Rock Physical Properties and CT Imaging of CO2-brine Displacement in Reservoir Sandstone

Recent CO2-brine drainage and imbibition experiments in natural sandstone reservoir analogue (23% porosity cylindrical Rothbach cored perpendicular to bedding, average permeability of 400 mD) demonstrate the implications of sub-core scale heterogeneity on fluid distribution of the involved phases and the associated geophysical response. The initially brine saturated specimen was drained by stepwise injecting liquid CO2, and changes in resistivity and ultrasonic velocity was monitored while simultaneously imaging the fluid distribution by an industrial CT-scanner. A similar procedure was subsequently used for re-imbibition with brine. The results indicate a close link between the response of the measured physical and the tomographically mapped minute saturation levels and provides a deeper understanding of the implications of the flooding and imbibition processes.