延长油田低渗储层改性表面活性剂驱提高采收率

Enhanced Oil Recovery Technology of Modified Surfactant Flooding in Low-permeability Reservoirs in Yanchang Oilfield

表面活性剂-纳米颗粒稳定泡沫在提高采收率(EOR)领域具有巨大潜力。评价含有N,N′-双(二甲基十四烷基基)-1,6-己二溴化铵(FSF)+二氧化硅/氮化硼泡沫流体,并确定最佳配方。稳定性研究表明,FSF泡沫的半衰期约为6 h,在二氧化硅(SiO_(2))和氮化硼(BN)颗粒的存在下,半衰期分别提高到27 h和33 h。在表面活性剂NP液中,油/盐水IFT由27.2 mN·m^(-1)降至5 mN·m^(-1)以下。接触角、zeta电位分析表明,岩石的润湿性质从中湿状态转变为强水湿状态。泡沫流体表现出假塑性流动行为。黏弹性剖面研究表明,泡沫在驱油过程中仍保持其“拖拽”特性。综上所述,FSF-NP泡沫具有良好的稳定性、界面活性和流变性,是延长油田低渗储层三次采油的理想驱油剂。

Surfactant-nanoparticle stabilized foams have great potential in the field of enhanced oil recovery(EOR). In this article, foam fluids containing N,N’-bis(dimethyltetradecyl)-1,6-hexanediammonium bromide(FSF) + silica/boron nitride were evaluated, and the optimal formulation was determined. Stability studies showed that the half-life of FSF foam was about 6 h, which was increased to 27 h and 33 h in the presence of silica(SiO_(2)) or boron nitride(BN)particles, respectively. In the surfactant NP solution, the oil/brine IFT decreased from 27.2 mN·m^(-1)to below 5 mN·m^(-1).The contact angle and zeta potential analysis showed that the wettability of the rock changed from a medium wet state to a strong water wet state. Foamy fluids exhibited pseudoplastic flow behavior. Viscoelastic profile studies showed that the foam retained its "drag" properties during oil displacement. In conclusion, FSF-NP foam has good stability,interfacial activity and rheology, and is an ideal candidate for tertiary oil recovery in low-permeability reservoirs in Yanchang oilfield.