适于油田污水的聚丙烯酰胺合成及配制工艺研究

Composition and preparation technique of polyacrylamide used in oil-field sewage

针对目前三次采油用聚丙烯酰胺相对分子质量低、易剪切降解、对盐敏感和不适应高温地层等问题,采用两种途径提高了聚丙烯酰胺的适用性。在由室内试验确定了复合引发剂最佳比值1∶1.3和质量浓度170 mg.L-1、合成最佳温度10℃、丙烯酰胺单体质量分数25%、电导率3.6μS.m-1和pH值6.57后,合成出相对分子质量高于2.6×107的聚丙烯酰胺,同时通过丙烯酰胺单体复配引入磺酸基团、苯乙烯磺酸基团或同时引入此两种基团,提高了聚合物的抗盐、抗温、抗剪切性能;后针对聚丙烯酰胺与地层水配伍性差的问题,优选出HEDP螯合剂、异噻唑烷酮杀菌剂和除氧剂硫脲,对聚合物稳定效果明显。该工艺的中试结果表明,现场污水配制溶液60 d后粘度保留率40.4%,满足了三次采油对聚丙烯酰胺的要求。

Aimed to the problems of lower molecular weight, easier shear degradation, sensibility to salt and inadaptability to higher temperature of pelyacrylamide used widely in current tertiary oil recovery, two approaches were adopted to enhance the adaptability of pelyacrylamide. Firstly, pelyacrylamide with 26 million molecular weight was compounded in lab through establishing optimum compounding initiator proportionality of 1：1.3 and mass concentration of 170 mg·L^-1, temperature of 10 ℃, acrylamide mass percentage of 25%, electrical conductivity of 3.6 μS·m^-1 and pH value of 6.57. The salt-resistance, thermal endurance and shear-resistance of polyacrylamide could be enhanced by introducing sulfonic acid group or styrene sulfonate group or drawing the two groups above at the same time. Secondly, chelator HEDP, bactericide isoquinoline ketone and oxygen scavenger thiourea were optimized to improve the compatibility of pelyacrylamide and formation water. The viscosity reserve rate of product solution prepared by sewage attains 40.4% after 60 days, so it is satisfactory in tertiary oil recovery.