# Modelling of Hydrate Dissociation in a Collapsing Packed Bed

**【摘要】：**正Modelling of hydrate dissociation in a sediment bed is needed to understand the gas evolution characteristics.The model would consider the subsidence of sediment bed during and after hydrate dissociation.Sediment collapse would affect the gas recovery from hydrated sediments and an understanding of the process is thus crucial to cost effective gas extraction from hydrate.The model gives us a picture of the collapse process in time.Sediment subsidence curves show that subsidence is a strong function of void ratio and compression index of the sediment.Lower void ratios resulted in almost linear dependence of subsidence on time,whereas higher void ratios produced a curvature in the plot.The effect was similar with lower compression indices producing gradual subsidence and higher values resulting in exponential curves.Total settlement plots illustrated a linear behaviour of settlement with time at low values of shear stress change.Larger values of both compression index and shear stress change caused markedly non linear relationship with time.Increasing iterations(in effect increasing the time of settlement) found settlements to taper off.The settlement curve obtained by the model was compared to the actual settlement curves of marine sediment under compression.It was found that when the model was set to the overburden pressure and other parameters of the experimental results,the prediction of settlement was acceptably close.The model will allow optimization of gas recovery efforts from hydrated sediments.