Polyaromatic Hydrocarbon-Based Host-Guest Complex for Heavy Oil Viscosity Reduction

Abstract

Abstract Polyaromatic hydrocarbons (PAHs) were known to interact with the micro-aggregates of asphaltene compound in heavy crude oil. This study aims at designing, synthesizing, and applying a water-soluble self-assembled viscosity reducer (SAVR) bearing PAHs to efficiently reduce the viscosity of heavy oil through the formation of host-guest complex. The synthesized SAVR product was composed of two chemical components A and B. In an emulsion comprising heavy oil and the SAVR, the PAH groups from the hydrophobic part (component A) strongly interacted with the asphaltene in heavy oil via π-π stacking and hydrophobic association to solubilize these components, the hydrophilic part (component B) of the SAVR self-assembled with component A via host-guest complex to improve the solubility of the entire SAVR in an aqueous environment. The collapse of the asphaltene component results in a decrease of the viscosity of heavy crude oil. The SAVR products were compatible with high-salinity water, and able to form stable oil-in-water (O/W) emulsions with heavy oil. The SAVR formulation exhibited high effectiveness in heavy oil viscosity reduction, the viscosity of heavy oil was decreased by 80% at a 1:1 mass ratio of A:B and an oil-to-water ratio of 7:3. At the heavy oil-water interface, the oil bulk was found to gradually disperse in the aqueous phase containing SAVR in the form of small oil droplets. This new chemical formulation has great potential in heavy oil displacement from a reservoir or treating produced heavy oil, ultra-heavy oil, oil sands, etc. Since the viscosity of the heavy oil can be substantially reduced, the oil can be more easily produced and transported for further processing in an economical and efficient manner.