Abstract:

With the large-scale implementation of chemical flooding, the demand for surfactants has increased sharply. Betaine surfactants are a type of efficient displacement agent suitable for multi-scenario exploitation in oilfields due to their excellent interfacial activity, salt resistance, and environmental friendliness. Molecular dynamics simulations were used to study the oil-water interface behavior and microscopic molecular configuration of betaine surfactants with different hydrophobic chain lengths and hydrophilic groups, so as to explore the interfacial activity of long-alkyl-chain betaine surfactants at the molecular level, and explain the recovery-enhancing mechanism. Through mutual verification between the simulation results and experimental data, microscopic explanations for macroscopic experimental phenomena were provided. Furthermore, the interfacial action mechanism of long-alkyl-chain betaine surfactants was summarized, providing guidance for the design of displacement agents based on the interface migration and distribution by molecular simulation.

Key words: long-chain alkyl betaine, interfacial property, molecular simulation, enhanced oil recovery