Improved oil recovery by low-salinity waterflooding

Several researchers at laboratories and organizations are working to identify, reproduce, and explain the low-salinity effect (LSE). The evidence, mounting rapidly from both field and laboratory studies, is examined aimed at facilitating identification of low-salinity waterflooding (LSW) targets and design of the floods. Webb with the co-workers provided the first field evidence of reduction in residual oil by LSE. Log/inject/log measurements showed that the residual oil within approximately 4 in. of a wellbore was reduced by up to 60% by use of LSW. Single-well chemical-tracer tests showed that high-salinity waterflooding (HSW) residual oil was reduced by approximately 13% original oil in place (OOIP) within a radius of 13 to 14 ft around the wellbore by LSW, consistent with laboratory core tests. Seccombe and co-workers reported that recovery of residual oil between wells separated by 1,000 ft.