Compared with the post-stack inversion,coupling features in impedance are complex.The pre-stack inversion can make full use of the information such as the amplitude and travel time and frequency of the prestack seismic data,more diverse logging data and geology,and yields geophysical parameters that are highly correlated with hydrate saturation.Seismic rock physics modeling of hydrate reservoirs is the basis for hydrate-oriented prestack inversion.Considering the microscopic pore structure and composition characteristics of hydrate reservoir rocks,this paper introduces SCA-DEM rock physics modeling methods.The influence of physicochemical parameters on the elastic characteristics of rock and its role in AVO characteristics are analyzed.The geophysical response of hydrates is discussed and a new hydrate seismic indicator is constructed.Seismic rock physics analysis shows that the indicator has a high correlation with hydrate saturation.Then,the seismic reflection equation based on hydrate indicator is derived and the feasibility analysis of the inversion is carried out. Finally, based on geological prior, we get the indicator using the actual pre-stack data and logging data in the Qiongdongnan sea of South China Sea.The real data application shows that the method has certain practicability and scientificity.
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