Wetting phenomena play a significant role in oil recovery from complex carbonate reservoirs under harsh conditions. Conventional waterflooding operations in most fractured carbonate reservoirs fail to imbibe the water into the oil-wet matrix, severely restricting production. The potential to alter the rock wettability from oil-wet to water- or neutral-wet is often considered the pre-requisite to a successful enhanced oil recovery (EOR) process.<br/>In this study, we investigated the effect of the carbon nanodots in high salinity brines with and without a surfactant on the static wetting and dynamic wettability alteration of carbonate reservoirs under realistic reservoir conditions. We targeted representative conditions of carbonate formations of Saudi Arabian oilfields. Henceforth, we used Arab-D reservoir rocks and crude oil samples in all tests. Moreover, we examined the pore-scale wettability alteration and oil displacement processes in-situ at different stages of the spontaneous imbibition tests using X-ray microtomography imaging on miniature (5 mm) core plugs.<br/>Results analyses demonstrated that the nanodots could alter the rock-oil-brine wettability to water-wet through capillary pressure reduction and disjoining pressure enhancement. A dilute amount (10-200 ppm) of the Carbon dots in seawater supported an impressive 15-20% incremental recovery over the neat seawater. Overall, the study supported a strong and favorable impact of the carbon dots as an effective and economically viable additive to waterflood operations in carbonate reservoirs.

Increased oil recovery in carbonate reservoirs with dilute carbon nanofluids

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.