A review of the mechanics of heavy-oil recovery by steam injection with chemical additives

Abstract

The efficiency improvement of steam injection (more oil, less steam) is a critical challenge in heavy oil recovery. Using chemical additives is one option to achieve this efficiency improvement, but many different mechanisms are involved in this process, and different considerations need to be taken depending on the existing conditions and chemical type. For example, many tested thermally stable chemicals—surfactants, nanofluids, and water-soluble solvents—were able to favorably alter the wettability. The underlying physics behind this favorable alteration and other mechanisms are not well comprehended yet, especially for new generation chemicals under thermodynamic conditions. The comprehensive review and discussion presented in this paper mainly focus on the improvements on heavy-oil and bitumen thermal recovery, particularly on the late-stage steam injection as well as the fundamentals of the residual oil development mechanism post-steam injection. More importantly, this paper presents the experimental result-based, and comparative analyses of potential chemical additives (alkali, ionic liquid, surfactants, hydrocarbon solvents, water-soluble solvents, and new generation chemicals) applied to improve heavy oil recovery. This analysis is necessary not only to further evaluate the chemical's performance on the recovery improvement—specifically at the late-stage steam injection—but also to investigate the underlying recovery mechanisms, such as viscosity reduction, wettability alteration, interfacial tension (IFT) reduction, foaming effect, and emulsification presented by the chemical additives. Based on the outputs obtained from different experimental methodologies, the underlying recovery mechanisms induced by the potential chemical additives were identified. The results revealed that synergy among the recovery mechanisms presented by chemical additives could potentially improve the heavy oil recovery by more than 80% during steam injection. A comprehensive analysis of the mechanics of the heavy oil recovery provides valuable substantiation and understanding, honoring the potential implications of utilizing chemical additives as potential steam additives to the heavy oil recovery process. The results present beneficial information and recommendations for oil fields operating under steam injection applications.