A state-of-the-art review of nanoparticle applications with a focus on heavy oil viscosity reduction

Abstract With the continuous depletion of easy-to produce oil resources, the effective and low-cost exploitation and upgrading of heavy oil becomes a key to alleviate the contradiction between energy supply and social energy demand. However, the presence of abundant heavy polar components such as asphaltenes and resins greatly increases oil viscosity, making it hard to flow in porous media and pipelines, hence, viscosity reduction measures are required and necessary. Nanoparticles have gained great attention in oil and gas industry in recent decades, and are recognized as effective viscosity reducers. In this paper, the possible functional mechanisms of nanoparticles as emulsifiers, asphaltene precipitation inhibitors, pour point dispersants and catalysts as well as the influential factors and the limitations were discussed. Moreover, the research advances in nanoparticle migration rules and fabrication of highly stable nanoparticles were reviewed. In the end, the possible challenges that may confront in upscale applications were analyzed. The main objective of this work is to provide a comprehensive review, highlighting the limitations of existing studies, and offering some recommendations to shed light on the follow-up studies.