A method to predict hydrate phase behavior in laboratory-prepared and natur
al porous media is presented. This model extends both the van der Waals and
Platteeuw (vdWP) approach and our fugacity-based approach to porous media
by accounting for the effects of both surface energy and pore size distribu
tion. Our fugacity approach quantitatively predicts the equilibrium pressur
e-temperature relation for hydrates in laboratory porous media above the no
rmal freezing point of water without any empirical corrections to the surfa
ce contact parameters, as have previously been required with the vdWP model
. A pore size distribution model that depends on the soil type and pressure
is developed and then used to predict methane hydrate formation in natural
porous environments. The maximum depth of ocean hydrates using our fugacit
y-based model with the pore size correction is calculated for seven drillin
g sites. Our predictions for the hydrate depth have an average deviation of
4.9% compared to the experimental data, which is less than the 11.6% AAD u
sing the common approach of assuming that the phase behavior in the pores i
s identical to that in the bulk.