Imaging and quantifying three-phase flow in porous media

Understanding the physics of natural flow systems that include three immiscible fluid phases in porous media is important to applications such as remediation of NAPL from the vadose zone, oil and gas recovery, and CO2 sequestration. Flow and transport in such systems are strongly influenced by the presence of fluid-fluid interfaces. A detailed understanding of how the three fluids interact in the pore space can be gained from visualization and quantification of the system, yet accurate delineation of three fluid phases via x-ray microtomography is not straightforward. Issues related to spreading films and the partial wetting of solid surfaces by oil and water present challenges beyond two-phase fluids systems. This research expands previous work on two-fluid-phase systems to three-fluid-phase systems, and the particular focus is the generation of a pore-scale experimental data set that expresses the dependency of average capillary pressures in the system on saturation, as well as interfacial areas per volume. Synchrotron-based x-ray computed microtomography is used to generate high-resolution images during drainage and imbibition, which are then analyzed to measure the saturations and interfacial areas.