PhD Oral Qualifying Examination : Fundamental understanding of methane hydrate formation and dissociation in sandy porous media

Speaker Yin Zhenyuan (Supervisors: A/Prof Praveen Linga & Mr Tan Hoon Kiang (LRGTC))

Host Department of Chemical and Biomolecular Engineering

Date/Time 10 Oct - 10 Oct, 2.00PM

Venue E3-06-02 , Faculty of Engineering, National University of Singapore

Synopsis

With the current estimation of about 20,000 trillion cubic meter (TCM) of CH4 trapped in hydrate-form, methane hydrate (MH) reservoirs have been considered as a potential energy resource. MH formation and dissociation in sandy porous media and the associated fluids production are the most intriguing processes to investigate in order to recover CH4 effectively. The objective of this research project is to improve our fundamental understanding of the kinetic behavior of methane hydrate formation and dissociation by means of numerical simulation and experimental investigation.

In this presentation, I will discuss a recent numerical modelling study on the processes of MH dissociation induced by depressurization and the corresponding gas production behavior in a 1.0L laboratory-scale hydrate reactor. The 2D axi-symmetric cylindrical simulation domain accurately describes the geometry of the hydrate reactor. The underlying physics captures the MH phase equilibrium, heat and multiphase fluids flow in porous media, and the hydrate dissociation intrinsic kinetic rate.

The simulation-predicted results shows an excellent agreement with previous experimental observations. In addition, the evolution of spatial distribution of key parameters (P, T, SA, SG and SH) provides a direct visualization of the dissociation process and elucidated several important phenomena. The parametric study on (a) the composite thermal conductivity of the hydrate bearing sand (kθ), (b) the absolute permeability of the sandy media (k), and (c) the dissociation reaction rate parameter (Kd) concluded that gas production in the 1.0L reactor is predominantly controlled by kθ and Kd, whereas k does not play a significant role. Future work includes numerical modelling the process of MH formation to account for the possible issue of heterogeneous distribution of SH.

Biography