储层孔隙结构的分形几何描述

储层岩石在0.2～50μm的尺度范围内具有良好的分形特征。根据分形几何原理,可推导出储层岩石孔隙分布、毛管压力、J函数和相对渗透率曲线以及岩石孔隙表面接触角的分形几何公式。前人指出,岩性相近岩石的J函数曲线相近,而推导出的J函数曲线分形几何公式表明,相近的实质是指孔隙的分维数和毛管弯曲度。根据毛管压力曲线和J函数曲线的分形几何公式计算孔隙的分维数,该法比扫描电镜法简便易行,便于广泛应用。根据毛管压力曲线,计算的孔隙分形参数,可用以了解储层水敏损害及酸化作用的程度。

FRACTAL GEOMETRY DESCRIPTION OF RESERVOIR PORE STRUCTURE

That the grain sizes are between 0.2～50 μm have fractal property.Acoording to the principle of the fractal geometry,the expressions of pore size distribution curve,capillary pressure curve,J function curve,relative permeability curve and equilibrium contact angle of the reservoir rocks could be derived.Leverett.et.al show that the reservoir rocks with the similar properties have unique J fanction curve.The expression derived for J function curve indicates that the reservoir rocks of this kind have the similar fractal dimension and pore tortuosity.The expression of the capillary pressure and J function curve could be used to calculate the fractal dimension of the reservoir rock pore structure and its change after the water sensitivity or acidizing.This method is simpler than scanning electron microscopy.