Laboratory investigation on effects of initial wettabilities on performance of low salinity waterflooding

• Initial neutral-wet condition provided the highest oil recovery.
• Low salinity waterflood increased oil recovery for all the wettability conditions.
• Fines migration and alteration of wettability during waterflood are important phenomena in low salinity waterflood.
• Low salinity waterflood may result in reduction in permeability.

This paper presents investigation on the relationship between rock wettability and oil recovery with low salinity water injection as secondary recovery process. Coreflooding experiments have been performed at room conditions on Berea cores with four different wettabilities ranging from water- to oil-wet. Brines and n-decane were used as displacing and displaced phases, respectively. The results showed that, for all the salinities, oil recovery increased as wettability changed from water- to neutral-wet conditions. Further change in rock wettability from neutral- to oil-wet condition resulted in decreased oil recovery. It was also interesting to observe that oil recovery is higher for low salinity waterflood (LSW) as compared to high salinity waterflooding when implemented as secondary recovery process. Increase in pressure drop and hence decrease in effective permeability was also observed during LSW process in most of the cases considered.