The kinetics of gas hydrate decomposition was studied using an isothermal/isobaric semi-batch stirred-tank reactor. Experiments were carried out using pure ethane and methane and mixtures of the two gases. The experimental set-up and procedure used was similar to that used by Kim et al. (1987), with one major modification;​ the addition of an on-line particle size analyser. The experiments were conducted at temperatures ranging from 274.15 K to 281.15 K and at pressures between 5 bar and 61 bar. A new mathematical model was developed to determine the rate constant of decomposition. The model accounts for the distribution of hydrate particle sizes when determining the intrinsic rate constant of decomposition. The effect of the rate of stirring on the rate constant was also investigated to establish the regime where mass and heat transfer effects were negligible. Data were then obtained to determine the intrinsic rate constant. It was found that the activation energy for decomposition is 10₄ kJ/mol for ethane and 81 kJ/mol for methane. The intrinsic rate constant of decomposition is 2.56x10⁸ mol/(m²•Pa•s) for ethane and 3.6x10⁴ mol/(m²•Pa•s) for methane.

The mathematical model was extended to describe the decomposition of hydrates of mixed gases. Experiments, using CH₄/C2H6 mixtures ranging from 25% CH₄ to 75% CH₄ were used to verify the model. For gas mixtures that formed structure hydrates, no new parameters were needed and the model was able to predict the intrinsic rate of decomposition. For gas mixtures that formed structure II hydrates, it was assumed that the intrinsic rate constant of ethane decomposition is the same as in structure I, and an intrinsic rate constant for structure II methane hydrate decomposition was obtained. The intrinsic rate constant and activation energy for methane hydrate decomposition in structure II are 8.06x10₃ mol/(m² •Pas) and 77.33 kJ/mol, respectively.

An implicit optimisation scheme was developed to find the Kihara potential parameters for methane and ethane. Phase equilibria calculations, using the new Kihara potential parameters, predict a transition from structure I to structure II in hydrates formed from methane/ethane mixtures.

A predictive model has been developed to determine the incipient hydrate formation conditions in porous media. Also, a criterion for the model's applicability was developed. The only additional information that is needed to determine the incipient hydrate formation conditions is the pore radius, surface energy per unit area and wetting angle. It was found that the model performed well in predicting the experimental data that were available in the open literature.