A method for enhancing oil recovery from a sandstone reservoir through low salinity waterflooding

Abstract

The present invention discloses a method for enhancing oil recovery from sandstone reservoirs through Low Salinity Waterflooding. The method involves collection and preparation of crude oil, formation brine, and core plug samples, followed by detailed compositional and ionic analyses. Multiple low-salinity brine samples with salinities ranging from 200-1100 ppm are prepared using sodium, potassium, magnesium, and calcium salts to simulate optimized flooding conditions. Core flooding experiments are conducted under secondary recovery mode using a positive displacement pump and Hassler Core Holder to evaluate the impact of varying salinity on wettability alteration and recovery efficiency. Parameters such as brine pH, Interfacial Tension, and Contact Angle are measured to assess fluid-rock interactions. The method identifies an optimal low-salinity brine composition that enhances oil recovery efficiency by pH increase of brine, reduction of oil-brine Interfacial Tension, and rock wettability modification, leading to reduced Residual Oil Saturation and improved oil recovery efficiency.