Numerical simulation on the marine landslide due to gas hydrate dissociation

Abstract

Marine landslide due to gas hydrate dissociation is a kind of potential heavy hazards. Numerical simulation was processed to investigate the deformation, landslide and effects of main factors on the critical scale of dissociation zone to induce marine landslides during/after dissociation of gas hydrate. A simple method for analyzing the critical scale was presented based on the limit equilibrium method. It is shown that the maximum settlement is located near the upper side of the dissociation zone. The soil near the lower side of the dissociation zone uplifts. There is a critical scale of dissociation zone over which landslide will occur under given conditions. Expansion modes of the dissociation zone have obvious effects on the critical scale.

Hydrate morphology and mechanical behavior of hydrate-bearing sediments: a critical review

“…In the residual state (Fig. 3a), water mainly exists in the form of absorbed water and isolated pockets of free water (capillary meniscus) (Lu and Likos 2004;Vanapalli et al 1996). The movement of water in this state is governed by film flow, which is such an extremely slow process (hydraulic conductivity Ks < 10 -11 m/s) (Peters 2013;Tokunaga 2009) that it is typically neglected.…”

“…When the pressure and/or temperature changes from the thermodynamic equilibrium state in the hydrate stability zone to the instability zone due to climate change, sea-level variation, and involvement in gas exploitation (e.g., depressurization, thermal stimulation, CH4-CO2 replacement, and inhibitor injection), the gas hydrate dissociates into water and gas (Goto et al 2016;Horozal et al 2017;Kwon et al 2008;Ruppel and Kessler, 2017;Sultan et al 2004;Wallmann et al 2018;Waite et al 2009). This dissociation will lead to degradation of the mechanical properties (e.g., stiffness, strength, dilation) of the hydrate-bearing sediment (HBS), resulting in various disasters, such as submarine landslides, differential subsidence of the seafloor, instability of the foundations of seafloor structures, destruction of the production well and the drilling installation (Brown et al 2006;Horozal et al 2017;Lu et al 2017;Jin et al 2019;Kayen et al 1991;Li and He 2011;Nixon and Grozic 2007;Scholz et al 2011;Song et al 2019a;Sultan et al 2004;Sun et al 2018;Xu and Germanovich 2006;Zander et al 2018). Therefore, it is paramount to ascertain the stability of the HBS for safe gas exploitation.…”

Simulation of a Submarine Landslide Using the Coupled Material Point Method

“…Submarine landslides are the most common and frequent geological hazards in the ocean [1,2]. Both natural and human activities, such as earthquake, gas hydrates dissociation [3,4], and hydrocarbon production [5], are able to trigger submarine landslides. As opposed to terrestrial landslides, submarine landslides normally affect a wider range of areas [6,7], not only posing a great risk to submarine pipelines and other seafloor structures [8,9] but also causing severe casualties due to tsunamis.…”

Experimental Research on Data Synchronous Acquisition Method of Subsidence Monitoring in Submarine Gas Hydrate Mining Area

“…If the conditions change, the hydrate releases methane gas and the physical properties of the seafloor sediment are also altered. As a result, the mechanical properties of seabed sediments are greatly reduced and the seabed is softened, causing large-scale submarine landslides, collapses, and the destruction of subsea engineering facilities [6,7,8]. Therefore, in-situ and long-term monitoring of subsidence during the exploitation of submarine gas hydrates is of great significance for the study of the formation mechanism of submarine landslides, hydrate environmental impact assessment, and early warning.…”