CN112302578B - Method for exploiting structural coal bed gas by horizontal well stress release - Google Patents
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- 239000003245 coal Substances 0.000 title claims abstract description 93
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000012530 fluid Substances 0.000 claims abstract description 44
- 238000005488 sandblasting Methods 0.000 claims abstract description 31
- 238000004519 manufacturing process Methods 0.000 claims abstract description 29
- 238000005553 drilling Methods 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000000843 powder Substances 0.000 claims abstract description 8
- 238000011084 recovery Methods 0.000 claims abstract description 8
- 238000007599 discharging Methods 0.000 claims abstract description 3
- 238000002347 injection Methods 0.000 claims description 35
- 239000007924 injection Substances 0.000 claims description 35
- 238000005406 washing Methods 0.000 claims description 9
- 238000005065 mining Methods 0.000 claims description 8
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 239000011435 rock Substances 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000009933 burial Methods 0.000 claims description 2
- 239000002817 coal dust Substances 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 10
- 230000000694 effects Effects 0.000 abstract description 7
- 238000003795 desorption Methods 0.000 abstract description 3
- 238000011010 flushing procedure Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 39
- 230000008901 benefit Effects 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
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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
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/261—Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation
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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
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/046—Directional drilling horizontal drilling
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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
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/06—Deflecting the direction of boreholes
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Abstract
A method for exploiting tectonic coal bed gas by horizontal well stress relief comprises the following steps: (a) constructing an L-shaped horizontal well along the direction of the stratum, drilling a horizontal well section in a structural coal top plate, and then putting a technical casing for well cementation after drilling; (b) the hydraulic jet is put into the hydraulic jet to carry out hydraulic sand blasting directional perforation from the far end to the near end; (c) injecting active water fracturing fluid from a wellhead by adopting a light sleeve fracturing mode after perforation; (d) adjusting a fracturing wellhead throttling valve to enable fracturing fluid and coal powder to be sprayed out from the wellhead quickly; (e) flushing the well after blowout, and putting into a drainage and production pipe column for drainage and gas production; (f) and when the daily gas production of the horizontal well is reduced to be below the industrial gas flow, taking out the discharging and extracting pipe column, and repeatedly injecting the fracturing fluid and performing the quick open flow process. The invention utilizes the solid-liquid-gas transportation channel formed by hydraulic sand-blasting perforation, and accelerates the desorption and seepage output of the tectonic coal coalbed methane by the stress release effect of the open flow of the fracturing fluid on the tectonic coal reservoir, thereby obviously improving the recovery ratio of the tectonic coal coalbed methane.
Description
Technical Field
The invention relates to a method for exploiting structural coal bed gas by horizontal well stress release, in particular to a method which is suitable for rapidly huffing and puff fracturing fluid in an L-shaped horizontal well and carrying pulverized coal to move, causes the release of ground stress to exploit the structural coal bed gas, and improves the recovery ratio of the structural coal bed gas, and belongs to the technical field of coal bed gas ground exploitation.
Background
The coal bed gas resources in China are rich, and the geological resource quantity of shallow coal bed gas with the predicted buried depth of 2000m reaches 36.8 multiplied by 1012m3And the amount of the natural gas is equivalent to that of the conventional natural gas resource. The coal bed gas is developed in a large scale, so that the situation of shortage of conventional oil gas energy in China can be relieved, the probability of coal mine gas accidents is reduced, the emission of greenhouse gases in coal mine production is reduced, and remarkable economic, environmental, safety and social benefits can be generated.
The thickness of the coal bed of the constructed coal in China, represented by the Yunnan east of Qian West, the two Huai nationality and the West edge of the Ordos basin, is large, the distribution is wide, and the resource quantity and the resource development potential of the coal bed gas are huge. Because the tectonic coal reservoir has the characteristics of high original ground stress, low permeability, high hydraulic fracturing transformation difficulty and the like, the traditional vertical well and horizontal well fracturing technology is difficult to obtain a better coal bed methane exploitation effect. In order to comprehensively promote the development work of the coal bed gas in the tectonic coal development area in China, the problems that the tectonic coal reservoir is poor in reconstruction effect in the traditional vertical well and horizontal well fracturing mode, the release degree of the protective layer pressure relief stress of a mining area is low and the like need to be solved, and new technology and new method for the stress release mining of the tectonic coal in-situ coal bed gas horizontal well are actively explored so as to obviously improve the ground development effect of the tectonic coal bed gas.
Disclosure of Invention
The technical problem is as follows: the invention aims to overcome the defects in the prior art and provide a method for exploiting tectonic coal bed gas by horizontal well stress release, which aims to solve the problems that the traditional vertical well and horizontal well fracturing has poor reconstruction effect on tectonic coal reservoirs, the tectonic coal bed gas has high desorption difficulty and seepage resistance, and a coal bed gas production well has short high-yield time, difficult stable production, low resource recovery ratio and the like.
The technical scheme is as follows: the invention discloses a method for exploiting structural coal bed gas by horizontal well stress release, which comprises the following steps:
(a) constructing an L-shaped horizontal well along the direction of the regional stratum at the position of 300-500 m of the buried depth of the target structural coal seam, wherein the L-shaped horizontal well is of a three-opening structure, a first-opening surface casing well cementation seals the upper loose stratum, a second-opening technical casing well cementation ensures safe drilling of a horizontal well section, the third opening is drilled in the top plate of the target structural coal seam, and a production casing is put into the horizontal well section after the third opening is drilled to prepare for perforation fracturing transformation;
(b) a hydraulic ejector is put into the L-shaped horizontal well, subsection hydraulic sand blasting directional perforation is carried out on the horizontal well section from the far end to the near end, and the length of a single sand blasting perforation section and the central distance of two sand blasting perforation sections are set;
(c) mounting a fracturing wellhead after sand blasting and perforating, injecting active water fracturing fluid from the wellhead by adopting a light sleeve injection fracturing mode, controlling the injection pressure in the injection process, wherein the highest injection pressure is less than 25MPa, and controlling the injection amount of the fracturing fluid;
(d) after the fracturing fluid is injected, a throttle valve of a fracturing wellhead is opened and adjusted, so that the injected fracturing fluid carries a large amount of coal powder in a target structure coal seam to be quickly sprayed out under the action of high pressure of the stratum, the stress of the target structure coal seam is released, and a first stress release area is formed; installing a solid-liquid separation device at a wellhead, and storing the fracturing fluid after the coal powder is separated out for reuse;
(e) after the open flow of the fracturing fluid is finished, putting the fracturing fluid into a well washing pipe column to wash a well in a positive circulation mode, and washing the coal powder precipitated in the shaft to the ground; after washing the well, putting a drainage and production pipe column and installing a drainage and production wellhead for drainage and gas production in the period of 1 year;
(f) when the daily gas production of the L-shaped horizontal well is attenuated to be below the specified value of the industrial gas flow, the discharging and extracting pipe column is taken out by using the underground operation vehicle, a fracturing wellhead is installed, the fracturing fluid is repeatedly injected into the shaft and the rapid open flow process is repeated, the stress release range of the target structure coal seam (1) is expanded, and a secondary stress release area is generated.
In the step (a), one opening and two openings in a three-opening structure of the L-shaped directional well are drilled in an overlying rock stratum of a target structure coal seam, the three openings are drilled in a top plate of the target structure coal seam to be 400-500 m, and the drilling track of the horizontal well section is 0-0.5 m away from the top surface of the target structure coal seam, so that the target structure coal seam (1) is directly communicated with a shaft after hydraulic sand blasting.
In the step (b), the segmental hydraulic sand blasting directional perforation is carried out, the length of a single set sand blasting perforation section is 8-10m, the central distance between two sand blasting perforation sections is 30-40 m, the sand blasting perforation density is 20-24 holes/m, the diameter of an eyelet is 15-17 mm, and the direction of the directional perforation is within the range of a cone (10) which is right below, left and right, and front and back within 45 degrees.
In the step (c), when the L-shaped horizontal well is injected with the active water fracturing fluid for the first time, 6-7 2500 type fracturing trucks are adopted for construction so as to ensure that the highest injection displacement exceeds 15m3/min。
In the step (c), the injection pressure is controlled to be 15-20 MPa in the injection process, and the injection amount of the fracturing fluid is controlled to be 300-400 m per 100m horizontal well section3。
In the step (d), the throttle valve for adjusting the fracturing wellhead controls the fracturing fluid to carry pulverized coal to be sprayed out from the wellhead at a speed of 4-6 m3/min。
In the step (e), the drainage and gas recovery mode is as follows:
the method comprises the following steps of (1) draining and gas recovery are carried out by adopting a 'tubular pump and a pumping unit', the tubular pump is driven to the bottom of a straight well section of the L-shaped horizontal well, and a middle-short radius deflecting screw drilling tool is required to be adopted for drilling in an increasing deflection section of the L-shaped horizontal well;
and (3) draining and gas production are carried out by adopting a jet pump, the jet pump is driven to the inclination increasing section of the L-shaped horizontal well, and the curvature radius of the inclination increasing section of the L-shaped horizontal well is not required.
In the step (f), when the active water fracturing fluid is repeatedly injected into the shaft, 4-6 high-pressure plunger pumps are connected in parallel to perform injection operation, so that the highest injection displacement can reach 9m3Min, controlling the stable injection pressure to be 8-10 MPa; after fracturing fluid is repeatedly injected, the fast open flow speed is controlled to be 4-6 m3/min。
Has the advantages that: due to the adoption of the technical scheme, the method for exploiting the tectonic coal bed gas by horizontal well stress release is adopted, and the reservoir pressure excitation and the stress release in the tectonic coal pressurized area are caused based on the carrying effect of the rapid flowback of the fracturing fluid on the tectonic coal pulverized coal, so that the desorption and seepage of the tectonic coal bed gas in the stress release area can be promoted, the gas production effect of the coal bed gas horizontal well is obviously improved, compared with the hydraulic sand-adding fracturing reformation technology adopted by the vertical well and the horizontal well widely adopted for the development of the tectonic coal bed gas in southwest, northwest and northeast areas of China, the resource recovery ratio of the tectonic coal bed gas in the well control range is improved, the ground exploitation engineering and equipment investment of the coal bed gas are saved, and better economic, environmental and social benefits are obtained. The method is simple, convenient to operate and has wide practicability in the technical field.
Drawings
Fig. 1 is a schematic diagram of a horizontal well stress relief mining method for tectonic coal seam gas according to the present invention.
In the figure: 1-purpose formation of coal seam; 2-L-shaped horizontal well; 3-surface casing pipe; 4-technical sleeve; 5-horizontal well section; 6, producing the sleeve; 7-a hydraulic ejector; 8, length of a jet perforation segment; 9-center distance of the sand blasting perforation section; 10-directional sand blasting perforation cone; 11 — first secondary stress relief region; 12-a second stress relief zone; 13-radius of curvature of the ramp section.
Detailed Description
The invention will be further described with reference to examples in the drawings to which:
as shown in fig. 1, the method for exploiting structural coal bed gas by horizontal well stress release of the invention comprises the following specific steps:
(a) constructing an L-shaped horizontal well 2 along the direction of the regional stratum at the position of 300-500 m of the burial depth of a target structure coal seam 1, wherein the L-shaped horizontal well 2 is of a three-opening structure, a first-opening surface casing 3 is used for cementing and sealing the upper loose stratum, a second-opening technical casing 4 is used for cementing and ensuring safe drilling of a horizontal well section 5, the third opening is used for drilling in the top plate of the target structure coal seam 1, and a production casing 6 is used for cementing after the third opening is finished, so that preparation is made for perforation fracturing reconstruction; one and two openings in a three-opening structure of the L-shaped directional well 2 are drilled in an overlying rock layer of the target structure coal seam 1, the three openings are drilled in a top plate of the target structure coal seam 1 for 400-500 m, and the drilling track of the horizontal well section 5 is 0-0.5 m away from the top surface of the target structure coal seam 1, so that the target structure coal seam 1 is directly communicated with a shaft after hydraulic sand blasting. The specific process for constructing the L-shaped horizontal well 2 is as follows:
(1) drilling an L-shaped horizontal well 2 to a diameter phi of 444.5mm, drilling to 15m below bedrock, putting a J55 steel-grade surface casing with an outer diameter phi of 339.7mm, cementing, and returning cementing cement slurry to the ground;
(2) the secondary drilling diameter phi of the L-shaped horizontal well 2 is 311.1mm, the screw tool is inclined and directionally drilled to 1-2 m above the target coal seam 1 to complete drilling, a J55 steel-grade production casing with the outer diameter phi of 244.5mm is put in and well cementation is carried out, and secondary well cementation cement slurry returns to 200m above the target structural coal seam 1;
(3) and (3) drilling the L-shaped horizontal well 2 with three openings with the diameter phi of 215.9mm, drilling the L-shaped horizontal well to a final hole along the target structural coal seam 1, putting an N80 steel-grade production casing with the outer diameter phi of 139.7mm, cementing the well, and returning the three-opening cementing cement slurry to 200m above the target structural coal seam 1.
(b) A hydraulic ejector 7 is arranged in the L-shaped horizontal well 2, subsection hydraulic sand blasting directional perforation is carried out on the horizontal well section 5 from the far end to the near end, and the length 8 of a single sand blasting perforation section and the central distance 9 of two sand blasting perforation sections are set; and carrying out subsection hydraulic sand blasting oriented perforation, wherein the length 8 of a set single sand blasting perforation section is 8-10m, the center distance 9 of two sand blasting perforation sections is 30-40 m, the density of the sand blasting perforation is 20-24 holes/m, the diameter of the perforation is 15-17 mm, and the direction of the oriented perforation is within the range of 10 cones within 45 degrees from left to right and front to back under the direction of the oriented perforation.
(c) Installing a fracturing wellhead after sand blasting and perforating, injecting active water fracturing fluid from the wellhead by adopting a light sleeve injection fracturing mode, controlling the injection pressure in the injection process, controlling the injection pressure to be 15-20 MPa and the highest injection pressure to be less than 25MPa in the injection process, and controlling the injection amount of the fracturing fluid to be 300-400 m per 100m horizontal well section3. When the L-shaped horizontal well 2 is injected with the active water fracturing fluid for the first time, 6-7 2500 fracturing trucks are adopted for construction so as to ensure that the highest injection displacement exceeds 15m3/min；
(d) After the fracturing fluid is injected, a throttle valve of a fracturing well head is opened and adjusted, the throttle valve of the fracturing well head is adjusted, and the speed of controlling the fracturing fluid to carry pulverized coal to be sprayed out from the well head quickly is 4-6 m3The injected fracturing fluid is enabled to carry a large amount of coal dust in the target structure coal seam 1 to be rapidly sprayed out under the action of high pressure of the stratum, so that the stress of the target structure coal seam 1 is released, and a first stress release area 11 is formed; installing a solid-liquid separation device at a wellhead, and storing the fracturing fluid after the coal powder is separated out for reuse;
(e) after the open flow of the fracturing fluid is finished, putting the fracturing fluid into a well washing pipe column to wash a well in a positive circulation mode, and washing the coal powder precipitated in the shaft to the ground; after washing the well, putting a drainage and production pipe column and installing a drainage and production wellhead for drainage and gas production in the period of 1 year; the drainage and gas production mode is as follows:
the 'tubular pump + oil pumping unit' is adopted for drainage and gas recovery, the tubular pump is lowered to the bottom of a straight well section of the L-shaped horizontal well (2), and the L-shaped horizontal well is required to be drilled in an inclination increasing section by adopting a middle-short radius inclination-making screw drilling tool;
and (3) draining and gas production are carried out by adopting a jet pump, the jet pump is driven to the inclination increasing section of the L-shaped horizontal well, and the curvature radius (13) of the inclination increasing section of the L-shaped horizontal well is not required at the moment.
(f) When the daily gas production of the L-shaped horizontal well 2 is reduced to be lower than the specified value of the industrial gas flow, the underground operation vehicle is utilizedTaking out the drainage and production pipe column, installing a fracturing wellhead, repeatedly injecting fracturing fluid into a shaft and performing a quick open flow process, expanding the stress release range of the target formation coal seam 1 and generating a second stress release area 12; when active water fracturing fluid is repeatedly injected into a shaft, 4-6 high-pressure plunger pumps are connected in parallel to carry out injection operation, so that the highest injection displacement can reach 9m3Min, controlling the stable injection pressure to be 8-10 MPa; after fracturing fluid is repeatedly injected, the fast open flow speed is controlled to be 4-6 m3/min。
Claims (6)
1. A method for exploiting structural coal bed gas by horizontal well stress release is characterized by comprising the following steps:
(a) constructing an L-shaped horizontal well (2) along the direction of a regional stratum at the position of 300-500 m of the burial depth of a target structural coal seam (1), wherein the L-shaped horizontal well (2) is of a three-opening structure, a first-opening surface casing (3) is used for cementing and sealing an upper loose stratum, a second-opening technical casing (4) is used for cementing to ensure that a horizontal well section (5) is safely drilled, a third opening is drilled in a top plate of the target structural coal seam (1), and a production casing (6) is used for cementing after the drilling of the third opening is finished to prepare for perforation fracturing reconstruction; one opening and the other opening in a three-opening structure of the L-shaped horizontal well (2) are drilled in an overlying rock stratum of the target structure coal seam (1), the three openings are drilled in a top plate of the target structure coal seam (1) for 400-500 m, and the drilling track of the horizontal well section (5) is 0-0.5 m away from the top surface of the target structure coal seam (1) so as to ensure that the target structure coal seam (1) is directly communicated with a shaft after hydraulic sand blasting and perforating;
(b) a hydraulic ejector (7) is arranged in the L-shaped horizontal well (2) in a downward mode, subsection hydraulic sand blasting directional perforation is conducted on the horizontal well section (5) from the far end to the near end, and the length (8) of a single sand blasting perforation section and the central distance (9) of two sand blasting perforation sections are set;
(c) mounting a fracturing wellhead after sand blasting and perforating, injecting active water fracturing fluid from the wellhead by adopting a light sleeve injection fracturing mode, controlling the injection pressure in the injection process, wherein the highest injection pressure is less than 25MPa, and controlling the injection amount of the fracturing fluid;
(d) after the fracturing fluid is injected, a throttle valve of a fracturing wellhead is opened and adjusted, so that the injected fracturing fluid carries a large amount of coal dust in the target structure coal seam (1) to be quickly sprayed out under the action of high pressure of a stratum, the stress of the target structure coal seam (1) is released, and a primary stress release area (11) is formed; installing a solid-liquid separation device at a wellhead, and storing the fracturing fluid after the coal powder is separated out for reuse;
(e) after the open flow of the fracturing fluid is finished, putting the fracturing fluid into a well washing pipe column to wash a well in a positive circulation mode, and washing the coal powder precipitated in the shaft to the ground; after washing the well, putting a drainage and production pipe column and installing a drainage and production wellhead for drainage and gas production in the period of 1 year; the drainage and gas production mode is as follows:
the 'tubular pump + oil pumping unit' is adopted for drainage and gas recovery, the tubular pump is lowered to the bottom of a straight well section of the L-shaped horizontal well (2), and the L-shaped horizontal well is required to be drilled in an inclination increasing section by adopting a middle-short radius inclination-making screw drilling tool;
a jet pump is adopted for water drainage and gas production, the jet pump is driven to the inclination increasing section of the L-shaped horizontal well, and the curvature radius (13) of the inclination increasing section of the L-shaped horizontal well is not required;
(f) when the daily gas yield of the L-shaped horizontal well (2) is reduced to be below the specified value of the industrial gas flow, the discharging and extracting pipe column is taken out by using the underground operation vehicle, a fracturing wellhead is installed, the fracturing fluid is injected into the shaft and the rapid open flow process is repeated, the stress release range of the target structure coal seam (1) is expanded, and a secondary stress release area (12) is generated.
2. The method for horizontal well stress relief mining of tectonic coal seam gas according to claim 1, characterized in that: in the step (b), the segmental hydraulic sand blasting directional perforation is carried out, the length (8) of a single sand blasting perforation section is set to be 8-10m, the central distance (9) between the two sand blasting perforation sections is 30-40 m, the density of the sand blasting perforation is 20-24 holes/m, the diameter of each hole is 15-17 mm, and the direction of the directional perforation is within the range of a cone (10) which is right below, left and right and front and back 45 degrees.
3. The method for horizontal well stress relief mining of tectonic coal seam gas according to claim 1, characterized in that: in the step (c), the L-shaped waterWhen active water fracturing fluid is injected into the horizontal well (2) for the first time, 6-7 2500 type fracturing trucks are adopted for construction so as to ensure that the highest injection displacement exceeds 15m3/min。
4. The method for horizontal well stress relief mining of tectonic coal seam gas according to claim 1, characterized in that: in the step (c), the injection pressure is controlled to be 15-20 MPa in the injection process, and the injection amount of the fracturing fluid is controlled to be 300-400 m per 100m horizontal well section3。
5. The method for horizontal well stress relief mining of tectonic coal seam gas according to claim 1, characterized in that: in the step (d), the throttle valve for adjusting the fracturing wellhead controls the fracturing fluid to carry pulverized coal to be sprayed out from the wellhead at a speed of 4-6 m3/min。
6. The method for horizontal well stress relief mining of tectonic coal seam gas according to claim 1, characterized in that: in the step (f), when the active water fracturing fluid is repeatedly injected into the shaft, 4-6 high-pressure plunger pumps are connected in parallel to perform injection operation, so that the highest injection displacement can reach 9m3Min, controlling the stable injection pressure to be 8-10 MPa; after fracturing fluid is repeatedly injected, the fast open flow speed is controlled to be 4-6 m3/min。
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| CN113155615A (en) * | 2021-04-26 | 2021-07-23 | 中国石油大学(北京) | Casing-cement interface fracture toughness testing method |
| CN113530497B (en) * | 2021-09-17 | 2021-12-07 | 中煤科工集团西安研究院有限公司 | Turning radial well device and sectional guiding horizontal fracturing well coal bed gas extraction method |
| CN114439428B (en) * | 2021-12-30 | 2023-08-25 | 中煤科工集团西安研究院有限公司 | Enhanced extraction method for coal bed gas horizontal well of coal group under goaf group |
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