The Illinois Basin Decatur Project (IBDP) pilot carbon capture and storage project is the subject of a comprehensive re-assessment. The primary objective is to integrate newly interpreted geological data, including horizons, faults, channels, and bars, into the existing static model; and discuss potential impacts. A refined understanding of the reservoir's architecture and a 3D injection simulation are pursued.
Key activities, including seismic and geological data interpretation, petrophysical analysis, geomechanical characterization, and the critical assessment of fracture pressures, have been employed. These activities have allowed the derivation of an updated static model that includes previously uninterpreted channels and bars as geobodies. This enhanced model forms the basis for 3D injection simulations.
Geological re-assessment of the reservoir shows segments of normal inverted faults that cut through it. More significantly, the interpretation of geobodies as pointbars in a fluvial environment due to the apparent lateral acretion observed in semblance volumes and the lateral property variations observed in the petrophysical analysis, improves the understanding of reservoir structure and character for simulation. The incorporation of new trends of previously uninterpreted channels and bars has added depth and complexity to our static model; as a result, the confidence in simulating the injection process has been enhanced, with the lateral complexity of the reservoir now playing a significant role in modifying connectivity for injection.
The geomechanical process was achieved by using previous sonic and density log analysis to calculate the vertical pressure, pore pressure, horizontal stresses, fracture pressure, and collapse pressure, to determine a normal stress regime for the area of review (AOR). Fault data taken from the static model identified six faults that cut the Mt. Simon formation. The faults were evaluated in the FSP software (Stanford University) indicating that the faults are stable and unlikely to become flow channels, “thief zones” for injected fluids.
