Alaska North Slope HYDRATE 02 Geo Data Well Multicomponent Inversion and NMR Log and Core Analysis of the B1 Sand Gas Hydrate Reservoir

Abstract The Collaborative Gas Hydrate R&D Project in Alaska, a joint initiative by the Japan Organization for Metals and Energy Security, the U.S. Department of Energy, and the U.S. Geological Survey, aims to advance understanding of gas hydrate reservoir systems and their production potential. As part of this effort, the HYDRATE 02 Geo Data Well (GDW) was drilled at the Kuparuk State 7-11-12 site to support a long-duration production test and provide high-resolution petrophysical data for reservoir characterization. This study presents an integrated log and core analysis of the B1 sand (unit B) hydrate-bearing reservoir, which was the focus of a 2023–2024 depressurization production test. Using a multicomponent inversion modeling program, we derived continuous profiles of porosity, gas hydrate saturation, and intrinsic and effective permeabilities across the B1 sand and adjacent shale intervals. The workflow uses well log and laboratory core data to initialize the reservoir parameters and construct a multimineral reservoir model, then executes the multicomponent inversion solver to generate best-estimated profiles for each key reservoir parameter. As a final step, data integration issues are investigated to assess the reliability of the inversion results. The modeling confirmed substantial heterogeneity in reservoir properties, with log- and core-derived porosities ranging from 10% to 40% and hydrate saturations increasing from near zero to roughly 90% in localized zones within the B1 sand reservoir section. The core-based and nuclear magnetic resonance-derived estimates of effective permeability varied widely with depth across the B1 sand reservoir section, influenced by lithological variability and hydrate distribution. Comparisons between core measurements and log data confirmed the reliability of the inversion results for porosity and intrinsic permeability; however, inconsistencies remained in the analyses of gas hydrate saturations and in the effective permeability estimates within the B1 sand reservoir section of the project-established GDW. Integrating petrophysical results from this study into future reservoir simulations of the production test results, as completed within the cooperative gas hydrate research project in Alaska, may help resolve these inconsistencies in the analysis of the B1 sand reservoir properties.