采油污水中保留聚合物对污水配制聚合物 溶液黏度的影响*

采用常规絮凝技术处理油田采出水,带负电荷的聚合物会形成含油絮集体,不仅造成聚合物的浪费,而且在油水处理系统形成劣化油(BS层)和含聚合物油泥沉积,影响原油脱水和污水净化,并滋生硫酸盐还原菌。为充分利用采油污水中的聚合物,首先采用综合破乳清水剂处理含聚合物采出液,在保证原油脱水和污水除油的同时,以分子形态原位保留采油污水中的聚合物,测定了保留聚合物(r-HPAM)的相对分子质量和水解度,研究了r-HPAM与污水中离子的相互作用以及含r-HPAM污水对配制高分子量聚丙烯酰胺(h-HPAM)溶液黏度的影响,分析了r-HPAM提高配注液黏度的增黏作用机制。结果表明,污水中的r-HPAM为低分子量(200×10⁴)、高水解度(46%)的聚合物,污水黏度为1.1 mPa·s。采用含r-HPAM的污水配制新鲜h-HPAM溶液,可以降低溶液的黏度损失。污水中的r-HPAM可作为牺牲剂与Ca²⁺、Mg²⁺、Fe²⁺和S^2-相互作用,抵消这些离子对新配制h-HPAM溶液黏度的损耗,其中对Fe²⁺和S^2-的影响最大。用含聚合物采出水配制高分子量聚合物溶液,对含聚合物采出水的循环利用和减少采出水的排放具有重要意义。

Effect of Retained Polymer in Oil Produced Wastewater on the Viscosity of Polymer Solution Prepared by Wastewater

When conventional flocculation technology is used to treat oilfield produced water,negatively charged polymers will form oil-bearing flocs.It not only causes the waste of polymer,but also forms degraded oil(BS layer)and polymer-containing sludge deposit in oil-water treatment system,which affects crude oil dehydration and sewage purification,and breeds sulfate-reducing bacteria.In order to make full use of the polymer in oil production wastewater,a comprehensive demulsifier was used to treat polymer-containing produced liquid.While ensuring crude oil dehydration and sewage degreasing,the polymer in oil production sewage was retained in situ in molecular form.The relative molecular mass and degree of hydrolysis of the retained polymer(r-HPAM)were measured,and the interaction between r-HPAM and ions in sewage and the effect of sewage containing r-HPAM on the viscosity of high molecular weight polyacrylamide(h-HPAM)solution were studied.What’s more,the viscosity increasing mechanism of r-HPAM on the viscosity of injection solution was analyzed.The results showed that the r-HPAM in sewage was a polymer with low molecular weight(200×10⁴)and high degree of hydrolysis(46%),and the viscosity of sewage was 1.1 mPa·s.Using sewage containing r-HPAM to prepare fresh h-HPAM solution could reduce the viscosity loss.The r-HPAM in sewage could be used as a sacrificial agent to interact with Ca²⁺,Mg²⁺,Fe²⁺and S^2-and offset the viscosity loss of h-HPAM solution by these ions.Among them,Fe²⁺and S^2-had the greatest impact.The preparation of high molecular weight polymer solution with polymer-containing produced water was of great significance to the recycling of polymer-containing produced water and reducing the discharge of produced water.