聚合物驱采油污水的水质深化处理技术

The Advanced Treatment Technology of Oily Produced Wastewater for the Polymer Flooding

为解决聚合物驱产出污水的重复利用和污水配制聚合物溶液时黏度损失率高的问题,考察了影响聚合物溶液的主要因素,合成了聚硅铝絮凝剂(PSi AS-1)并对其净水性能进行了评价,用OIL Scale Chem结垢预测软件模拟了净化水在地层条件下的结垢趋势,采用激光粒度仪分析了聚合物溶液中的微粒粒径。研究结果表明,聚合物溶液中的Fe^(2+)、Ca^(2+)、Mg^(2+)、S^(2-)和悬浮物对聚合物溶液黏度的影响较大,在污水配聚合物溶液时必须进行控制;配方为50 mg/L的PFS(聚铁助凝剂)+200 mg/L的PSi AS-1+8 mg/L助沉剂的水处理剂能降浊除钙,使经深化处理后的净化水中Ca^(2+)、Mg^(2+)离子和残余聚合物含量均大幅降低,不含还原性二价铁离子和硫化物,含油量和悬浮物含量均较低。该净化水中少量的聚集体微粒的平均粒径在100 nm以下,远小于地层孔隙直径,不会发生碳酸钙垢堵塞地层的情况,可满足污水配制驱油用聚合物溶液的技术要求。

In order to resolve high viscosity-loss-rate problems in preparing the polymer solution using the produced wastewater of polymer flooding, the main factors affecting polymer solution viscosity were investigated and polysilicon aluminum flocculant were synthesized. Besides, flocculant purification performance and viscosity stability were evaluated, scaling trend of purified water under stratigraphic conditions was simulated by Oil Scalechem prediction sotiware, and the particle size of the polymer system was analyzed by laser granulometry. The results indicated that the effect of Fe^2＋, Ca^2＋, Mg^2＋, S^2- and suspended solids content in solution on the viscosity of the polymer solution was greater than that of the others, hence, it must be controlled in preparing polymer solution. The optimal dosing formula of the flocculant with the performance of removal of turbidity and calcium was as follows, 50 mg/L PFS ＋ 200 mg/L PSiAS-1 ＋ 8 mg/L setting agent. The content of Ca^2＋, Mg^2＋ and residual polymer of the purified water, obtained by deepened processing with the flocculant, decreased sharply, and the oil content and suspended solid content was lower, moreover, the purified water hardly contained Fe^2＋. The average particle size of suspended particles （SS） in purified water was less than 100 nm, which was smaller than the pore diameter or the cores, so formation could not be blocked by SS. As a result, the purfied water could be reused for preparing the polymer flooding solution.