Relative Flow of Bacteria and Oil in Porous Media

Abstract

The relative permeability of porous media has been shown by a number of investigators to play a big factor in determining the recoveries resulting from both water floods and tertiary floods. Solutions of bacilli strains of bacteria in water, Bacterial Enhanced Oil Recovery (BEOR) have previously been shown to be effective in improving oil recoveries from Carbonates using laboratory core-flooding experiments. One of the mechanisms indicated was a change in rock relative permeability due to changes in wettability of the flooded system from oil-wet to more water-wet conditions. The causes of these changes are the interaction of bacteria with crude oil in situ producing gases, surfactants, other chemicals like acids and mild organic polymers. This wettability alteration increases the oil relative permeability, decreases the water relative permeability, and reduces the residual oil saturation (ROS). These factors and others, in turn, result in an improvement in the bacterial flood recovery over recoveries obtained by water flooding alone. The objectives of this work are to describe and quantify the relative permeability alteration occurring in BEOR processes and the study the factors that would enhance such alteration and improve oil recovery.