NEW REGIONAL MAPPING AND INSIGHTS INTO THE SEQUESTRATION POTENTIAL OF THE TENNESSEE BASAL SANDSTONE

This study expands on previous works evaluating the carbon sequestration potential of the Tennessee Basal sandstone (Mulderink and Bradley, 1986; Tsouris, et. al., 2002; Smyth, et. al. 2007; SECARB and ARI, 2011). New regional evaluation by Battelle includes additional well data, mapping, and petrophysical analyses furthering our understanding of depth, thickness, lateral extent, and salinity of the basal sandstone across central and western Tennessee. In addition, newly discovered well data including reports of dynamic testing from the DuPont Johnsonville Site Study Well (JSSW), obtained through communication with the Tennessee Geological Survey, have been integrated into our study.

The Tennessee basal sandstone is Cambrian in age and lies above the Precambrian unconformity with basement rocks comprised of granite, metasediments, arkose and siltstone (SECARB and ARI, 2011; Stehle and Collins, 1992). Historically, the basal sandstone has been evaluated for wastewater injection in Tennessee and determined to be confined by the Conasauga Group consisting of very low permeability shales and shaley carbonate rocks (Mulderink and Bradley, 1986; Lloyd and Reid, 1986). Previous work by Tsouris, et. al. (2002) suggests the properties of the basal sandstone are an average porosity of 9.2 % and an average permeability of 15.9 mD.

This study highlights the importance of integrating local site characterization into a regional context as a first pass for determining potential site feasibility with an understanding of basin dynamics and deposition. New regional work indicates the most prospective zone is in the lowermost basal sand with higher that reported average porosities observed in north central Tennessee. Updated maps of the presence, depth structure and thickness of the basal sandstone are presented with the addition of sensitivity modeling suggesting the properties and thickness required for injection and storage to be feasible for carbon sequestration. The need for local calibration of stratigraphy and reservoir quality is ultimately required to de-risk presence and storage potential in this sparse data setting for onsite sequestration.