NUMERICAL MODELING OF ST. FRANCOIS AQUIFER RESPONSE TO CO2 INJECTION, SPRINGFIELD, MO

Pumping and pressure injection tests from the City Utilities of Springfield Southwest Power Plant (SWPP) site in Missouri were analyzed for local hydrogeologic characteristics of the St. Francois aquifer. Pumping tests revealed the highest zone of hydraulic conductivity to be 1.269E-04 cm/s in the upper part of the Reagan Sandstone. Comparison of Peres et al. and Hvorslev solution results for the pressure injection tests revealed there was no wellbore skin effect on the hydraulic conductivity readings. Hydraulic conductivity results were used to calculate intrinsic permeabilities for input into the program PetraSim to generate conceptual models of carbon dioxide (CO₂) injection into the aquifer. Both radial and compositional models will be used to show migration of the CO₂ phases from the site of injection. Models consist of a 30 year model with constant injection rate and models with a 30 year injection period followed by several hundred years shut-off period. Injection rate was limited by keeping the maximum allowable pressure change within a range of 4 MPa above static. Maximum allowable injection rate for the Lamotte Sandstone is 1.0 kg/s in the single layer radial model and 2.05 kg/s in the multi-layer radial model. Maximum allowable injection rate for the Reagan Sandstone is 18.0 kg/s in the single layer radial model and 23.4 kg/s in the multi-layer radial model. Completion of compositional models will reveal plume migration patterns under injection and retrograde conditions with a pressure gradient.