沉淀法去除压裂返排液中的残余硼交联剂

Study on method of precipitation removal of residual boron crosslinker in fracturing flowback fluid

为处理瓜胶压裂返排液中存在的残余硼交联剂,达到返排液重复利用的目的,研究了硼酒石酸钡沉淀法对于残余硼交联剂的去除,考察了pH值、反应时间、物料配比等因素的影响,采用甲亚胺-H酸分光光度法测定硼含量,同时考察了沉淀法除硼后再配液的可行性。结果表明,硼酒石酸钡法去除硼的效果显著,破胶液中植物胶寡糖对其影响小,最优条件为:pH=10.5,酒石酸与硼的反应时间1 h,钡与硼酒石酸根离子的结合时间2 h,反应配比n(H2BO3^-)∶n(Ba^2+)∶n(C4H4O6^2-)=2∶5∶4。再配液时用甘露醇掩蔽剩余交联剂,较佳条件为:n(硼)∶n(甘露醇)=1∶1.8。

In order to treat the boron crosslinker remained in the backflow of guar fracturing fluid so as to recycle the backflow,the removal effect of residual boron crosslinker by barium borate precipitation method was studied,and the influence of pH value,reaction time and material ratio were investigated.The content of boron was determined by azomethine-H acid spectrophotometry,and the feasibility of the precipitation method after boron removal was investigated at the same time.The results showed that the removal effect of boron by the method of barium borate was remarkable,and the effect of plant gum oligosaccharide on it was small.The optimum conditions are determined as follows:pH is 10.5,the reaction time of tartaric acid with boron was 1 h,the binding time of barium with boron tartrate ion was 2 h,and reaction ratio is n(H2BO3^-)∶n(Ba^2+)∶n(C4H4O6^2-)=2∶5∶4.Mannitol was used to mask the remaining crosslinking agent in the remanufacturing solution,and the better condition was n(boron)∶n(mannitol)=1∶1.8.