Pore Structure Effects on Elastic Wave Propagation in Carbonate Rocks

Abstract The study of the physical properties of reservoir rocks is necessary for the development of enhanced oil recovery methods in the oil industry. In the case of prolific carbonate reservoirs, rock characterization remains challenging due to their complex and heterogeneous micro- and macrostructures, which contain pores of various types and sizes. Wellbore logs provide information that can be correlated with near-well porosity and the presence of discontinuities. In core samples, the propagation of elastic waves provides information about the structure of the pore system. Moreover, relationships between pore structure and rock properties can be investigated experimentally. However, this is limited by the equipment capabilities and the availability of reservoir plugs for testing. On the other hand, numerical models enable an understanding of the main factors influencing rock properties at a reduced cost and research time. This work focuses on numerical modeling of wave propagation in carbonate rocks using the finite element method, introducing a flexible approach for representing heterogeneous and complex pore systems. Since the models of pore structure are user-defined, they are useful for parametric studies and for developing correlations that are difficult to obtain experimentally. The rock properties obtained through numerical simulation were compared with those predicted by the Xu and Payne rock physics model, showing excellent agreement. Additionally, the numerical predictions were compared with experimental measurements from a real carbonate sample, demonstrating the approach's applicability to realistic rock systems. The accuracy of the wave propagation simulation was investigated for a range of modeling parameters, highlighting the robustness of the method in capturing the influence of pore-scale features on elastic responses. Overall, the contributions of our work demonstrate that wave propagation using finite element modeling offers a powerful tool for evaluating the material properties of heterogeneous porous media and supporting the development of advanced characterization models.