Intensified Steam Injection Process for In-Situ Upgrading and Recovery of High-Sulfur Extra-Heavy Oil by Co-Injection of Nickel-Based Oil-Soluble Catalyst and Multicomponent Hydrogen-Donor Solvent

Abstract

Abstract Steam injection is the most widely used technique for heavy crudes recovery. However, it has exposed some economic and environmental concerns due to excessive cost and huge consumption of fresh water and energy. In this work, the mixture of nickel-based oil-soluble catalyst and multicomponent hydrogen-donor solvent is proposed as additives for intensifying steam injection process. Its effectiveness in accelerating in-situ upgrading and oil recovery was evaluated for a carbonate, high-sulfur extra-heavy oil reservoir in Cuba. In this work, the initial oil-saturated rock (from Boca de Jaruco Oilfield, Cuba) as an object of this study was crushed and packed in a self-designed steam-tube). In addition, using a steam-tube, the catalytic performance of the proposed catalytic composition of nickel-based oil-soluble catalyst and a cheap and available multicomponent hydrogen-donor solvent (heavy naphtha as a petroleum cut) by analyzing the recovery performance as well as the changes of produced oil including physical properties and chemical composition. Furthermore, a 4D computed tomography technique was used to estimate the distribution of composition in oil-saturated core by analyzing high resolution microtomography images. According to the results of the steam tube experiments, the presence of the proposed catalytic composition is favourable for improving both upgrading and recovery of high-sulfur extra-heavy crude oil. Compared with steam injection without additive, in the presence of nickel-based oil-soluble catalyst and multicomponent hydrogen-donor solvent, a higher oil recovery of 28% was yielded (only 15.14% for steam injection without additive), also production started earlier, and production rate was faster. The co-injection of catalyst and solvent saves about 30 % steam amount. Steam injection reduced oil viscosity from 11347 mPa.s to 8711 mPa·s at 50 °C. The presence of catalyst and solvent can further reduce the oil viscosity to 7348 mPa·s with a higher content of light fractions (saturates and aromatics) and lower content of high-molecular weight fractions (resins and asphaltenes), which means that the degree of in-situ upgrading, and oil quality was improved. All these improved performances make the developed additive (mixture of nickel-based oil-soluble catalyst and multicomponent hydrogen-donor solvent) a great potential in the field application for improving the efficiency of steam injection. The results of the 4D computed tomography (visualizations) showed a high distribution of the catalytic solution in the porous medium of carbonate rock. This work presents an effective method for improving the efficiency of steam injection by co-injection of nickel-based oil-soluble catalyst and multicomponent hydrogen-donor solvent, which not only helps to ease the economy and environmental problems due to excessive cost and huge consumption of fresh water and energy, but also obtain a higher quality produced oil. This has profound significance for heavy oil production as well as subsequent transportation and refinery process.