Abstract:

The alternating mechanisms of flow resistance to porous wall and the mechanism of enhancing water injection by using nano-particle of SiO₂ were investigated with the nano-particle adsorption method. When the hydrophobic nano-particles were adsorbed on the surface of porous walls, a layer of nanometer particles was formed instead of hydrated layer. The wettability of porous wall then could be translated to strongly hydrophobicity from hydrophilicity, and the slip effects on the nano-particles layer happened. The flow resistance could be reduced obviously, and the fluid velocity was enlarged obviously. A series of experiments were made to validate the feasibility to form the slip effects on the porous wall by nano-particle adsorption method. The results of displacement experiment show that the water-phase effective permeability could increase about 47 percent averagely. The Lattice Boltzmann Method was used to simulate the slippage length on the porous wall induced by nano-particle adsorption method.

Key words: hydrophobic nano-particle of SiO₂, reducing pressure and enhancing water injection mechanism, nano-particle adsorption method, rock pore, fluid flow, slippage effect, wettability, permeability, experimental study

摘要：

研究了疏水性纳米SiO₂颗粒在岩石微孔道孔壁的吸附对岩石孔壁的阻力特性的改变机制,探讨了纳米SiO₂降压增注机理。疏水性纳米颗粒吸附在地层岩石微孔道表面并形成纳米吸附层,使亲水孔壁表面呈现强疏水性并形成水流滑移层,较大幅度地降低了流动阻力,从而提高了水流速度。通过润湿性变化、吸附电镜扫描等系列实验,证明了岩石微孔道中产生纳米滑移效应的可能性。流动实验结果表明,经含纳米颗粒流体处理后,岩心的水相渗透率大幅度提高,平均达到47%。同时用Lattice Boltzmann方法(LBM)模拟了含疏水性纳米SiO₂颗粒流体处理前后的实际渗流问题,间接计算出了纳米颗粒吸附造成的滑移长度。

关键词: 纳米SiO₂, 降压增注机理, 吸附法, 岩石孔隙, 流体流动, 滑移效应, 润湿性, 渗透率, 实验研究