Analysis of Variation in Longwall-Induced Permeability Under Different Mining Depths

Details

• Personal Author:
  Addis JD ; Ajayi KM ; Harris, Marcia L. ; Khademian Z ; Schatzel, Steven J.
• Description:
  Longwall-induced deformation could compromise the stability of shale gas wells positioned in the abutment pillars of current and future coal reserves. Consequently, gas from the casing(s) could flow towards the mine increasing the risk of explosive gas accumulation beyond the mandated limits. To assess the impact of this hypothetical scenario, the permeabilities of the surrounding strata are required to be quantified for potential gas flow to the mine. However, varying mining depths for different coal reserves could significantly impact permeability. Therefore, this study presents an analysis of longwall-induced permeability under shallow, <152 m (<500 feet), and deep cover, >274 m (>900 feet), using measurements obtained from different study sites in southwestern Pennsylvania along with discrete fracture network (DFN) modeling in 3DEC and Fracture Flow Code (FFC). The field study measured permeability changes for specific strata, and the numerical model predicted the permeability changes for all the strata in the overburden. At the study site, the maximum permeability measured over the abutment pillar at the Uniontown horizon is 2.17×10-14 m2 (22 mD) and 1.75×10-14 m2 (18 mD) for deep and shallow cover sites, respectively. These findings provide a measure for comparing the potential risk of a hypothetical breach under a shallow and a deep cover. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety Ventilation
• Keywords:
  Coal Mines Explosive Gases Gas Flow Longwall Mining Underground Mines
• Series:
  Mining Publications
• ISBN:
  9781032551463
• Publisher:
  CRC Press
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• NIOSHTIC Number:
  nn:20069428
• Citation:
  Underground Ventilation: Proceedings of the 19th North American Mine Ventilation Symposium (NAMVS 2023), June 17-22, 2023, Rapid City, South Dakota. Tukkaraja P ed. London: CRC Press, 2023 Sep; :507-514
• Editor(s):
  Tukkaraja P
• Federal Fiscal Year:
  2023
• Peer Reviewed:
  False
• Source Full Name:
  Underground Ventilation: Proceedings of the 19th North American Mine Ventilation Symposium (NAMVS 2023), June 17-22, 2023, Rapid City, South Dakota
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d9a49b9935b7924d88e7c9b3ea2684da495e0de56817267070c95a8682a0134cad0d2bf03c4f45bb7fb61da5d6b8b497b0a20532bf654e04d6d8aec703fd64ff
• Download URL:
  https://stacks.cdc.gov/view/cdc/215650/cdc_215650_DS1.pdf
• File Type:
  [PDF - 1.82 MB ]