Characterization and Numerical Simulation of Remaining Oil in Water-Wet Sandstones Based on Micro-CT Displacement Experiment and VOF Model

Abstract

Abstract Eocene sandstones in the Huanghekou Depression, Bohai Bay Basin, China are characterized by highly variable macroscopic petrophysical properties and heterogeneous microscopic pore structures, and thus control fluid flow behavior and remaining oil distribution in porous rock. In this paper, X-ray CT coreflooding experiments were performed on three sandstone samples with different petrophysical properties. In addition, an integrated approach based on image processing, pore network modeling and the traditional volume of fluid (VOF) model served to quantify the fluid flow behavior and remaining oil distribution in porous rocks. Pore throat size and pore connectivity are the key factors controlling the fluid flow in porous rocks. The water phase advances rapidly along the dominant fluid flow channels and results in a rapid increase of oil displacement efficiency in the sandstones with good pore connectivity. The water flooding rate is also a vital factor affecting the fluid flow by controlling the number of capillaries. The findings provide useful insights into the variation of remaining oil during water flooding process and the fluid flow behaviors in heterogeneous sandstone.