Evaluating method for heterogeneity of multiple porosity sandstone

Heterogeneity fractal description of multiple porosity sandstone was established in this paper. Mercury injection experiment was conducted over 25 core samples, which could help to calculate the rock fractal factor and quantitative describe the heterogeneity of multiple porosity sandstone. Compared with coefficient of variation, the fractal factor had better interrelationship with rock permeability, porosity, threshold pressure, minimum wet saturation, and mean pore size. There was a linear relation between fractal factor and minimum wet saturation, which was suitable for both absolute homogeneous and heterogeneous rock. As the filling of mercury in the knaggy pore space made the pore flow channel more uniform, the fractal factor in the mercury ejection process is smaller than that of mercury injection process.