SHUMAKER, ROBERT C., LI ZHENG, and T. H. WILSON, West Virginia University, Geology and Geography, Morgantown, WV; and JOSEPH P. LEMON and JOHN BUURMAN, Columbia Natural Resources Inc., Charleston, WV

ABSTRACT: Original and Imposed Secondary Porosity, Heterogeneity, in the Mississippian Big Injun Reservoir, Granny Creek Field, West Virginia

The Granny Creek field of West Virginia is situated at the outer margin of detached Alleghanian structure above the eastern margin of an aulcogen called the Rome Trough in the Appalachian foreland. Minor movement of basement faults has influenced paleozoic sedimentation and the location of Alleghanian detached structure creating heterogeneity in the Mississippian Big Injun reservoir. Secondary oil recovery from the reservoir suggests the presence of heterogeneities not immediately apparent from primary production data. These heterogeneities are reflected by rapid communication between certain adjacent wells usually along northeast trends. Hydrofrac completion of injection wells is considered to have broken the brittle sand and carbonate seal above the reservoir permitting injected flu ds to follow fracture zones, likely small reverse faults that are associated with small, northeast-trending, detached structures located on the eastern flank of a much larger basement structure. Reprocessing of conventional seismic data has permitted identification of breaks in reflection coherency that we correlate with the imposed fracture permeability (Heterogeneity) identified in adjacent "problem" wells.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.