Seismic Identification and Saturation Prediction of Natural Gas Hydrate in the Qiongdongnan Basin
Qiongdongnan basin is a newly discovered gas hydrate exploration target area in China.There are two types of gas hydrate(i.e.pore hydrate and chimney hydrate),which are characterized by different seismic reflection characteristics.However,there are limitations in using bottom simulating reflections(BSR)in seismic profiles to identify gas hydrate in deep water area of Qiongdongnan basin.For the identification and saturation prediction of gas hydrate in Qiongdongnan basin,AVO forward modeling and broadband seismic inversion analysis are carried out in this study.The elastic parameter characteristics of natural gas hydrate were clarified,and geophysical identification methods for gas hydrate were established.Then,isotropic and anisotropy quantitative saturation evaluation methods were established for pore and chimney hydrates respectively.Based on broadband seismic inversion and saturation prediction using high quality seismic data,this study successfully identified pore hydrate and chimney hydrate in Qiongdongnan basin,and delineated gas hydrate enrichment areas.Three hydrate deposits with maximum saturation above 50%have been selected,the prediction effect of which is further confirmed by drilling exploration.Our results contribute to the selection of hydrate drilling stations and reduce the risk of hydrate drilling in Qiongdongnan basin,and the research method has guiding significance for hydrate exploration in other similar basins.
gas hydratesseismic reflection characteristicsbroadband seismicsaturationenrichment regionpetroleum geology
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