A Simple Recipe for Estimating the Change in Elastic Properties of Porous Rocks with Solid Infill

Abstract

Summary Quantifying the impact of pore fill on elastic properties of porous rocks is of ongoing interets in geophysics. Previous experiements show that the change of the solid pore fill can produce larger change in effective elastic properties of porous rocks than predicted by exisiting models. This effect may result from the heterogeneous stress distribution within the pore space due to the existence of stiff and soft pores. In this paper, we present a new solid substitution scheme based on the concept of a triple pore structure, including stiff, compliant and so-called intermediate pores. Comparison of the model predictions against ultrasonic measurements on an Octodecane-saturated sandstone reveal a reasonable fit for the bulk modulus but a small discrepancy for the shear modulus, performing more accurately than previous models. This discrepancy might be resulted from the instability of ultrasonic measurements at relative small confining pressure.