A two-phase, three-dimensional numerical model was developed to simulate the dissociation and formation of hydrates (composed of water and any stable mixture of methane, ethane, or propane) when a conventional gas reservoir is in contact with hydrates. This model was developed in order to address fundamental questions on the feasibility of dissociating hydrates using the depressurization that accompanies production of a conventional gas reservoir. The major implications of the simulation are quite favorable, suggesting that massive hydrate can be dissociated at appreciable rates without an external source of heat energy. These results support the continued evaluation of gas hydrates as a potential resource and indicate a need for model validation. Because of scant documentation on the production of gas from hydrates in the literature, this simulator could not be validated using conventional methods. An alternative means of testing was required. A three part procedure, based on the availability of data, was devised to test different components of the simulator. The testing consisted of a qualitative examination of the total system and a quantitative testing of the two portions of the model (i.e., the production of a conventional gas reservoir and the dissociation of massive hydrate). Existing resources were used in the first two parts of this testing. An examination of the dissociation of massive hydrate was the third step toward model validation. Based on the encouraging findings of the first two parts of testing, a laboratory simulation of the behavior of a gas hydrate reservoir during pressure reduction was undertaken. In the DOE/METC Gas Hydrates Laboratory, an experiment was designed to produce gas from depressurization and dissociation of synthesized methane hydrate. The flow rate was allowed to vary. The data from this experiment have been used to test and refine the simulator. 5 refs., 7 figs.