Drilling results suggest that the thickness of natural gas hydrates (NGHs) in the Shenhu Area, South China Sea (SCS) are spatially heterogenous, making it difficult to accurately assess the NGHs resources in this area. In the case that free gas exists beneath hydrate deposits, the frequency of the hydrate deposits will be noticeably attenuated, with the attenuation degree mainly affected by pore development and free gas content. Therefore, the frequency can be used as an important attribute to identify hydrate reservoirs. Based on the time-frequency characteristics of deposits, this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows. Firstly, the support vector machine (SVM) method was employed to study the amplitude versus frequency (AVF) response based on seismic and well logging data. Afterward, the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform. Then, the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion. The inversion results can effectively broaden the frequency band, reflect the NGHs distribution, and reveal the NGHs reservoirs of two types, namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type. Moreover, the inversion results well coincide with the drilling results. Therefore, it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs, which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.

Shu-yu Wu;Jun Liu;Hua-ning Xu;Chang-ling Liu;Fu-long Ning;Hong-xian Chu;Hao-ran Wu;Kai Wang

School of Engineering,China University of Geosciences,Wuhan 430074,China;Yantai Coastal Zone Geological Survey Center,China Geological Survey,Yantai 264001,China;Chinese Academy of Geological Sciences,Beijing 100037,China;Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266061,China;The Key Laboratory of Gas Hydrate,Ministry of Natural Resources,Qingdao Institute of Marine Geology,Qingdao 266071,China

中国地质（英文）

[1]Shu-yu Wu;Jun Liu;Hua-ning Xu;Chang-ling Liu;Fu-long Ning;Hong-xian Chu;Hao-ran Wu;Kai Wang-.Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area, South China Sea)[J].中国地质（英文）,2022(02):251-266

NGHs

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