抗盐聚合物对采出液和采出水油水分离特性的影响研究

Effect of Salt-Tolerant Polymer on Oil/Water Separation Characteristics of Produced Liquid and Produced Water

大庆油田部分区块抗盐聚合物驱采出液进入地面系统后出现了处理难度大幅度上升等问题。针对大庆油田萨中开发区北部和杏八区丁块应用的两种抗盐聚合物,采用室内配制的模拟介质研究了其对采出液和采出水油水分离特性的影响规律及影响机制,发现两种聚合物均造成采出液和采出水中O/W型乳状液稳定性显著增大。影响机制主要为抗盐聚合物分子团具有油水界面活性并带有过剩负电荷,吸附在油滴表面会降低油水界面张力,增大采出液的油水乳化程度,同时还会增大油滴表面的过剩负电荷密度、产生阻碍油珠间相互聚集和聚并的静电斥力和空间位阻;此外,抗盐聚合物对水相的增黏作用还降低了油珠的上浮速度。该研究可为抗盐聚合物驱采出液处理药剂、工艺和设备研发提供理论指导。

The difficulty of processing salt-tolerant polymer flooding produced fluid in part of Daqing Oilfield has been greatly increased after it entered the surface system.In this paper,the influencing law and mechanism of the two kinds of salt-tolerant polymers on the oil-water separation characteristics of produced liquid and produced water are studied by using simulated medium prepared indoors in the northern Sazhong development block and Xingba district Ding block in Daqing oilfield.It is found that the stability of O/W type emulsions in produced fluid and produced water increased significantly with both polymers.The main mechanism is that salt-tolerant polymer molecular groups have oil-water in-terface activity and have an excess negative charge which can reduce the oil-water interfacial tension and increase the emulsification degree of produced liquid when it sticks to the surface of the oil droplets.At the same time,it can also increase the excess negative charge density on the surface of the oil droplets,produce the electrostatic repulsion and steric hindrance which prevent the oil droplets from gathering and coalescing.In addition,the thickening effect of the salt-tolerant polymer on the aqueous phase also reduces the floating velocity of the oil droplets.This study can provide theoretical guidance for the de-velopment of reagents,processes and equipment for the treatment of produced liquid by salt-tolerant polymer flooding.