边界层流体对低渗透油藏渗流特性的影响

以去离子水在半径为2.5μm和1.0μm微圆管中流动的实验结果为基础,拟合得到去离子水在微圆管中的有效流动半径公式和基于边界层流体的不同半径毛管束视渗透率公式,并比较了视渗透率与理论渗透率之间的关系.研究结果表明:随着管径尺寸的减小,边界层流体对渗流特性的影响变大;边界层流体厚度是压力梯度的函数,并随压力梯度的增加而按指数规律递减;毛管束视渗透率随压力梯度增大而增大,并最终趋近于理论值.边界层流体是导致低渗透油藏非线性渗流特性的主要因素之一.

Influence of boundary-layer fluid on the seepage characteristic of low- permeability reservoir

Based on the experimental results of the deionized water flowing in the micro-tubes of 2.5 μm and 1 μm radii,the formula of the effective radius of the deionized water flowing in the micro-tubes and the apparent permeability formulas of different capillary radii (2.5 μm and 1 μm) are obtained by fitting,the apparent permeability curves are compared with the theoretical permeability values calculated according to factual micro-tube radii (2.5 μm and 1 μm).It is shown that,the influence of the boundary fluid on the seepage characteristic of the low-permeability reservoir increases with the decrease of the micro-tube radius;the thickness of the boundary layer is the function of pressure gradient,and it exponentially declines with the increase of the pressure gradient;the apparent permeability of capillary bundle increases with the pressure gradient increasing,it finally tends to its theoretical value.The boundary-layer fluid is one of the main factors causing the nonlinear seepage law of low-permeability reservoir.