Non-Fickian Diffusion Affects the Relation between the Salinity and Hydrate Capacity Profiles in Marine Sediments

TL;DR

This paper demonstrates that non-Fickian diffusion processes, such as thermal diffusion and gravitational segregation, significantly influence the relationship between salinity profiles and hydrate capacity in marine sediments, challenging previous Fickian-based models.

Contribution

It introduces amended relations accounting for non-Fickian diffusion effects and applies them to real field data, improving the understanding of hydrate-salinity interactions.

Findings

Non-Fickian diffusion significantly affects salinity-hydrate relations.

Amended models better fit field measurements.

Thermal diffusion and gravitational segregation are crucial factors.

Abstract

On-site measurements of water salinity (which can be directly evaluated from the electrical conductivity) in deep-sea sediments is technically the primary source of indirect information on the capacity of the marine deposits of methane hydrates. We show the relation between the salinity (chlorinity) profile and the hydrate volume in pores to be significantly affected by non-Fickian contributions to the diffusion flux---the thermal diffusion and the gravitational segregation---which have been previously ignored in the literature on the subject and the analysis of surveys data. We provide amended relations and utilize them for an analysis of field measurements for a real hydrate deposit.