Site Selection for Carbon Sequestration in Saline Reservoirs

Leetaru, H.E. ¹,  Frailey, S.M. ¹, Morse, D.G. ¹, Finley, R.J., Korose C.P. ¹, and McBride, J.H. ²

¹Illinois State Geological Survey

²Brigham Young University

Deep saline reservoirs represent the largest component in the portfolio of geologic storage capacity for sequestered CO₂; therefore, adequate evaluation of these reservoirs is of paramount importance.  An evaluation of a potential sequestration site commonly includes: regional analysis of porosity and permeability, analysis of the reservoir seal, subsurface structure mapping of the target reservoir, identification of transmissive faults that might leak CO₂, evaluation of the lateral continuity of the reservoir, and delineating the limits of potable water.  During site selection it is important to evaluate the effects of displacing water out of deeper strata and inadvertently moving it into shallower outcrops, subcrops, or into areas with potable water. 

The best sites for carbon sequestration are those with saline reservoir strata that are overlain by structurally controlled oil and gas fields.  These areas not only have structural closure, but, also have proven seals that mitigate against CO₂ leakage.  The Ordovician age St. Peter Sandstone and the Cambrian age Mt. Simon Sandstone are the two most significant Illinois Basin targets for CO₂ storage in saline reservoirs.  Using the shallow hydrocarbon producing fields as structural control, it is estimated that the St. Peter has a potential storage volume of 2,000 MMtonnes and the Mt. Simon could store up to 5,900 MMtonnes in these structural traps.