a recovery standard; the method fully exerts the characteristics of good fracturing effect of the ground vertical well, high displacement extraction efficiency and low extraction cost of the underground bedding drill hole, reasonably plans the space-time connection relationship of the ground vertical well and the underground bedding drill hole for gas extraction, changes the vertical extraction well entering the exhaustion period into the gas injection well, improves the utilization rate of the ground vertical well, reduces the gas extraction cost and promotes effective treatment of the gas of the continuous excavation tense mine.
Description
Technical Field
The invention relates to the technical field of coal seam gas extraction, in particular to a method for continuously extracting coal seam gas from an underground well and an aboveground well.
Background
Coal bed gas extraction modes can be generally divided into two main types: one is aboveground gas extraction, and the other is underground gas extraction. The method for extracting the gas from the well mainly comprises the step of constructing a vertical well or a horizontal well on the ground to a coal seam for gas extraction, has the characteristics of long extraction period, high extraction yield, high extraction concentration and no influence of underground extraction engineering, and has higher engineering cost and later-stage extraction equipment and pipeline maintenance cost. The underground gas extraction mainly adopts a mode of performing gas extraction by constructing bedding or crossing drill holes in an underground roadway, has the characteristics of simple construction mode, low extraction cost and wide action range, but has low extraction efficiency, low extracted gas concentration and great influence on the extraction engineering by the underground mining engineering. At present, coal bed gas is extracted from the upper part and the lower part of a well simultaneously or extracted in one mode, so that the coal mine gas treatment cost is too high or the extraction efficiency is low. In order to overcome the problems, the invention provides a method for continuously extracting coal seam gas from an upper well and a lower well,
disclosure of Invention
The invention aims to overcome the respective defects of gas extraction on the existing coal mine and gas extraction under the existing coal mine, and provides a method for alternately extracting coal seam gas under the coal mine, which respectively exerts the characteristics of good fracturing and permeability-increasing effects of a ground vertical well, high extraction yield, high gas injection and displacement extraction efficiency and low extraction cost of a down-hole bedding borehole, and realizes the high-efficiency, reliable and low-cost extraction of the coal seam gas.
A method for continuously extracting coal seam gas from an upper well and a lower well comprises the following steps:
1) constructing a row of vertical drilling penetrating coal seams on the ground;
2) sequentially injecting fracturing fluid, sand-carrying fluid and displacing fluid into the vertical well drilling to perform hydraulic fracturing on the coal bed;
3) after hydraulic fracturing is finished, supercritical CO is injected into the vertical well2Carrying out supercritical CO2Coal bed fracturing;
4) installing ground gas extraction equipment and extraction data acquisition equipment on a vertical drilling wellhead to extract coal bed gas in a well;
5) carrying out underground pre-excavation roadway tunneling, constructing a plurality of rows of bedding drill holes in a stoping roadway to a coal seam, and connecting the bedding drill holes into an underground gas extraction system;
6) when the gas extraction amount of the ground vertical well is lower than the peak extraction amount for 7 days
And (3) removing the ground gas extraction equipment, connecting the vertical drilling well into a ground gas injection system, intermittently injecting gas into the vertical drilling well, and performing gas injection displacement on the coal seam gas well and extraction of the underground bedding borehole until the coal seam reaches the extraction standard.
Further, the vertical drilling wells are positioned on the inclined central axis of the underground working face to be mined, and the vertical drilling well spacing is 80-800 m.
Further, the fracturing pressure of the coal seam hydraulic fracturing is more than 20 MPa.
Further, coal bed supercritical CO2The fracturing pressure of the fracturing is more than 30 MPa.
Furthermore, the transverse distance between the outermost bedding drill hole in each row of bedding drill holes and the adjacent vertical drill hole is 10-150 m, and the distance between the underground bedding drill holes is 1-15 m.
Further, the gas injected by the ground well gas injection system is air and CO2Or N2。
Further, the gas injection pressure of the ground gas injection system for injecting gas into the vertical well is 0.8MPa-2 MPa.
Has the advantages that: according to the invention, a row of vertical wells is constructed from the ground to the coal seam, so that the advantage that the gas extraction of the ground vertical well is not influenced by the underground excavation engineering is exerted. And the coal seam is fractured twice, so that the development of coal seam fractures is greatly promoted, and the yield of drilling is increased. Along with the progress of ground well gas extraction engineering, the extraction yield of a drilled well is continuously reduced, when the drilled well enters a failure period, ground gas extraction equipment is dismantled and connected to a ground well gas injection system, coal bed gas is injected upwards for displacement and is extracted from a down-hole bedding borehole, the maintenance cost of the ground extraction equipment and a pipeline can be effectively saved, the utilization rate of a ground vertical well is improved, the extraction efficiency is increased, and an extraction blank zone is eliminated.
Drawings
FIG. 1 is a layout view of a gas extraction borehole in and out of a well;
FIG. 2 is a cross-sectional view A-A of FIG. 1;
in the figure: 1-vertical drilling, 2-coal bed, 3-bedding drilling, 4-ground gas extraction equipment and extraction data acquisition equipment, 5-stoping roadway and 6-cutting hole.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1-2: a method for extracting coal seam gas from the top and the bottom of a well in an alternative mode comprises the following steps:
1) a row of vertical drilling wells 1 are constructed from the ground to penetrate through a coal seam 2, the vertical drilling wells 1 are positioned on the inclined central axis of a working face to be mined, the diameter of each vertical drilling well 1 is 139.7mm, the drilling intervals are 400m, and the distance from the vertical drilling well 1 closest to the open-cut hole 6 is 400 m;
2) sequentially injecting fracturing fluid, sand-carrying fluid and displacing fluid into the vertical well 1 to perform coal-bed hydraulic fracturing, wherein the fracturing pressure of the coal-bed hydraulic fracturing is 25 MPa;
3) after the hydraulic fracturing is finished, supercritical CO is injected into the vertical well 12Supercritical CO2The fracturing pressure of the fracturing is 35 MPa;
4) a ground gas extraction device and an extraction data acquisition device 4 are installed at the wellhead of the vertical drilling well 1 to extract coal bed gas in the well;
5) and (3) excavating a stoping roadway, constructing a plurality of rows of bedding drill holes 3 perpendicular to the trend of the working face on the coal seam in the stoping roadway, wherein the distance between the bedding drill holes is 5-8 m, the aperture is 113mm, and the distance between the bedding drill holes 3 at the outer side and the adjacent vertical drill holes is 50 m.
6) The extraction peak gas production of the ground vertical well is 1600m3And d, when the extraction is 300d, the gas production rate of the drilled well is less than 320m for 7 consecutive days3At the moment, the ground gas extraction equipment is dismantled and connectedGas injection system for surface well, intermittently injecting CO2And performing gas injection displacement on the coal bed gas well and underground bedding drilling extraction at the gas injection pressure of 1MPa until the coal bed reaches the extraction standard.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (5)
1. A method for replacing and extracting coal seam gas on a well and under a well is characterized in that: the method comprises the following steps:
1) constructing a row of vertical drilling penetrating coal seams on the ground;
2) sequentially injecting fracturing fluid, sand-carrying fluid and displacing fluid into the vertical well drilling to perform hydraulic fracturing on the coal bed;
3) after hydraulic fracturing is finished, supercritical CO is injected into the vertical well2Carrying out supercritical CO2Coal bed fracturing;
4) installing ground gas extraction equipment and extraction data acquisition equipment on a vertical drilling wellhead to extract coal bed gas in a well;
5) pre-digging a stoping roadway underground, constructing a plurality of rows of bedding drill holes in the stoping roadway to a coal seam, and connecting the bedding drill holes into an underground gas extraction system;
6) when the gas extraction amount of the ground vertical drilling well is less than one fifth of the peak extraction amount for 7 days continuously, removing ground gas extraction equipment, connecting the vertical drilling well to a ground gas injection system, intermittently injecting gas into the vertical drilling well, and performing gas injection displacement on the coal seam gas well and extraction of underground bedding drill holes until the coal seam reaches the extraction standard; the vertical drilling wells are positioned on the inclined central axis of the underground working face to be mined, and the vertical drilling well spacing is 80-800 m; the transverse distance between the drilling holes of the outermost bedding in each row of bedding drilling holes and the adjacent vertical drilling holes is 10-150 m, and the distance between the drilling holes of the underground bedding is 1-15 m.
2. The method for continuously extracting coal seam gas from the well and the underground according to claim 1, characterized by comprising the following steps: the fracturing pressure of the coal seam hydraulic fracturing is more than 20 MPa.
3. The method for continuously extracting coal seam gas from the well and the underground according to claim 1, characterized by comprising the following steps: coal bed supercritical CO2The fracturing pressure of the fracturing is more than 30 MPa.
4. The method for continuously extracting coal seam gas from the well and the underground according to claim 1, characterized by comprising the following steps: the gas injected by the ground gas injection system is air and CO2Or N2。
5. The method for continuously extracting coal seam gas from the well and the underground according to claim 1, characterized by comprising the following steps: the gas injection pressure of the ground gas injection system for injecting gas into the vertical well is 0.8MPa-2 MPa.
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| CN112983358A (en) * | 2021-02-10 | 2021-06-18 | 中国石油大学(北京) | Method for exploiting coal bed gas by injecting carbon dioxide between same well seams of horizontal well |
| CN113236338B (en) * | 2021-04-14 | 2024-01-12 | 中国煤炭地质总局勘查研究总院 | Mine gas anti-reflection method and device |
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| US6280000B1 (en) * | 1998-11-20 | 2001-08-28 | Joseph A. Zupanick | Method for production of gas from a coal seam using intersecting well bores |
| CN101915083B (en) * | 2010-08-13 | 2011-06-22 | 山西晋城无烟煤矿业集团有限责任公司 | Method for extracting coalbed gases from coal mines by upper and lower combination |
| CN102678092B (en) * | 2012-04-01 | 2015-09-16 | 河南省煤层气开发利用有限公司 | A kind ofly abovegroundly combine construction coal and the coal bed gas method of adopting altogether down |
| CN103104222B (en) * | 2013-02-01 | 2015-07-29 | 中北大学 | Ground peupendicular hole combines extraction coal bed gas method with concordant long drilled holes |
| CN105332684B (en) * | 2015-11-13 | 2017-09-12 | 重庆大学 | A kind of water under high pressure is quick-fried and CO2The coal bed gas displacement extraction technique that pressure break is combined |
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