Influence of centrifugal forces on phase structure in partially saturated media

Abstract

Centrifugal methods are gaining increased attention for use in hydrologic experiments within partially saturated media. Through use of a Modified Invasion Percolation (MIP) model, we examine the influence of a stabilizing centrifugal (buoyancy) force on the invasion of a light non‐wetting fluid (e.g., air) into a heterogeneous porous media initially saturated with a denser, wetting fluid (e.g., water). Results show that while capillary heterogeneity controls phase structure outside of a centrifugal field, the influence of capillary heterogeneity varies with angular velocity in a centrifugal field. As the angular velocity is increased, the invasion processes and phase structure become increasingly insensitive to heterogeneity, regardless of its style or orientation. Because phase structure critically influences flow processes and petrophysical properties (pressure‐saturation, relative permeability, electrical resistivity, etc.), the design of centrifugal experiments must carefully consider this interplay between capillary heterogeneity and centrifugal force.