Structural Impacts on the Deposition and Reservoir Development in the Conasauga Group in Ohio

Abstract

Reservoir storage potential in Cambrian age siliciclastics and carbonates of the Conasauga Group in central Ohio was structurally influenced by the Grenville Front and proto-Illinois-Michigan basins to the west, the Waverly Arch in the center, and the Rome Trough to the east. These features created a unique environment in which the Conasauga Group developed porous and permeable sandstone facies in the lowermost Nolichucky Formation, and meteoric karst in the immediately underlying upper Maryville Formation carbonates as a result of sea level changes. Both the sandy Nolichucky and vugular upper Maryville show great potential for CO₂ storage as stacked reservoirs. Wireline data for 178 wells were analyzed along with available whole core and sidewall core to map and characterize porosity distribution and variability. Statistically derived vug indicators delineate porosity fairways in the upper Maryville Formation. The results indicate the sandstones are shoreline features and the karst is related to subaerial exposure and basement faults. The sandy Nolichucky has an estimated aerial extend of 13,300 square miles, an average thickness of 36 feet, an average porosity of 10%, and the permeability is typically greater than 20 mD. Localized zones of high porosity and permeability were found in the upper 100 feet of the Maryville that average at 7% porosity with permeabilities up to 43,700 mD in the best karsted zones. The karsted upper Maryville and sandy Nolichucky are traceable well to well and detailed maps highlight areas of potential CO₂ storage reservoirs. This study provides insight into the continuity of storage reservoirs throughout Ohio as well as improving the geologic understanding of the Cambrian age. This work was supported by U.S DOE Award DE-FE0023330 and Ohio DSA Award CDO-D-14-16.

AAPG Datapages/Search and Discovery Article #90218 © 2015 Eastern Section Meeting, Indianapolis, Indiana, September 20-22, 2015