A holistic review of harsh conditions resistant surfactants for enhanced oil recovery in dense carbonate reservoir

Energy supply demand and no more change in the world oil reservoirs still nominate the surfactant EOR (Enhance Oil Recovery) as a technically promising approach. Effective multi-mechanism of surfactants can improve the oil recovery factor, especially in the carbonate reservoirs. Hence, more oil of higher salinity and temperature must tailor for chemical EOR methods as the oil field developed. However, surfactants always suffer from high adsorption, low stability, and poor performance in harsh conditions, i.e. high temperature, high salinity/hardness (HT/HS), and dense properties of carbonate rocks. So far, no unique procedure or rigorous framework exist to systematically select the best surfactant for EOR regarding the harsh conditions of dense carbonates. Therefore, before any blind research in an EOR project, database and iterative-time consuming procedures like phase behavior lab tests, comprehensive knowledge of chemical components' interaction and synergy must be documented. In this study, we first review the microscopic/macroscopic challenges of surfactant EOR in dense carbonates regarding pertinent characteristics of these types of reservoirs. Considering the harsh conditions, this study demonstrates the best practices to narrow surfactant formulations such as hydrophobic modification, blending approach, multiple hydrophilic groups in the surfactant structure, etc. Moreover, numerious strategies, including structural enhancement, scarifying agents, and inhibitors, are presented herein to mitigate surfactant retention and scale issues. Finally, the research gaps and perspective as flooding time scale, optimized core length, and microemulsion viscosity measurement are addressed.