Measurement of Residual Gas Saturation in Water-Driven Gas Reservoirs: Comparison of Various Core Analysis Techniques

Abstract The objective of this study was to derive values of residual gas saturation (Sgr) for water-driven gas reservoirs using various core analysis methods: steady-state waterflood, co-current imbibition, centrifuge and counter-current imbibition. The relative dearth of published data comparing various core analysis methods, and the uncertainty in estimating Sgr for gas reservoirs under water-drive, resulted in the decision to attempt to determine an optimum laboratory protocol to evaluate Sgr. Core samples from various reservoirs, representing a range of porosity and permeability values, were selected for testing. The various analyses were conducted to represent a range of field displacement mechanisms where viscous, capillary or gravity forces may dominate.