Ca^(2+)与Mg^(2+)对聚合物黏度影响及其增黏方法

INFLUENCES OF Ca^(2+) AND Mg^(2+) ON THE VISCOSITY OF THE POLYMER SOLUTION AND THICKENING METHOD

大庆油田长垣西区注入污水中Ca^(2+)与Mg^(2+)质量浓度较高,导致聚驱效果不理想。研究了高质量浓度Ca^(2+)与Mg^(2+)污水对聚合物体系黏度的影响,提出了草酸作为Ca^(2+)、Mg^(2+)络合剂提高聚合物体系黏度的方法。结果表明:与长垣北区注入水相比,长垣西区注入Ca^(2+)、Mg^(2+)质量浓度较高,接近前者5倍;长垣西区污水配制的聚合物溶液黏度较低,与北区污水配聚相比黏度损失近26.3%;通过向溶液中添加适量草酸可以有效改善聚合物溶液性能;当络合剂与二价离子摩尔浓度比略大于1:1时,化学驱采收率增幅最大,与不添加络合剂聚合物体系相比提高了5.3%。

The mass concentrations of Ca2＋and Mg2＋ in the injected sewage of West Block of Daqing Oilfield Pla- canticline are rather higher, thus the imperfect polymer flooding effects are caused. The influences of the high-mass- concentration sewage on the viscosity of the polymer solution are studied, and moreover the method to improve the viscosity of the polymer system is presented by taking oxalic acid as the complexing agent of the ions. The results show that comparing with the injected sewage in Placanticline North Block, the mass concentrations of the above i- ons are rather higher than the former： near five times; the prepared polymer solution viscosity in the previous sew- age is rather lower and lost almost 26. 3% than that of the later; by means of adding appropriate amount of oxalic acid, the performances of the polymer solution can be effectively improved; when the molar concentration ratio be- tween the complexing agent and divalent ion is a bit higher than 1 ： 1, the incremental recovery of the chemical flooding is the optimal and moreover higher by 5.3% than the polymer system without any complexing agent.