Shaley sandstone is heterogeneous at a seismic scale. Gassmann＇s equation is suited for fluid substitution in a homogeneous medium. To study the difference between shaley sandstone effective elastic moduli calculated...Shaley sandstone is heterogeneous at a seismic scale. Gassmann＇s equation is suited for fluid substitution in a homogeneous medium. To study the difference between shaley sandstone effective elastic moduli calculated by mean porosity as a homogeneous medium, and those calculated directly from the sub-volumes of the volume as a heterogeneous medium, computational experiments are conducted on Han＇s shaley sand model, the soft-sand model, the stiff-sand model, and their combination under the assumption that the shaley sandstone volume is made up of separate homogenous sub-volumes with independent porosity and clay content. Fluid substitutions are conducted by Gassmann＇s equation on rock volume and sub-volumes respectively. The computational data show that at seismic scale, there are minor differences between fluid substitution on rock volume and that on sub-volumes using Gassmann＇s equation. But fluid substitution on sub-volumes can take consideration of the effects of low porosity and low permeability sub-volumes, which can get more reasonable data, especially for low porosity reservoirs.展开更多
基金supported by National Natural Science Function of China (No. 41074098)National 973 Basic Research Program (No. 2007CB209606)
文摘Shaley sandstone is heterogeneous at a seismic scale. Gassmann＇s equation is suited for fluid substitution in a homogeneous medium. To study the difference between shaley sandstone effective elastic moduli calculated by mean porosity as a homogeneous medium, and those calculated directly from the sub-volumes of the volume as a heterogeneous medium, computational experiments are conducted on Han＇s shaley sand model, the soft-sand model, the stiff-sand model, and their combination under the assumption that the shaley sandstone volume is made up of separate homogenous sub-volumes with independent porosity and clay content. Fluid substitutions are conducted by Gassmann＇s equation on rock volume and sub-volumes respectively. The computational data show that at seismic scale, there are minor differences between fluid substitution on rock volume and that on sub-volumes using Gassmann＇s equation. But fluid substitution on sub-volumes can take consideration of the effects of low porosity and low permeability sub-volumes, which can get more reasonable data, especially for low porosity reservoirs.
