Identifying Longwall-Induced Fracture Zone Height Through Core Drilling

Details

• Personal Author:
  Dougherty H ; Kim BH ; Su D ; Van Dyke MA ; Zhang P
• Description:
  The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a post-mining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64 degree, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457-m wide and 3657-m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones in longwall gobs. [Description provided by NIOSH]
• Subjects:
  Body Height Coal Coal Mining Geology Hazardous Substances Mining Occupational Health Oil And Gas Industry Safety
• Keywords:
  3D Author Keywords: Core Coal Industry Coal Mining Coal Seams Drilling Environmental Control Environmental Stress Fracture Zones Fracturing Gas Industry Geologic Models Geologic Strata Hazard Controls Hazards Height Factors Longwall Longwall Mining Mining Industry Models Natural Gas Pillar Mechanics Rock Mechanics Simulation Methods Strata Control Subsidence Three Dimensional Underground Mining

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• Series:
  Mining Publications
• ISSN:
  2524-3462
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 10 ; OSHA Region 3 ; Pennsylvania ; 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
• Volume:
  39
• Issue:
  4
• NIOSHTIC Number:
  nn:20065472
• Citation:
  Min Metall Explor 2022 Aug; 39(4):1345-1355
• Contact Point Address:
  Mark Alexander Van Dyke, CDC NIOSH, Pittsburgh Mining Research Division, Pittsburgh, PA
• Email:
  mso2@cdc.gov
• Federal Fiscal Year:
  2022
• NORA Priority Area:
  Mining
• Peer Reviewed:
  True
• Source Full Name:
  Mining, Metallurgy & Exploration
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:21e1987a9b95aebb8a9790cd44745e47570d02028160fd7eebd9cd40319810a61af33ca31fc882a31be9a1809007b775b0d7d11905d50e2ba06252dbd0eb9aff
• Download URL:
  https://stacks.cdc.gov/view/cdc/215556/cdc_215556_DS1.pdf
• File Type:
  [PDF - 2.54 MB ]