Effect of Nanoparticles on Asphaltene Aggregation in a Microsized Pore

During oil recovery process, the equilibrium state of asphaltene-oil solution system and colloidal system in porous media is altered, which could cause asphaltene to precipitate from crude oil in rock pores. This severely results in the alteration of wettability, permeability, and porosity of formation and damages oil reservoir formation. Nanoparticles have recently been considered as effective asphaltene inhibitors. Several experimental works were carried out to study the impact of nanoparticles on asphaltene precipitation. The majority of these studies were performed using core flooding experiments in bulk phase. However, few experimental investigations were performed to directly reveal the impact of nanoparticles on asphaltene aggregation based on the direct pore-scale visual evidence. In this work, a novel method was employed to make direct visualization and measurement on the kinetics of asphaltene aggregation in the presence of nanoparticles in a microcapillary. NiO, SiO2, and Fe3O4 nanoparticles were used. We directly measured the diameter and number and analyze size distribution of asphaltene aggregate particles in a microsized pore. The results indicate that the nanoparticles can significantly inhibit the aggregation of asphaltene particles in a microsized pore due to adsorption of asphaltene particles onto nanoparticle surfaces. The effect of nanoparticle concentration was investigated. Higher concentration of nanoparticles could contribute to the inhibition of aggregation of asphaltene particles. The asphaltene precipitation and aggregation can be prevented more effectively at higher concentration of asphaltene precipitant in the presence of nanoparticles.