Water-in-crude oil emulsion stability studied by critical electric field measurements. Correlation to physico-chemical parameters and near-infrared spectroscopy

Twenty-one crude oils and condensates of different origins have been thoroughly characterised including SARA (saturates, aromatics, resins, asphaltenes) data, interfacial elasticity, total acid number (TAN), density, viscosity, interfacial tension (IFT) and molecular weight. In addition all samples have been characterised by near-infrared (NIR) spectroscopy. A cell was developed to measure emulsion stability at applied electric fields. The cell produces values of stability of crude oil/water emulsions in a fast and simple manner. Emulsions of the 21 crude samples at different water cuts have been characterised by the electric field technique. The emulsion stability data have been correlated with both the physico-chemical data and NIR spectra. Asphaltene content and aggregation state, in addition to interfacial elasticity, are shown to be important contributions to emulsion stability as defined above. NIR spectra are shown to be informative with regard to emulsion stability.