가스 하이드레이트 탐사를 위한 해저 CSEM탐사 설계변수 고찰

초록

In this paper, we have investigated general operating and design parameters of marine controlled source electromagnetic (CSEM) survey for gas hydrate detection. Numerical forward modelings were executed in terms of frequency and source-receiver offset with variable resistivity of depth to the gas hydrate layer. To estimate the detectability of gas hydrate layer, the total electric field of the gas hydrate model was normalized by that of the half-space model response. As a result, we confirmed that as the depth to the gas hydrate layer increases, the domain of transmission frequency and source-receiver offset with the maximum detectability moves to the area of low frequency band and far offset range. On the basis of this result, we propose operating and design parameters of Marine CSEM survey - source-receiver offset, source height from seafloor and transmission frequency - at the East sea where the existence of gas hydrate has been confirmed. In addition, to analyze characteristics of air wave, we carried out numerical modelings with variable sea depth.

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