Abstract
Improving the recovery factor of conventional oil reservoirs is a critical factor in offsetting the inevitable decline of oil fields and keeping step with the world's demand for hydrocarbons. This paper describes a laboratory experiment to investigate the impact of brine salinity on oil recovery during waterflooding and to ascertain if there exist any relationship between salinity and type of oil in terms of recovery. During the flooding experiment, the cores were individually flooded with the high salinity and low salinity recovery brines in a secondary stage recovery process, to recover the crude oil (heavy and light) with which they were earlier saturated with. Recovery brine salinity ranged from 5000ppm to 30000ppm and a distilled water of 0ppm. Results obtained showed that high salinity recovery brine showed better recovery than the low salinity brine, for both the heavy and light oil. The high salinity brine recovered 61% and 63% of the heavy and light oil in place respectively, while the low salinity brine recovered 51% and 56% of the heavy and light oil in place. The results obtained are attributed to reduction in viscosity ratio, wettability alteration, reduction in interfacial tension and natural variations between cores. There was no definite relationship between crude oil type and the salinity of injected brines. It is recommended that studies to investigate the impact of salinity on cores containing clays should be carried out. These studies if successful will help in our bid to increase recovery factor during secondary recovery of the stranded oils in discovered fields.
