用于CO_2驱的助混剂分子优选及评价

Molecular Optimization Design and Evaluation of Miscible Processing Aids Applied to CO_2 Flooding

中国油藏开展CO2驱油技术,普遍存在着油藏混相压力高,导致混相驱难以实现及采收率低的问题,为此,借鉴CO2-水体系的微乳液领域中所使用的表面活性剂,以氟代烷烃链和非氟OAc链作为亲CO2端,以烷烃类结构作为亲油端,研制了合成有机助混剂。利用界面张力测试,分析其在煤油和原油油样中降低CO2-油样界面张力和CO2驱最小混相压力的作用并进行优选。测试结果表明,筛选出的两类新型助混剂(全乙酰葡萄糖十二烷基酯分子与柠檬酸三异丙酯分子)都具有较好的助混效果。在某油田原油的应用测试中,在CO2驱替气中加入全乙酰葡萄糖十二烷基酯分子后,CO2-油样界面张力平均降低28.7%,CO2驱最小混相压力降低27.47%,效果明显,具备进一步研究以投入工程应用的价值。

Aiming at the fact that universal high miscible pressures existed in domestic reservoirs by CO2 flooding technology available inChina tend to resulting in poor miscible displacement,and low target oil recovery efficiency,this paper drew the experiences from availablestructural characteristics of surfactants applied in microemulsion of CO2-water systems,by taking fluoro-alkane chains and non-fluoro-OAcchains as the CO2-philic ends,taking alkane structure as the lipophilic ends,designed the synthetic organic assistants（aids）. The aids＇ ef-fects for reducing CO2-crude oil interfacial tension and minimized miscible pressure of CO2 flooding were analyzed and optimized by sur-face tension testing in CO2- kerosene system and CO2-crude oil system. The aids＇ effects for reducing CO2-crude oil interfacial tension andminimized miscible pressure（MMP） of CO2 flooding were analyzed and optimized by surface tension testing in CO2- kerosene system andCO2-crude oil system. The result shows that the new two aids with per-acetylated glucose dodecyl ester molecules and citric acid isopropylester molecules do have better miscible processing effects for minimizing the interfacial tension of the CO2-crude oil system and reducingthe MMP. The case study suggests that per-acetylated glucose dodecyl ester could cause the surface tension down averagely by 28.7% andthe MMP of CO2 flooding down by 27.47%,possessing the value of further research in support of engineering application.