Reconsideration of Steam Additives to Improve Heavy-Oil Recovery Efficiency: Can New Generation Chemicals Be a Solution for Steam-Induced Unfavorable Wettability Alteration?

In this paper, the interfacial properties of a rock/heavy-oil/steam system were measured to observe the degree of wettability alteration when adding new generation chemicals to steam to improve the displacement efficiency and reduce the amount of CO2 by minimizing the need for steam. A heavy-crude-oil obtained from a field in Alberta (27780 cP at 25 degrees C) was used in all experiments, and the measurements were repeated on different types of substrates (quartz and calcite). Interfacial tension tests between heavy-oil and steam were also conducted to study the change in interfacial properties. All measurements in this research were performed at a range of temperatures up to 200 degrees C in a high-temperature-high-pressure cell. In gaining a comprehensive evaluation of this mechanism, several impacting factors such as pressure, phase change, and type of rock were taken into consideration and evaluated separately. Different types of new generation chemical additives-biodiesel, switchable-hydrophilicity tertiary amines (SHTA), nanofluids (dispersed SiO2 and ZrO2), ethers, alcohols, and chelating agents-were applied to the steam with a range of concentrations throughout interfacial tension and contact angle measurements to evaluate the wettability alteration performance at steam temperature and pressure. The irreversible mechanism of wettability state was the result when phase change occurred with the presence of brine. Wettability alteration and interfacial tension reduction in steam conditions were achieved after involving these new generation chemicals. Also, optimum chemical concentration was determined through interfacial tension and contact angle measurements. The study and analysis of chemical additive applications provide a more robust understanding of steam-induced wettability alteration mechanisms in a rock/heavy-oil/steam system. In summary, conventional steam additives can be altered by these cost-effective and thermally stable new generation chemicals showing potential for wettability improvement and interfacial tension reduction in practical applications.