The Effects of Different Types of Dispersants on Asphaltene Aggregation and on the Stability of Asphaltene Dispersions

The effects of two different synthetic dispersants were characterized using two independent optical methods. The study examined their impact on both the aggregation of asphaltenes (isolated from various crude oils using a standard procedure) and the stability of model asphaltene-containing dispersions. In the model n-heptane/toluene medium, the two dispersants had markedly different effects on asphaltene aggregation and dispersion stability. One dispersant failed to disperse asphaltenes because it self-associated into large micelles (≥100 nm in radius) in the n-heptane medium, thereby destabilizing the system. Consequently, a key design criterion for future dispersants and stabilizers should be a molecular structure that minimizes self-association in nonpolar media while maximizing affinity for asphaltenes.