A finite-element study of the influence of grain contacts on the elastic properties of unconsolidated sandstones

The grain-grain interaction in a sandstone rock can result in an overall elastic response of the system, which is primarily determined by the grain contact stiffness and the grain contact volume fraction. In this paper, we propose a numerical algorithm to vary the contact volume fraction based on 3D Digital Rock images from x-ray microtomography (μ-CT). We then calculate the effective elastic moduli of the model systems for various contact parameters using the Finite Element Method. Using an extensive fitting procedure, we find a set of empirical equations that model the effective bulk and shear moduli of the system. We show that our proposed set of empirical equations can accurately predict the mechanical properties of unconsolidated sandstones rocks.