STRATIGRAPHY OF THE BEREA SANDSTONE, BIG CREEK GAS FIELD, MCDOWELL COUNTY, WEST VIRGINIA

The Big Creek gas field of McDowell County, West Virginia, is an old field (discovered in the late 1940's) producing primarily from the Berea Sandstone with lesser production from Upper Mississippian sandstones, Big Lime, Upper Devonian sands and the Devonian shale. A series of cross sections suggest that the interval identified as Berea in the southern part of the field, in fact, may be two sand bodies juxtaposed: an older Upper Devonian Gordon sand and a younger, thin Berea sand. The Gordon sand was exposed on a shallow shelf and subjected to erosion. The Berea Sand is a product of the reworking of the liberated sands. Both the remnant Gordon sand and the Berea sand are variable in thickness; the older unit thickness dependent on how much surface erosion took place and the younger unit's thickness dependent on how much sand was made available at any location. Gas production appears to be concentrated in the lower unit directly below the unconformity separating the two sands as indicated by temperature logs.