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.

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