Improving the Centrifuge Technique by Measuring Local Saturations

Abstract

Abstract A significant new improvement in the centrifuge method is proposed. It consists in continuously recording the local saturation variation by using an ultrasonic device at different locations along the core, while centrifuging at any given time. The experimental procedure consists in recording flight times of ultrasonic waves at three locations along the core and then determining local saturation by a simple specific calibration, which leads to correspondence between the ultrasonic signal and saturation. By using this procedure, direct determinations of oil/brine capillary pressure curves are obtained by studying equilibrium regimes. Meanwhile, local saturation measurements make it possible to investigate the transient regime in order to compute relative permeability curves. Then relative permeability curves are estimated by using a least-squares technique. The relative permeability curves representative of the centrifuge experiment are in good agreement with the curves obtained by using the unsteady-state technique for a sandstone sample.