耐温抗盐降压增注用表面活性剂室内研究

Indoor research of heat-and-salt-resistant surfactants used for step-down augmented injection

针对低渗油藏油井注水开发问题,开发出一种耐温抗盐的降压增注用表面活性剂,以脂肪酸二乙醇酰胺和脂肪醇聚氧乙烯醚(磺酸盐)表面活性剂进行复配,另外,加入一定比例的聚硅氧烷聚醚松香胺表面活性剂,进一步增强其表面活性,引入性能优良的松香胺,使其表现出更好的驱油增注效果,并从油水界面张力、耐温抗盐性、洗油率等方面对其进行了室内性能的对比评价。结果表明,0.3%质量浓度的降压增注用表面活性剂A在地层温度70℃下,能在较短的时间内将油水界面张力降低到5.0×10-3mN/m以下,洗油率达到σ=48.5%,洗油效果较好;在150℃和含盐量20000 mg/L的条件下,也表现出较高的表面活性,表面张力低至24 mN/m;同时表现出良好的润湿性,使岩石表面发生了润湿反转,消除了低渗孔喉处的贾敏效应,根据物模实验,降压率可达到25.55%,起到良好的降压增注驱油的效果。

For the water injection development problem of the low permeability reservoirs wells,the heat-and-salt resistant surfactants used for step-down augmented injection were developed.Fatty acid diethanolamide was compounded with fatty alcohol polyoxyethylene ether(sulfonate).In addition,a percentage of polysiloxane polyether amine rosin surfactant was to join to further enhance its surface activity.Introducing the excellent performance of rosin amine was to make its show better oil displacement effect of augmented injection.Meanwhile,the comparison of indoor performance evaluation was conducted from the oil-water interfacial tension,heat-and-salt resistance,oil washing rate and so on.The results showed that for the surfactant A used for step-down augmented injection with a mass concentration of 0.3%,the oil-water interfacial tension could reduced below 5.0×10-3mN/m in a short time at the formation temperature of 70℃,and the oil washing effect was good(σ=48.5%).Under the condition of 150℃and salt content of 20000 mg/L,it was observed high surface activity and the surface tension was as low as 24 mN/m.At the same time,it showed good wettability,which made the surface of the rock wettability reversal,and eliminated the Jamin effect at the low-permeability pore throat.According to the core displacement simulation experiment,the depressurization rate could reach 25.55%,which played a good effect of reducing pressure and increasing oil flooding.