Method and apparatus for measuring capillary pressure and foam transport in porous media

Abstract

A coreflood method that treats a consolidated porous medium, e.g., as a bundle of capillaries of various sizes as a surfactant alternating gas (SAG) method of foam injection. An electrical resistivity tool is used to monitor and measure in-situ changes in water and gas saturation while a high-resolution pressure transducer measures the pressure drop across the sample. A consolidated rock sample pre-saturated with a surfactant solution is injected with a small slug of gas and then a surfactant solution is injected until a steady state flow is observed. Graphical analysis of the saturation and pressure profile in each cycle allows the estimation of water saturation, saturation of the mobile and trapped fractions, and a corresponding pressure drop. Similarly, graphical analysis of the saturation and pressure profile in multiple SAG cycles generates a data set as a function of pore size, water saturation, and capillary pressure. The data are used for a variety of foam analyses to generate a capillary pressure curve for foam transport in a porous medium, to generate initial-residual (IR) gas saturation curve, estimation of gas trapping coefficient, estimation of limiting capillary pressure, critical water saturation, and/or other foam flow characterization.