Hydrate-bearing sediments are relevant to the organic carbon cycle, seafloor instability, and as a potential energy resource. Sediment characteristics affect hydrate formation, gas migration and recovery strategies. We combine the physics of granular materials with robust compaction models to estimate effective stress and capillary pressure in order to anticipate the pore habit of methane hydrates as a function of the sediment characteristics and depth. Then, we compare these results to an extensive database of worldwide hydrate accumulations compiled from published studies. Results highlight the critical role of fines on sediments mechanical and flow properties, hydrate pore habit and potential production strategies. The vast majority of hydrate accumulations (92% of the sites) are found in fines-controlled sediments at a vertical effective stress between σ′z = 400 kPa and 4 MPa, where grain-displacive hydrate pore habit prevails in the form of segregated lenses and nodules. While permeation-based gas recovery by depressurization is favored in clean-coarse sediments, gas recovery from fines-controlled sediments could benefit from enhanced transmissivity along gas-driven fractures created by thermal stimulation.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Support for this research was provided by the KAUST Endowment at King Abdullah University of Science and Technology. This study was conducted by the authors at KAUST. Gabrielle E. Abelskamp edited the manuscript.