Microscopic Distribution of Wetting and Nonwetting Phases in Sandstones During Immiscible Displacements

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Abstract
Summary: A novel technique has been developed and used to study the microscopic distribution of wetting and nonwetting phases in reservoir rocks during immiscible displacements. The underlying principle is the use of appropriate fluids, serving as the wetting and the nonwetting phases, that can be solidified in situ, one at a time, without altering to any significant extent the position and orientation of the phases acquired at capillary equilibrium conditions. After both phases are solidified, the rock matrix is etched and replaced by a resin to enhance the quality of polishing. Polished sections are then serially made at each 5- to 10-μm depth and photomicrographed, wherein the three phases are distinguishable from each other. Experimental results have been obtained with Berea sandstone and the phase distribution is being analyzed. Relative permeabilities measured with the other phase solidified compare very well with conventional results obtained by the Penn State steady-state method, using Soltrol™ and brine. Wettabilities of the fluid pairs were also visualized directly by this new technique.