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| | Abstract | | Marine controlled-source electromagnetic (CSEM) survey is considered as a technique in practice for the exploration of hydrocarbon resources including gas hydrate. We suggest the new data analysis method to improve the resolution of gas hydrate using the fictitious wave domain by numerical simulation. In the forward modeling, transforming the Maxwell equation from the diffusive domain to the fictitious wave domain reduces computational time (Mittet, 2010). However, the characteristic of the propagation in the fictitious wave domain has not well exploited for the estimation of sub-seafloor resistivity structure. In the present study, we conduct numerical simulations using a three dimensional resistivity model as a sub-seafloor structure including gas hydrate. Our results show that the received waveforms in the fictitious wave domain highlight the gas hydrate responses better than in the diffusive domain. We then tested to see if the transform from the diffusive domain to the fictitious wave domain is possible or not for further utilization of the transform. As a result of the censoring singular value decomposition method, we achieved the sensitivity of the hydrate responses becomes about twice as much than the case in the diffusive domain. The method improves the identification of gas hydrate by wave separation. |
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