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Subtle Discontinuity Analysis and Reservoir Characterization of Marcellus Shale in the Appalachian Basin, Taylor County, West Virginia

Lierong Zhu, Tim Carr, Tom Wilson, and Dengling Gao
Department of Geology and Geography, West Virginia University, Morgantown, WV

The Marcellus Shale of Middle Devonian in Appalachian basin currently are successful shale-gas reservoirs in North American. This study extracts subtle discontinuity from seismic data at Taylor County, West Virginia with emphasis on the orientation of discontinuity and reservoir characterization that can guide horizontal well drilling and fracture stimulation design.

A southwest-northeast synclinal fold is in the northern part of study are. A northwest-southeast discontinuity crosses the northeast part of survey area. The 3D curvature images the subtle discontinuity with four discontinuity zones. The Ant tracking attribute shows the orientations of discontinuities, which carries two regional joint sets. The earlier J1 joints orientate approximately N52E, and the later J2 joints trends around N45W. There is a low angle between the J1 joints and the maximum compressive normal stress of the contemporary tectonic stress field. Horizontal well drilling is perpendicular to the J1 joints, and hydraulic fracture stimulations are parallel to J1 joints, which can assist the extension of fractures to the maximum. There are areas of crosscutting N45W discontinuities that are interpreted as fracture swarms, which is related to cross-strike structural discontinuity. These areas may form reservoir barriers or areas where hydraulic fracturing could be ineffective due to energy largely loss along faults and open fractures. The average porosity calculated from neutron porosity and density is around 15%. Uranium concentration is more positively related with total organic carbon than GR, and the average total organic carbon of Marcellus Shale interval estimated from uranium concentration in study area ranges from 4% to 6.5%.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013