Application of digital rock characterization and elastic simulation to rock physics modelling in shale reservoirs

The complex pore structure and diverse mineralogy of shale impart specific elastic properties to the saturated rock, characterized by notable heterogeneity and pronounced frequency dependence. These intricate elastic behaviors of shale present challenges to conventional rock physics-based quantitative interpretation of reservoirs. This study employed an integrated approach combining cross-band rock physics measurement, digital rock imaging, and numerical simulations. The research focused on the inter-salt shale oil reservoir of the Qianjiang Formation (Jianghan Basin, China), to investigate anisotropy and dispersion phenomena. Initially, various scanning imaging techniques were applied to analyze the microstructural features of natural rocks, leading to the creation of a set of virtual cores by numerical reconstruction. Subsequently, static and dynamic elastic simulations were performed to monitor wave-induced fluid flow, revealing the influence of microstructure, mineral composition, and physical properties on dispersion and attenuation. Finally, based on the simulations, the applicability of various rock physical theories was evaluated, and we proposed a set of anisotropic dispersion theory models consistent with the geological characteristics and elastic response rules of shale oil reservoirs. The results compare satisfactorily with ultrasonic velocity, well-logging data, and stress-strain measurements. This approach underscores the value of integrative research, combining experimental data, theoretical models, and digital rock physics techniques, offering new insights into the refinement of quantitative reservoir characterization in complex geological environments.