A Coupling Distinct Element Modeling Method for Gas Production on Methane Hydrate Bearing Sediments

Methane Hydrate (MH) is generally distributed in deep sea and permafrost region and abundant in reserve. It has been a great attraction as a new green energy with serval countries being active in conducting trial tests of MH gas production. However, extracting MH will weaken the original soil structure and even trigger some environmental disaster such as submarine landslide. Given that most simulators for the mechanical response and gas production evaluation of MH bearing sediments fail to describe large deformation of sediments and observe microscopic-level information such as particle migration. The idea of a simulator for studying the multi-field behavior of MH bearing sediments basing on the Distinct Element Method (DEM) is proposed. By using an existing DEM model implemented in commercial DEM software PFC and a multi-phase flow simulator TOUGH + HYDRATE (T + H) targeting MH geological system, a coupled simulator for MH bearing sediments is established which is suitable for multi-scale investigation including salinity effects. This coupling is based on updating parameters from environmental information calculated by T + H and soil mechanical response in porosity calculated by PFC. Validation of this simulator is performed by comparing numerical results with analytical ones.