(3hf) Laboratory and Numerical Studies of Fluid Production from Methane Hydrate Deposits in Geologic Media

Research Interests: Gas hydrate-bearing sediment; Fluid flow through porous media; heat transfer; hydrate reaction kinetics; numerical modelling; optimization method

Teaching Interests: Heat and mass transfer; Fluid Dynamics; Numerical methods in Chemical Engineering; Matlab Programming

Natural gas has been considered as the best transition fuel into the future carbon-constraint world. The ever-increasing demand for natural gas has prompted expanding research and development activities worldwide for exploiting natural gas hydrates as a future source of energy. Gas hydrates are solid crystalline compounds in which gas molecules are lodged within the lattices of water molecules. Natural gas hydrate deposits involve mainly CH₄ and occur in two distinctly different geologic settings: in the permafrost and in the ocean sediments near the continental margin. The large resource volume (around 3,000 trillion cubic meters of CH₄) and the high energy storage capacity (170 vCH₄/ vMH) of naturally-occurring gas hydrate necessitates the studies from both laboratory, field, and numerical simulations to address the knowledge gaps that are important to the prediction of gas production from hydrate deposits.

A novel experimental apparatus consisting of a high-pressure reactor and a fluid production unit was set up with the objectives of (a) synthesizing hydrate-bearing sediments that are representative of naturally occurring hydrate-bearing samples; and (b) investigating the hydrate dissociation and the associated fluid production behavior under various production strategies, i.e. depressurization, thermal stimulation, etc. Besides, a state-of-the-art numerical model coupling the effects of thermo-hydro-chemical was developed to simulate the kinetic behavior of gas hydrate in the sandy medium. Through implementing a history-matching algorithm (particle swarm optimization), an excellent agreement was achieved between the numerical results and the experimental observation of the evolution of pressure and temperature.

A series of important parameters were calibrated including the thermophysical properties of hydrate-bearing sediments and the kinetic rate parameters of hydrate reaction. In addition, our numerical results successfully derived the spatial heterogeneity of the hydrate-bearing sample, which can be validated by the X-ray CT and MRI images. Moreover, the key physical process controlling the hydrate formation and dissociation process was identified with the potential application of designing optimal field production strategy. The high-quality experimental data and the history-matching workflow developed in this study is highly transferable to field-scale and pore-scale study in the near future.