Modeling Hydrate Formation in Media with Broad Pore Size Distributions

Abstract

We show how the modification by Henry et al. of the earlier van der Waals-Plateeuw thermodynamic model can be used to interpret data for hydrates in small pores even when there is a broad distribution of pore sizes. Pore size distribution effects explain the previously reported discrepancy between calculated and measured equilibrium pressures for nominal 7.5 nm radius pores. On the basis of the model, pore volume distributions are reconstructed for the silica gel samples in which the hydrates were formed and compared with distributions constructed from desorption isotherms. The excellent agreement between the calculations and experimental data supports the interpretation of how the pore size distribution present in the silica gel samples affects the observed equilibrium pressures.

Effects of Halogen Ions on Phase Equilibrium of Methane Hydrate in Porous Media

“…In pure bulk water, the original and modified van der Waals and Platteeuw models can be used to predict hydrate phase equilibrium conditions [27][28][29][30]. When hydrate was formed in a porous medium, Henry et al [31] gave the expression of the capillary pressure effect on the chemical potential difference between the empty hydrate lattice and the pure water phases.…”

Characteristics of CO2 Hydrate Formation and Dissociation in Glass Beads and Silica Gel

“…In other words, the capillary inhibition of porous medium makes the CO 2 hydrate equilibrium pressure increased at a certain temperature. The effects were mainly caused by the additional resistance effect of capillary surface tension, which leads to lower water activity and affects hydrate equilibrium condition [28]. It is important to address the discrepancy of activity between bulk water and pore-water for understanding the hydrate equilibrium pressure increase in silica gel pores and glass beads pores reported in these study.…”

The influence of temperature, pressure, salinity and capillary force on the formation of methane hydrate

“…Some models (Clarke et al, 1999;Wilder et al, 2001;Sandler, 2001, 2003;Seo et al, 2002) have referred to this formula. However, the formula is only suitable for chemical difference of water during the formation process.…”