INTEGRATION OF GIS MAPPING AND REGIONAL GEOLOGY OF CARBONATE FORMATIONS IN THE APPALACHIAN BASIN

Using GIS methods, basin structure, depth, and thickness maps were created for seven major Paleozoic carbonate intervals of the Appalachian basin: Mississippian Greenbrier Group, Middle Devonian Onondaga Limestone, Early Devonian Helderberg Limestone, Late Silurian Lockport Dolomite, Late Ordovician Trenton Limestone, Late Ordovician Black River Group, and Late Cambrian Knox Group. The maps were integrated with regional geology, including basin tectonics, and were used for assessing suitability of the various formations for developing underground storage caverns by dissolving the formations using acid. Using geologic and economic criteria, limestone formations at depths between 1200 and 3050 m, with thickness greater than 60 m, and containing a high proportion of calcite relative to other minerals were identified as the most suitable for developing underground storage caverns. Using GIS, pipeline and railroad intersections were mapped and integrated with the geologic maps to identify specific sites.

Tectonic features were examined for their effect on development of storage caverns in the carbonate formations. Severe folding and faulting of the carbonate formations near the Appalachian structural front make this area unsuitable for developing storage caverns. Deeper occurrences of the formations and localized faulting are associated with the Rome Trough. Suitability of the carbonate formations for developing storage caverns is limited to the west by the Cincinnati Arch because of decreased depths and thicknesses of the formations.

The presence of common shale interbeds, quartz sand, chert, and unconformities results in some of the formations being unsuitable for developing underground storage using acid dissolution. Shale and quartz content is associated with siliciclastic sedment sources related to uplift, and common unconformities within formations are present in areas of relative sea-level fluctuations. The Lockport Dolomite and Knox Group are dolomitic, which hampers the dissolution process and overall suitability. The overall analysis indicates that the Greenbrier Group, Helderberg Limestone, and Black River Group are the most suitable formations for developing underground storage using acid dissolution.