吸附水层对低渗透油藏渗流的影响机理

以玻璃微珠表面吸附水层随离心转速的变化实验为基础,得到了吸附水层厚度与驱动压力梯度的经验关系公式。利用这一结果,研究吸附水层对油藏中水渗流规律的影响。研究结果表明,在中、高渗透率油藏中,由于孔隙喉道较大,吸附水层厚度对渗流横截面的影响很小,渗流特征基本符合达西定律;而在低渗透油藏中,尤其在低流速的情况下,孔隙喉道半径与吸附水层厚度处于同一数量级,吸附水层厚度就成了影响水渗流规律的主要因素。变化的吸附水层厚度可以解释低渗透油藏中低流速下的非达西渗流特征。

Influential mechanism of adsorbed water layers on percolation in low permeability oil reservoir

The change of adsorbed water layers at the fine glass bead surface with centrifugal rotation speed was investigated by experiment. The empirical relationship for the thickness of the adsorbed water layers and driving pressure gradient was given. The effects of the adsorbed water layers on rule of water percolation were briefly investigated by using the result. In medium and high permeability oil reservoir,owing to its bigger pore/throat, the thickness of the adsorbed water layers shows little effect on the percolation lateral section, and the percolation characteristic is basically accordant widi Darcy Law. Whereas in low permeability oil reservoir, the radius of pore/throat has the same order of magnitude as the thickness of the adsorbed water layers especially in case of low flow velocity, so the thickness of the adsorbed water layers became a key factor influencing the rule of the water percolation. The changing thickness of the adsorbed water layers can be used to interpret the non-Darcy percolating character in case of low flow velocity of the low permeability oil reservoir.