部分水解聚丙烯酰胺/乳酸铬在油田污水条件下的成胶特性研究

Gelling Characteristic of Partially Hydrolyzed Polyacrylamide/Lactic Acid Chromium Gel in Oilfield Sewage

为了采用油田污水配制性能优良的聚合物弱凝胶调驱剂,研究了油田污水中各组分对部分水解聚丙烯酰胺/乳酸铬成胶性能的影响,优选出适合污水条件下的部分水解聚丙烯酰胺/乳酸铬凝胶体系,考察了该凝胶体系对岩心的封堵作用。结果表明:随着Na^+、Mg^(2+)、Ca^(2+)浓度及矿化度的增加,部分水解聚丙烯酰胺/乳酸铬成胶时间缩短、凝胶黏度增加;随S2-浓度增加,成胶时间延长、凝胶黏度降低,S2-加量大于30 mg/L时,体系难以成胶;含油量对凝胶的成胶无影响;凝胶最佳配方为:三氯化铬与乳酸摩尔比1∶8,部分水解聚丙烯酰胺、交联剂和硫脲的质量浓度分别为2000、200和800 mg/L,该凝胶体系的成胶时间为25 h,成胶后的黏度为20 Pa·s,对岩心的封堵率达85%以上,可用油田采出污水配制。

In order to prepare polymer weak gel profile control agent with high performance using oilfield sewage,the influence of sewage component on the gelling property of partially hydrolyzed polyacrylamide/lactic acid chromium gel was studied. The optimum formula of partially hydrolyzed polyacrylamide/lactic acid chromium gel system that was suitable for sewage was selected,and the plugging effect was investigated. The results showed that the gelling time of partially hydrolyzed polyacrylamide/lactic acid chromium gel system decreased and gel viscosity increased with the increase of Na＋,Mg（2＋）and Ca（2＋） concentration and salinity. The gelling time increased and gel viscosity decreased with increasing concentration of S2-. When the concentration of S2-was more than 30 mg/L,it was hard to gel. The oil content had no effect on gel. The optimum formula of gel was obtained as follows： 1∶8 the molar ratio of chromium trichloride to lactic acid,2 g/L partially hydrolyzed polyacrylamide,200 mg/L crosslinking agent,800 mg/L thiourea. The gelling time was 25 hrs and the viscosity of gel was 20 Pa·s. The core plugging rate could reach more than 85% in three different permeability cores,indicating good compatibility between the gel and sewage.