A review on surfactant retention on rocks: mechanisms, measurements, and influencing factors

Surfactants play a vital role in chemical enhanced oil recovery (cEOR). The amount of surfactant loss caused by retention during flooding through reservoir rock is still a challenge in surfactant-based cEOR techniques, and directly impacts the economics of a cEOR project. This review focuses on the mechanisms behind the retention of several surfactants on different rock/mineral types such as sandstone, carbonates, quartz, kaolinite, calcite, etc. Measurement techniques of surfactant retention reported in the literature are also presented. Lastly, this review illustrates retention minimization strategies for different types of surfactants. Alkalis have been widely examined in minimizing surfactant retention, mostly in sandstones. Other chemicals such as ammonia, nano-particles, ionic liquids, polymers, and sacrificial agents have also been used to reduce surfactant retention. This review also discusses the influencing factors that can significantly impact the strategy to minimize surfactant retention.