稠油开采用甜菜碱表面活性剂性能研究

Study on the Performance of Betaine Surfactant Used in Heavy Oil Production

为探究稠油热采用表面活性剂的作用机理和构效关系,测定了8种不同结构的长链烷基羧酸/磺酸甜菜碱溶液与稠油的界面张力,考察了温度、矿化度、二价离子对界面张力的影响,并利用微观可视化实验方法进行了驱油性能的研究。实验结果表明:烷基链长度、疏水基支链化和亲水基尺寸是影响甜菜碱降低界面张力能力的主要结构因素,直链羧基甜菜碱C16BC与海上稠油具有最佳的协同效应,能将油水界面张力降至1.0×10^(-4)m N/m数量级;温度、矿化度和二价离子对甜菜碱降低界面张力能力影响不大。驱油过程中,C16BC通过超低界面张力高效启动原油,提高洗油效率;同时,形成的水包油型乳状液,有利于运移;并且,乳状液在运移过程中部分聚并,形成具有一定黏度的前端油墙,增加流动阻力,扩大波及范围。C16BC溶液在微流控芯片中的驱油效率比地层水驱提高了24.9%,表现出良好的应用前景。

In order to explore the mechanism and structure-activity relationship of surfactants used in the thermal treatment of heavy oil,the interfacial tension between eight different long-chain alkyl carboxylic acid/sulfonic acid betaine solutions and heavy oil was measured.The effects of temperature,mineralization degree,and divalent ions on interfacial tension were investigated,and the oil displacement performance was studied using microscopic visualization experimental methods.The experimental results show that alkyl chain length,hydrophobic group branching,and hydrophilic group size are the main structural factors affecting the ability of betaine to reduce interfacial tension.Straight chain carboxyl betaine C16BC has the best synergistic effect with offshore heavy oil,which can reduce the interfacial tension between oil and water to the order of 1.0 × 10^(-4)m N/m.Temperature,salinity,and divalent ions have little effect on the ability of betaine to reduce interfacial tension.During the oil displacement process,C16BC efficiently starts the crude oil through ultra-low interfacial tension,improving the oil washing efficiency.Meanwhile,the water in oil emulsion formed is conducive to migration.Moreover,during the migration process,the emulsion partially coalesces,forming a front end oil wall with a certain viscosity,increasing flow resistance and expanding the coverage range.The oil displacement efficiency of C16BC solution in microfluidic chips has been improved by 24.9%compared to formation water displacement,demonstrating good application prospects.