油田聚合物驱采出污水絮凝过程研究

针对油田聚合物驱（简称聚驱）采出污水,通过对油滴粒度分布、絮凝指数、油水分离特性和Zeta电位等指标的测定,研究了聚合物、温度、药剂以及搅拌强度对絮凝过程的影响,并探讨了影响聚驱采出污水油水分离效果的主要原因.结果表明,静电排斥并不是聚驱采出污水异常稳定的主要原因. 聚驱采出污水的油水分离特性与水驱采出污水相比存在显著差别,主要因为聚合物阻碍了小油滴的碰撞絮凝. 投加250mg/L由改性聚醚类破乳剂和弱阳离子絮凝剂复合而成的CHP-03药剂,可以有效克服聚合物的阻碍作用,获得92%的含油去除率. 该药剂在絮凝过程中并不依靠电中和机理来实现油滴的脱稳. 在现场条件下,温度的提高不能明显地促进油滴絮凝的有效性. 适当的高速搅拌可以加快絮体生长. 油滴之间的聚结破乳滞后于絮凝,絮凝的后期应避免剧烈搅拌,防止尚未聚结破乳的油滴重新分散.

Flocculation of Wastewater Produced in Polymer Flooding

The particle size distribution, flocculation index, Zeta potential and oil content in water were tested during flocculation of wastewater produced in polymer flooding of oil field. CHP-03, a mixture of a modified pluronic demulsifer and a weak-cationic flocculant, was used to improve the efficiency of oil droplet collision. The effects of polyacrylamide, temperature, and mixing speed on flocculation dynamics are discussed. Polyacrylamide affects the oil-water separation by obstructing the aggregation of small oil droplets, but electrostatic repulsion is not a major factor in preventing flocculation. The local temperature has a limited effect on flocculation. Fast mixing favors the growth of flocs, while slow mixing is suitable for the coalescence of oil droplets. Addition of 250mg/L CHP-03 can enhance the oil-water separation and remove 92% of the oil content.