Multi-Scale Petrophysical Modeling and Characterization of Heterogeneous Carbonate Reservoirs Based on Facies-Constrained Seismic Waveform Integration

The accurate petrophysical characterization of unconventional reservoirs, particularly deeply buried fractured–vuggy carbonate systems, remains challenging due to extreme heterogeneity, ultra-low permeability, and strong scale dependency of reservoir properties. Conventional formation evaluation workflows often fail to reconcile geological observations at the core scale with log- and seismic-scale petrophysical interpretations in a physically consistent manner.In this study, we propose an integrated geological–geophysical petrophysical characterization workflow that links core and thin-section observations, electrofacies classification, and seismic data through an electrofacies-constrained seismic waveform-guided inversion framework. Rock types identified from core and petrographic analyses are translated into electrofacies at the log scale to represent pore-structure variability. Electrofacies are incorporated as conditional constraints in a Bayesian seismic waveform-guided porosity inversion framework. Electrofacies-dependent porosity priors derived from well-log statistics restrict the admissible pore-structure space, while seismic waveform similarity controls the lateral propagation of high-frequency porosity features, implicitly embedding seismic facies within the inversion.The resulting porosity volume exhibits enhanced vertical resolution and improved lateral continuity, allowing thin-layer and non-layered heterogeneities to be resolved beyond the limitations of conventional impedance-based inversion. Recognizing that permeability is not directly observable at the seismic scale, permeability is subsequently derived from the inverted porosity volume under electrofacies control, ensuring that pore connectivity and flow characteristics are consistently represented at the appropriate scale.This workflow establishes a causally consistent and scalable solution for advanced petrophysical characterization and formation evaluation of heterogeneous unconventional reservoirs. By integrating geological constraints with seismic waveform-driven inversion, the proposed method effectively bridges core-, log-, and seismic-scale information and demonstrates strong potential for application in complex carbonate systems as well as other unconventional plays.