CN112145132A - Well drilling method for extracting coal bed gas of adjacent closed goaf group - Google Patents
Well drilling method for extracting coal bed gas of adjacent closed goaf group Download PDFInfo
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- CN112145132A CN112145132A CN202011085327.5A CN202011085327A CN112145132A CN 112145132 A CN112145132 A CN 112145132A CN 202011085327 A CN202011085327 A CN 202011085327A CN 112145132 A CN112145132 A CN 112145132A
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- goaf
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- 238000005553 drilling Methods 0.000 title claims abstract description 41
- 239000003245 coal Substances 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000005516 engineering process Methods 0.000 claims abstract description 4
- 238000005065 mining Methods 0.000 claims description 11
- 238000004364 calculation method Methods 0.000 claims description 3
- 230000001186 cumulative effect Effects 0.000 claims description 3
- 239000012530 fluid Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000000605 extraction Methods 0.000 abstract description 12
- 238000004891 communication Methods 0.000 abstract description 2
- 239000011435 rock Substances 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 235000009781 Myrtillocactus geometrizans Nutrition 0.000 description 1
- 240000009125 Myrtillocactus geometrizans Species 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/006—Production of coal-bed methane
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
Abstract
The invention relates to a well drilling method for extracting coal bed gas of adjacent closed goaf groups, which solves the problems of small influence radius, small extraction amount, small extraction age limit and the like of the existing closed goaf coal bed gas extraction method. The well trajectory of the method is a single-hole bottom directional hole in a straight line-curve form, and the method specifically comprises the following steps: and selecting the intersection of the direction of the central axis of the gob group inclination and the central axis of the gob trend as a well position, and starting deflecting along the direction of the central axis of the gob group inclination when drilling to the position of the fracture zone of the top plate of the gob by using the conventional drilling process technology, wherein the target area of the final hole layer is in the caving zone range of the gob. The method reasonably reduces the drilling footage, fully reveals the effective communication area of the goaf, and has great popularization significance for improving the productivity of the goaf and the extraction age limit.
Description
Technical Field
The invention relates to the technical field of coal bed gas, in particular to a well drilling method for extracting coal bed gas of adjacent closed goaf groups.
Background
At present, mine areas all over the country have a large number of abandoned mines, and the area of the abandoned mines in some mine areas can reach thousands of square kilometers. A large amount of coal bed gas exists in the goaf of the abandoned mine, and the conventional method is adopted for developing the coal bed gas of the goaf at present, namely, a goaf is provided with a goaf vertical well, the extraction influence radius of the method is limited, the resource amount in a single closed goaf is limited, and the extraction age limit of the goaf vertical well is severely limited.
Disclosure of Invention
The invention aims to solve the problems of small influence radius, small extraction amount, small extraction age limit and the like of the existing closed goaf coal bed gas extraction method, and provides a drilling method for extracting coal bed gas of adjacent closed goaf groups.
The invention is realized by the following technical scheme:
a well drilling method for extracting coal bed gas of adjacent closed goaf groups is characterized in that a well bore track is a single-hole bottom directional hole in a straight line-curve form, and specifically comprises the following steps: and selecting the intersection of the direction of the central axis of the gob group inclination and the central axis of the gob trend as a well position, and starting to perform deflection along the direction of the central axis of the gob group inclination by utilizing the natural deflection trend of the rock stratum when drilling to the position of the fracture zone of the top plate of the gob by using the conventional drilling process technology, wherein the target area of the final hole layer is in the caving zone range of the gob.
As a preferred technical scheme, the closed goaf group is formed by adopting a strike longwall coal mining process, and the residual coal rate is not lower than 30%.
As an optimal technical scheme, when the goaf group is inclined to the axis direction, the inclination rate is determined to be 7-9 degrees/30 m for facilitating the control of drilling cost.
As a preferred technical scheme, the target area of the final hole horizon is within the caving zone range of the goaf, and the marking characteristic is that the drilling fluid (mud and gas) at the position is seriously leaked or even does not flow back.
As the preferred technical scheme, the well body adopts a three-opening well body structure, an opening section is drilled to 10m below bedrock, and a surface casing is used for cementing; drilling a second opening section to 30m above a goaf roof fracture zone, and cementing by a technical casing; and the three-opening section starts to perform deflecting at the position of a roof fracture zone of the goaf, the layer of a final hole is in the caving zone range of the goaf, and the open hole completion is performed.
As a preferred technical scheme, the height of the fissure zone is formed by an empirical formula
Determining, wherein: hCrack (crack)-height of the crack band, m; m is cumulative mining height, M; c-calculating the error value, and taking 5.6 m; n-number of coal layering layers.
As a preferred technical scheme, the height of the falling belt is calculated by an empirical formula
Determining, wherein: hCap with heating means-height of the landing strip, m; m is mining height, M; c-error value in calculation.
According to the method, through optimizing the structure of the well body of the goaf, the single-hole-bottom directional hole with the well body track in a straight line-curve form is designed by utilizing the natural deviation tendency of the rock stratum, the development of the coal bed gas of the adjacent goaf group is realized on the basis of not increasing the drilling cost, the regional closed goaf coal bed gas resource is extracted to the maximum extent, and the drilling, extraction, gathering and transportation costs of the original goaf coal bed gas well group are reduced. The method reasonably reduces the drilling footage, fully reveals the effective communication area of the goaf, and has great popularization significance for improving the productivity of the goaf and the extraction age limit.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic plan projection diagram of coal bed gas extracted from adjacent closed goaf groups by the method.
FIG. 2 is a schematic cross-sectional view of coal bed gas extracted from adjacent closed goaf groups by the method.
Detailed Description
In order that those skilled in the art will better understand the present invention, a more complete and complete description of the present invention is provided below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The invention provides a well drilling method for extracting coal bed gas of adjacent closed goaf groups, in particular to a single-hole-bottom directional hole which is formed by a strike longwall coal mining process and has a residual coal rate of not less than 30%, wherein a rock stratum has a strong natural deflecting trend and an obvious hole deflecting trend, and a well drilling well trajectory is in a straight line-curve form.
The method specifically comprises the following steps:
s1, determining the heights of a fracture zone and an caving zone according to geological data of a goaf: the height of the fissure zone is calculated by an empirical formula
Determining, wherein: hCrack (crack)-height of the crack band, m; m is cumulative mining height, M; c-calculating the error value, and taking 5.6 m; n-number of coal layering layers; the height of the falling belt is calculated by empirical formula
Determining, wherein: hCap with heating means-height of the landing strip, m; m is mining height, M; c-error value in calculation, take 2 m.
S2, well position selection: and selecting the intersection of the inclined central axis direction of the goaf group and the trend central axis of the edge goaf as a well position.
S3, drilling by using a conventional drilling process technology: the well body adopts a three-opening well body structure, one opening section is drilled to 10m below bedrock, and the surface casing is used for cementing wells; drilling a second opening section to 30m above a goaf roof fracture zone, and cementing by a technical casing; the three-section starts deflecting at the position of a top plate fracture zone of the goaf, and adopts a single-arc section (straight-deflecting-horizontal) three-section form, so that the section is relatively simple, the tool selection is convenient, and the construction is easy to control; the three-section manufacturing slope section well section is relatively short, so that the lower friction resistance of a drill string is reduced, a drilling tool can safely and smoothly pass through a bending section, the drilling cost is controlled, and the build slope is determined to be 7-9 degrees/30 m; the final hole level is in the caving zone range of the goaf, and the marking characteristic is that the drilling fluid at the position is seriously leaked or even does not flow back, and the open hole completion is carried out.
And after drilling is finished, performing coal bed gas extraction operation on the ground by using a water ring pump/booster set.
The method of the invention is further supported and described below with reference to a specific example:
the example is described by taking a Yue City mine goaf of blue flame company, a Limited liability company of the Shanxi Jincheng smokeless coal mining group as an example.
The Yueyeng mine is supported by a hydraulic support, when the support moves forwards, the instantaneous pressure of a top plate is much larger than that of a unit pillar support, the length of a working surface is much longer than that of the previous support, the suspension space of the support is enlarged, and the collapse height of the Yueyeng mine is determined to be 16.48m by combining the actual situation of the Yueyeng mine; the method is characterized in that a Yueyeng mine coal seam is mined in two layers, the layering thickness is much larger than that of the former coal seam, so that the development degree of a overlying strata crack belt caused by layered mining is considered to be more severe, and is generally 110% -140%, and therefore the maximum height of the crack belt can be calculated to be 65m according to an empirical formula.
As shown in figures 1 and 2, a Yuetcheng mine has a 1# goaf, a 2# goaf and a 3# goaf, the well position is selected to be in the 1# goaf, drilling construction is carried out, and a 425mm drill bit is used for drilling to 10m below bedrock in one section, and 377.70mm surface casing is used for cementing; in the second-opening section, a 311.15mm drill bit is used for drilling to 30m above a crack zone of a top plate of the 3# coal goaf, and a 244.5mm technical casing is used for cementing; and in the third-opening section, a 215.9mm drill bit is used for drilling into a target area of a 10m caving zone of the top plate of the 3# gob, and the open hole completion is carried out.
The technical solutions in the embodiments of the present invention are clearly and completely described above, and the described embodiments are only a part of the embodiments of the present invention, but 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.
Claims (7)
1. A well drilling method for extracting coal bed gas of adjacent closed goaf groups is characterized in that: the well bore track is a single-hole bottom directional hole in a straight line-curve form, and specifically comprises the following steps: and selecting the intersection of the direction of the central axis of the gob group inclination and the central axis of the gob trend as a well position, and starting deflecting along the direction of the central axis of the gob group inclination when drilling to the position of the fracture zone of the top plate of the gob by using the conventional drilling process technology, wherein the target area of the final hole layer is in the caving zone range of the gob.
2. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1, characterized by comprising the following steps: the closed goaf group is formed by adopting a strike longwall coal mining process, and the residual coal rate is not lower than 30%.
3. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1, characterized by comprising the following steps: when the goaf group inclines in the axial direction, the deflecting rate is 7-9 degrees/30 m.
4. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1, characterized by comprising the following steps: the target area of the final hole level is in the caving zone range of the goaf, and the marking characteristic is that the drilling fluid at the position is seriously leaked or even does not flow back.
5. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1, characterized by comprising the following steps: the well body adopts a three-opening well body structure, one opening section is drilled to 10m below bedrock, and the surface casing is used for cementing wells; drilling a second opening section to 30m above a goaf roof fracture zone, and cementing by a technical casing; and the three-opening section starts to perform deflecting at the position of a roof fracture zone of the goaf, the layer of a final hole is in the caving zone range of the goaf, and the open hole completion is performed.
6. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1 or 5, characterized by comprising the following steps: the height of the fissure zone is calculated by an empirical formula
Determining, wherein: hCrack (crack)-height of the crack band, m; m is cumulative mining height, M; c-calculating the error value, and taking 5.6 m; n-number of coal layering layers.
7. The well drilling method for extracting coal bed gas of the adjacent closed goaf group according to claim 1 or 5, characterized by comprising the following steps: the height of the falling belt is calculated by empirical formula
Determining, wherein: hCap with heating means-height of the landing strip, m; m is mining height, M; c-error value in calculation.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011085327.5A CN112145132A (en) | 2020-10-12 | 2020-10-12 | Well drilling method for extracting coal bed gas of adjacent closed goaf group |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114439428A (en) * | 2021-12-30 | 2022-05-06 | 中煤科工集团西安研究院有限公司 | Enhanced extraction method for coal bed gas horizontal well under through goaf group |
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Cited By (2)
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| 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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Application publication date: 20201229 |