Ketone solvent as a wettability modifier for improved oil recovery from oil-wet porous media

Abstract

The main objective of this research is to investigate a novel class of oxygenated solvents that can enhance the oil recovery from oil-wet rocks by multiple mechanisms, such as wettability alteration, oil-viscosity reduction, and oil swelling, in the presence of brine (connate water and/or fracturing water). The compound studied for the first time in this research is 3-pentanone (3p), a symmetric short ketone that can partition into both oil and brine at reservoir conditions. It can act as a solvent by itself, but this paper is focused on the potential mechanisms of oil recovery when an aqueous solution of 1.1 wt% 3p in reservoir brine (3pRB) is in contact with oil and oil-wet rock.Results show that the average contact angle of oil droplets on oil-aged calcite surfaces was rapidly reduced to 26° with 3pRB, in contrast to 123° with RB, without affecting the oil/brine interfacial tension. Spontaneous imbibition results show that the oil recovery factor reached 50.0% with 3pRB and 10.0% with RB at Day 3. The final recovery factor was 51.0% with 3pRB and 12.0% with RB. The subsequent forced imbibition determined the Amott index to water of 0.76 with 3pRB and 0.23 with RB, indicating a clear, positive impact of 3pRB on oil recovery by water imbibition in the cores tested. The main mechanism of oil recovery by 3pRB in this research is the wettability change as demonstrated by the contact-angle experiment.