Integrating Modern Suite of Geophysical Logs, Geochemistry, and Seismic Data for Characterizing Deep Aquifers

The 5000 ft deep, 1000 ft thick Lower Ordovician Arbuckle Group aquifer in Kansas has been evaluated as a suitable medium for large scale Carbon Capture and Storage (CSS). The petrophysical properties governing flow and transport in this carbonate aquifer are extremely variable due to the presence of complex interbeds of fractured, vuggy dolomite and shale. The extent of the CO₂ plume needs to be demonstrated to the EPA every six months and shown to be in compliance with modeled projections in order to continue injection. Therefore, detailed and accurate characterization of the injection and confining zones is vital.

Spectral Gamma Ray, Triple combo log suite, Magnetic Resonance Image (MRI), and Dipole Sonic were used to characterize pore volume, distribution, and connectedness, and also to identify potential sources of drinking water. The MRI data was used with a new (patent pending) Flow Zone Interval method to estimate permeabilities. The confining potential of the caprock was estimated using MRI based pore throat data to calculate entry pressure. The Extended Range Micro Imager log and Computed Tomography (CT) scan were used to characterize fractures.

The stratification and delineation of hydrostratigraphic units derived from geophysical logs was validated by formation geochemistry, and ionic and isotopic analyses. Geochemical logs and thin sections were analyzed for mineralogy and soil characterization to enable reaction kinetics modeling and determining potential for plugging pore space due to mineral precipitation.

Drill stem and injectivity tests were conducted to determine the relationship between laboratory, log, and field scale estimates of permeability. 3-D seismic data was collected to map formation structures and characterize the geologic fabric regionally. The entire set of data was finally integrated into a 3-D reservoir model using Schlumberger’s (geocellular) Petrel Geology/ Modeling software.