Formation of layered fracture and outburst during gas hydrate dissociation

Hydrate dissociation in marine sediments may cause large hazards. Two types of new hazard phenomena, outburst and layered fracture, are observed in laboratory experiments and the initiation mechanism is discussed. Experiments are carried out in a two-dimensional rectangular box and a one-dimensional cylinder, respectively. It is shown that layered fracture and outburst can appear after hydrate dissociation and are related closely to dissociation speed, permeability, strength of hydrate-bearing sediment and over-layered stratum. Outburst often occurs at low permeability, high strength of over layered stratum and high pore pressure, while layered fracture is just on the contrary.