Effects of Longwall-Induced Subsurface Deformations and Permeability Changes on Shale Gas Well Integrity and Safety Under Shallow Cover

Details

• Personal Author:
  Addis J ; Dougherty H ; Gangrade V ; Hollerich C ; Minoski T ; Schatzel S ; Su, Daniel W. H. ; Van Dyke M ; Watkins E ; Zhang P
• Description:
  This paper presents the results of a 2018 NIOSH (National Institute for Occupational Safety and Health) study to evaluate longwall-induced subsurface deformations and permeability changes and their effects on shale gas well integrity and safety under shallow cover. A study site was selected over a southwestern Pennsylvania coal mine, which extracts 457-meter-wide longwall faces under 147 meters of cover. One in-place inclinometer (IPI) well and three permeability monitoring wells were drilled and installed over a 38-m by 84-m centers abutment pillar. In addition to the inclinometer well and monitoring wells, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the first 457-meter-wide longwall panel on the south side of the abutment pillar mined by. Comparisons of a series of FLAC3D finite difference simulation results and the surface, subsurface, and underground instrumentation results show that the measured IPI casing deformations are in reasonable agreement with those predicted by the FLAC3D models, and that the measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models. Measured permeability changes were incorporated into a preliminary calculation to evaluate the effect of a hypothetical shale gas well leak on longwall ventilation, which indicates negligible impact after completion of first panel mining. Results from this 2018 research clearly indicate that under shallow cover, the measured horizontal displacements within the abutment pillar are at least one order of magnitude higher than those measured in a 2017 study under deep cover and slightly higher than those measured in a 2014 study under medium cover. [Description provided by NIOSH]
• Subjects:
  Geology Mining Occupational Health Safety
• Keywords:
  3D Analytical Models Coal Mines Environmental Stress Gases Geologic Models Geotechnical Engineering Ground Control Ground Stability Longwall Mining Mathematical Models Models Monitoring Systems Pillar Mechanics Rock Mechanics Roof Supports Stress Three Dimensional Underground Mines Underground Mining

  More +
• Series:
  Mining Publications
• Publisher:
  American Rock Mechanics Association (ARMA)
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  New York ; OSHA Region 2 ; 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:20057677
• Citation:
  53rd US Rock Mechanics/Geomechanics Symposium, June 23-26, 2019, New York, New York. Alexandria, VA: American Rock Mechanics Association (ARMA), 2019 Jun; :ARMA 19-0013
• Federal Fiscal Year:
  2019
• NORA Priority Area:
  Mining ; Oil and Gas Extraction
• Peer Reviewed:
  False
• Source Full Name:
  53rd US Rock Mechanics/Geomechanics Symposium, June 23-26, 2019, New York, New York
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:52700257001ba523f67b20ff6231a06edda1d7f3520e5325ab08f4309d1cc27c029cf053915f499a794f9f0c1c81e061a62c02b5aa89e1c5268af39e3ee7827d
• Download URL:
  https://stacks.cdc.gov/view/cdc/227922/cdc_227922_DS1.pdf
• File Type:
  [PDF - 1.87 MB ]