Exploring capillary trapping efficiency as a function of interfacial tension, viscosity, and flow rate

Abstract

We present experimental results based on computed x-ray microtomography (CMT) for quantifying capillary trapping mechanisms as a function of fluid properties using several pairs of analog fluids to span a range of potential supercritical CO2-brine conditions. Our experiments are conducted in a core-flood apparatus using synthetic porous media and we investigate capillary trapping by measuring trapped non-wetting phase area as a function of varying interfacial tension, viscosity, and fluid flow rate. Experiments are repeated for a single sintered glass bead core using three different non-wetting phase fluids, and varying concentrations of surfactants, to explore and separate the effects of interfacial tension, viscosity, and fluid flow rate. Analysis of the data demonstrates distinct and consistent differences in the amount of initial (i.e. following CO2 injection) and residual (i.e. following flood or WAG scheme) non-wetting phase occupancy as a function of fluid properties and flow rate. Further experimentation and analysis is needed, but these preliminary results indicate trends that can guide design of injection scenarios such that both initial and residual trapped gas occupancy is optimized.