Characterization and Control of Formation Damage During Waterflooding of a High-Clay-Content Reservoir

Abstract

ABSTRACT Permeability damage was suspected as a factor contributing to post-completion production declines observed during waterflooding of a friable to unconsolidated sandstone. A loss in water injectivity also indicated that near-wellbore damage may be occurring. This paper summarizes the laboratory studies undertaken to evaluate and understand permeability damage in this formation. The experimental program consisted primarily of coreflooding experiments to evaluate the influence of injection fluid composition, temperature, mineralogy, and flow velocity on permeability damage. The significance of damage during brine injection was observed to be a strong function of mineralogy. Permeability losses of greater than 60% were observed in cores from some sand intervals, while little or no damage was apparent in cores from another zone in the same well. In the sands that were susceptible to brine damage, a critical velocity below which permeability damage did not occur was repeatedly established. The occurrence of a critical velocity, along with other observations, indicate that the primary damage mechanism is fines migration.