CN116733523A - Combined production method of structural coal and gas - Google Patents
Combined production method of structural coal and gas Download PDFInfo
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- CN116733523A CN116733523A CN202310752760.7A CN202310752760A CN116733523A CN 116733523 A CN116733523 A CN 116733523A CN 202310752760 A CN202310752760 A CN 202310752760A CN 116733523 A CN116733523 A CN 116733523A
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- 239000003245 coal Substances 0.000 title claims abstract description 106
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 239000012530 fluid Substances 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 21
- 238000007599 discharging Methods 0.000 claims abstract description 4
- 238000005086 pumping Methods 0.000 claims description 6
- 238000005553 drilling Methods 0.000 claims description 5
- 239000011435 rock Substances 0.000 claims description 3
- 239000002817 coal dust Substances 0.000 claims 1
- 238000011010 flushing procedure Methods 0.000 claims 1
- 238000005065 mining Methods 0.000 abstract description 16
- 239000007789 gas Substances 0.000 description 56
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 238000004891 communication Methods 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 239000003345 natural gas Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Earth Drilling (AREA)
Abstract
The invention relates to a combined production method of structural coal and gas, which comprises the following steps: s1, constructing a first mine from the ground and enabling a first well section of the first mine to be located in a coal seam; s2, forming fracturing holes in the first well section into the coal layer; s3, injecting fracturing fluid into the fracturing holes by utilizing fracturing equipment so as to fracture the coal seam by utilizing the fracturing fluid and form a stress relief area; s4, after the stress release area is formed, discharging the fracturing fluid in the first mine; s5, gas entering the first well section from the stress release area is produced; s6, constructing a main vertical shaft communicated with the first well section from the ground so as to mine the coal seam; wherein, the step S3, the step S4 and the step S5 are sequentially performed at least once. Therefore, the method for combined mining of the structural coal and the gas has the advantages of economically utilizing the gas of the coal mine and increasing the safety of coal mine mining.
Description
Technical Field
The invention relates to the technical field of mining, in particular to a combined mining method for structural coal and gas.
Background
The zones where the structural coal develops are all zones with local structural compressive shear stress concentration zones and the zones with the strongest structural deformation, and are often coal seam gas enrichment zones. Because the structural coal is formed in the stress concentration area and is formed after the coal body is crushed, the structural coal is generally large in porosity and easy to generate the phenomenon of gas outburst. Since the 80 s of the last century, coal mining in China is restricted by gas disaster upgrading, coal mine gas explosion and coal and gas outburst accidents along with the increase of coal mining depth. Coal mine gas is also natural gas, is a gas resource associated with coal and symbiotic with coal, takes methane as a main component, and belongs to unconventional natural gas, and the unconventional natural gas is also called coal bed gas. In the related art, it is difficult to economically utilize coal mine gas and to perform gas control at the same time when coal mining.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, embodiments of the present invention provide a method of combined production of structural coal and gas.
The method for combined mining of the structural coal and the gas comprises the following steps:
s1, constructing a first mine from the ground and enabling a first well section of the first mine to be located in a coal seam;
s2, forming fracturing holes in the first well section into the coal layer;
s3, injecting fracturing fluid into the fracturing holes by utilizing fracturing equipment so as to fracture the coal seam by utilizing the fracturing fluid and form a stress relief area;
s4, after the stress release area is formed, discharging the fracturing fluid in the first mine;
s5, gas entering the first well section from the stress release area is produced;
s6, constructing a main vertical shaft communicated with the first well section from the ground so as to mine the coal seam;
wherein, the step S3, the step S4 and the step S5 are sequentially performed at least once.
Therefore, the method for combined mining of the structural coal and the gas has the advantages of economically utilizing the gas of the coal mine and increasing the safety of coal mining.
In some embodiments, the step S1 includes
S11, drilling from the ground by using a drill bit, wherein the drill bit vertically drills down to a first preset depth, a casing pipe is arranged in the drill bit, and cementing fluid is used on the outer side of the casing pipe so as to seal a fourth series of loose rock stratum;
s12, using a two-way drill bit to drill downwards to a second preset depth, arranging two-way sleeves in the two-way drill bit so as to form a second well section of the first mine, and cementing the two-way sleeves to the ground;
s13, drilling into a coal seam by using a three-way drill bit, and arranging three-way sleeves in the three-way drill bit so as to form an inclined well section and a first well section positioned in the coal seam, wherein the second well section, the inclined well section and the first well section are communicated in sequence.
In some embodiments, in the step S13, the first well section extends along the coal seam strike;
the size of the one-open drill bit is 444.5mm, and the inner diameter of the one-open casing pipe is 339.7mm;
the size of the two-open drill bit is 311.1mm, and the inner diameter of the two-open casing pipe is 244.5mm;
the size of the three-opening drill bit is 215.9mm, and the inner diameter of the three-opening casing pipe is 139.7mm.
In some embodiments, in step S2, a frac hole is opened in the first wellbore section 13 using the hydraulic injector 2;
in the step S3, the pressure of the fracturing fluid injected into the fracturing holes is less than 30MPa;
in the step S3, the flow rate of the fracturing fluid injected into the fracturing holes is more than or equal to 20m 3 /min。
In some embodiments, in the step S3, the pressure of the fracturing fluid injected into the fracturing holes is 20MPa or more and 25MPa or less.
In some embodiments, after the stress relief zone is formed in the step S4, a flow rate of the fracturing fluid carrying pulverized coal is greater than or equal to 5m by controlling a throttle valve on a wellhead of the first mine 3 /min is less than or equal to 6m 3 /min。
In some embodiments, after the completion of the injection of the fracturing fluid in step S4, the first mine is washed to flush the coal fines precipitated in the first mine to the surface;
in the step S4 and the step S5, the first mine is drained and the gas is produced by using a tubular pump and a pumping unit.
In some embodiments, when the daily gas production in the first wellbore section decays below the industrial gas flow specification, the steps S3, S4 and S5 may be performed again in order to expand the area of the stress relief zone and produce gas.
In some embodiments, in the step S6, a lifting device is installed at a wellhead of the main vertical shaft, and after the gas concentration in the main vertical shaft direction is less than 0.75%, the main vertical shaft is excavated along the first shaft section inlet roadway.
The method for combined production of the structural coal and the gas further comprises the step S7 of constructing a plurality of branch well sections positioned in the coal seam from the first well section, and after the branch well sections are provided with fracturing holes, sequentially implementing the step S3, the step S4 and the step S5 at least once in the branch well sections.
Drawings
Fig. 1 is a schematic view of a first mine according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a main vertical shaft according to an embodiment of the invention.
Reference numerals:
a first mine 1, a first casing 11, a second casing 12, a first well section 13, a deflecting well section 14 and a second well section 15;
a hydraulic ejector 2;
a main vertical shaft 3, a lifting device 31;
a first stress relief region 41, a second stress relief region 42;
and a coal seam 5.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The following describes a method of combined production of structural coal and gas according to an embodiment of the present invention with reference to the accompanying drawings. As shown in fig. 1 and 2, the combined production method of the structural coal and gas according to the embodiment of the invention comprises the following steps:
s1, constructing a first mine 1 from the ground, and enabling a first well section 13 of the first mine 1 to be located in a coal seam 5;
s2, forming fracturing holes in the first well section 13 into the coal seam 5;
s3, injecting fracturing fluid into the fracturing holes by utilizing fracturing equipment so as to fracture the coal seam 5 by utilizing the fracturing fluid and form a stress relief zone;
s4, after a stress release area is formed, discharging fracturing fluid in the first mine 1;
s5, gas entering the first well section 13 from the stress release area is collected;
s6, constructing a main vertical shaft 3 communicated with the first well section 13 from the ground so as to mine the coal seam 5;
wherein, step S3, step S4 and step S5 are sequentially performed at least once.
According to the method for constructing coal and gas combined production, the first mine 1 is arranged so that the first well section 13 is located in the coal seam 5, after the fracturing holes are formed in the first well section 13, the fracturing fluid is used for fracturing the coal seam 5 to form a stress release area, and after coal blocks in the stress release area are broken, gas can enter the first well section 13 through the cracks and the fracturing holes so as to be discharged out of the coal seam 5 through the first mine 1. And after gas is produced, the main vertical shaft 3 communicated with the first shaft section 13 can be arranged, so that the first mine 1 can act as a ventilation shaft after the gas production is finished, the safety of the produced coal seam 5 is improved, and the construction cost can be reduced.
According to the method for combined mining of the structural coal and the gas, the step S3, the step S4 and the step S5 are sequentially carried out at least once. Therefore, when the gas content in the first pipe section 13 is low, the steps S3, S4 and S5 can be sequentially performed again, so that the stress relief area can be enlarged, more gas can enter the first well section 13, the economic utilization of gas can be improved, and the safety of the coal seam 5 can be further increased.
Therefore, the method for combined mining of the structural coal and the gas has the advantages of economically utilizing the gas of the coal mine and increasing the safety of coal mining.
As shown in fig. 1 and 2, in some embodiments, the first mine 1 is a three-open structure mine, so that the first mine 1 can be structurally stable. Specifically, step S1 includes step S11, step S12, and step S13.
In step S11, a drill bit is used to drill from below the ground, the drill bit is drilled vertically downwards to a first preset depth, an open casing 11 is arranged in the drill bit, and cementing fluid is used on the outer side of the open casing 11 so as to seal the loose rock stratum of the fourth system. Specifically, the size of one open bit was 444.5mm, and the inner diameter of one open casing 11 was 339.7mm. The first predetermined depth is greater than the fourth depth of the region or the bottom of an open borehole is below the shallow uncompacted formation. For example, the first preset depth is 200m or more.
In step S12, a two-way drill bit is used to drill down to a second predetermined depth, and a two-way casing 12 is disposed within the two-way drill bit to form a second wellbore section 15 of the first wellbore 1, the two-way casing 12 being cemented to the surface. Specifically, the size of the bi-parting drill bit is 311.1mm and the inside diameter of the bi-parting sleeve 12 is 244.5mm. The bottom of the secondary drilling hole (the second preset depth) is positioned near the upper part of the roof of the mined coal seam 5 and cannot exceed the depth of the roof. For example, the second preset depth is 500m or more. The two split sleeves 12 are positioned inside the one split sleeve 11.
In step S13, a triple drill bit is used to drill into the coal seam 5, and a triple casing is disposed within the triple drill bit to form a slant well section 14 and a first well section 13 located within the coal seam 5. The second wellbore section 15, the deflecting wellbore section 14 and the first wellbore section 13 are in communication in sequence. Specifically, the size of the three-open drill bit was 215.9mm, and the inner diameter of the three-open casing was 139.7mm. For example, the deviated wellbore section 14 may be in the depth range of 500m to 520 m. The three-open sleeve can prevent the horizontal well from being blocked due to collapse after the coal seam 5 is fractured, and is used for preparing perforation fracturing and reservoir modification.
In some embodiments, the first wellbore section 13 is constructed spread along a coal seam. The first interval 13 may be a horizontal interval or an inclined interval. Specifically, in step S13, the first wellbore section 13 extends along the coal seam 5. For example, the first well section 13 is a horizontal well section extending in the left-right direction, and the left side of the first well section 13 communicates with the lower port of the deflecting well section 13.
As shown in fig. 1 and 2, in step S2, a fracturing hole is opened into the coal seam 5 in the first well section 13. Specifically, directional perforation is performed in stages in the first wellbore section 13 in the direction of extension of the first wellbore section 13 in a direction adjacent to the casing section 3 so as to form fracturing holes. For example, directional jet fracturing holes are segmented from right to left in the first wellbore section 13.
In some embodiments, in step S2, a frac hole is opened in the first wellbore section 13 using the hydraulic injector 2. I.e. perforating with hydraulic power. For example, directional jet fracturing holes are staged from right to left in the first wellbore section 13 using the hydraulic injector 2.
As shown in fig. 1 and 2, in step S3, a fracturing fluid is injected into the fracturing aperture using a fracturing device to fracture the coal seam 5 and form a stress relief zone using the fracturing fluid. Specifically, after the fracturing fluid continues into the fracturing apertures, the coal seam 5 may be fractured with substantial pressure to form stress relief zones (crushed coal block areas) where gas may enter the first wellbore section 13 from the gaps between the coal blocks. For example, the fracturing fluid is water.
In some embodiments of the present invention, in some embodiments,in step S3, the pressure of the fracturing fluid injected into the fracturing holes is less than 30Mpa. Specifically, the pressure of the fracturing fluid injected into the fracturing holes is more than or equal to 20MPa and less than or equal to 25MPa, and a plurality of fracturing trucks are adopted for construction so that the flow rate of the fracturing fluid injected into the fracturing holes is more than or equal to 20m 3 And/min. Thereby ensuring the safety of the fracturing process and improving the fracturing efficiency.
As shown in fig. 1 and 2, after the stress relief zone is formed in step S4, the fracturing fluid in the first mine 1 is drained. Specifically, after the stress relief zone is formed, gas is flushed into the fracturing apertures and the first wellbore section 13, so that the fracturing fluid and the constructed coal fines carried by the fracturing fluid can be ejected from the wellhead of the first wellbore 1. The fracturing fluid that fails to be ejected can be pumped out through the pump body so that the gas is discharged out of the first mine 1.
In some embodiments, after the stress relief zone is formed in step S4, the flow rate of the fracturing fluid carrying the pulverized coal is greater than or equal to 5m by controlling the throttle valve on the wellhead of the first mine 1 3 /min is less than or equal to 6m 3 And/min. Specifically, a throttle valve is arranged on the wellhead of the first mine 1, and the discharge flow (speed) of the fracturing fluid can be regulated by controlling the throttle valve during the process of fracturing fluid discharge. Controlling the throttle valve to enable the flow of the fracturing fluid carrying pulverized coal to be sprayed out to be more than or equal to 5m 3 /min is less than or equal to 6m 3 And/min, the safety of gas production can be improved.
In some embodiments, after the completion of the injection of the fracturing fluid in step S4, the first well 1 is washed to flush the coal fines precipitated in the first well 1 to the surface, thereby reducing the coal fines of the first well 1 for vans gas.
As shown in fig. 1 and 2, in step S5, gas from the stress relief zone into the first wellbore section 13 is produced. Specifically, a drainage string is disposed in the first mine 1, and gas in the first mine 1 (the first well section 13) can be pumped by using the pumping arrangement.
In some embodiments, in step S4 and step S5, the first well 1 is drained and mined using a tubular pump and a pumping unit. That is, after the residual fracturing fluid is pumped out by the pipe pump and the pumping unit, the gas in the first mine 1 (the first well section 13) is pumped out by the pipe pump and the pumping unit.
Step S3, step S4 and step S5 are sequentially performed at least once. Specifically, step S3, step S4, and step S5 may be sequentially performed a plurality of times. When the daily gas production in the first wellbore section 13 decays below the specified value of the industrial gas flow, steps S3, S4 and S5 may be performed again in order to enlarge the area of the stress relief zone and to produce gas. Specifically, when the content in the first mine 1 (the first well section 13) is low, the drainage string is taken out by using the underground operation vehicle, the fracturing equipment is installed again, and the fracturing fluid is used again to fracture the coal seam 5 so as to fracture more coal seams, enlarge the stress relief zone and form a new stress relief zone. And (5) gas production is carried out after the fracturing fluid is discharged. Thereby, the area of the stress relief zone can be enlarged so that more gas enters the first well 1 (first well section 13). For example, after the coal seam 5 is fractured by the fracturing fluid for the first time, a first stress relief zone 41 is formed, and then drainage and gas production are performed; when the gas content is low, the second stress relief area 42 is formed after the coal seam 5 is fractured by the fracturing fluid for the second time, and then drainage and gas production are carried out.
As shown in fig. 1 and 2, in step S6, a main vertical shaft 3 in communication with the first well section 13 is constructed from the surface to produce the coal seam 5. Specifically, the main vertical shaft 3 communicates with an end of the first shaft section 13 remote from the inclined shaft section 14, so that the first mine 1 can serve as a ventilation shaft of the main vertical shaft 3. The main vertical shaft 3 has a larger diameter in order to transport equipment for mining the coal seam 5. For example, the main vertical shaft 3 communicates with the right side of the first well section 13.
In some embodiments, in step S6, a lifting device 31 is installed at the wellhead of the main shaft 3, and after the gas concentration in the main shaft 3 is less than 0.75%, the excavation work is performed from the main shaft 3 along the first shaft section 13 inlet roadway. Thus, the coal seam 5 which is already fractured can be conveniently mined, the mining difficulty can be reduced, and the safety of mining the coal seam 5 can be improved.
The combined production method of the structural coal and the gas according to the embodiment of the invention further comprises a step S7 of constructing a plurality of branch well sections positioned in the coal seam 5 from the first well section 13, and after the fracturing holes are formed in the branch well sections, sequentially implementing the step S3, the step S4 and the step S5 at least once in the branch well sections. That is, without constructing the second section 15, a branch section may be constructed from the first section 13. The coal seams 5 at different locations may be fractured in the branch wellbore section to form stress relief zones within the coal seams 5 at the different locations to produce gas within the coal seams 5 at the different locations. While the branch wellbore section is being produced, a first wellbore section 13 may be plugged at a partial location. Thereby increasing the efficiency of gas production.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
For purposes of this disclosure, the terms "one embodiment," "some embodiments," "example," "a particular example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the invention.
Claims (10)
1. A method for combined production of structural coal and gas, comprising the steps of:
s1, constructing a first mine from the ground and enabling a first well section of the first mine to be located in a coal seam;
s2, forming fracturing holes in the first well section into the coal layer;
s3, injecting fracturing fluid into the fracturing holes by utilizing fracturing equipment so as to fracture the coal seam by utilizing the fracturing fluid and form a stress relief area;
s4, after the stress release area is formed, discharging the fracturing fluid in the first mine;
s5, gas entering the first well section from the stress release area is produced;
s6, constructing a main vertical shaft communicated with the first well section from the ground so as to mine the coal seam;
wherein, the step S3, the step S4 and the step S5 are sequentially performed at least once.
2. The combined production method of structural coal and gas according to claim 1, wherein the step S1 comprises
S11, drilling from the ground by using a drill bit, wherein the drill bit vertically drills down to a first preset depth, a casing pipe is arranged in the drill bit, and cementing fluid is used on the outer side of the casing pipe so as to seal a fourth series of loose rock stratum;
s12, using a two-way drill bit to drill downwards to a second preset depth, arranging two-way sleeves in the two-way drill bit so as to form a second well section of the first mine, and cementing the two-way sleeves to the ground;
s13, drilling into a coal seam by using a three-way drill bit, and arranging three-way sleeves in the three-way drill bit so as to form an inclined well section and a first well section positioned in the coal seam, wherein the second well section, the inclined well section and the first well section are communicated in sequence.
3. The method for combined production of structural coal and gas according to claim 2, wherein,
in step S13, the first well section extends along the coal seam strike;
the size of the one-open drill bit is 444.5mm, and the inner diameter of the one-open casing pipe is 339.7mm;
the size of the two-open drill bit is 311.1mm, and the inner diameter of the two-open casing pipe is 244.5mm;
the size of the three-opening drill bit is 215.9mm, and the inner diameter of the three-opening casing pipe is 139.7mm.
4. The method for combined production of structural coal and gas according to claim 1, wherein,
in the step S2, a fracturing hole is formed in the first well section 13 by using the hydraulic injector 2;
in the step S3, the pressure of the fracturing fluid injected into the fracturing holes is less than 30MPa;
in the step S3, the flow rate of the fracturing fluid injected into the fracturing holes is more than or equal to 20m 3 /min。
5. The method for combined production of structural coal and gas according to claim 4, wherein in the step S3, the pressure of the fracturing fluid injected into the fracturing holes is 20MPa or more and 25MPa or less.
6. The method according to claim 1, wherein in step S4, after the stress relief zone is formed, a flow rate of the fracturing fluid ejected with pulverized coal is controlled to be 5m or more by controlling a throttle valve on a wellhead of the first mine 3 /min is less than or equal to 6m 3 /min。
7. The method for combined production of structural coal and gas according to claim 6, wherein,
in the step S4, after the fracturing fluid is completely sprayed out, flushing the first mine so as to flush the coal dust precipitated in the first mine to the ground;
in the step S4 and the step S5, the first mine is drained and the gas is produced by using a tubular pump and a pumping unit.
8. The method of combined production of structural coal and gas according to claim 1, wherein when daily gas production in the first wellbore section decays below an industrial gas flow specification, the steps S3, S4 and S5 are performed again in order to expand the area of the stress relief zone and produce gas.
9. The method according to claim 1, wherein in step S6, a lifting device is installed at the wellhead of the main shaft, and after the gas concentration in the main shaft direction is less than 0.75%, the main shaft is excavated along the first shaft section inlet roadway.
10. The method of combined production of structural coal and gas according to any one of claims 1 to 9, further comprising the step S7 of constructing a plurality of branch well sections located in a coal seam from the first well section, and after the fracturing holes are opened in the branch well sections, sequentially performing the step S3, the step S4 and the step S5 at least once in the branch well sections.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310752760.7A CN116733523A (en) | 2023-06-25 | 2023-06-25 | Combined production method of structural coal and gas |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310752760.7A CN116733523A (en) | 2023-06-25 | 2023-06-25 | Combined production method of structural coal and gas |
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| CN116733523A true CN116733523A (en) | 2023-09-12 |
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| CN202310752760.7A Pending CN116733523A (en) | 2023-06-25 | 2023-06-25 | Combined production method of structural coal and gas |
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