Fast Screening of LSW Brines Using QCM-D and Crude Oil-Brine InterfaceAnalogs

This work focuses on a potentially economic incremental oil-recovery process, where a brine amended withinexpensive salts (in contrast to expensive surfactants and other chemicals) is injected into a reservoir toincrease oil production. Historically, this process received the name of low salinity waterflooding (LSW)although the salinity is not always low(er). Nevertheless, we keep using this terminology for historicalreasons. The idea of LSW has been known for three decades, but to the best of our knowledge no specific brinerecipes that guarantee success have been presented so far. The reasons hide in the problem's complexity,disagreements in the scientific community, and a race to publish rather than to understand the fundamentalprinciples behind the process. In this paper, we present an experimental model system that captures many of the important fundamentalfeatures of the natural process of crude oil attachment to mineral surfaces, but at the same time decomposesthis complex process into simpler parts that can be more precisely controlled and understood. Wesystematically investigate the first-order chemical interactions contributing to the well-known strongattachment of crude oil to minerals using SiO2 as a mineral for its surface chemistry simplicity. Our preliminary results suggest that magnesium and sulfate ions are potent in detaching amino/ammonium-based linkages of crude oil with a SiO2 surface. However, when used together in the form ofMgSO4, they lose part of their activity to the formation of a MgSO4 ion pairs. We also find that sulfate-detachment propensity stems not from the interaction with prototype mineral surface, but rather from theinteractions with the crude oil-brine interface analog. We continue the systematic study of the ion effectson crude oil detachment, with and more results following in the future.