Water and gas flows in hydrate-bearing sediments

Gas hydrate plays a critical role in new energy resource, global carbon budget, and submarine instability. Enhanced understanding on how gas hydrates influencing these issues largely depends on in-depth understanding of multiphase flow in hydrate-bearing sediments particularly during hydrate formation and dissociation processes. However, appropriate selection of flow parameter values for hydrate simulators is not available. Published parameter values show large discrepancies among hydrate simulators as well as between numerical and experimental studies. Based on experimental results of single-phase flow in hydrate-bearing sediments, recommended flow parameters for hydrate-bearing sediments are λ = 1, S_rw = 0.1, and S_rg = 0.55 for the Brooks and Corey model and m = 0.7, S_rw = 0.1, and S_rg = 0.5 for the van Genuchten model. In general, current hydrate simulators underestimate residual gas saturation S_rg, which will lead to overestimated rate of gas production from hydrate deposits. These results are also relevant to multiphase flow in porous media undergoing diagenesis, bio-clogging, or mineral precipitation and dissolution.