CN114165196A - Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine - Google Patents
Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine Download PDFInfo
- Publication number
- CN114165196A CN114165196A CN202111478209.5A CN202111478209A CN114165196A CN 114165196 A CN114165196 A CN 114165196A CN 202111478209 A CN202111478209 A CN 202111478209A CN 114165196 A CN114165196 A CN 114165196A
- Authority
- CN
- China
- Prior art keywords
- well
- goaf
- extraction
- fracturing
- situ
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003245 coal Substances 0.000 title claims abstract description 150
- 238000000605 extraction Methods 0.000 title claims abstract description 131
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000005553 drilling Methods 0.000 claims abstract description 49
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000007789 gas Substances 0.000 claims description 48
- 239000004568 cement Substances 0.000 claims description 31
- 238000011065 in-situ storage Methods 0.000 claims description 24
- 239000012530 fluid Substances 0.000 claims description 15
- 238000005065 mining Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 239000004576 sand Substances 0.000 claims description 9
- 238000005452 bending Methods 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 230000000903 blocking effect Effects 0.000 claims description 4
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 239000002699 waste material Substances 0.000 abstract description 7
- 230000005012 migration Effects 0.000 abstract description 5
- 238000013508 migration Methods 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 206010017076 Fracture Diseases 0.000 description 18
- 208000010392 Bone Fractures Diseases 0.000 description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 239000011435 rock Substances 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 239000006004 Quartz sand Substances 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000000844 anti-bacterial effect Effects 0.000 description 2
- 239000003899 bactericide agent Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000005476 size effect Effects 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000001550 time effect Effects 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/006—Production of coal-bed methane
-
- 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
-
- 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
- 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
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
-
- 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
- E21B43/30—Specific pattern of wells, e.g. optimising the spacing of wells
-
- 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
-
- 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
- E21B7/20—Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes
Landscapes
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Physics & Mathematics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
Abstract
The invention discloses a closed coal mine in-situ-goaf coalbed methane comprehensive high-efficiency extraction method, which comprises the following steps of a, obtaining geological conditions for closing a coal mine goaf; b, positioning the drilling positions of the fracturing well and the extraction well; c, drilling to construct the fracturing well; d, communicating the fracturing well with the goaf; e, drilling to construct the extraction well; and f, extracting coal bed gas. The method for closing the coal mine in-situ-goaf coalbed methane comprehensive efficient extraction has a simple structure, reasonably arranges the fracturing wells and the extraction wells based on the coalbed methane occurrence migration rule, and forms the coalbed methane in the coal mine in-situ-goaf into a unified and communicated gas-containing system, thereby improving the extraction efficiency, reducing the waste of extraction resources, reducing the extraction difficulty and danger, and being beneficial to the reasonable utilization of the resources.
Description
Technical Field
The invention relates to the technical field of coal bed gas development, in particular to a comprehensive high-efficiency extraction method for closing coal bed gas in a coal mine in-situ-goaf.
Background
China sets a capacity removal target of the coal industry, obsolete capacity is actively eliminated between 2016 and 2019, the obsolete capacity is accumulated to be eliminated by 9.2 hundred million tons in the coal industry of China, and the quantity of closed coal mines of China reaches 1.5 million predicted in 2030. Direct closing or abandonment of the mine results in huge waste of resources and may also induce safety, environmental and social problems. On one hand, after the coal seam is mined, the working face roof falls off to form a goaf, and residual methane gas in the coal seam and the coal-series mud shale is transported to a fracture zone through fractures to be enriched and stored; on the other hand, a part of coal bed gas resources still exist in the in-situ coal bed which is not influenced by mining in the mine range; the two parts of coal bed gas resources are comprehensively utilized and extracted, so that the resource waste can be reduced, and the cost is saved; meanwhile, the method can bring remarkable social and economic benefits.
The existing goaf coal bed gas ground extraction methods are more, and generally include methods of ground vertical well extraction, "L" -shaped well extraction, horizontal well extraction and the like; but the method can simultaneously consider that the in-situ coal bed gas resources and the goaf resources which are not influenced by mining in the mining area are less, and the patent CN112796712A discloses a goaf and coal bed fracturing comprehensive extraction method, which takes the problem into consideration, but neglects the development condition of multiple coal beds and the objective rule of coal bed gas migration in the goaf, and has low coal bed gas extraction efficiency and total extraction amount.
Disclosure of Invention
The invention aims to provide a comprehensive high-efficiency extraction method for closing coal bed gas in a coal mine in-situ-goaf, which aims to solve the problems in the prior art.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a comprehensive high-efficiency extraction method for closing coal bed gas in a coal mine in-situ-goaf, which comprises the following steps:
step a, obtaining geological conditions for closing a coal mine goaf;
b, positioning the drilling positions of the fracturing well and the extraction well;
c, drilling to construct the fracturing well;
d, communicating the fracturing well with the goaf;
e, drilling to construct the extraction well;
and f, extracting coal bed gas.
Preferably, in the step a, the method for obtaining the geological condition of closing the coal mine goaf is to establish a goaf geological model and simulate the height of a caving zone, a fissure zone and a bending subsidence zone after mining and the development range of an O-shaped ring.
Preferably, in the step b, the position of the fracturing well is selected to be on an in-situ coal seam 130-170 m away from the goaf; the extraction well is arranged on the O-shaped ring of the goaf close to the ore bed and is positioned on the same horizontal axis with the fracturing well.
Preferably, in the step c, the first fracturing well is drilled to 20-30 m below bedrock, a surface casing is put into the first fracturing well, and cement is used for cementing the first fracturing well and the first fracturing well is raised to the ground surface; and drilling the second fracturing well to 10-20 m below the lower coal seam, putting a production casing, cementing the well by using cement, and returning to the ground surface.
Preferably, in the step d, the step of communicating the fracturing well with the gob is perforating, fracturing and sand adding.
Preferably, in the step d, the upper coal seam and the lower coal seam are fractured in a layering manner in the fracturing step, and fracturing fluid is used as a medium in the fracturing step to fracture in the peripheral direction of the fracturing well.
Preferably, in the step d, the step of adding sand is to fill proppant into the fractured fractures of the upper coal seam and the lower coal seam to prevent the fractures from being closed and blocking seepage channels.
Preferably, in the step e, the extraction well is drilled to 20m-30m below bedrock, the surface casing is put into the extraction well, cement is used for cementing the extraction well, and the extraction well returns to the ground surface; drilling the extraction well II to the top of the bent subsidence zone, putting a technical casing, cementing the well by using cement, and returning the well to the ground surface; and drilling the extraction well III to the bottom of the fractured zone, and putting a sieve hole pipe into the extraction well III, wherein the sieve hole pipe is fixedly connected to the bottom end in the technical casing in a hanging manner.
Preferably, in the step d, in order to ensure the drilling safety of the extraction well, compressed air is used as an internal circulation medium for the first opening and the second opening of the extraction well; and the three openings of the extraction well use nitrogen as an internal circulation medium.
Preferably, in the step e, the step of extracting the coal bed gas is to seal the well mouth of the fracturing well, and perform negative pressure extraction from the well mouth of the extraction well through a ground extraction device.
The invention discloses the following technical effects: the invention discloses a closed coal mine in-situ-goaf coalbed methane comprehensive high-efficiency extraction method, which comprises the steps of arranging a fracturing well in an in-situ coalbed near a closed coal mine goaf, fracturing multiple layers of in-situ coalbeds, manufacturing fracturing cracks, communicating the fracturing wells with the goaf, and unifying a gas-containing system; an extraction well is arranged on the O-shaped ring of the goaf for extraction, the well body structure is optimized, and the extraction efficiency is improved; the in-situ coal bed is communicated with the goaf through the fracturing seams, the coal bed gas of the in-situ coal bed is collected through the negative pressure of the goaf, the coal bed gas resource is used to the maximum extent, the extraction is convenient, the extraction efficiency is improved, the extraction residue is reduced, and the resource waste is reduced. The method for closing the coal mine in-situ-goaf coalbed methane comprehensive efficient extraction has a simple structure, reasonably arranges the fracturing wells and the extraction wells based on the occurrence migration rule of the coalbed methane, and forms the coalbed methane in the coal mine in-situ-goaf into a unified and communicated gas-containing system, thereby improving the extraction efficiency, reducing the extraction participation waste, reducing the extraction difficulty and danger, and being beneficial to the reasonable utilization of resources.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a structural diagram of a closed coal mine in-situ-goaf coalbed methane comprehensive efficient extraction system;
FIG. 2 is a schematic of the fracturing process of the present invention;
FIG. 3 is a schematic diagram of the principles of the present invention;
wherein, 1, fracturing a well; 2. extracting a well; 3. firstly, opening a well cementation cement sheath; 4. a surface casing; 5. secondly, opening a well cementation cement sheath; 6. producing a sleeve; 7. putting a coal seam; 8. an interbedded rock formation; 9. a coal seam is laid; 10. pressing cracks; 11. a technical sleeve; 12. a hanger; 13. a perforated pipe; 14. bending the sinking belt; 15. a fissure zone; 16. a collapse zone; 17. an "O" ring; 18. mining a crack; 19. the direction of gas transport; 20. a gob; 21. a ground extraction device; 22. the earth surface; 23. and a through hole.
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.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Referring to fig. 1-3, the invention provides a comprehensive high-efficiency extraction method for closing coal bed gas in a coal mine in-situ-goaf, which comprises the following steps:
step a, obtaining geological conditions for closing a coal mine goaf;
b, positioning the drilling positions of the fracturing well 1 and the extraction well 2;
c, drilling construction fracturing well 1;
d, communicating the fracturing well 1 with the goaf 20;
e, drilling construction extraction wells 2;
and f, extracting coal bed gas.
The invention discloses a closed coal mine in-situ-goaf coalbed methane comprehensive high-efficiency extraction method, which comprises the steps of arranging fracturing wells 1 at in-situ coal bed distribution positions near a closed coal mine goaf 20, fracturing multiple layers of in-situ coal beds, manufacturing fracturing cracks 10, communicating the goaf 20 and unifying a gas-containing system; arranging the extraction wells 2 in the goaf 20 for extraction, optimizing the well body structure and improving the extraction efficiency; the in-situ coal bed is communicated with the goaf 20 through the pressure cracks 10, the coal bed gas of the in-situ coal bed is collected through the negative pressure of the goaf 20, the coal bed gas resources are used to the maximum extent, extraction is convenient, the extraction efficiency is improved, the extraction residues are reduced, and the resource waste is reduced.
In the step a, the method for obtaining the geological condition for closing the coal mine goaf is to establish a goaf 20 geological model and simulate the heights of a caving zone 16, a fissure zone 15 and a bending subsidence zone 14 and the development range of an O-shaped ring 17 after mining. Rock mechanical parameters can be obtained by closing a geological report and a pit closing report of a coal mine, a geological model of the goaf 20 can be established through software simulation deduction, geological conditions of the goaf 20 are displayed vividly, and data support is provided for coal bed gas exploitation and positioning of the fracturing well 1 and the extraction well 2.
Furthermore, rock mechanical parameters including but not limited to tensile strength, shear strength, bulk modulus and the like of a coal seam roof and a coal seam floor are extracted from a mine geological report and a closed pit report of a closed coal mine, a three-dimensional geological model of a goaf 20 can be established through 3DEC software, stoping of a working face is simulated, and the height of a caving zone 16, a fractured zone 15 and a bending subsidence zone 14 and the distribution of O-shaped rings 17 can be shown visually. 3DEC is a calculation analysis program which is based on a discrete unit method and is used as a basic theory to describe the mechanical behavior of a discrete medium, and has wide application in the aspects of researching the problems of permeability characteristics (fracture flow) of a rock mass structure, dynamic stability, medium fracture expansion under the action of blasting, rock burst, rock mass strength size/time effect, multi-field coupling (such as water-temperature-force coupling) and the like. 3DEC is a common software for those skilled in the art and will not be described in detail herein.
Further, the O-shaped ring 17 is a main channel for air leakage and seepage of the goaf 20; the gob 20 mining-induced fractures exhibit two stage characteristics: the first stage starts from the cutting of the hole, the absciss crack is pushed to increase along with the working surface, and the middle absciss crack of the goaf 20 grows most; in the second stage, from the beginning of the reduction of the middle separation rate of the goaf 20, the middle cracks tend to be compacted, and the peripheral separation cracks and the caving cracks are kept, so that a communicated crack development area, namely an O-shaped ring 17 of the mining-induced cracks, is formed around the goaf 20.
In the step b, the position of the fracturing well 1 is selected on a coal seam which is 130-170 m away from the goaf 20; the extraction well 2 is arranged on an O-shaped ring 17 of the goaf 20 close to the in-situ coal seam and is positioned on the same horizontal axis with the fracturing well 1. The selected position of the fracturing well 1 has gentle stratum and no collapse column and fracture structure, and the gas content of the in-situ coal bed and the smooth drilling of the fracturing well 1 are ensured. The purpose of the fracturing well 1 is to communicate the upper coal seam 7, the lower coal seam 9 and the goaf 20, facilitate fracturing, and manufacture a fracturing fracture 10 as a flow channel of coal bed gas.
In the step c, drilling the fracturing well 1 to 20-30 m below the bedrock, putting the surface casing 4 into the fracturing well, cementing the fracturing well by using cement, and returning the fracturing well to the ground surface 22; and drilling a second fracturing well 1 until the depth is 10-20 m below the lower coal seam 9, putting a production casing 6, cementing the well by using cement, and returning the well to the ground surface 22. Cement is used for cementing between the surface casing 4 and the wall of the first open well to form a cement sheath 3 for first open well, and cement is used for cementing between the production casing 6 and the wall of the second open well to form a cement sheath 5 for second open well; the second-cut well extends to the lower part of the lower coal seam 9 and penetrates through the stratum 8 between coal seams, so that the in-situ coal seam is conveniently fractured; the fracturing work is mainly carried out within the production casing 6.
In the step d, the steps of communicating the fracturing well 1 and the goaf 20 comprise perforating, fracturing and sand adding; in the step of fracturing, the upper coal seam 7 and the lower coal seam 9 are fractured in a layering way, and in the step of fracturing, fracturing fluid is used as a medium; the step of sand adding is to fill proppant into the fracturing cracks 10 of the upper coal seam 7 and the lower coal seam 9 to be fractured so as to prevent the fracturing cracks 10 from being closed and blocking seepage channels. After the fracturing well 1 is constructed, perforating at a position corresponding to the in-situ coal bed, communicating the in-situ coal bed through the production casing 6 and the second well cementing cement sheath 5 to form a through hole 23, then pressing high-pressure fracturing fluid into the in-situ coal bed from the through hole 23, and pressing a pressure crack 10 in the in-situ coal bed; then, a propping agent is mixed and fed into the fracturing fracture 10 to prop the fracturing fracture 10 and prevent the fracturing fracture 10 from being closed under the action of the ground pressure; and (3) continuously fracturing and adding sand until the fracturing crack 10 penetrates through the in-situ coal bed and is communicated into the goaf 20, fracturing fluid enters the goaf 20 from the fracturing crack 10 through the goaf crack 18 to cause the fracturing fluid pressure to drop suddenly, at the moment, the pump is turned off to stop fracturing, and the fracturing fluid is removed after fracturing is finished. The coal bed gas of the upper coal bed 7 and the lower coal bed 9 flows to the goaf 20 along the gas migration direction 19, and is extracted and utilized by the extraction well 2.
Furthermore, a special perforating gun in the construction of the coal bed gas well is used for perforating towards the periphery horizontally, and a through hole 23 is formed by perforating the production casing 6 and the second-opening well cementing cement sheath 5 to communicate the fracturing well 1 with the in-situ coal bed.
Furthermore, the fracturing fluid is a heterogeneous unstable chemical system formed by a plurality of additives according to a certain proportion, is a working fluid used for fracturing and reforming a coal seam, and has the main function of transmitting high pressure formed by surface fracturing equipment into a stratum so as to break the stratum to form a crack and convey a propping agent along the crack. The proportion of the fracturing fluid in the invention includes but is not limited to clear water, 1.0% KCl and 0.05% bactericide.
Furthermore, the propping agent is also called as fracturing propping agent, and is mainly used for entering the stratum along with high-pressure fracturing fluid after fracturing work and filling the fracturing fluid into the fracturing fracture 10 to play a role in supporting the fracturing fracture 10 from being closed due to stress release, thereby keeping high flow conductivity, ensuring smooth circulation of coal bed gas and increasing yield; according to the characteristics of the stratum, the proppant is a mixed proppant prepared by mixing 40-70-mesh ceramsite and 20-40-mesh quartz sand, and when the proppant is used, the proppant is mixed in fracturing fluid for use.
Furthermore, in consideration of the distance between the upper coal layer 7 and the lower coal layer 9, a packer or sand filling is used for carrying out separate-layer fracturing on the upper coal layer 7 and the lower coal layer 9 during fracturing, and the fracturing effect is guaranteed.
In the step e, drilling the extraction well 2 to 20-30 m below the bedrock, putting the surface casing 4 into the extraction well, cementing the extraction well by using cement, and raising the extraction well to the ground surface 22; drilling the extraction well 2 II to the top of the bent subsidence zone 14, putting the technical casing 11 in the well, cementing the well by using cement, and returning the well to the ground surface 22; and drilling the extraction well 2 to the bottom of the fractured zone 15 by three openings, and putting the sieve hole pipe 13 into the extraction well, wherein the sieve hole pipe 13 is fixedly connected to the bottom end in the technical casing 11 in a hanging manner. The method comprises the following steps that after one opening of an extraction well 2, a surface casing 4 is put into the extraction well, and after the other opening of the extraction well 2, a technical casing 11 is put into the extraction well, and the main purpose is to reinforce the extraction well 2 and prevent the extraction well 2 from collapsing, and the method is similar to that of a fracturing well 1; drilling the extraction well 2 to the upper part of the goaf 20, drilling the extraction well to the lower part of the fractured zone 15, and communicating the O-shaped ring 17 of the goaf 20 with the ground surface 22 to facilitate extraction; the perforated pipe 13 which is arranged after the three openings is used for supporting the three openings of the extraction well 2, and is convenient for residual coal bed gas in the goaf 20 and coal bed gas of an in-situ coal bed entering the goaf 20 through the fracturing crack 10 to enter the extraction well 2 for extraction.
Further, the surface casing 4 of the extraction well 2 and the wall of a well to be drilled are also cemented by cement and are raised to the ground surface 22 to form a cementing ring 3 to be the same as the structure of the fracturing well 1.
Furthermore, a second open hole of the extraction well 2 is cemented with the technical casing 11 to form a second open well cement sheath 5, which has the same cementing principle and application as the fracturing well 1.
Further, a perforated pipe 13 is suspended and fixed at the bottom end of the technical casing 11 by means of a hanger 12, which hanger 12 is a downhole tool for suspending a liner from an upper casing string. Liner cementing is realized through the liner hanger 12, and the liner cementing device is mainly used for reducing the damage of stratum shearing acting force to the sieve tube 13 and is beneficial to maintaining a gas transmission channel. By the back connection of the tail pipe, the problem that the drilling operation is influenced due to the abrasion of the upper-layer sleeve can be solved; by using the liner suspension well cementation technology, the using amount of the casing can be reduced, and the drilling cost is saved. Hanger 12 is a common attachment in the drilling field and is not described in detail herein for purposes of prior art.
In the step d, in order to ensure the drilling safety of the extraction well 2, compressed air is used as an in-well circulation medium for the first extraction well 2 and the second extraction well 2; and the three openings of the extraction well 2 use nitrogen as an internal circulation medium. The gas drilling technology is a drilling technology which takes gas as a circulating medium to replace drilling fluid, can effectively improve the drilling speed, reduce the abrasion speed of a drill bit, reduce the drilling cost, overcome the problems of drilling fluid loss, stratum water sensitivity and the like, and meet the drilling requirements of water-deficient environments and polar environments. Compressed air is used as a circulating medium only for drilling of a non-productive layer; the three openings enter the goaf 20 and contain coal bed gas with certain concentration, so that nitrogen is adopted as an internal circulation medium, explosion is avoided, and safety is improved.
In the step e, the step of extracting the coal bed gas is to seal the well mouth of the fracturing well 1, and negative pressure extraction is carried out from the well mouth of the extraction well 2 through the ground extraction device 21. The wellhead sealing of the fracturing well 1 is realized through cement or other structures, and the coal bed gas is prevented from leaking from the fracturing well 1; a ground extraction device is arranged in an extraction area, and a goaf 20 under an extraction well 2 is extracted, so that the goaf 20 forms a negative pressure environment, the flow of coal bed gas at other positions to the goaf 20 through a pressure crack 10 is accelerated, and the extraction speed and the yield are further improved.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Geological profile: the high gas mine is arranged before the coal mine is closed, the main coal mining layer Taiyuan group No. 15 has the average thickness of 5.88m, the coal mining layer on the No. 15 coal seam is the No. 12 coal seam, the average thickness is 2.10m, and the average distance is 44.50 m. 12. No. 15 coal bed is anthracite, and the in-situ coal bed gas content is more than 10m3/t，The gob 20 has good sealing performance, the methane concentration is more than 85%, and the goaf 20 has potential of in-situ coal bed gas exploration and development.
According to the density, the tensile strength, the volume modulus, the shear modulus, the internal friction angle and the cohesion rock mechanical parameters of the top floor and the bottom floor of the coal bed extracted from the mine geological report and the pit closing report of the closed coal mine, a goaf 20 geological model is established through 3DEC software, the size of the model is 240m multiplied by 200m multiplied by 160m, horizontal constraints are applied to the front boundary, the rear boundary, the left boundary and the right boundary so that the goaf does not displace, the bottom boundary is fixed, the top is a free boundary, equivalent gravity load is applied, excavation is simulated, and the height of a collapse zone 16, a fracture zone 15 and a bending subsidence zone 14 and the development range of an O-shaped ring 17 are determined through fracture development and vertical displacement change.
A fracturing well 1 is arranged at a position which is located 150m +/-20 m away from the surrounding of the well-closed goaf 20 and is gentle in stratum and not affected by mining, collapse columns, fracture structures and surface factors; arranging an extraction well 2 above the O-shaped ring 17 of the goaf 20 close to the fracturing well 1; the extraction well 2 and the fracturing well 1 are positioned on the same horizontal axis.
Determining the position and thickness information of a coal seam according to the coal field exploration drilling data, and constructing a drilling fracturing well 1; firstly, drilling a 311mm drill bit to 20m below bedrock, putting a 244.5mm surface casing 4, cementing by using cement to form a cementing well-opening cement sheath 3, and returning to the ground surface 22; and drilling a 215.9mm drill bit to 10m below the No. 15 coal seam, putting a 139.7mm production casing 6, cementing by using cement to form a cement sheath 5 for secondary open well cementing, and returning to the ground surface 22.
Using a 127 gun to horizontally perforate a No. 15 coal seam at a phase angle of 60 degrees and 16 holes/m; respectively fracturing No. 15 coal beds and No. 12 coal beds by a sand filling method in consideration of the coal bed spacing of more than 25 m; clear water, 1.0 percent of KCl and 0.05 percent of bactericide are used as fracturing fluid; because a stress concentration area exists from the coal seam to the goaf 20, the 40-70-mesh ceramsite and the 20-40-mesh quartz sand large-particle-size combined propping agent are used for preventing cracks from being closed and blocking a seepage channel; when the coal seam is pressed through to the goaf 20, the construction pressure is greatly reduced, and the pump is stopped.
According to the vertical spreading condition of three zones of the goaf 20 obtained by 3DEC simulation, drilling a hole in the extraction well 2, namely drilling to 20m below bedrock by using a 444.5mm drill bit, putting into a surface casing 4 with the thickness of 339.7mm, cementing by using cement, and returning to the ground surface 22 to form a cementing ring 3; secondly, drilling to the top of a bent subsidence zone 14 by using a 311.1mm drill bit, lowering a 244.5mm technical casing 11, cementing wells by using cement, raising the well to the ground surface 22 to form a second-cut well cementing cement sheath 5, thirdly, drilling to the lower part of a fractured zone 15 by using a 215.9mm drill bit, suspending a sieve hole pipe 13 at the bottom of the technical casing 11 by using a hanger 12, and lowering the sieve hole pipe 13 into a third-cut drill hole, wherein the sieve hole pipe 13 and the technical casing 11 are stored for an overlapping length of 10 m; in order to ensure the safety of well drilling, the first and second exploitation uses compressed air as a well circulation medium, and the third exploitation uses nitrogen as a compressed medium.
And (3) sealing the wellhead of the fracturing well 1 by using cement, connecting a ground extraction device 21 to the wellhead of the extraction well 2 for negative pressure extraction, and comprehensively and efficiently extracting the coal bed gas in the in-situ-goaf.
The method for closing the coal mine in-situ-goaf coalbed methane comprehensive efficient extraction has a simple structure, reasonably arranges the fracturing well 1 and the extraction well 2 based on the coalbed methane occurrence migration rule, and closes the coalbed methane in the coal mine in-situ-goaf to form a unified and communicated gas-containing system, thereby improving the extraction efficiency, reducing the waste of extraction resources, reducing the extraction difficulty and danger, and being beneficial to the full utilization of coalbed methane resources.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The above embodiments are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (10)
1. A comprehensive high-efficiency extraction method for closing coal bed gas in a coal mine in-situ-goaf is characterized by comprising the following steps:
step a, obtaining geological conditions for closing a coal mine goaf;
b, positioning the drilling positions of the fracturing well (1) and the extraction well (2);
c, drilling to construct the fracturing well (1);
d, communicating the fracturing well (1) with the goaf (20);
e, drilling to construct the extraction well (2);
and f, extracting coal bed gas.
2. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 1, characterized by comprising the following steps: in the step a, the method for obtaining the geological condition of closing the coal mine goaf is to establish a goaf (20) geological model and simulate the height of a caving zone (16), a fissure zone (15) and a bending subsidence zone (14) after mining and the development range of an O-shaped ring (17).
3. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 2, characterized by comprising the following steps: in the step b, the position of the fracturing well (1) is selected to be on an in-situ coal seam 130-170 m away from the goaf (20); the extraction well (2) is arranged on the O-shaped ring (17) of the goaf (20) close to the coal seam and is positioned on the same horizontal axis with the fracturing well (1).
4. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 1, characterized by comprising the following steps: in the step c, once the fracturing well (1) is drilled to 20-30 m below bedrock, a surface casing (4) is put in, and cement is used for cementing the well and the well is raised to the ground surface (22); and drilling the second fracturing well (1) to 10-20 m below the lower coal seam (9), putting a production casing (6), cementing the well by using cement, and raising the well to the ground surface (22).
5. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 1, characterized by comprising the following steps: in the step d, the steps of communicating the fracturing well (1) and the goaf (20) are perforating, fracturing and sand adding.
6. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 5, characterized by comprising the following steps: in the step d, the upper coal seam (7) and the lower coal seam (9) are fractured in a layering mode in the fracturing step, and fracturing fluid is used as a medium in the fracturing step and is fractured towards the peripheral direction of the fracturing well (1).
7. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 6, characterized by comprising the following steps: in the step d, the step of adding sand is to fill proppant into the fractured fractures (10) of the upper coal seam (7) and the lower coal seam (9) to prevent the fractures (10) from being closed and blocking seepage channels.
8. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 4, characterized by comprising the following steps: in the step e, drilling the extraction well (2) to 20-30 m below bedrock, putting the surface casing (4) into the extraction well, cementing the extraction well by using cement, and returning the extraction well to the ground surface (22); drilling the extraction well (2) to the top of the bent subsidence zone (14), setting a technical casing (11), cementing the well by using cement, and raising the well to the ground surface (22); and the extraction well (2) is drilled to the bottom of the fractured zone (15) in three times, a sieve hole pipe (13) is arranged, and the sieve hole pipe (13) is fixedly connected to the bottom end in the technical casing (11) in a hanging manner.
9. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 8, characterized by comprising the following steps: in the step d, in order to ensure the drilling safety of the extraction well (2), compressed air is used as an internal circulation medium for the first opening and the second opening of the extraction well (2); and the three openings of the extraction well (2) use nitrogen as an internal circulation medium.
10. The method for closing coal mine in-situ-goaf coalbed methane comprehensive efficient extraction according to claim 1, characterized by comprising the following steps: in the step e, the step of extracting the coal bed gas is to seal the well mouth of the fracturing well (1), and negative pressure extraction is carried out from the well mouth of the extraction well (2) through a ground extraction device (21).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111478209.5A CN114165196A (en) | 2021-12-06 | 2021-12-06 | Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111478209.5A CN114165196A (en) | 2021-12-06 | 2021-12-06 | Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114165196A true CN114165196A (en) | 2022-03-11 |
Family
ID=80483628
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111478209.5A Pending CN114165196A (en) | 2021-12-06 | 2021-12-06 | Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114165196A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114635667A (en) * | 2022-03-31 | 2022-06-17 | 四川盐业地质钻井大队 | Method for plugging cracks around well of brine recovery well group |
| CN115660235A (en) * | 2022-12-28 | 2023-01-31 | 北京科技大学 | Method for predicting yield of one-well multi-purpose coal bed gas well in whole production process |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090315388A1 (en) * | 2008-06-20 | 2009-12-24 | Solvay Chemicals, Inc. | Mining method for co-extraction of non-combustible ore and mine methane |
| CN109139094A (en) * | 2018-10-26 | 2019-01-04 | 山西晋城无烟煤矿业集团有限责任公司 | A kind of roller ground gas pumping method |
| CN110552735A (en) * | 2019-09-27 | 2019-12-10 | 宁夏煤炭勘察工程有限公司 | Method and system for combined extraction of coal seam gas and gas near goaf |
| CN112593936A (en) * | 2020-11-27 | 2021-04-02 | 陕西彬长孟村矿业有限公司 | Advanced comprehensive prevention and control method for multiple disaster areas of deep mine |
| CN112647906A (en) * | 2020-12-18 | 2021-04-13 | 华能煤炭技术研究有限公司 | Method for extracting gas from ground of multi-goaf without coal pillar |
| CN112796712A (en) * | 2021-03-26 | 2021-05-14 | 山西省煤炭地质勘查研究院 | Comprehensive extraction method for fracturing of goaf and coal seam |
-
2021
- 2021-12-06 CN CN202111478209.5A patent/CN114165196A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090315388A1 (en) * | 2008-06-20 | 2009-12-24 | Solvay Chemicals, Inc. | Mining method for co-extraction of non-combustible ore and mine methane |
| CN109139094A (en) * | 2018-10-26 | 2019-01-04 | 山西晋城无烟煤矿业集团有限责任公司 | A kind of roller ground gas pumping method |
| CN110552735A (en) * | 2019-09-27 | 2019-12-10 | 宁夏煤炭勘察工程有限公司 | Method and system for combined extraction of coal seam gas and gas near goaf |
| CN112593936A (en) * | 2020-11-27 | 2021-04-02 | 陕西彬长孟村矿业有限公司 | Advanced comprehensive prevention and control method for multiple disaster areas of deep mine |
| CN112647906A (en) * | 2020-12-18 | 2021-04-13 | 华能煤炭技术研究有限公司 | Method for extracting gas from ground of multi-goaf without coal pillar |
| CN112796712A (en) * | 2021-03-26 | 2021-05-14 | 山西省煤炭地质勘查研究院 | Comprehensive extraction method for fracturing of goaf and coal seam |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114635667A (en) * | 2022-03-31 | 2022-06-17 | 四川盐业地质钻井大队 | Method for plugging cracks around well of brine recovery well group |
| CN114635667B (en) * | 2022-03-31 | 2024-04-12 | 四川盐业地质钻井大队 | Method for plugging brine production well group Zhou Liexi |
| CN115660235A (en) * | 2022-12-28 | 2023-01-31 | 北京科技大学 | Method for predicting yield of one-well multi-purpose coal bed gas well in whole production process |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110397428B (en) | Displacement coalbed methane yield increasing method for coalbed methane jointly mined by vertical well and U-shaped butt well | |
| CN102852546B (en) | Method for pre-pumping coal roadway stripe gas of single soft protruded coal seam of unexploited area | |
| CN102337919B (en) | A four-period-five-purpose hole-drilling high-efficiency gas extracting process | |
| CN107905834A (en) | A kind of hypotonic high prominent coal seam architecture gas production method | |
| CN102392677A (en) | Permeability improvement technology for coal bed gas reservoir cap by using three-dimensional fracture network modification | |
| CN104929567A (en) | Low-cost construction process for passing through goaf | |
| CN114165196A (en) | Comprehensive efficient extraction method for closing coal bed gas in-situ-goaf of coal mine | |
| CN111236906B (en) | Method for improving fracture complexity through normal-pressure or deep shale gas main fracture deep plugging | |
| CN104806217A (en) | Combined separated layer fracturing, grouping and layer-combining mining method for coal bed well group | |
| CN108756884A (en) | Coal mine tight roof full face ground shifts to an earlier date outburst elimination method | |
| CN102852490A (en) | High gas suction and discharge process method for complex well | |
| CN107620581B (en) | Construction method of one-well dual-purpose coal mine shaft inspection hole | |
| CN106437632A (en) | Coal ore long goaf zone Vans drainage method | |
| CN105351001A (en) | Gas extraction method for region reinforcement of gob-side entry retaining | |
| CN110173238A (en) | The anti-reflection extraction of high seam three-dimensional roadway layout networking explosion thick gas method entirely | |
| CN111022108A (en) | Method for extracting gas in goaf | |
| CN109339856A (en) | A kind of method that face gas is administered | |
| CN113107450A (en) | Staged fracturing gas advanced extraction method for horizontal well of soft-hard interaction coal seam | |
| CN114294046B (en) | Coal mine area full-coverage underground three-dimensional extraction method | |
| RU2387784C1 (en) | Method for preliminary degassing of coal beds | |
| CN112627723A (en) | Ground drilling method for coal bed gas development of coal mine goaf | |
| CN107503789B (en) | Low gaseous mine high-productivity faces gas ground extraction method | |
| CN103032059B (en) | A kind of directed hydraulic pressure burst communicatin exploitation method | |
| CN112664172A (en) | Blasting infiltration method for ground immersion | |
| CN116988733A (en) | Mining-while-mining and filling coal mining method based on roof horizontal well side drilling holes |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |