Natural gas could be recovered from hydrate deposits by either of two basic methods (1) thermal stimulation in which an external source of energy is provided and (2) lowering of the equilibrium pressure (depressurization) in which the energy of the hydrate-containing and the surrounding media is utilized. In this work, we have measured and modeled mathematically the dissociation of hydrates in consolidated and unconsolidated porous media. Hydrates were formed in laboratory samples of Ottawa sand and Berea sandstone using miscible and non-miscible hydrate formers. A state-of-the-art, computer-controlled transient hot wire needle probe apparatus was developed for the measurements of thermal conductivity of pure hydrates and hydrate-containing porous media. We have measured the thermal conductivity of hydrate-containing Ottawa sand and Berea sandstone samples in order to determine the physical properties necessary for the mathematical models. We have also measured the electric resistivity of methane hydrate-containing Berea sandstone in order to verify the formation of the hydrate and to track the dissociation front during hydrate depressurization. Two mathematical models were developed for the process of hydrate dissociation in porous media using the two recovery schemes thermal stimulation and depressurization. 10 refs., 9 figs., 1 tab.