Reconsideration of Steam Additives to Improve Displacement Efficiency: Can New Generation Chemicals be Solution for Steam Induced Unfavorable Wettability Alteration?

Abstract

In this paper, contact angles in a rock/heavy-oil/steam system were measured to observe the degree of wettability alteration when unconventional chemicals were added to steam. A heavy-crude-oil obtained from a field in Alberta (27,780 cP at 25°C) was used in all contact angle measurements and the measurements were repeated on different types of substrates (quartz and calcite). In addition to this observation, surface tension tests between heavy-oil and steam were also conducted to study the change in interfacial properties. All measurements in this research were conducted at a range of temperatures up to 200°C in a high-temperature-high-pressure IFT device. 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 novel chemical additives—biodiesel, Switchable-Hydrophilicity Tertiary Amines (SHTA), nanofluids (dispersed SiO2 and ZrO2), ethers, alcohols, and chelating agents—were ere applied to the steam with a range of concentrations throughout surface tension and contact angle measurements to evaluate wettability alteration performance at steam temperature and pressure. The observation presented that pressure does not contribute substantially to the wettability state and was perceived to be more oil-wet in steam conditions—as also confirmed by our previous research. The irreversible mechanism of wettability state was the result when phase change occurred with the presence of brine. Wettability alteration and surface tension reduction in steam condition were achieved after involving these unconventional chemicals, an example being in the steam with biodiesel application. In addition, optimum chemical concentration was also observed through surface tension and contact angle measurements. The study and analysis of chemical additives applications provides a stronger understanding of steam-induced wettability alteration mechanisms in a rock/heavy-oil/steam system. In summary, conventional steam additives can be altered by these novel chemicals that are both cheaper and more thermally stable, thus showing potential and appearing promising for steam wettability improvement and surface tension reduction in steam applications.