CN110991081A - Method for determining extracted gas quantity of adjacent layer based on ground drilling extracted gas - Google Patents
Method for determining extracted gas quantity of adjacent layer based on ground drilling extracted gas Download PDFInfo
- Publication number
- CN110991081A CN110991081A CN201911317094.4A CN201911317094A CN110991081A CN 110991081 A CN110991081 A CN 110991081A CN 201911317094 A CN201911317094 A CN 201911317094A CN 110991081 A CN110991081 A CN 110991081A
- Authority
- CN
- China
- Prior art keywords
- gas
- ground
- borehole
- extracted
- concentration
- 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.)
- Granted
Links
- 238000005553 drilling Methods 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims abstract description 16
- 239000003245 coal Substances 0.000 claims abstract description 58
- 238000000605 extraction Methods 0.000 claims abstract description 36
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052799 carbon Inorganic materials 0.000 abstract description 7
- 238000012360 testing method Methods 0.000 abstract description 5
- 239000010410 layer Substances 0.000 description 21
- 238000010276 construction Methods 0.000 description 3
- 238000005065 mining Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F7/00—Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
The invention discloses a method for determining the gas extraction amount of an adjacent layer based on gas extraction of a ground borehole, wherein a high-position borehole is constructed around the ground borehole, so that the ground borehole and the high-position borehole are positioned at the same extraction layer; then respectively extracting gas from the ground drill hole and the high-position drill hole, and then measuring the concentration of the gas extracted from the high-position drill hole, the concentration of the gas extracted from the ground drill hole and the flow of the gas extracted from the ground drill hole; and then constructing a ground drilling extraction multi-coal-seam gas source-dividing calculation model according to a mass conservation law, namely the pure gas quantity flowing into the ground hole in unit time is equal to the pure gas quantity flowing out of the ground hole, and the non-gas quantity flowing into the ground hole in unit time is equal to the non-gas quantity flowing out of the ground hole. And substituting the measured data and the known data into the source-dividing calculation model to obtain the flow of the gas of the adjacent coal seam flowing into the ground borehole. According to the method, the carbon isotope test is not needed, so that the time for determining the gas extraction quantity of the adjacent layer is effectively shortened, and the accuracy of the obtained gas extraction quantity of the adjacent layer can be effectively ensured.
Description
Technical Field
The invention relates to a method for determining gas extraction quantity of multiple coal seams, in particular to a method for determining gas extraction quantity of an adjacent layer based on gas extraction of ground drilling.
Background
The extraction of coal seam group gas by ground drilling is one of the most common methods for gas extraction in coal mines. For a protective layer mining mine, gas extracted by ground drilling is mainly formed by mixing two parts of gas in a goaf of the coal seam and pressure relief gas in an adjacent layer. And the source-dividing calculation of the multi-coal-seam gas extracted by the ground drilling has important significance for the investigation of the extraction effect of the coal seam, particularly the adjacent layer. At present, the source-dividing calculation of the ground borehole extraction mixed gas is mainly carried out by a carbon isotope test method, and the principle is that the carbon isotope difference of different coal seams is obvious (namely, the proportion of different carbon isotopes in the gas extracted by the extraction borehole is measured by utilizing the difference of the carbon isotopes of the coal seam and an adjacent layer), and a quantitative analysis source calculation model of each coal seam gas source is established on the basis of the calculation model, so that the extraction gas quantity of the adjacent layer extracted by the ground borehole can be obtained and used for the research of a subsequent adjacent layer; although the method can obtain the extracted gas quantity of the adjacent layer, the method has the defects of long time for testing data, expensive equipment for testing isotope analysis, high difficulty in popularization and the like.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the method for determining the extracted gas quantity of the adjacent layer based on the ground drilling extracted gas, and the carbon isotope test is not needed, so that the time for determining the extracted gas quantity of the adjacent layer is effectively shortened, the accuracy of the extracted gas quantity of the adjacent layer can be effectively ensured, meanwhile, the construction is simple, the required cost is low, and the method is convenient for using various different coal beds.
In order to achieve the purpose, the invention adopts the technical scheme that: a method for determining the extracted gas quantity of an adjacent layer based on the extracted gas of a ground borehole comprises the following specific steps:
A. constructing a ground borehole on the coal mine ground, and enabling the ground borehole to penetrate through an adjacent coal seam and extend into the top plate of the coal seam to extract gas; then constructing a high-position drill hole around the ground drill hole, so that the gas inlet end of the high-position drill hole and the gas inlet end of the ground drill hole are positioned at the same extraction layer; (because the two are positioned at the same extraction horizon, the extracted gas is all extracted fromThe goaf is diffused to the same height of the top plate, so that the goaf and the top plate are approximately equal) so as to determine the gas concentration c extracted by the high-position drill hole in the coal seam0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1；
B. Respectively extracting gas from the ground borehole and the high-position borehole, and respectively measuring the concentration c of the gas extracted from the high-position borehole0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3；
C. Establishing a ground drilling extraction multi-coal-seam gas source-dividing calculation model, and c2The concentration of gas entering a ground borehole adjacent to a coal seam is percent; q1Standard condition flow of coal bed gas gushing into ground borehole, m3/min；Q2Standard condition flow m of gas flowing into ground hole near coal seam3Min; setting the gas entering the ground borehole adjacent to the coal seam as pure gas; (because the gas in the adjacent layer before pressure relief is original gas, is not disturbed by mining and has no other gas entering, even if the coal bed is mined, the pressure relief gas in the adjacent layer is gushed out but not the other gas entering, so the extracted pressure relief gas can be determined as pure gas)
Namely:
C2＝100% (1)
according to the law of conservation of mass, the amount of pure gas in the gas flowing into the surface borehole is equal to the amount of pure gas in the gas flowing out of the surface borehole per unit time, i.e.:
Q1c1+Q2c2＝Q3c3(2)
according to the law of conservation of mass, the amount of non-gas flowing into the surface borehole per unit time is equal to the amount of non-gas flowing out of the surface borehole, i.e.:
Q1(1-c1)＝Q3(1-c3) (3)
the system of equations consisting of equations (1) to (3) yields:
Q2＝Q3c3-Q1c1(5)
the formula (4) and the formula (5) are calculation models of the ground drilling extraction multi-coal-seam gas source distribution:
D. according to the gas concentration c extracted by the high-position drilling hole measured in the step B0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3(ii) a And the concentration c of the gas extracted by the high-level drilling0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1And D, substituting the model into the ground borehole gas extraction multi-coal-seam gas source-dividing calculation model obtained in the step C to obtain the standard condition flow Q of the gas flowing into the ground borehole from the coal seam1And the standard condition flow Q of gas flowing into the ground borehole from the adjacent coal seam2；
E. D, obtaining the standard condition flow Q of the gas of the adjacent coal seam gas gushing into the ground borehole2Namely the gas extraction quantity of the adjacent coal seam in unit time.
Compared with the prior art, because the gas concentration of the ground drilled hole extraction goaf cannot be directly measured, the high-position drilled hole is constructed around the ground drilled hole, so that the gas inlet end of the high-position drilled hole is close to the gas inlet end of the ground drilled hole, and the gas concentration extracted by the high-position drilled hole in the coal seam can be determined to be equivalent to the gas concentration extracted by the ground drilled hole in the coal seam; then respectively extracting gas from the ground drill hole and the high-position drill hole, and then measuring the concentration of the gas extracted from the high-position drill hole, the concentration of the gas extracted from the ground drill hole and the flow of the gas extracted from the ground drill hole; and then constructing a ground drilling extraction multi-coal-seam gas source-dividing calculation model according to a mass conservation law, namely, the pure gas quantity flowing into the ground hole in unit time is equal to the pure gas quantity flowing out of the ground hole, and the non-gas quantity flowing into the ground hole in unit time is equal to the non-gas quantity flowing out of the ground hole. And substituting the measured data and the known data into the source-dividing calculation model to obtain the flow of the gas of the adjacent coal seam flowing into the ground borehole. Therefore, the method does not need to carry out carbon isotope test, thereby not only effectively shortening the time for determining the gas extraction quantity of the adjacent layer, but also effectively ensuring the accuracy of the obtained gas extraction quantity of the adjacent layer, and meanwhile, the method has the advantages of simple construction, lower required cost and convenience for use and popularization of various coal seams.
Drawings
FIG. 1 is a schematic view of the construction layout of the present invention.
Detailed Description
The present invention will be further explained below.
As shown in fig. 1, the method comprises the following specific steps:
A. constructing a ground borehole on the coal mine ground, and enabling the ground borehole to penetrate through an adjacent coal seam and extend into the top plate of the coal seam to extract gas; then constructing a high-position drill hole around the ground drill hole, so that the gas inlet end of the high-position drill hole and the gas inlet end of the ground drill hole are positioned at the same extraction layer; (because the two are positioned at the same extraction layer position, the extracted gas is diffused to the same height of the top plate from the goaf, so that the extracted gas and the goaf are approximately equal) so as to determine the gas concentration c extracted by the high-position drill hole in the coal seam0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1；
B. Respectively extracting gas from the ground borehole and the high-position borehole, and respectively measuring the concentration c of the gas extracted from the high-position borehole0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3；
C. Establishing a ground drilling extraction multi-coal-seam gas source-dividing calculation model, and c2The concentration of gas entering a ground borehole adjacent to a coal seam is percent; q1Standard condition flow of coal bed gas gushing into ground borehole, m3/min；Q2Standard condition flow m of gas flowing into ground hole near coal seam3Min; setting the gas entering the ground borehole adjacent to the coal seam as pure gas; (because the gas in the adjacent layer before pressure relief is original gas, is not disturbed by mining and has no other gas entering, even if the coal bed is mined, the pressure relief gas in the adjacent layer is gushed out but not the other gas entering, so the extracted pressure relief gas can be determined as pure gas)
Namely:
C2＝100% (1)
according to the law of conservation of mass, the amount of pure gas in the gas flowing into the surface borehole is equal to the amount of pure gas in the gas flowing out of the surface borehole per unit time, i.e.:
Q1c1+Q2c2＝Q3c3(2)
according to the law of conservation of mass, the amount of non-gas flowing into the surface borehole per unit time is equal to the amount of non-gas flowing out of the surface borehole, i.e.:
Q1(1-c1)＝Q3(1-c3) (3)
the system of equations consisting of equations (1) to (3) yields:
Q2＝Q3c3-Q1c1(5)
the formula (4) and the formula (5) are calculation models of the ground drilling extraction multi-coal-seam gas source distribution:
D. according to the gas concentration c extracted by the high-position drilling hole measured in the step B0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3(ii) a And the concentration c of the gas extracted by the high-level drilling0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1And D, substituting the model into the ground borehole gas extraction multi-coal-seam gas source-dividing calculation model obtained in the step C to obtain the standard condition flow Q of the gas flowing into the ground borehole from the coal seam1And the standard condition flow Q of gas flowing into the ground borehole from the adjacent coal seam2；
E. D, obtaining the standard condition flow Q of the gas of the adjacent coal seam gas gushing into the ground borehole2Namely the gas extraction quantity of the adjacent coal seam in unit time.
Claims (1)
1. A method for determining the extracted gas quantity of an adjacent layer based on the extracted gas of a ground borehole is characterized by comprising the following specific steps:
A. constructing a ground borehole on the coal mine ground, and enabling the ground borehole to penetrate through an adjacent coal seam and extend into the top plate of the coal seam to extract gas; then constructing a high-position drill hole around the ground drill hole, so that the gas inlet end of the high-position drill hole and the gas inlet end of the ground drill hole are positioned at the same extraction layer; thereby determining the gas concentration c extracted from the coal seam by the high-position drill hole0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1；
B. Respectively extracting gas from the ground borehole and the high-position borehole, and respectively measuring the concentration c of the gas extracted from the high-position borehole0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3；
C. Establishing a ground drilling extraction multi-coal-seam gas source-dividing calculation model, and c2The concentration of gas entering a ground borehole adjacent to a coal seam is percent; q1Standard condition flow of coal bed gas gushing into ground borehole, m3/min；Q2Standard condition flow m of gas flowing into ground hole near coal seam3Min; setting the gas entering the ground borehole adjacent to the coal seam as pure gas;
namely:
C2＝100％ (1)
according to the law of conservation of mass, the amount of pure gas in the gas flowing into the surface borehole is equal to the amount of pure gas in the gas flowing out of the surface borehole per unit time, i.e.:
Q1c1+Q2c2＝Q3c3(2)
according to the law of conservation of mass, the amount of non-gas flowing into the surface borehole per unit time is equal to the amount of non-gas flowing out of the surface borehole, i.e.:
Q1(1-c1)＝Q3(1-c3) (3)
the system of equations consisting of equations (1) to (3) yields:
Q2＝Q3c3-Q1c1(5)
the formula (4) and the formula (5) are calculation models of the ground drilling extraction multi-coal-seam gas source distribution:
D. according to the gas concentration c extracted by the high-position drilling hole measured in the step B0Concentration c of gas extracted from ground drilling3Standard gas flow Q extracted from ground drilling3(ii) a And the concentration c of the gas extracted by the high-level drilling0Equal to the concentration c of gas extracted in the coal seam by drilling on the ground1And D, substituting the model into the ground borehole gas extraction multi-coal-seam gas source-dividing calculation model obtained in the step C to obtain the standard condition flow Q of the gas flowing into the ground borehole from the coal seam1And the standard condition flow Q of gas flowing into the ground borehole from the adjacent coal seam2；
E. D, obtaining the standard condition flow Q of the gas of the adjacent coal seam gas gushing into the ground borehole2Namely the gas extraction quantity of the adjacent coal seam in unit time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911317094.4A CN110991081B (en) | 2019-12-19 | 2019-12-19 | Method for determining gas extraction amount of adjacent layer based on gas extraction of ground drilling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911317094.4A CN110991081B (en) | 2019-12-19 | 2019-12-19 | Method for determining gas extraction amount of adjacent layer based on gas extraction of ground drilling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110991081A true CN110991081A (en) | 2020-04-10 |
| CN110991081B CN110991081B (en) | 2023-06-16 |
Family
ID=70063025
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911317094.4A Active CN110991081B (en) | 2019-12-19 | 2019-12-19 | Method for determining gas extraction amount of adjacent layer based on gas extraction of ground drilling |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110991081B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105257335A (en) * | 2015-10-16 | 2016-01-20 | 中国矿业大学 | Ground drilling well extraction pressure relief coal seam and goaf gas effect evaluation and control method |
| CN105447600A (en) * | 2015-12-09 | 2016-03-30 | 贵州省矿山安全科学研究院 | Dynamic source-sharing prediction method for gas emission quantity of mining face |
| CN106503357A (en) * | 2016-11-02 | 2017-03-15 | 河南理工大学 | Method based on the effective extraction radius of layer-through drilling Gas characteristic measurement |
| CN108301866A (en) * | 2018-04-16 | 2018-07-20 | 中煤科工集团西安研究院有限公司 | Mining of closed distance coal seam group adjacent layer gas pressure relief directional drilling stops pumping method |
| WO2018201714A1 (en) * | 2017-05-02 | 2018-11-08 | 中国矿业大学 | Accurate extraction method for coal mine gas |
| CN109446602A (en) * | 2018-10-15 | 2019-03-08 | 内蒙古科技大学 | A kind of Numerical Experimental Method of surface vertical borehole extraction super high seam gas |
| CN109630088A (en) * | 2018-12-05 | 2019-04-16 | 中煤科工集团重庆研究院有限公司 | Method for determining arrangement position of high-position drilling hole |
| CN109667562A (en) * | 2018-12-19 | 2019-04-23 | 中煤科工集团重庆研究院有限公司 | Mining body gas well up-down combined universe extraction method |
| CN109736876A (en) * | 2018-12-19 | 2019-05-10 | 中煤科工集团重庆研究院有限公司 | Large-diameter directional long-drill-hole extraction method for gas roof gushed by mining body |
| US20190145259A1 (en) * | 2017-03-20 | 2019-05-16 | China University Of Mining And Technology | Method for stepwise construction of preferential gas migration pathway at stope in coal seam |
-
2019
- 2019-12-19 CN CN201911317094.4A patent/CN110991081B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105257335A (en) * | 2015-10-16 | 2016-01-20 | 中国矿业大学 | Ground drilling well extraction pressure relief coal seam and goaf gas effect evaluation and control method |
| CN105447600A (en) * | 2015-12-09 | 2016-03-30 | 贵州省矿山安全科学研究院 | Dynamic source-sharing prediction method for gas emission quantity of mining face |
| CN106503357A (en) * | 2016-11-02 | 2017-03-15 | 河南理工大学 | Method based on the effective extraction radius of layer-through drilling Gas characteristic measurement |
| US20190145259A1 (en) * | 2017-03-20 | 2019-05-16 | China University Of Mining And Technology | Method for stepwise construction of preferential gas migration pathway at stope in coal seam |
| WO2018201714A1 (en) * | 2017-05-02 | 2018-11-08 | 中国矿业大学 | Accurate extraction method for coal mine gas |
| CN108301866A (en) * | 2018-04-16 | 2018-07-20 | 中煤科工集团西安研究院有限公司 | Mining of closed distance coal seam group adjacent layer gas pressure relief directional drilling stops pumping method |
| CN109446602A (en) * | 2018-10-15 | 2019-03-08 | 内蒙古科技大学 | A kind of Numerical Experimental Method of surface vertical borehole extraction super high seam gas |
| CN109630088A (en) * | 2018-12-05 | 2019-04-16 | 中煤科工集团重庆研究院有限公司 | Method for determining arrangement position of high-position drilling hole |
| CN109667562A (en) * | 2018-12-19 | 2019-04-23 | 中煤科工集团重庆研究院有限公司 | Mining body gas well up-down combined universe extraction method |
| CN109736876A (en) * | 2018-12-19 | 2019-05-10 | 中煤科工集团重庆研究院有限公司 | Large-diameter directional long-drill-hole extraction method for gas roof gushed by mining body |
Non-Patent Citations (7)
| Title |
|---|
| DINGQI LI: "A new technology for the drilling of long boreholes for gas drainage in a soft coal seam", 《ELSEVIER》, pages 107 - 112 * |
| 任仲久;: "高位钻孔抽采技术在工作面瓦斯治理中的应用", 中州煤炭, no. 02, pages 52 - 54 * |
| 党利鹏;: "高瓦斯工作面瓦斯涌出与分源治理方案研究", 能源技术与管理, no. 02, pages 24 - 26 * |
| 吕兆海;来兴平;王晓军;翟小伟;于志金;岳晓军;: "高瓦斯特厚煤层条件下首分层抽采技术实践", 煤炭工程, no. 05, pages 71 - 74 * |
| 李兴;杜少华;李洪生;米帅;: "高瓦斯综采工作面瓦斯涌出预测与立体防治技术研究", 河北工程大学学报(自然科学版), no. 01, pages 98 - 102 * |
| 李文超: "玉华煤矿瓦斯抽采技术研究", 《中国优秀硕士学位论文全文数据库 工程科技I辑》, pages 021 - 411 * |
| 王华: "坚硬顶板综采面采空区瓦斯抽采技术优化及应用研究", 《中国优秀硕士学位论文全文数据库 工程科技I辑》, pages 021 - 188 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110991081B (en) | 2023-06-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113464121B (en) | Method for determining gamma geosteering drilling track of azimuth while drilling | |
| Guo et al. | Longwall horizontal gas drainage through goaf pressure control | |
| CN103902827B (en) | Flow unit division method of carbonate-rock horizontal wells | |
| WO2016095462A1 (en) | TS-q METHOD FOR EVALUATING FLOOR WATER INRUSH RISK IN DEEP MINE COAL SEAM MINING | |
| CN105021662B (en) | Adopt workplace regimen real-time dynamic monitoring test unit and test method | |
| CN103472498B (en) | The die test new method of hydrofracturing In-situ stress measurements | |
| CN105628549B (en) | A kind of coal seam can desorbing mash gas content direct quickly full-automatic measuring method | |
| CN104405372A (en) | Method for testing vertical three zone heights of stope cover rock based on high level borehole flow | |
| CN104564043A (en) | Flow diversion chamber capable of testing flow diversion capacity of fracture network of tight reservoir by gas and working method thereof | |
| CN105333904A (en) | Coal rock upward borehole gas parameter measurement method | |
| CN103696801A (en) | Method for testing surface borehole pressure relief gas drainage range | |
| Yang et al. | Analysis of abnormally high water production in coalbed methane vertical wells: A case study of the Shizhuangnan block in the southern Qinshui Basin, China | |
| CN108825226A (en) | A kind of method and device for assessing gas production after pressure using chemical tracer | |
| CN104345022A (en) | Method for directly testing permeability of underground coal seam | |
| US12091971B2 (en) | Tracer diffusion device, system for tracing development of water conducting fracture zone and relataed method | |
| Qin et al. | CFD simulations for longwall gas drainage design optimisation | |
| CN107817191A (en) | A kind of method of coal bed gas extraction validity check | |
| CN110991081B (en) | Method for determining gas extraction amount of adjacent layer based on gas extraction of ground drilling | |
| CN101892842B (en) | Method for uncovering coal in vertical shaft | |
| CN112362371A (en) | Method for verifying reliability of gas content determination by long-distance closed coring process | |
| CN205422679U (en) | A testing tool that is used for horizontal gas well specific retention section | |
| Liu et al. | Numerical simulation of parameters optimization for goaf gas boreholes | |
| CN110413951B (en) | Determination method for coal bed methane well drainage and production speed | |
| CN105569623A (en) | Combined wellhead testing device for injection well and combined wellhead testing method | |
| CN111075442A (en) | Method for verifying extension length of fracturing main crack of coal-bed gas well |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |