Low Salinity Water Treatment Solved the Water Saturation Challenges and Improved Recovery

Abstract Low Salinity Water Injection, LoSal, has the potential of enhancing hydrocarbon recovery when compared to conventional water injections. Despite its value, it brings a huge challenge to the formation evaluation and reservoir characterization engineers due to its effect on the formation water salinity. The heterogeneity of reservoirs permeability maximizes the challenge since it controls the distribution of the injected low salinity across the reservoir. This variation in the water salinity makes the determination of water saturation in the newly drilled wells and in the monitoring wells a challenge for the reservoir characterization engineers. This study introduces a solution to the challenge. It is found that mixing the LoSal water with predetermined volume of acid in clastic reservoirs or alkaline in carbonate reservoirs changes the LoSal water resistivity to the value of the original water. This treatment also maintains the required properties of the injected fresh water. The choice of the volume and the type of the acid and the alkaline is determined based on the original formation water salinity and the reservoir lithology. Multiple measurements are performed on different plugs in the laboratory where excellent results are obtained. Also, it is found that the acid and/or alkaline treated water enhanced the oil recovery compared to the non-treated low salinity water.