纳米颗粒水基分散液在岩心微通道中的双重减阻机制及其实验验证

提出了纳米颗粒水基分散液的力学-化学双重减阻机制,并通过对比岩心切片吸附纳米颗粒前后以及冲刷前后的表面微结构、润湿性的变化,进行了实验验证. 研究结果表明,经纳米颗粒水基分散液处理之后的岩心切片表面表现为强亲水性, 并且存在一层致密的纳米颗粒吸附层;冲刷之后岩心切片表面的纳米颗粒吸附层依然存在, 但其表面已逐渐转变为强/超疏水性,反映了纳米颗粒吸附层表面的表面活性剂被逐渐清洗干净. 注水初期,主要表现为表面活性剂的化学减阻作用.随着注水过程的进行, 主要体现为以疏水表面的滑移效应为主的力学减阻机制.岩心驱替实验结果表明, 纳米颗粒水基分散液驱替后的岩心的水相渗透率平均提高幅度达84.3%, 减阻效果显著,证实了纳米颗粒水基分散液的力学-化学双重减阻机制.

Dual drag reduction mechanism of water-based dispersion with hydrophobic nanoparticles in core microchannel and experimental verification

Dual drag reduction mechanisms of water-based dispersion with nanoparticle is proposed. A contrastive study is take to verify the mechanism, in which the changes of surface microstructure and wettabilities of the core slices take place before and after treating by dispersion with hydrophobic nanoparticles and scouring by water. The results show that the surface of core slice which is treated by water-based dispersion with hydrophobic nanoparticles has strong hydrophilic property, and a compact nanoparticle adsorption layer forms on it. The nanoparticle adsorption layer still exists after scouring, but the core slice surface is changed into strong/super hydrophobic, reflecting that the surfactants which are adsorbed on the nanoparticles adsorption layer surface are gradually cleaned. The water-based dispersion with hydrophobic nanoparticles are mainly manifested as the chemical surfactant drag reduction effect during initial injection. With the injection continued, the mechanical drag reduction induced by the slip effect of super hydrophobic surface is reflected mainly. Core displacement results show that the water-phase effective permeability could increase about 84.3% on average. The results strongly confirm the dual drag reduction mechanism of the water-based dispersion with hydrophobic nanoparticles.