SUBSURFACE GEOLOGICAL UNDERSTANDING WITH ULTRA-DEEP AZIMUTHAL RESISTIVITY (UDAR)

Over the past decade, Ultra-Deep Azimuthal Resistivity (UDAR) technology has transformed geosteering operations by delivering reservoir mapping at depths of tens of meters. This capability has redefined workflows, improved well data integration, and raised expectations across the oil and gas industry. UDAR is now essential for understanding complex geological scenarios, enhancing depositional system interpretation, and updating 3D geological models. Both real-time and post-drill applications deliver significant value for comprehensive reservoir assessment. Integrating UDAR with geological and geophysical data provides a view of subsurface architecture, improving predictions of reservoir quality and areal distribution. Post-drill 3D inversion analysis further strengthens geological models, enhancing predictability of reservoir architecture and connectivity—critical for planning future wells and optimizing development strategies. Finally, in complex settings, UDAR planning asks for synthetic modeling to validate response capabilities and limitations. This paper presents three case studies demonstrating UDAR’s geological applications: • Deltaic Environment: Real-time UDAR mapping of sand distribution and clinoform progradation improved depositional understanding and reservoir prediction. • Lacustrine Turbiditic Channel Complex: UDAR guided well placement in the “sweet spot” and validated the sedimentological model in areas with limited control points; post-drill inversion redefined depositional system conceptual model of the field. • Carbonate Platform: UDAR logging to identify fracture patterns driving water influx, from advanced synthetic model to simulate tool response and inversions, to logging and interpretation coupled with deep sonic imaging.