Assessment of CO2 Storage Potential in the Mt. Simon Sandstone in Indiana via Direct Mapping of Pay

The Cambrian Mt. Simon Sandstone is commonly identified as a key element in future onshore energy systems in the United States. However, a review of Mt. Simon geologic characterization in public databases shows very limited information for key geologic parameters. Here, a new geologic reservoir characterization was undertaken for the Mt. Simon that focuses on the state of Indiana. Although deep saline reservoirs are usually lacking data, sufficient well and sample-derived data is available for the Mt. Simon to construct characterizations of the primary volumetric parameters at high spatial resolution. These parameters were obtained via inspection of raster well-log data from 135 wells. Gamma-ray log data were used to conduct a regional correlation that resulted in the recognition of 10 stratigraphic intervals between the base of the Potosi Dolomite and the Precambrian basement. Formation density-log data from 52 wells were then used to estimate porosity using calibration to core-derived porosity information from 15 wells. These data were used to map total porosity-feet for each stratigraphic interval at 7 %, 10 %, and 15 % porosity cut-offs. Incorporating considerations for immobile water and carbon dioxide density, the estimated best, or most likely, estimate (10 % porosity cut-off) for total potential geologic storage (not discounted for efficiency) in Indiana is 664 billion metric tons (bmt). In comparison, the 7 % threshold produces 873 bmt but with higher risk of non-viability. Similarly, the 15 % porosity cut-off generates 261 bmt with correspondingly higher reservoir quality. Mathematical attempts to discount storage volumes in order to address how much of the gross thickness is not viable and, to account for partial pore fluid displacement, commonly utilize a low cumulative storage efficiency, perhaps 5 % or less. However, our approach, which focuses on direct mapping of net area, net pay thickness, and porosity-of-net thickness, removes several of the common components of composite efficiency, suggesting that higher efficiency values may be viable.