Heavy Oil Upgrading and Enhanced Recovery in a Continuous Steam Injection Process Assisted by Nanoparticulated Catalysts

Abstract

Abstract Heavy (HO) and extra–heavy oil (EHO) production is complicated due to its high asphaltene content that lied to adverse rheological properties. In addition, the upgrading of these unconventional oils at surface or sub-surface conditions is a low cost-effective process because of the large amounts of energy needed. Accordingly, several in-situ techniques for enhancing HO and EHO recovery with objective of upgrading the oil and improving its viscosity and mobility have been employed. In this sense, nanoparticulated catalysts have demonstrated a synergistic effect in the enhancement of oil recovery and the improvement of the pyshicochemical properties of HO and EHO such as viscosity, API gravity and content of heavy hydrocarbons such as asphaltenes. Hence, this work aims at investigate the effect of catalytic active nanoparticles in the improvement of the efficiency in recovery of a continuous steam injection process. Nanoparticles were selected trough batch-adsorption experiments and the subsequent evaluation of the temperature for catalytic steam gasification in a thermogravimetric analyzer. A nanoparticulated support was functionalized with 2 wt% of NiO and/or PdO nanocrystals in order to improve the catalytic activity of the nanoparticles. Also, successfully a methodology for evaluating the effect of nanoparticulated catalyst in processes of continuous vapor injection was developed. Oil recovery was evaluated using a slim tube filled with a non-confined sand pack in steam injection scenarios in absence and presence of a water-based nanofluid. The displacement test was carried out by (1) constructing the base curves, (2) estimating the oil recovery by the continuous injection of vapor in absence of nanofluid and (3) identifying the influence of the nanoparticles in the enhanced recovery of oil. It was found that functionalized nanoparticles lead to higher adsorption of asphaltenes, higher degrees of asphaltenes self-association and lowered the temperature of n-C7 asphaltenes steam gasification. It was also observed that the oil recovery increased up to 46% for the system assisted by nanoparticles in comparison with the vapor injection without the nanocatalyst. API gravity of crude oil increased from 7.2 to 12.1°. A reduction of 59% in oil apparent viscosity was also observed. Additionally, trough n-C7 asphaltene and residue content it was demonstrated that nanoparticles are an excellent alternative for HO and EHO upgrading in processes involving vapor injection. n-C7 asphaltene content decreased a 5.2 percentile points after vapor injection in presence of nanoparticles in comparison with the virgin EHO. Also, the residue content (620°C+) decreased a 47%. Improved oil recovery due to nanoparticles injection could be attributed to three main reasons: i) wettability alteration of the porous media, ii) viscosity reduction due to reduction of the asphaltene aggregate and iii) crude oil upgrading. This study should generate a better landscape about the use of catalytic nanoparticles in the improvement of enhanced oil recovery processes and its application in local and international scenarios.