Petrophysical Joint Inversion of Electrical and Seismic Tomographic Data Including Shear Waves

Abstract

Petrophysical characterization in near-surface environments remains challenging due to the high heterogeneity, sharp contrasts in fluid content, and complex hydrogeological structures. This work introduces a novel petrophysical joint inversion (PJI) framework that integrates SH-wave seismic refraction tomography (SRT) with electrical resistivity tomography (ERT) and, optionally, time-domain induced polarization (IP) data, replacing the conventional approach based on P-wave velocity and Wyllie’s equation with the Castagna relation for S-wave velocity. By reducing sensitivity to pore-fluid effects, the framework preserves robust saturation estimates while significantly improving porosity reconstruction in both its spatial distribution and absolute values. A synthetic example and two field case studies with contrasting hydrogeological layering demonstrate the capability of our method to provide physically consistent, fully quantitative, and high-resolution characterization of complex near-surface scenarios, extending the scope of PJI beyond classical applications. Additionally, in settings where the IP contribution is limited, the strong sensitivity of S-waves to site lithology allows for a comprehensive characterization without including IP data, which are required in traditional approaches to fully characterize complex scenarios, thereby reducing survey costs and overall complexity.