Abstract

Hydrocarbon exploration in the Tripura Fold Thrust Belt is challenging due to its complex deformation structures and dynamic tectonic regime. While seismic data provides valuable insights, resolution constraints may limit the precise characterization of certain subsurface features of structurally complex zones, leading to drilling complications such as wellbore breakouts, stuck pipe incidents, and tool heldups. To address these issues, high-resolution image logs (FMI, LWD) & Stress Anisotropy from DSI logs are used to identify structural discontinuities, fault planes, and bedding orientations, aiding in improved structural interpretation at the borehole scale. In-situ stress magnitudes and orientations are critical for geomechanical analysis, influencing wellbore stability, drilling risks, and reservoir performance. This paper demonstrates how an integrated well-log model can be used to evaluate in-situ stress conditions in the Upper, Middle, and Lower Bhuban formations (key hydrocarbonbearing intervals) in the Tripura Fold Thrust Belt, located in the North-East part of India, based on data from three key wells with depths ranging from 2500m to 4200m+. Regional stress regime analysis shows that the dominant stress condition from the Tipam to the Middle Bhuban formation is a normal faulting regime (Sᵥ > SHmax > Shmin), with a vertical maximum principal stress (S₁). However, in the central part of the Middle Bhuban Formation, a notable rotation of the stress field is observed in those study wells, transitioning from a normal faulting regime to strike-slip faulting (SHmax>SV>Shmin) to a reverse faulting regime (SHmax>Shmin>SV), where S₁ becomes horizontal. This stress rotation suggests localized tectonic reactivation or structural complexity, driven by regional compressional forces in addition to lithological heterogeneities. The developed stress model shows a consistent correlation with the World Stress Map 2025, indicating reliable alignment with regional stress orientations