CO2 Injection Into a Deep Saline Aquifer: Porosity Measurements, Numerical Modeling, and Costs Associated with Uncertainty of Petrophysical Parameters

Anthropogenic levels of atmospheric greenhouse gases, particularly carbon dioxide (CO2) have increased rapidly over the last several decades and coincide with rising temperatures globally. One possible solution is to capture CO2 before it is released into the atmosphere by large point sources, such as fossil fuel power plants. Once captured, the CO2 can be condensed and transported to a storage facility. Of the available options for storage of condensed CO2, geologic sequestration in deep saline aquifers is considered the most viable option. Porosity measurements were obtained for nearly 100 core samples of the Knox and Stones River groups from the middle Tennessee area as part of a larger project for the Tennessee Division of Geology, characterizing the potential for geologic CO2 sequestration in Tennessee. Certain formations within these groups were found to exhibit higher porosity (higher storage potential) than others. Measured porosity values were quite low, ranging from 0.21 – 10.67 % with a median value of 1.21 %. These data can be used to aid in the decision-making process concerning possible geologic targets for geologic CO2 sequestration in Tennessee. A sensitivity analysis was also performed using a numerical model for geologic carbon sequestration (STOMP). Intrinsic permeability, porosity, pore compressibility, the van Genuchten residual liquid saturation, α and m parameters, and the Brooks and Corey residual liquid and gas saturations were varied independently and their influence on CO2 storage was determined. Changes in costs based on the parameter variations were calculated to evaluate the relative importance of the various parameters. The most influential parameters were intrinsic permeability, the van Genuchten m parameter, and the Brooks and Corey residual gas saturation. These results highlight the need for accurate measurement of intrinsic permeability and capillary pressure-saturation parameters in addition to more commonly measured properties like porosity