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 fow 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 fow 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 is 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 fow to the mine by a signifcantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas fow to the mine by over 70%. Similarly, changes in the fracture water saturation level signifcantly affect the gas fow. In all cases, the potential gas fow to the mine is higher if the casing breach occurs at an increased gas well pressure. These fndings provide critical information regarding the impact of each of the parameters associated with gas fow 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 Health Hazards Longwall Mining Mining Industry Pillar Mechanics Stone Mines Structural Failure Underground Mines
• Series:
  Mining Publications
• ISSN:
  2524-3462
• Document Type:
  Text
• Genre:
  Journal Article
• 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
• Volume:
  39
• Issue:
  6
• NIOSHTIC Number:
  nn:20066226
• Citation:
  Min Metall Explor 2022 Dec; 39(6):2333-2341
• Contact Point Address:
  Kayode M. Ajayi, CDC NIOSH, Pittsburgh, PA, USA
• Email:
  ony2@cdc.gov
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Mining ; Oil and Gas Extraction
• Peer Reviewed:
  True
• Source Full Name:
  Mining, Metallurgy & Exploration
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:2d8746973a4a90dfd79dd2be9ee55f58af97d93340058b3b5726ce5ccdee0cc5518646a2adf16a2ea2ba3ba55ec13a0fe42a65c0adc6e3dc6cc3b3dd17b0f2fb
• Download URL:
  https://stacks.cdc.gov/view/cdc/215584/cdc_215584_DS1.pdf
• File Type:
  [PDF - 1.59 MB ]