Low permeability reservoir usually has small pore throat.Based on this characteristic, the mechanism of microscopic fluid flowin microtubes was studied using one-dimensional microtubeswith inner diameters of 5, 10, 15, 20 μm with deionized water and kerosene as the flow media.The relationshipsamong flow rate, boundary layer thickness and pressure gradient are revealed.Microtubule surface wettabilitywas changed from hydrophilic to hydrophobic with mixtures of dimethyldichlorosilane, kerosene, and siliconearein different proportions to form four different simulated oil viscosities to study the law governing the fluid flow. The results show that the fluid flow rate hada linearrelationship with pressure gradient, but nonlinearity of fluid flow gradually increased with decrease of the microtubule diameter. Also, the higher the driving pressure, the smaller the effective boundary layer thickness, and the ratio of effective fluid boundary layer thickness to microtubulediameter decreased with pressure gradient. The fluid velocity was higher than that before modification of the microtubule wall from hydrophilic to hydrophobic,and the larger the size of microtubules, the more significant the effect. The pressure gradientincreased significantly from 1.26 MPa/m to 6.83 MPa/m when the viscosity of the flow media was changedfrom 2.40 mPa·s to 10.20 mPa·s.
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