ISOPACH AND STRUCTURAL CONTOUR MAPPING OF THE LOWER MISSISSIPPIAN BEREA SANDSTONE USING GIS, GUERNSEY COUNTY, OHIO

The Lower Mississippian Berea Sandstone is a prolific oil and gas producer in the Appalachian basin. In Guernsey County, Ohio, the Berea sandstone is mainly a secondary producer; the primary producing formation is the Silurian Clinton Formation. The prominent structural feature in Guernsey County is the low amplitude Burning Springs Anticline. We examined 507 drillers' logs in an attempt to determine the isopach thickness and the subsea structure of the Berea sandstone in Guernsey County. The drillers' logs are available from the Ohio Geological Survey. The formation depth information was appended to a database that included GIS spatial data. Missing ground level information was determined by superimposing well locations over Digitial Elevation Models (DEM) of Guernsey county.

Structural contour and isopach maps were drawn using the Rockworks99 program. Isopach thickness ranges from a minimum of 3 feet to a maximum of 160 feet. The thickest Berea section occurs along a northeast-southwest trend that is located in the northern part of the county. The subsea depth of the Berea varies from -46 feet to over -500 feet. The shallowest subsea depth occurs in a northeast-southwest trend in the northern part of the county. The deepest Berea occurs in the southern part of the county. These results are consistent with previously published sedimentological models of Berea deposition. Finally, no apparent relationship exists between isopach thickness, subsea depth and producing wells.