Rockmass Permeability Induced by Longwall Mining Under Deep Cover: Potential Gas Inflow from a Sheared Gas Well

Details

• Personal Author:
  Ajayi KM ; Esterhuizen, Gabriel S. ; Khademian Z ; Kim BH ; Schatzel, Steven J. ; Su, Daniel W. H.
• Description:
  The stability of shale gas wells drilled through current and future coal reserves can be compromised by ground deformations due to nearby longwall mining. Depending on the longwall-induced rockmass permeability, the high-pressure explosive gas from the damaged well may reach mine workings and overwhelm the mine ventilation systems. This study uses geomechanical models to estimate the rockmass permeability induced by mining. A two-panel longwall model of a deep, 341-m-cover mining site in southwestern Pennsylvania is constructed in 3DEC to explicitly model the rockmass by a Discrete Fracture Network (DFN) technique. Stress-induced fracture apertures and permeabilities are calculated across the model and are validated against permeability measurements. A Fracture Flow Code (FFC) is developed to use these results to predict potential inflow to the mine should a gas well breach occur. One hundred DFN realizations are simulated, and the results show that for a gas pressure of 2.4 MPa, the average of the predicted inflow rates to this deep-cover mine is 0.03 m3/s, significantly lower than the average inflow of 0.92 m3/s for a shallow-cover mine (145 m deep) studied in the previous work (Khademian, et al. 2021). The result can help assess the potential hazards of a shale gas well breach for mine safety and evaluate the ventilation requirements to mitigate the risk. [Description provided by NIOSH]
• Subjects:
  Geology Mining Occupational Health Safety Ventilation
• Keywords:
  Environmental Stress Explosive Gases Fracturing Gases Ground Falls Hazards High Pressure Longwall Mining Mechanical Properties Mining Industry Models Risk Assessment Rock Mechanics Stress Underground Mines Ventilation Systems

  More +
• Series:
  Mining Publications
• ISBN:
  9781713845089
• Publisher:
  Society for Mining, Metallurgy & Exploration (SME)
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  Colorado ; OSHA Region 10 ; OSHA Region 3 ; OSHA Region 8 ; Pennsylvania ; Utah ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division ; SMRD - Spokane Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  100-105
• NIOSHTIC Number:
  nn:20065279
• Citation:
  MineXchange: 2022 SME Annual Conference and Expo, February 27-March 2, 2022, Salt Lake City, Utah, preprint 22-021. Englewood, CO: Society for Mining, Metallurgy & Exploration, 2022 Feb; :100-105
• Federal Fiscal Year:
  2022
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  MineXchange: 2022 SME Annual Conference and Expo, February 27-March 2, 2022, Salt Lake City, Utah, preprint 22-021
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:632ea19033f071319a9ebafeb9a17d5b9b166902304c5c434829a3cc6d435928957238e07a892aa9bba95a8bddb2d1b608c11cbfb8fa536baeaf10f639ed5e53
• Download URL:
  https://stacks.cdc.gov/view/cdc/215503/cdc_215503_DS1.pdf
• File Type:
  [PDF - 524.54 KB ]