Drop-Drop Coalescence: The Effect of Temperature and Equilibration Time on Wilmington Crude Oil in a Weakly Alkaline Brine: Topical Report

摘要

Coalescence data were obtained for Wilmington crude oil droplets in sodium bicarbonate brine using a vertically inclined spinning drop tensiometer. The effect of temperature and aging on drop-drop coalescence was evaluated. In most cases, film drainage is considered to be the rate-limiting process prior to coalescence. Results indicate that coalescence time is dependent on temperature, being long at low temperature and short at high temperatures. Aging of the oil drops in alkaline brine appeared to decrease coalescence time although the effect was more noticeable at high temperature. Natural surfactants produced from the reaction of bicarbonate brine with strong acids in Wilmington crude oil appeared to inhibit drop-drop coalescence probably due to a surfactant concentration gradient which was providing resistance to flow at the interface. The period of time that interfacial tension remained at a dynamic minimum was directly related to coalescence time. A spinning drop tensiometer was found to be useful in obtaining drop-drop coalescence data. The apparatus is simple to operate and could be used in laboratory optimization of the mechanisms of oil mobilization and oil bank formation. 16 refs., 6 figs., 3 tabs. (ERA citation 12:030066)