Low-salinity waterflooding in non-polar oil

Abstract

Enhanced oil recovery by low-salinity waterflooding is considered to have positive results only when polar components exist in oil. This study shows that low-salinity brine can result in incremental recovery for non-polar oil through fines-assisted waterflooding. Despite the traditional view of fines migration that it should be avoided because of its detrimental effect on reservoir permeability, this work shows that permeability decline is a main mechanism in the low-salinity effect on non-polar oil. Laboratory coreflood tests were performed on a clay-rich Berea outcrop core and a clean sand core to investigate the effect of clay migration when the core is saturated with non-polar oil. The results show that fines migration reduces residual saturation by 18%. In addition, a decrease in the water volume production was observed due to the decrease in water relative permeability.