Chapter 10 - Relative Permeability

Abstract

This chapter concentrates on those laboratory core tests most commonly used to determine relative permeability data input to dynamic reservoir simulation models to predict or match reservoir production, and oil and gas recovery factors. Relative permeability, residual and critical saturations, and reservoir wetting states are defined. Alteration to core wettability as a result of drilling mud contamination, core recovery and laboratory preparation, and the requirement to restore core wettability to reservoir conditions are explained. Sample preparation methods, test equipment, test states, test procedures and data reporting requirements for the principal water–oil, gas–oil and water–gas relative permeability tests using unsteady-state, steady-state and centrifuge techniques are detailed. The assumptions inherent in analytical solutions for unsteady-state and steady-state experiments are described, and the application of numerical solutions are explained. The advantages and drawbacks/issues associated with each test state (“fresh”, “cleaned” and “restored”) and test method are described, and quality control checks and diagnostics are summarised. The techniques used to process and refine experimental data prior to simulation input are illustrated.