复合驱体系化学剂静态损失评价方法研究

化学剂的损失程度直接影响化学段塞的使用效率。仅考察经油砂吸附后的化学剂损失,不能全面反映驱替过程中的化学剂静态损失程度。为此系统考察了三元复合驱体系经油砂和油相吸附后,表面活性剂质量分数和组成、NaOH质量分数及三元体系与原油间界面张力的变化。三元复合驱组成为:HPAM1.5g/L,表面活性剂上限质量分数0.3%,NaOH上限质量分数1.2%。实验结果表明,经油砂7次吸附后,表面活性剂质量分数从0.28%降至0.02%;NaOH质量分数从1.10%降至0.71%;三元体系经油砂5次吸附后,与原油间的界面张力已无法降至10^-3mN/m数量级。经油砂吸附后的三元体系与油相作用后,表面活性剂质量分数降低,最大降幅达50%,表面活性剂分子量明显升高;而NaOH质量分数降幅较小,最大降幅仅为15.22%;经油砂3次吸附后的三元体系与油相作用后,与原油间的界面张力已无法降至10^-3mN/m数量级。建议将油砂吸附与油相充分作用相结合,综合评价驱替液的化学剂静态损失程度。

New Evaluation Method of Static Chemical Agent Loss Degree in Compound Flooding System

Chemical agent loss degree had direct effect on the utilization efficiency of Chemical slug. Previous studies mainly focused on static chemical agent adsorption degree on rock surface. Factors of influencing chemical agent loss degree could not be fully considered by this way. To solve this problem, the changes of surfactant and NaOH mass fraction, composition of surfactant and interfacial tension were systematically investigated after the adsorption of alkali/surfactant/polymer (ASP) system in multiple oil sand and crude oil. The composition of ASP was obtained as follows: 1.5 g/L hydrolyzed polyacrylamide (HPAM), 0.3% ceiling mass fraction of surfactant, and 1.2% ceiling mass fraction of NaOH. The results showed that both rock surface adsorption and oil phase adsorption not only reduced the mass fraction of surfactant and NaOH, but also change the composition of surfactant, and eventually led to the changes of interfacial tension between ASP system and crude oil. The mass fraction of surfactant decreased from 0.28% to 0.02%, and that of NaOH decreased from 1.10% to 0.71% for ASP system after 7 times oil sand adsorption. In addition, the interfacial tension between ASP system after 5 times oil sand adsorption and crude oil could not be reduced to 10^-3 mN/m order of magnitude. For ASP system after mixing with the crude oil, the mass fraction of surfactant decreased substantially and the largest decline reached 50%, while the molecular weight of surfactant obviously increased. Compared with surfactant, the mass fraction variation of NaOH was smaller with largest fall of only 15.22%. The interfacial tension between ASP system after 3 times oil sand adsorption and crude oil greatly increased which could not be reduced to 10^-3 mN/m order of magnitude after mixing with the crude oil. In order to comprehensively evaluate the changes of above properties, a new evaluation method was proposed which combined multiple sand adsorption with crude oil adsorption.