Vulnerability of Seafloor at Shenhu Area, South China Sea Subjected to Hydrate Dissociation
This study develops a hybrid model for investigating seafloor instability subjected to hydrate dissociation by combining the limit equilibrium slope stability analysis and numerical modeling of fluid flow and heat transport. This model is employed to study a slope configured according to the geological settings of hydrate reservoirs located at Shenhu area, South China Sea, under mild and sustaining warming scenarios. The vulnerable settings and the controlling factors are quantitatively identified through a parametric study. The results indicate that the slope is stable under the mild seafloor warming scenario in a short timescale. Under the sustaining warming scenario, the slope fails in the order of hundreds of years. The predicted slip onset is located at the top of the hydrate reservoir. The slope is particularly vulnerable to the presence of low permeable and tight sediments, and highly-concentrated hydrates. The permeability of the overburden layer plays a dominant role in determining the vulnerability of the slope, while the impact of the permeability, hydrate saturation, and porosity of the hydrate reservoir is secondary.
KeywordsMethane hydrate Seafloor instability THC coupled process South China Sea
The work is supported by the Chinese National Natural Science Foundation (with grant No. 41572267, 51639008, and 51239010), and the Fundamental Research Funds for the Central Universities.
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