The Effect of injected water salinity on oil recovery

Abstract

Core flooding experiments were performed to study the effect of injected water salinity on oi8l recovery. The experiments were conducted at a temperature of 90??C and a net overburden pressure of 1500 psi using Berea sandstone core samples and Arabian Light crude oil. Different concentrations of NaCl Brines (5500-200, 000 mg/1), treated sea water, Wasia water, and 100,000 (mg/1) synthetic Arab-D water were used as displacement fluids. As a result of this study, it was found that oil recovery increases as the injeced water salinity increses upto 100,000 (mg/1). Increasing the salinity beyond 100,000 (mg/1) did not give a significant increase in oil recovery. The increase in oil recovery was found to be supported by a decrease in the 1FT as a function of water salinity up to 100,000 (mg/1), where the Lft started to increase slightly beyond this salinity. The relative permeability ratio (Kro/Krw) was found to increase as the injected water salinity increases. The compatibility tests conducted showed that when connate Arab-D water was mixed with sea water at 90?C, calcium sulphate precipitated. However, analysis of the core flooding effluents did not show any incompatibility problems due to injection of Wasia, and sea waters.