The Effect of Salt Movement and Migration on Geological Structures, Abnormal Pore Pressure, and Associated Risks in the Dezful Carbonate Basin, Southwest Iran

Salt tectonics is a globally significant geological process that profoundly influences basin evolution, hydrocarbon trapping, and drilling safety in many sedimentary provinces, such as the Gulf of Mexico, North Sea, and Zagros Basin. However, understanding how salt movement interacts with compressional tectonics to modify structural geometry and pore pressure remains a critical challenge. This study focuses on the Dezful Embayment in the Zagros Basin, where salt mobility within the Gachsaran Formation exerts a dominant control on deformation style, pore pressure regimes, and drilling risks. Using integrated seismic interpretation, well log analysis, and structural modeling, an anticline in southwestern Iran was investigated to evaluate the interplay between salt migration and regional compression. Results reveal that the Gachsaran Formation functions as a major detachment horizon, generating structural disharmony between subsalt and suprasalt packages. Subsalt units (Asmari, Pabdeh, Gurpi, and Ilam formations) exhibit pronounced fold-axis rotation and misalignment relative to the overlying Gachsaran, Mishan, and Aghajari formations, which deform more smoothly due to stress buffering by the salt layer. Localized salt thickening at anticline crests correlates with abnormal pore pressure zones, and borehole instability. Drilling data confirm mud losses, saltwater influx, and wellbore collapse within these complex intervals. Overall, the findings demonstrate that halokinetic processes intensify operational risks by forming unpredictable pressure compartments and complex fracture networks. This study not only enhances understanding of salt–tectonic interactions in the Dezful Embayment but also provides practical insights for safer and more efficient drilling strategies in salt-prone basins worldwide.