Low-salinity waterflooding has proven to be a valuable enhanced oil recovery method, improving volumetric sweep efficiency and reducing residual oil saturation. This method, also coined adjusted brine chemistry, has allowed the research community to gain insight into the situationally dominant mechanisms of low-salinity waterflooding. Complex in situ relationships are generally separated into rock-fluid and fluid-fluid interactions. While wettability alteration is utilized to evaluate rock-fluid interactions, rheological properties effectively characterize the crude oil-water interface present to both upstream and downstream operations of the petroleum industry. High interfacial viscoelasticity has been shown to improve oil recovery, but the complex relationships among surface-active organic components are still not understood. Naphthenic acids work in opposition to asphaltenes by softening the interfacial structure creating a film resistant to rupture yet pliable under deformation forces. Due to experimental constraints, rheological evidence of this behavior exists only at low temperatures. A spinning drop tensiometer was used to evaluate the effect of various naphthenic acid species concentration in low-salinity brine on interfacial viscoelastic properties at high temperature. Shear and dilatational rheology experiments provide insight into naphthenic acid behavior at the interface and are qualitatively compared with spinning drop results at low temperature. Spinning drop data, although still under investigation, suggest naphthenic acids have a lesser effect on interfacial viscoelastic properties at high temperature. Titration and partitioning experiments provided analytical support for the temperature-dependent rheological results. The intent of the commissioned spinning drop instrument was to evaluate its ability to characterize interfacial dynamics. Spinning drop data show diverging results with respect to other rheological techniques, introducing the need to further understand this competing phenomenon.
展开▼
