Facies Analysis and New Exploration Target in the Devonian Gordon Stray Sandstone of West Virginia
Mcbride, Patrick S. and Richard Smosna
West Virginia University, Morgantown, WV
West Virginia’s Jacksonburg-Stringtown field has produced 22 MMBO to date and continues to produce oil through waterflood operations. Based on 10 full-bore cores from Wetzel and Tyler Counties, we interpret the reservoir—the Gordon Stray sandstone—as a barrier-island complex, comprising (from bottom to top) lower-shoreface, upper-shoreface, and foreshore sandstone and conglomerate. Tying core interpretations to 123 well logs enables the several facies to be mapped. A north-south thick along the eastern part of the field reflects a period of aggrading deposition, and conglomerate in the northeast indicates the presence of a stream that supplied coarse sediment to the barrier complex. Facies distributions show that water depth increased seaward (west) as well as around the southern tip of the barrier island. The major pay zone occurs stratigraphically within the middle of the shoreface facies, a fine- to medium-grained, well sorted sandstone with good permeability. This pay zone may be best developed to the northeast and southeast, compartmentalized by an intervening shaly zone which perhaps accumulated within a small recess into the barrier. The barrier island then prograded rapidly westward, laying down a thin sandstone. Immediately above the barrier-beach facies are washover sandstone and lagoonal mudstone. Mapping of these back-barrier facies identifies two washover lobes in the western part of the field, spilling eastward into the lagoon. This map pattern strongly suggests that another thick barrier-island complex exists at some close distance west of the Jacksonburg-Stringtown field, a previously unknown exploration target in the Upper Devonian Gordon Stray sandstone.
AAPG Search and Discovery Article #90031©2004 AAPG Eastern Section Meeting, Columbus, Ohio, October 3-5, 2004