Optimised synthesis of betaine surfactant for integrated air foam oil displacement and corrosion inhibition

This research tackles the critical challenge of enhancing oil recovery while mitigating corrosion in high-salinity reservoirs, a key factor in improving the economic efficiency and longevity of oilfield operations. By developing an integrated binary system working fluid (cocoamidopropyl betaine – hexamethylenetetramine (CBH)) for air-foam flooding and corrosion inhibition, the study presents a multifunctional solution that combines superior foaming and corrosion inhibition properties. Zwitterionic surfactants are synthesised through quaternisation reactions using cocamidopropyl dimethylamine (PKO), dodecyl dimethyl tertiary amine (12 DMA), cetyl dimethyl tertiary amine (16DMA), and monochloroacetic acid (MCA) as raw materials. The optimal surfactant, CABT-12, is identified through foaming performance evaluations, with a concentration of 1.0% delivering the best results. The corrosion inhibition efficiency reaches its peak when CABT-12 is combined with hexamethylenetetramine at 500 mg/L, achieving an efficiency of 99.48%. The CBH formulation exhibits excellent thermal stability, salt resistance, and oil resistance, with surface tension sharply decreasing to a critical micelle concentration of 0.036%. Laboratory oil displacement experiments show that increasing the injection volume and rate of the CBH formulation significantly boosts oil recovery efficiency. The findings suggest that the CBH formulation holds great promise for enhancing oil recovery while effectively mitigating corrosion in high-salinity reservoirs.