Influence of the Interfacial and Structure- Forming Properties of Asphaltenes and Resins on Water-in-Oil Stability

摘要

Stable water-in crude oil emulsions often form during crude oil production and bitumen extraction, which significantly complicate petroleum recovery and refining operations. It is widely reported that the stabilization of the emulsion droplets is mainly due to the presence of asphaltenes and resins in the crude oil. These compounds appear to adsorb on the water/oil interface and create a rigid protective film, thus preventing drop coalescence.rnThe objective of the study is to determine if emulsion Stability is related to the relative amount of asphaltenes and resins on the water-oil interface. The interfacial composition is qualitatively estimated from the interfacial tension measurements of asphaltenes and resins in heptol-water mixtures.rnThe interfacial tension measurements of these model oils against water have shown that resins have greater interfacial activity than the asphaltenes. However, the interfacial tension of mixture of 1:1 ratio by mass ofrnresins to asphaltenes was close to that of "pure" asphaltenes. It appears that asphaltenes predominantly adsorb on the interface. An increase in the resin to asphaltene ratio caused the shift of the interfacial tension to that of "pure " resins. This might indicate that at high resin: asphaltene ratios, resins substitute asphaltenes on the interface. The change in the interfacial composition is expected to affect emulsion stability. The next phase of the project will be to conduct stability tests of emulsions composed from the same model oils. The composition of the asphaltenes and resins on the emulsion interface will also be determined by gravimetric analysis and related to the interfacial tension measurements.