Evaluation of Parameters Influencing Potential Gas Flow to the Mine in the Event of a Nearby Unconventional Shale Gas Well Casing Breach

Details

• Personal Author:
  Ajayi KM ; Khademian Z ; Schatzel, Steven J.
• Description:
  The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine creating safety concerns. To provide recommendations for developing guidelines that ensure a safe co-existence of longwall mining and unconventional shale gas production, this study evaluates the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach using a discrete fracture network (DFN) model. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements. The results show that a decrease in fracture aperture (potentially due to longwall-induced stress in the likely vicinity of the breach location) reduces the potential gas flow to the mine by a significantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas flow to the mine by over 70%. Similarly, changes in the fracture water saturation level significantly affect the gas flow. In all cases, the potential gas flow to the mine is higher if the casing breach occurs at an increased gas well pressure. These findings provide critical information regarding the impact of each of the parameters associated with gas flow in the event of a shale gas casing breach near a longwall mine and could help towards the development of guidelines to ensure a safe coexistence of both industries. [Description provided by NIOSH]
• Subjects:
  Hazardous Substances Mining Occupational Health Safety
• Keywords:
  Coal Mines Fracture Zones Gas Flow Guidelines Health Hazards Longwall Mining Mining Industry Models Pillar Mechanics Stone Mines Stress Structural Failure Underground Mines

  More +
• Series:
  Mining Publications
• ISBN:
  9781713845089
• Publisher:
  Society for Mining, Metallurgy & Exploration (SME)
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  Colorado ; OSHA Region 3 ; OSHA Region 8 ; Pennsylvania ; Utah
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  320-325
• NIOSHTIC Number:
  nn:20065276
• Citation:
  MineXchange: 2022 SME Annual Conference and Expo, February 27-March 2, 2022, Salt Lake City, Utah, preprint 22-063. Englewood, CO: Society for Mining, Metallurgy & Exploration, 2022 Feb; :320-325
• 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 22-063
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:b41d61c6c3a67c3e05e0a02b1c2db814c7aff8e148e54ffa00aeb1b3eb4ebde4355df1480105a081d693bd3cb08b89444c0a90aaf657e13fdb20a271e2d29394
• Download URL:
  https://stacks.cdc.gov/view/cdc/215500/cdc_215500_DS1.pdf
• File Type:
  [PDF - 337.60 KB ]