弱碱三元复合驱硅质垢形成影响因素与机理研究

在弱碱三元复合驱驱油过程中,弱碱药剂碳酸钠会导致油层及采出系统中形成硅质垢,不仅会造成油层伤害,还会给生产带来极大不便.因此,开展弱碱三元复合驱硅质垢形成影响因素与机理研究,可对现场防垢除垢技术起到理论指导作用,进一步促进弱碱三元复合驱技术的推广应用.采用硅钼黄分光光度法,研究了pH值、温度和碳酸盐垢等3个主要因素对硅质垢形成的影响.结果表明,pH=8.2-10.2,随pH值增大,硅成垢趋势减弱;温度为25℃-65℃,随温度升高,硅成垢趋势减弱;碳酸盐垢可促进硅质垢生成,并且随碳酸盐垢含量的增加,硅成垢趋势增强.此外,依据硅酸聚合经典理论,详细分析了弱碱三元复合驱中硅质垢的形成机理,概括为：单分子硅酸→多聚硅酸→硅酸凝胶→硅质垢.

Study on Influencing Factors and Mechanism of Silicon Scaling in Weak Base ASP Flooding

During the weak base alkaline-surfactant-polymer （ASP） flooding, weak base chemical sodium carbonate may lead to silicon scaling in the reservoir and produced system, which will not only do harm to reservoir and oilfield, but also to production. Thus, the paper carried out this research which not only will provide some theoretical guidance for scale control and removal but promote the application and development of weak base ASP flooding. The influence of pH value,temperature and carbonate scale were studied by using of silico-molybdenum yellow spectrophotometry. The results show that： in the range of pH 8.2 - 10. 2 or temperature 25℃-65℃, when pH value or temperature increased, the tendency of silicon scaling decreased respectively ; carbonate scale could promote silicon scaling, and when carbonate scale increased, the tendency of silicon scaling increased. Moreover, based on the classical theory of silicic acid polymerization,this paper expounded in detail the forming mechanism of silicon scale. It can be summarized as follows： mOno-silicic acid → poly-silicic acid → silicic acid gel → silicon scale.