合水油田含聚合物采出水处理技术的研究与应用

Research andapplication of polymer containing produced water of Heshui oil field

长庆合水油田采出水废水中含有大量的聚合物、水凝胶,采出水水体发黑、黏度大、乳化稳定性强、难破乳,难以用常规污水处理方法进行处理。在对水质成份进行详细分析后,认为水体发黑的原因是其中的二价铁离子与硫化物形成了黑色的硫化铁胶体固形物。用“氧化→解聚→絮凝”新工艺对合水油田采出水进行处理,效果十分显著。首先对含聚水中聚合物氧化解聚,破坏其结构稳定性,然后用适量的过碳酸钠(SPC)使硫化铁胶体脱色,随后再进行絮凝沉淀,使用200~350ppm的SPC和2~5ppm的阳离子聚丙烯酰胺和聚合硫酸铁组合的复合絮凝剂,可以使含聚采出水的悬浮物下降到30mg·L^(-1)以下,pH约为7.0,且有效降低了水体的色度和浊度,其中浊度降低率达到98.02%,铁离子去除率为96.46%。较好地解决了含聚废水水体发黑、不易沉降、难处理等问题,有效改善了采出水水质,达到回注要求。

The produced waste water of Zhuang 7 and Zhuang 10 in the Heshui oil field contains a large amount of polymers and hydrogels.The produced water is blackened,has high viscosity and strong emulsification stability,difficult to demulsify and to be treated with conventional sewage treatment methods.After a detailed analysis of the composition of the water,it is believed that the water blackening is caused by the formation of black Iron(Ⅲ) sulfide colloidal solids between ferrous ions and sulfides.In order to improve the treatment efficiency of wastewater containing polymers,the process of "oxidation→depolymerization→flocculation" was adopted to treat the produced water from the Heshui Oil Production Plan.First,the polymer in the water is depolymerized to destroy its stable structure,then an appropriate amount of Sodium percarbonate(SPC) is used to decolorize the Iron(Ⅲ) sulfide colloid,and then flocculate and precipitate.The composite flocculant composed of 200~350 ppm SPC and 2~5ppm cationic polyacrylamide with polymeric Iron(Ⅲ) sulfate can reduce the suspended solids in the polymer containing produced water to below 30 mg · L^(-1),with a pH of about 7.0,and effectively reduce the chromaticity and turbidity of the water body.The turbidity reduction rate reached 98.02%,and the iron ion removal rate was 96.46%.It has effectively solved the problems of blackening,difficult settling,and difficult treatment of wastewater containing polymers,and effectively improved the quality of produced water.This method has fast reaction time,strong stability,repeatability,and adaptability of the agent,and can meet the actual needs of oil reservoir development and production.