A Preliminary Analysis of the Carbon Dioxide Storage Capacity in the Upper Cambrian Basal Sandstone of the Midwest Region

Medina, Cristian R.¹; Rupp, John A.^1
1 Indiana Geological Survey, Bloomington, IN.

Porosity values collected from core analyses and geophysical logs from the Upper Cambrian basal sandstone in the Midwest Regional Carbon Sequestration Partnership (MRCSP) region indicate a predictable decrease in porosity with depth. Using this relationship and the methodology presented in the Carbon Sequestration Atlas of the United States and Canada, we estimate the potential geologic storage capacity of CO₂ in this deep saline aquifer. The variables that affect the volumetric calculations include: 1) the area that defines the region being assessed; 2) the porosity of the stratigraphic unit; 3) the gross thickness of the basal sandstone; and 4) the CO₂ storage efficiency factor, which accounts for material properties, including reservoir continuity and effective porosity. We conduct a sensitivity analysis to create different scenarios for CO₂ storage capacity, which is highly sensitive to changes of the subsurface properties of the unit being studied. The porosity and thickness of the deep saline aquifer unit can be grouped together by means of the net porosity feet, which is calculated using the regional trend of decreasing porosity with depth: φ(d) = 16.36 * e^-0.00012*d (r²=0.41), where φ equals porosity and d is depth in feet. In order to have some insight about how realistic this equation is, we compare the theoretical values of net porosity with those obtained from geophysical logs. This approach generates solutions of the spatial distribution of net porosity feet that facilitate the calculation of storage volume potential at specific localities within the region, which are in agreement with the value of 86,000 million metric tons of CO₂ estimated by the MRCSP for the capacity of the Mount Simon Formation in the states of Indiana, Kentucky, Michigan, and Ohio.

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009