Research on Conductivity Mechanism and Saturation Model Development of Fractured‐Vuggy Carbonate Reservoirs

Carbonate rocks exhibit complex pore structures composed of matrix pores, vugs, and fractures, which result in non‐Archie behavior in resistivity measurements and present significant challenges for reservoir evaluation. The rapid advancement of digital rock physics offers new approaches to address the complexities in saturation assessment of carbonate reservoirs. In this study, digital rock models of matrix pores, vugs, and fractures were constructed using computed tomography scans and stochastic functions. Finite element simulations were performed to visualize current flow within the pore structures and to quantify the respective contributions of conductive structures to overall resistivity. The results show that matrix pores generally conform to Archie’s law, fractures act as efficient parallel channels, and vugs behave as series‐connected elements with surrounding pores. Based on these findings, a new conductivity and saturation model for fractured‐vuggy carbonates was established by representing the conductive structures with a mixed series–parallel configuration. Compared to the conventional Archie equation, the new model improved saturation prediction accuracy by 8.50% and demonstrated strong applicability in field applications. This study provides direct visualization of the current flow and quantitative evaluation of conductive contributions from distinct pore structures and establishes relationships between saturation and petrophysical parameters, offering valuable guidance for the exploration of carbonate reservoirs.