改性纳米流体化学性能及提高采收率效果分析

Analysis ofn the Chemical Properties of Modified Nanofluids and Their Effectiveness in Improving Oil Recovery

通过硅酸钠与浓硫酸制备纳米SiO2颗粒,经硅烷偶联剂KH792对其表面进行改性,结合傅里叶红外、X射线能谱仪、SEM及热分析仪等测试手段对其结构进行表征分析,分析了其驱油物理化学机制,研究了改性后纳米SiO2对渗吸采收率过程的影响特性。结果表明:KH792可以成功接枝纳米SiO2,改性后纳米颗粒大小均匀,维持在28 nm左右,粒径为10~60 nm,表明有机链以及活性基团—CH3可有效抑制纳米颗粒本身的团聚现象。高质量浓度纳米SiO2会显著影响岩石表面的润湿性,降低油水界面张力至1.542 mN·m^(-1)。随着纳米流体质量浓度从300 mg·L^(-1)增至1 800 mg·L^(-1),渗吸采收率可从9.96%增至34.36%。改性纳米SiO2流体对渗吸采收率的影响会随体系渗透率、温度、矿化度以及pH的增加而增加。

Nano SiO_(2) particles were prepared from sodium silicate and concentrated sulfuric acid,and their surface was modified with silane coupling agent KH792.The structure was characterized and analyzed using Fourier transform infrared,X-ray energy dispersive spectroscopy,SEM and thermal analysis methods.The physical and chemical mechanisms of oil recovery were analyzed,and the influence characteristics of modified nano SiO_(2) on the process of permeation recovery were studied.The results showed that KH792 could successfully graft onto nano SiO_(2),and the modified nanoparticles remained uniformly size at around 28 nm,with a particle size range of 10~60 nm.This indicated that organic chains and active groups—CH_(3) could effectively inhibit the aggregation phenomenon of the nanoparticles themselves.High mass concentration of nano SiO_(2) significantly affected the wettability of rock surfaces,reducing the interfacial tension between oil and water to 1.542 mN·m^(-1).As the mass concentration of nanofluids increased from 300 mg·L^(-1) to 1800 mg·L^(-1),the infiltration recovery rate could increase from 9.96%to 34.36%.The effect of modified nano SiO_(2) fluid on the infiltration recovery rate increased with the increase of system permeability,temperature,mineralization degree,and pH.