The effect of precipitant on asphaltene aggregation and deposition

Abstract

Asphaltenes are fraction of crude oil that cause serious problems in the petroleum industry. The goal of this study is to compare trends in asphaltene aggregation and deposition. More specifically, to relate the asphaltene aggregation particle-particle collision efficiency to the deposition rate by varying the precipitant carbon number and concentration. Establishing a relationship between the aggregation and deposition behavior of asphaltenes will provide valuable insight into both processes. The amount of asphaltenes that are destabilized with different precipitants and at various concentrations was obtained from centrifugation experiments, and the collision efficiency for asphaltene aggregation was calculated using a geometric population balance model. The results revealed that for a fixed volume fraction of precipitant, the asphaltene-asphaltene collision efficiency decreased with higher carbon number precipitants. Decreasing the precipitant concentration resulted in lower collision efficiency. A correlation between collision efficiency and mixture solubility parameter was established for the oil used and different precipitants. In order to investigate asphaltene deposition behavior using different precipitants, the deposition rate was measured using capillary flow. The consistency of the capillary deposition apparatus has been improved by considering the initial inner diameter of the capillary. Scanning electron microscopy (SEM) images of the asphaltene deposits were obtained and used to assess the mixing of oil and precipitant.