Optimizing oil-water interfacial rheology for in-situ synthesis of nanoparticles and asphaltene control during oil production

Abstract

Asphaltene precipitation and deposition lead to plugging of oil production tubulars and damage in near wellbore porous media. This study addresses this challenge by shedding light on optimization of in-situ synthesis conditions of Fe2O3 nanoparticles to enhance asphaltene adsorption. The approach involves utilizing dynamic interfacial tension (IFT) and interfacial elasticity as the key factors influencing the in-situ synthesis. Model oils were prepared by dissolution of a dead oil in different ratios of toluene/vacuum gasoil to control the aggregate size, hydrophilicity, and interfacial film formation capability of asphaltene. Emulsions of iron salt solution (brine) in the model oils were prepared for the in-situ synthesis. The iron cation molarity and the water content of the emulsions were adjusted by considering the oils-brine dynamic IFT and interfacial elasticity as well as the emulsions stability with temperature. The most stable emulsions were exposed to in-situ synthesis at reservoir-temperature. The texture and structure of the synthesized nanoparticles were characterized well and their asphaltene adsorption capacity was measured. Results indicate that, although the dynamic IFT is a footprint of the hydrophilicity and size distribution of the asphaltene aggregates in the interface, the interfacial elasticity shows the aggregates arrangement and thus interfacial film formation, leading to the emulsions stability and efficient synthesis. The in-situ synthesized nanoparticles are crystalline α-Fe2O3 with the size of smaller than 75 nm. The crystalline structure of the nanoparticles is further developed by increasing the synthesis time period and water content of the starting emulsion. The higher the water content, the more is the adsorbed carbonaceous species on the in-situ synthesized nanoparticles. Characterization data and thermogravimetric analysis confirm that the adsorbed species are mostly monolayer asphaltenes. Most of the adsorption takes place in early time of the synthesis, thereafter there is a marginal increase in the adsorption with time. Dynamic IFT and interfacial elasticity provide unique data for in-situ synthesis of nanoparticles for asphaltene adsorption and thus aggregation control.