Temperature-Dependent Mechanical Properties of Geo-Materials: Insights from Molecular Dynamics Simulations

The mechanical properties of geo-materials play a critical role in hydrocarbon extraction and geothermal energy development. The thermal response of many geo-materials’ elastic properties remains unclear. We conduct molecular dynamics (MD) simulations to investigate the temperature dependency of mechanical properties of geo-materials, including kerogen, quartz, illite, and calcite. Young’s modulus, Poisson’s ratio, shear modulus, and critical stress are systematically evaluated at different temperatures and crystallographic orientations. The simulations indicate that increasing temperature leads to a pronounced reduction (over 50%) in Young’s and shear moduli for kerogen. Illite exhibits a clear decline (30%) in Young’s modulus due to its layered structure, which contributes to anisotropic deformation. Young’s and shear moduli of quartz have a mild decrease with temperature. Calcite displays intermediate declines of about 10% in Young’s modulus in the X and Z directions and 6% decrease in the Y direction. The shear modulus of calcite decreases by 7% in the X and Z directions, and by 15% decrease in the Y direction. Poisson’s ratio remains largely invariant for the materials we have examined, indicating a consistent volumetric deformation response despite temperature changes. All geo-materials in this study exhibit a decreasing trend in critical stress with increasing temperature. These findings provide key insights into the thermo-mechanical stability of geo-materials, particularly in high-temperature environments. Our work sets the basis for the investigation of the cross effect neglected in the classical relationship between stress and strain in solid mechanics.