Pore-Space Microstructure and Clay Content Effect on the Elastic Properties of Sandstones

Abstract

The elastic moduli of shaly sandstones and the effect of pore aspect ratios and clay content on the elastic properties of shaly sandstones are calculated using an isotropic dual porosity model. It is shown that the elastic moduli and velocities of shaly sandstones are affected by the clay content, pore aspect ratios, and the fluid. The bulk and shear moduli increase with an increase in the aspect ratios of sandstones related to pores whether the sandstones are saturated by water or dry. The P-wave and S-wave velocities of water-saturated shaly sandstones both increase with the increase of the pore aspect ratios. The bulk and shear moduli decrease with an increase in clay content. The relationships between the elastic moduli of the rocks and the clay content are linear, which is in agreement with the laboratory measurements by Han. The bulk modulus of shaly sandstone is sensitive to fluid change when the pore aspect ratio is small.