Investigation of the methane hydrate surface area during depressurization-induced dissociation in hydrate-bearing porous media

Abstract

Listen

Translate article

The surface area of hydrate dissociation in porous media has a dependence on the morphology of hydrate (blue) in sediments (brown): (a) grain-coating type, (b) pore-filling type and (c) cementing or bridging type. The surface area of hydrate during dissociation in porous media is essentially important for the kinetics of hydrate dissociation. In this study, the methane hydrate surface area was investigated by the comparison results of experiments and numerical simulations during hydrate decomposition in porous media. The experiments of methane hydrate depressurization-induced dissociation were performed in a 1D high pressure cell filled with glass beads, an improved and valid 1D core-scale numerical model was developed to simulate gas production. Two conceptual models for hydrate dissociation surface area were proposed based on the morphology of hydrate in porous media, which formed the functional form of the hydrate dissociation surface area with porosity, hydrate saturation and the average radius of sand sediment particles. With the establishment of numerical model for depressurization-induced hydrate dissociation in porous media, the cumulative gas productions were modeling and compared with the experimental data at the different hydrate saturations. The results indicated that the proposed prediction equations are valid for the hydrate dissociation surface area, and the grain-coating surface area model performs well at lower hydrate saturation for hydrate dissociation simulation, whereas at higher hydrate saturation, the hydrate dissociation simulation from the pore-filling surface area model is more reasonable. Finally, the sensitivity analysis showed that the hydrate dissociation surface area has a significant impact on the cumulative gas production.