Crude oil vanadium and nickel content can predict emulsification tendency

Abstract

Most crude oils in contact with water form water-in-oil emulsions. The stability of these emulsions will vary. When spilled crude oil emulsifies, it becomes viscous and expands in volume, becoming more difficult to recover, chemically disperse, or ignite. The ability to better predict the emulsion-forming behavior of a specific crude oil would greatly aid oil spill response decisions. The problem is complex because of the various stabilizing mechanisms, This study identified surface active agents, that is, porphyrins, as key compounds that contribute to the emulsification of crude oil, particularly fresh crude oil. This research not only identified these metal-porphyrin agents but also determined the mechanism for their emulsion stabilization. These porphyrin complexes are known to be associated with the metals vanadium and nickel. Because the vanadium and nickel levels of a specific crude oil are available from its published assay, they can be used to predict the emulsification of oil early in the spill. The study has also established that a concentration level of over 15 ppm of vanadium and nickel is required to form a stable emulsion for fresh crude oil. It should be stressed that the vanadium-nickel index applies to fresh crude oil. A second emulsification mechanism was also observed during this research that was related to the weathering of the crude oil. Extensive data to support this mechanism are presented and may provide a valuable tool for oil spill response.