Alkali-surfactant-polymer injection for enhanced oil recovery: from optimal chemical formulation experiments to coring simulation

Abstract

Chemical Enhanced Oil Recovery (CEOR) has gained significant attention, wherein the use of alkaline surfactant polymer (ASP) solutions has proven to be effective. The generation of a middle-phase microemulsion between the ASP solution and oil is key factor for the success of the flooding process in which exhibits ultralow interfacial tensions, thereby contribute increased the recovery efficiency. Prior research has emphasized the importance of the middle-phase microemulsion in the CEOR process. Additionally, experimental designs and response surface methodologies have been commonly employed to analyze multiple variables and their interactions, thereby facilitating the determination of the optimal concentration of components in an ASP solution for the highest quality microemulsion phase. These methodologies have proven to be effective in navigating the complexities of the ASP system and ensuring the attainment of favorable outcomes. In this article, an experimental design and response surface method employed to accurately determine the optimum concentration of surfactants in an ASP solution required to achieve the best quality of the microemulsion phase. Subsequently, the determined optimal ASP formulation was applied in core flooding tests to evaluate its efficiency in an actual reservoir condition such as salinity and temperature to ensure the reliability and comparability of the results. Ten sandstone cores were utilized to evaluate the impact of varying injection volumes on the recovery factor during ASP flooding. The study identified the optimal concentration of surfactants and the highest effective injection volume was determined. These findings underscore the significance of accurately determining the ASP formulation and injection volume for successful CEOR operations. The study's outcomes contribute implications for the optimization of ASP flooding processes in the enhanced oil recovery. Furthermore, the study opens avenues for future research aimed at refining ASP flooding techniques.