Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing
The No. 21 coal seam in the Zhengzhou mining area is a soft, three-layer, low-permeability coal seam prone to outbursts. The three-layer structure includes the coal seam and the roof and floor layers, which exhibit high gas contents and poor permeability. The dynamic hazards caused by coal and gas o...
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| Format: | Article |
| Language: | English |
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Wiley
2022-01-01
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| Series: | Geofluids |
| Online Access: | http://dx.doi.org/10.1155/2022/7958712 |
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| author | Zhengjie Shang Zhaofeng Wang Zhiheng Cheng Hongbing Wang Liang Chen Lei Li Jianhua Fu Hao Liu |
| author_facet | Zhengjie Shang Zhaofeng Wang Zhiheng Cheng Hongbing Wang Liang Chen Lei Li Jianhua Fu Hao Liu |
| author_sort | Zhengjie Shang |
| collection | DOAJ |
| description | The No. 21 coal seam in the Zhengzhou mining area is a soft, three-layer, low-permeability coal seam prone to outbursts. The three-layer structure includes the coal seam and the roof and floor layers, which exhibit high gas contents and poor permeability. The dynamic hazards caused by coal and gas outbursts are very serious. A new permeability-increasing fracturing technique that combines hydraulic perforation and hydraulic fracturing was developed specifically for the geologic conditions of the gas-bearing No. 21 coal seam. Numerical simulations were developed to study the influence of the technique on the stress distribution and permeability of the coal around the borehole. In addition, the extracted borehole gas concentrations and extraction amounts at multiple sites were investigated before and after using the technique. The study shows that the permeability-increasing fracturing technique destroys the concentrated stress coal pillars via the development of fractures between boreholes in exposed hydraulically perforated coal. The coal stress within the zone with an effective increase in permeability decreased by 30%. Furthermore, the permeability in this zone increased by three times, and the average extracted gas concentration increased by over six times. The gas pressure in the No. 21 coal seam decreased from 1.1 MPa to 0.4 MPa, and the gas content decreased from 15.96 m3/t to 5.6 m3/t. All outburst prediction indexes measured on site did not exceed their respective limits. The technique not only effectively eliminated the dynamic hazards caused by coal and gas outbursts but also achieved efficient gas extraction in the Zhengzhou mining area. |
| format | Article |
| id | doaj-art-807dce1a888b4f3da1ad2afcc474c53d |
| institution | Kabale University |
| issn | 1468-8123 |
| language | English |
| publishDate | 2022-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geofluids |
| spelling | doaj-art-807dce1a888b4f3da1ad2afcc474c53d2025-02-03T06:04:48ZengWileyGeofluids1468-81232022-01-01202210.1155/2022/7958712Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic FracturingZhengjie Shang0Zhaofeng Wang1Zhiheng Cheng2Hongbing Wang3Liang Chen4Lei Li5Jianhua Fu6Hao Liu7School of Safety Science and EngineeringSchool of Safety Science and EngineeringNorth China Institute of Science and TechnologySchool of Civil and Resource Engineering University of Science and Technology BeijingNorth China Institute of Science and TechnologySchool of Safety Science and EngineeringSchool of Safety Science and EngineeringCollege of Aerospace EngineeringThe No. 21 coal seam in the Zhengzhou mining area is a soft, three-layer, low-permeability coal seam prone to outbursts. The three-layer structure includes the coal seam and the roof and floor layers, which exhibit high gas contents and poor permeability. The dynamic hazards caused by coal and gas outbursts are very serious. A new permeability-increasing fracturing technique that combines hydraulic perforation and hydraulic fracturing was developed specifically for the geologic conditions of the gas-bearing No. 21 coal seam. Numerical simulations were developed to study the influence of the technique on the stress distribution and permeability of the coal around the borehole. In addition, the extracted borehole gas concentrations and extraction amounts at multiple sites were investigated before and after using the technique. The study shows that the permeability-increasing fracturing technique destroys the concentrated stress coal pillars via the development of fractures between boreholes in exposed hydraulically perforated coal. The coal stress within the zone with an effective increase in permeability decreased by 30%. Furthermore, the permeability in this zone increased by three times, and the average extracted gas concentration increased by over six times. The gas pressure in the No. 21 coal seam decreased from 1.1 MPa to 0.4 MPa, and the gas content decreased from 15.96 m3/t to 5.6 m3/t. All outburst prediction indexes measured on site did not exceed their respective limits. The technique not only effectively eliminated the dynamic hazards caused by coal and gas outbursts but also achieved efficient gas extraction in the Zhengzhou mining area.http://dx.doi.org/10.1155/2022/7958712 |
| spellingShingle | Zhengjie Shang Zhaofeng Wang Zhiheng Cheng Hongbing Wang Liang Chen Lei Li Jianhua Fu Hao Liu Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing Geofluids |
| title | Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing |
| title_full | Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing |
| title_fullStr | Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing |
| title_full_unstemmed | Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing |
| title_short | Permeability Enhancement Technology for Soft and Low-Permeability Coal Seams Combined with Hydraulic Perforation and Hydraulic Fracturing |
| title_sort | permeability enhancement technology for soft and low permeability coal seams combined with hydraulic perforation and hydraulic fracturing |
| url | http://dx.doi.org/10.1155/2022/7958712 |
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