Accurate prediction of enhanced oil recovery from carbonate reservoir through smart injection of nanoparticle and biosurfactant

Selecting the most suitable enhanced oil recovery (EOR) method and subsequently an accurate prediction of EOR are essential in reservoir engineering. Generally, interfacial tension (IFT) and wettability alteration are effective agents on EOR. The aim of this work is to understand how contact angle can be changed additionally to the IFT changes. Different tests on IFT, wettability alteration, and core flooding of limestone slabs using rhamnolipid, N-doped graphene nanoparticle, and a mixture of aqueous solution of rhamnolipid with N-doped graphene were performed. Rhamnolipid at the CMC (250 mg/l) had just a significant effect on IFT reduction so that IFT decreased from 8.1(brine/oil system) to 0.4 mN/m. N-doped graphene at the CMC (500 mg/l), had only a significant effect on wettability so that it altered the slabs wettability from strongly oil wet (θ = 133.5°) toward strongly water-wet (θ = 51.5°). When both were used simultaneously at their CMC, the contact angle and IFT reached to 56° and 0.97 mN/m, respectively. Based on core flooding tests, 8.2%, 18.1%, and 24.2% of OOIP were obtained using N-doped graphene, rhamnolipid, and a mixture of them at their CMC, respectively. Our results showed that IFT has a more important role on Sor than the wettability change. The findings of this study can help for better understanding of the mechanism behind EOR using the combination of the biosurfactants and nanoparticles.