Low Salinity Oil Recovery: An Exciting New EOR Opportunity for Alaska's North Slope

TLDR

Laboratory studies over many years indicate that injecting water with salinity below about 5,000 ppm can improve oil recovery, though the mechanisms remain uncertain and resemble those of alkaline flooding. Recent successful field trials have prompted a serious evaluation of implementing low‑salinity EOR at field scale. Four sets of single‑well chemical tracer tests conducted in Alaska confirmed that the favorable laboratory results can be replicated in the field. The tracer tests in Ivishak, Kuparuk, and Kekiktuk sandstones reduced residual oil saturation and increased waterflood recovery by 8–19 % (6–12 % OOIP), leading to active evaluation of low‑salinity recovery on the North Slope.

Abstract

Abstract Laboratory studies conducted over a period of many years have indicated that oil recovery could be improved by injecting lower salinity water (less than about 5,000 ppm). Although the recovery mechanisms are still uncertain, they appear to be similar to those found in alkaline flooding. Recent successful field trials have led to serious evaluation of field-scale implementation of low salinity EOR. Four sets of single well chemical tracer tests (SWCTT) performed in Alaska confirmed that the favorable laboratory results could be replicated in the field. The SWCTT results (two in the Ivishak sandstone, one each in the Kuparuk and Kekiktuk sandstones) showed that waterflood residual oil saturation (Sorw) was substantially reduced by low salinity water injection. The low salinity EOR (LoSal) benefits ranged from 6 to 12% OOIP, resulting in an increase in waterflood recovery of 8 to 19%. Based on these encouraging results, low salinity oil recovery is being actively evaluated for North Slope reservoirs.