Examination of the Effect of Salinity on the Recovery of Petroleum in the Course of Water Flooding: An Experimental Approach

Abstract Petroleum sector is actively and persistently involved in search of novel techniques to optimize petroleum extraction in the course of water flooding. The oil and gas industry is constantly searching for different methods to optimize oil recovery during water flooding. The type of core material or formation being studied and the salinity of the water injected are two crucial variables that can have a substantial effect on oil recovery. Little is known, nevertheless, about how salt affects petroleum or oil recovery during water flooding utilizing clay-containing core samples. This study investigated the impact of salinity on oil recovery carried out using two core samples obtained from shale rocks. The core sample labelled A was from Kogi state and core B was from Rivers State. Initially both core samples were dried in an oven at 88°C to cause natural fractures and connect the pore spaces then saturated with brine of 20g/l salinity and light crude oil of viscosity 3.35cp to simulate reservoir conditions within the core samples. The porosity of the samples was determined by liquid saturating method and the effective permeability was calculated using Darcy’s law. Core flooding tests were conducted by injecting brine and varying the salinity levels at 10g/l to 30g/l to displace 20 ml of light crude oil originally saturated in each core sample. The results and analysis of the tests showed that the core sample B recovered more oil than sample A. The recovery factor efficiency of core A was 24%, 31.5%, 51%, 53%. and the core sample B was 26%, 42%, 50.8%, 52.1%. The oil recoveries at breakthrough increased significantly with increasing salinity. The difference in oil recoveries for both core samples in breakthrough and final recoveries was observed at 30g/l of brine salinity where core B recovered 8.8% higher than core A. At 50g/l brine salinity, the oil recovery efficiency did not change for both core samples while changing the concentration of brine relative to the initial brine used. The findings of this study and the data retrieved shows the improvement of oil recovery factor increases as brine salinity increases which can be attributed to interfacial tension reduction and viscosity alteration.