Synergistic effect of nickel nanoparticles with tetralin on the rheology and upgradation of extra heavy oil

Abstract

Heavy oil is a boon and a bane, the former due to its untapped energy potential and the latter due to the difficulties in production, flow assurance, and upgradation challenges. Nanotechnology applications for oil and gas industry are at their nascent stage of development, amongst these, heavy oil upgradation using nanoparticles is an area of emerging research. In this work, a synergistic effect of nickel nanoparticles (<100 nm) and solvent tetralin have been studied on the rheological properties and composition of extra-heavy crude oil (EHO). Tetralin is used as a solvent and hydrogen donor due to its superior property in dissolving asphaltene clusters. Near-zero shear viscosity of EHO were determined after 7-hour thermal stimulations at 90 °C using viscometer. This is proceeded by the measurement of viscosity of EHO under different shear rates (1–1000 s−1). Changes imparted by addition of nickel nanoparticles on the viscoelastic properties of the EHO samples were determined by oscillating stress or strain. Concentration of 0.2 wt% nickel nanoparticle was observed to achieve maximum reduction in the viscosity of EHO. To simulate high-temperature environment, aquathermal upgrading of EHO-nanoparticle sample was carried out at 230 °C for 5 h using nanoparticle dispersion in water. The compositional changes of the EHO structure due to nickel nanoparticles were determined using FT-IR, GC–MS, and the SARA characterization tests. These tests confirmed the effect of catalytic properties of nickel nanoparticles in upgrading the EHO. Lastly, a new mechanism describing the dynamics of the nickel nanoparticle in contact with asphaltene clusters has been proposed for better understanding.