Asphaltene Particles Growth in Live Oils - Experimental Study on Kinetics of Aggregation at Reservoir Conditions

Abstract

Despite the extensive researches on asphaltene behavior in crude oils, kinetics and mechanisms of asphaltene aggregation in live oils as a controversial issue remains a topic of debate in the literature. In this work, the kinetics of asphaltene aggregation is explored in two live oils with different stabilities at reservoir conditions of pressure and temperature. The obtained results show that by increasing the temperature, the aggregation mechanism in unstable oil follows a crossover behavior between diffusion-limited aggregation (DLA) and reaction-limited aggregation (RLA), with dominance of RLA mechanism at the highest temperature. As temperature decreases, the diffusion of the asphaltene particles controls the aggregation process which depends on the rate of growth and frequency of particles. In stable oil, the RLA mechanism is mainly responsible for kinetics of particles growth with partial DLA behavior at initial steps of aggregation process. The observed differences in dynamics of asphaltene aggregation process could be attributed to the stability of oil, which depends on the rate of aggregation rather than asphaltene content of oil. Presented results may be helpful for better understanding of the asphaltene aggregation process as well as more accurate modeling of asphaltene phase behavior in live oils at elevated pressure and temperature.