Oral Defense Examination : Methane hydrate formation and dissociation in porous media

Speaker Chong Zheng Rong (Supervisor: A/Prof Praveen Linga)

Host Department of Chemical and Biomolecular Engineering

Date/Time 20 Nov - 20 Nov, 10.00AM

Venue E5-02-32 , Faculty of Engineering, National University of Singapore

Synopsis

Natural gas hydrate is a potential source of energy for the future. In nature, around 20,000 TCM of natural gas is stored in hydrate reservoirs in permafrost and continental margins. However, the fundamental understandings on how hydrates form and dissociate in porous media and how gas and water are produced from hydrate bearing sediment (HBS) remain unclear. In this thesis, the formation and dissociation kinetics of methane hydrates under various conditions similar to the natural conditions of hydrate reservoir are experimentally investigated. For the first part of the thesis, the effects of various salts (KCl, MgCl2 and NaCl) and sand sizes (between 0.063 – 3.0 mm) on methane hydrate formation and dissociation were experimentally investigated in an excess gas environment. These studies reported significant effect of salts and sand size on the kinetics of hydrate reactions and the distribution of hydrates respectively. For the second part of the thesis, a new experimental facility capable of creating water saturated HBS to mimic aqueous-rich marine conditions and acquiring gas/water production simultaneously was established. A fine-tuned experimental procedure was developed to produce consistent HBSs (40% SH, 50% SA, 10% SG), enabling the comparison of gas/water production behavior under both thermal stimulation (278.7 K – 285.2 K) and depressurization (2.1 – 5.0 MPa) approaches. In both studies, clear interdependence between gas and water production was observed. This thesis provided valuable insights on the formation and dissociation behavior of methane hydrate in porous media and revealed the opportunity to enhance gas recovery through effective control on water production.

Biography