NON-EQUILIBRIUM PHASE TRANSITIONS OF HYDRATE DYNAMICS IN RESERVOIRS USING A RECTIVE TRANSPORT SIMULATOR Bjørn KVAMME ∗ , Khaled JEMAI, Mohammad Taghi VAFAEI, Khadijeh QORBANI Nashaqi Department of Physics and Technology University of Bergen N-5007 Bergen, Allegaten 55 NORWAY ABSTRACT CO 2 can be stored in aquifers in the form of CO 2 -Hydrate if suitable temperature and pressure conditions for hydrate formation exist in the reservoir. Hydrates in reservoirs are generally not able to establish equilibrium and not likely to be uniform in terms of compositions and corresponding free energies. In a flowing system Gibbs free energy is a function of temperature, pressure and distribution of masses in all co-existing phases and its gradients with respect to these variables determine directions of phase transitions. So even if CO 2 hydrate may form due to temperature and pressure conditions the hydrate may re-dissociate by contact with under saturated water. As a result the analyses of phase transitions have to be based on the combined first and second laws of thermodynamics. In this work we present a first order Taylor expansion for thermodynamic properties of hydrate outside of equilibrium and apply classical nucleation theory to estimate kinetic rates for hydrate formation kinetics, and similar rates in cases of dissociation. Classical nucleation theory is applied in this paper for illustration purposes since it makes direct use of the thermodynamic changes due to super saturation (or under saturation). To handle the non-equilibrium phase transitions related to flow in porous media we have applied and extended a reactive transport simulator, RetrasoCodeBright (RCB). RCB is capable to handle competing processes of formation and dissociation of hydrates as pseudo reactions. Hydrates can therefore be implemented into the structure of the code as pseudo minerals. Non-equilibrium thermodynamics of hydrate with appropriate kinetic models in a fashion similar to competing processes of mineral formation and dissolution is employed in each node and each time step according to the temperature and pressure. One of the important aspects of hydrate phase transitions in sediments is the volume changes associated with hydrate compared to groundwater. Formation of hydrate results in roughly 10% volume increase and corresponding development of stress on surrounding sediments. Hydrate formation, and possible sequences of formation and dissociation might lead to sediment failure. An advantage of RCB platform is the implicit geomechanical analysis. A simple model for simulation of CO 2 injection into an aquifer system connected by a fractured cap rock layer is presented to illustrate the new hydrate reservoir simulator. The associated geomechanical analysis is also presented and discussed. Keywords: gas hydrates, CO 2 storage, phase transition dynamics, geomechanics, reactive transport simulator ∗ Corresponding author: Phone: (+47)55580000 Fax (+47) 55583380 , bjorn.kvamme@ift.uib.no Proceedings of the 8th International Conference on Gas Hydrates (ICGH8-2014), Beijing, China, 28 July - 1 August, 2014