Advanced Logging Techniques for Characterizing a Complex Turbidite Reservoir in the Norwegian Sea

In the Norwegian Sea, a deep-marine turbidite reservoir containing gas condensate was discovered within a four-way structural closure. In the Adriana prospect, two wells were drilled—one for discovery and one for appraisal. Early petrophysical evaluation was challenging due to the absence of core data and complete reliance on well-log interpretation. As this was a new discovery in a relatively unexplored area, limited reservoir information made it difficult to validate log-derived parameters or characterize heterogeneity, creating uncertainty in static and dynamic modeling and volumetric estimation. These limitations were later addressed through an extensive core-acquisition program, essential for refining reservoir characterization and improving the understanding of petrophysical properties (special core analysis (SCAL) ongoing). To evaluate lateral connectivity, reservoir quality, and permeability, a comprehensive data-acquisition campaign was executed, including triaxial resistivity, array sonic, borehole imaging, nuclear magnetic resonance (NMR), dielectric logging, neutron-induced spectroscopy, and high-resolution density and neutron measurements. A multiphysics inversion method was developed to enhance the interpretation of multifrequency dielectric dispersion and geochemical spectroscopy. Standalone dielectric measurements struggle to estimate salinity accurately in high-salinity formation waters, but this limitation was mitigated by incorporating chlorine and formation-sigma responses through the multiphysics approach. Combining NMR porosity with total organic carbon (TOC) helped better constrain hydrocarbon properties. The method integrates the sensitivities and uncertainties of each measurement to provide improved solutions for porosity, Sw, formation-water salinity, Archie's coefficients (m and n), and hydrocarbon properties. By coupling these results with spectroscopy-driven mineralogy and porosity evaluations, the multiphysics inversion (MPI) delivers precise petrophysical parameters with associated uncertainties. Core data from the appraisal well, combined with advanced logs, enabled reliable Sw determination through integration of triaxial resistivity, density, neutron, dielectric, and NMR data. This approach refined porosity, water salinity, Archie's coefficients, and hydrocarbon density, improving Sw accuracy and distinguishing hydrocarbon-bearing from water-saturated intervals. The comprehensive logging program reduced uncertainty in Sw and permeability evaluation, strengthening confidence in reservoir quality and lateral connectivity. The advanced interpretation enhanced overall petrophysical understanding and provided a robust foundation for appraisal and future field development.