含油污水下向流过滤器集水单元结垢沉积行为及影响研究

Study on Saling Deposition in Water Collecting Tubes of Produced Water Downward Flow Filter in Oilfield

以改善油田污水水质、提高污水处理系统的运行平稳性为目标,结合下向流过滤器集水工艺的特征及其在生产运行中暴露的问题,分析了集水单元结垢沉积物的特性。考虑集水单元的材质及结构布局,建立模拟实验装置,研究了过滤速度、采出污水聚合物质量浓度对结垢沉积行为的影响,得出实验条件下的结垢沉积规律,明确了集水单元布孔支管构造形式对结垢沉积的影响,揭示了集水单元结垢沉积的内在机理。结果表明,集水单元结垢沉积物以FeS和Fe_(2)O_(3)为主,同时有一定量的CaCO_(3)和硅铝酸盐,与集水管内壁高强度聚集和黏结,这种沉积行为受温度、过滤速度和水质特性的共同影响。地面系统水温环境适宜硫酸盐还原菌的繁殖,其借助表面结垢物的掩护而加速集水单元基体的垢下腐蚀,过滤速度具有“成垢”和“剥离”的双重作用机制,采出污水见聚则会引起“共沉积”与“螯合增溶”的综合效应,同时集水单元构造结构决定的电偶腐蚀也加剧结垢沉积行为。

The influences of filtration rate and polymer concentration in produced water on the scaling deposition behavior were studied by building the simulation experiment device,considering the characteristics of downward flow filter water collection process and the problems existing in production.Based on the material and internal structure in the water collection tube,a experimental unit model was established,in order to investigate the effect of structure of water collection tube on scaling deposition.In addition,the internal mechanism for the scaling deposition in the water collection tube was discussed.The results indicate that FeS,Fe_(2)O_(3),CaCO_(3),and aluminosilicate are the main constituents of scaling depositions in the water collection tube.The high intensitive aggregation and adhesion between the scaling deposition and the inner wall of the water-collecting tube are proved to be influenced by temperature,filtration rate and water quality.The water temperature environment of the surface system provides a suitable propagating environment of the sulfate-reducing bacteria(SRB),which is used to accelerate the corrosion beneath the scale in the water collection tube.The filtration rate shows two mechanisms of"scaling"and"stripping".The polymer in waste water would induce a synergy effect between"co-deposition"and"chelate solubilization".Besides of that,the galvanic corrosion by the structure of the water collection tube is proved to be the internal mechanism for accelerating the scaling deposition.