Reversibility of Asphaltene Precipitation Using Temperature-Induced Aggregation

In this work, kinetic asphaltene precipitation was investigated using temperature fluctuations. Asphaltene precipitation was previously identified as a fully reversible process by altering the solution pressure of composition but only partially reversible using temperature changes. Slow kinetic asphaltene precipitation plays a critical role in the accurate monitoring of asphaltene precipitation, and previous reversibility studies need to be revisited in light of this phenomenon. Previous studies used a combination of precipitant addition and temperature changes to conclude that precipitated asphaltenes do not fully redissolve when the mixture temperature is changed. Modeling results reveal that precipitated asphaltenes should not be expected to redissolve, regardless of the magnitude of temperature changes, after a precipitant (e.g., dodecane) is added to the mixture. Consequently, this study was designed to isolate the influence of slow kinetics, precipitant addition, and temperature changes on the solubility and reversibility of asphaltene precipitation. Temperature cycling experiments were performed to investigate the reversibility of asphaltene precipitation and revealed that the process is fully reversible with temperature changes. This finding reinforces that, for the system in this study, asphaltene phase behavior is controlled by equilibrium thermodynamics and not a colloid stabilization model.