Low salinity brine injection for EOR on alaska north slope (ans)

Displacement of oil from reservoir rock pore spaces is a function of many interacting variables, among which the reservoir wetting state has been shown to be one of the most important, which is affected by the rock lithology; oil chemistry and brine salinity. Therefore, efficient and cost-effective oil recovery requires an understanding of the nature and, where possible, the optimal manipulation of these interacting variables. This paper presents results from coreflooding experiments carried out to evaluate the potential of low salinity brine injection on EOR for ANS. All corefloods were conducted on representative ANS cores using formation fluid samples in an indigenously designed and developed coreflooding apparatus. The low salinity brine injection EOR potential was studied under secondary recovery mode. Injection brine salinities were varied from reservoir brine salinity of 22,000 TDS to 5500 TDS. Corefloods were also conducted using ultra low salinity ANS lake water, which is considered as a potential source of low salinity water. Additionally, oil-brine-rock system wettabilities were also determined using the Amott-Harvey wettability indices. The general trend consistently observed in all the coreflood experiments was reduction in residual oil saturation of up to 20% and slight increase in the Amott-Harvey wettability Index with decrease in salinity of the injected brine at reservoir temperature. Experimental results are also compared with similar studies reported in the literature, which show reasonable agreements when Sor-lAH as well as Sor-salinity relationships are compared. Our results clearly indicate that low salinity waterfloods have the potential for enhancing oil recovery on ANS in the secondary recovery process and are directly applicable in water injection based EOR processes.