Mineralogical Characterization and Macro/Microstrain Analysis of the Marcellus Shales

Details

• Personal Author:
  Gupta, Kailash ; Mishra B ; Sabolsky EM ; Yakaboylu GA
• Description:
  Due to the complex structure of the brittle formations like shale, their microcracking and mechanical deformation behavior are not well known. To understand the fundamental factors at the micron scale, Marcellus shales were cored both parallel and perpendicular to the bedding orientation and mechanically tested through triaxial creep test under constant stress. The parallel-bedded shales exhibited higher level of permanent strain in the radial direction, which increased with increasing time. This also confirmed their anisotropic nature due to the bedding. Their advanced characterization via X-ray diffraction (XRD) and Raman spectroscopy techniques before and after the creep tests revealed the mineralogical heterogeneity, and the presence of an organic matter (kerogen) concentrated in the microcrack areas. Besides, the XRD peak shifts and changes in peak shape indicated that there was a certain level of macrostrain and microstrain in the shale. Further investigation of the XRD peak shape (integral breadth) changes using the Williamson-Hall method demonstrated a higher concentration of lattice defects and associated microstrain (inhomogeneous lattice strain) present in the calcite phase compared to the quartz. The parallel-bedded shales also revealed a higher level of microstrain with respect to the perpendicular-bedding. The results proved that the microcracking (initiation and propagation) and associated mechanical deformation of the Marcellus shales were mostly influenced by the presence of organic matter, microstrain level (defect concentration) in the calcite mineral, and the bedding orientation. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  Author Keywords: Size Effect Bonded-particle Model Compressive Strength Geologic Formations Geotechnical Engineering Griffith Theory Mining Industry Mohr-Coulomb Failure Criterion Rock Mechanics Underground Mines
• ISSN:
  1365-1609
• Document Type:
  Text
• Funding:
  Contract
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  134
• NIOSHTIC Number:
  nn:20068336
• Citation:
  Int J Rock Mech Min Sci 2020 Oct; 134:104442
• Contact Point Address:
  Brijes Mishra, Department of Mining Engineering, West Virginia University, 1374 Evansdale Drive, Morgantown, WV, 26506, USA
• Email:
  brijes.mishra@mail.wvu.edu
• Federal Fiscal Year:
  2021
• Performing Organization:
  West Virginia University
• Peer Reviewed:
  True
• Start Date:
  20160914
• Source Full Name:
  International Journal of Rock Mechanics and Mining Sciences
• End Date:
  20200831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:420815c53a0dad5f8b76b8a73d614022d9a5e3ff7f0da25543519d03806d478b61280de6bccd87141a2771f2b410169cd232f07ac0bc0db155366d62c543b1f3
• Download URL:
  https://stacks.cdc.gov/view/cdc/230503/cdc_230503_DS1.pdf
• File Type:
  [PDF - 11.79 MB ]