Microfluidic platform to evaluate asphaltene deposition during solvent-based extraction of bitumen

Abstract Viscosity reduction is necessary for economical heavy oil production. Dilution of heavy oil with light hydrocarbons is one of the extraction methods as an alternative to the thermal processes. However, in-situ upgrading of heavy oil leads to asphaltene deposition, which causes pore clogging and prevents diluted oil to drain in the direction of production well. Understanding the asphaltene precipitation and deposition mechanism on hydrophilic and hydrophobic porous media improves the efficiency of the solvent-based extraction methods and accuracy of solvent selection in both experiment and simulation. In this work, two different patterns of microfluidic platforms were used to study asphaltene deposition in porous media. Porous media were treated with a silane to evaluate the effect of wettability alteration on asphaltene deposition. Quantitative analysis of the detection point of asphaltene deposition showed faster precipitation from n-pentane in comparison with n-decane as heavier solvent. Helium Ion Microscopy (HIM) analysis was performed on precipitated asphaltene to evaluate the effect of different solvents on the structure of asphaltene precipitates. Moreover, a high-resolution Total Internal Reflection Fluorescence (TIRF) microscopy was used to identify the morphology of precipitated asphaltenes and results compared with HIM analysis. It was found that precipitated asphaltene with n-decane had larger asphaltene particles but fine precipitates from n-pentane led to higher aggregation and flocculation. Formation damage and pore blockage of deposited asphaltene from n-pentane was noticeably higher than n-decane.