Linear Waterflood Behavior and End Effects in Water-Wet Porous Media

Introduction

Theory indicates that linear waterfloods should exhibit scaling and stabilization properties in both oil-wet and water-wet porous media. Experimental verification of these properties in oil-wet media was obtained some time ago, and more recently, Perkins employing a high permeability unconsolidated sand and a low oil-to-water viscosity ratio, has obtained flooding data in a water-wet medium which follow the pattern of scaling and stabilization. Also, Root and Calhoun have found similar trends in the displacement of gas by liquids from unconsolidated sands. In general, however, the experimental evidence appears still somewhat conflicting since scaling and stabilization of water floods in water-wet media has not been observed in most of the studies to date.

The purpose of this paper is to provide a more comprehensive picture of waterflood behavior in waterwet media and to corroborate the validity of the scaling and stabilization concepts. The need for differentiating between the intrinsic nature of water-oil displacements inside a porous medium and perturbating secondary end effects is discussed, pertinent experimental procedures are outlined and the results of flooding tests conducted at low and at high oil-to-water viscosity ratios on consolidated, water-wet Alundum cores are analyzed.