A novel Kozeny-Carman-based permeability model for hydrate-bearing sediments

Abstract

Permeability governs fluid flow in hydrate-bearing sediments (HBSs) and directly affects gas production efficiency. Reported models relating permeability to hydrate saturation are usually embedded with parameters whose physical meaning is not clear or difficult to determine. It limits their applicability in numerical simulations and practices. In this study, we proposed an innovative permeability-hydrate saturation model based on the Poiseuille's law and the Kozeny-Carman equation. The proposed model has single one parameter, the void ratio, which is physically sound and easily determined. This model was verified by experimental data and other existing models, and proved to have a satisfying performance in predicting the permeability of HBSs. The prediction results reached an asymptote in the range of kmeas/2≤kpredict≤2kmeas. For a given hydrate saturation, the normalized permeability decreases nonlinearly as void ratio increases. The sensitivity of permeability of HBS to changes in void ratio is higher at high hydrate saturation. Overall, the proposed model can capture the main feature of permeability with hydrate saturation for coarse-grained HBS. The remaining uncertainty in this model underscores the important role of hydrate distribution, heterogeneity, anisotropy, and pore geometry of HBSs that are not characterized by the hydrate saturation and the void ratio.