Citric acid-based N-alkyl amides for enhanced oil recovery application in the carbonate reservoir: Sustainable laboratory-scale synthesis and recovery performance

Various chemical compounds and nanoparticles have been developed and utilized for upstream oilfield applications, regardless of their environmental impact. The majority of these oilfield chemicals were designed from oil-based starting materials and synthesized in multi-steps using hazardous solvents. However, there is an urge to improve sustainability in developing oilfield chemicals to reduce CO₂ emissions and utilize eco-friendly materials. Herein, we propose a sustainable synthesis of citric acid-based N-alkyl amides using solvent-free reaction and green starting material. The N-alkyl amide compounds were prepared by condensation reaction between citric acid and N,N-dimethyl-1,3-propanediamine (DMPA) or N,N-diethylethylenediamine (DEEA). The resulting compounds demonstrated good stability in reservoir conditions and were used for enhanced oil recovery. The structure/property relationships between the N-alkyl amides and their oil recovery performance were investigated systemically. The CA-based N-alkyl amides resulted in cumulative oil recovery of 44.7%–48.3%, which is 90% higher than the commonly used surfactants such as α-Olefin Sulfonate (AOS) and Cetrimonium bromide (CTAB). This study paves the way to develop green-based materials for upstream applications to move toward efficient and cleaner production.