Abstract: A new method was proposed to measure the thickness of the boundary layer, and the thickness of the boundary layer under different viscosity and different pressure gradient was measured. The research results show that under the same pore throat radius and pressure gradient, the relation between the viscosity of the fluid and the proportion of the boundary layer is linear. The greater the viscosity, the greater the proportion of the boundary layer. Under the same viscosity and pressure gradient, with the increase of pore throat radius, the proportion of the boundary layer decreases rapidly. Under the same viscosity and pore throat radius, with the increase of the pressure gradient, boundary layer ratio decreases and tends to be stable. In addition by drawing the boundary layer thickness ratio chart, the influence of viscosity and displacement pressure gradient on nonlinear seepage is analyzed, and the results further confirme that the boundary layer is the fundamental reason for the nonlinear flow characteristics in tight oil cores.

Key words: Boundary layer, Tight oil, Pressure gradient, Pore throat radius, Viscosity, Nonlinear characteristics

摘要： 鉴于目前称重法测量边界层厚度的缺陷，建立了一种新方法，并测定了不同孔喉尺寸下的致密岩心在不同黏度、不同压力梯度条件下的边界层厚度。研究结果表明，在相同的孔喉半径和压力梯度下，流体黏度与边界层所占比例成线性关系，且黏度越大，边界层比例越大；在相同的黏度和压力梯度下，随着孔喉半径的增大，边界层比例迅速减小；在相同的黏度和孔喉半径下，随着压力梯度增大，边界层比例逐渐减小并趋于稳定。另外，通过绘制边界层厚度比例图版，分析黏度和驱替压力梯度对非线性渗流的影响，进一步证实边界层是导致致密油藏岩心出现非线性流动特征的本质原因。

关键词: 边界层, 致密油, 压力梯度, 孔喉半径, 黏度, 非线性特征