Three-Phase Flow in Porous Media: Wettability Effect on Residual Saturations During Gravity Drainage and Tertiary Waterflood

Abstract

Abstract Three-phase flow configurations occur in many situations in petroleum engineering, gravity assisted gas displacement, tertiary waterflood, water alternating gas process (W.A.G.). Therefore residual saturations (oil and gas) knowledge during three-phase flow is a crucial point for reservoir engineers. In this paper we present experimental results dealing with the influence of wettability on two and three-phase flow in porous media in short (0.25m) and long (1m) cores. Forced displacement of gas by water and oil have been performed on the short cores while gas/oil gravity drainage in presence of irreducible water (Swi) followed by a tertiary waterflood have been performed on the long cores. For all the experiments the saturation profiles are measured using a dual-energy gamma-ray attenuation technique. Originality of the experiments lies on the fact that gas/oil gravity drainage and tertiary waterflood are performed on the same core during the same experiment. Two phase flow is obtained at the bottom of the core (in the capillary head region) while three-phase flow is observed in the upper part of the core. Local measurement of saturation profiles show that residual oil saturation at the end of gravity drainage depends on wettability. However we do not observe a wettability effect on three-phase residual gas saturation. Behaviour of three-phase residual oil saturation is much more complicated because its value and saturation profile depends strongly on wettability.