Multiple seismic attribute analyses for determination of bottom simulating reflector of gas hydrate seismic data in the
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ORIGINAL RESEARCH PAPER
Multiple seismic attribute analyses for determination of bottom simulating reflector of gas hydrate seismic data in the Ulleung Basin of Korea Doan Huy Hien • Seonghyung Jang Youngwan Kim
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Received: 15 June 2009 / Accepted: 21 January 2010 / Published online: 11 February 2010 Ó Springer Science+Business Media B.V. 2010
Abstract The bottom simulating reflector (BSR), the boundary between the gas hydrate and the free gas zone, is considered to be the most common evidence in seismic data analysis for gas hydrate exploration. Multiple seismic attribute analyses of reflectivity and acoustic impedance from the post-stack deconvolution and complex analysis of instantaneous attribute properties including the amplitude envelope, instantaneous frequency, phase, and first derivative of the amplitude of seismic data have been used to effectively confirm the existence of a BSR as the base of gas hydrate stability zone. In this paper, we consider individual seismic attribute analysis and integrate the results of those attributes to locate the position of the BSR. The outputs from conventional seismic data processing of the gas hydrate data set in the Ulleung Basin were used as inputs for multiple analyses. Applying multiple attribute analyses to the individual seismic traces showed that the identical anomalies found in two-way travel time (TWT) between 3.1 and 3.2 s from the results of complex analyses and l1 norm deconvolution indicated the location of the BSR.
D. H. Hien Petroleum Resources Technology Field of Study School of Engineering, University of Science and Technology, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350, Republic of Korea e-mail: [email protected] S. Jang (&) Y. Kim Petroleum and Marine Research Division, Korea Institute of Geoscience and Mineral resources (KIGAM), 92 Gwahang-no, Yuseong-gu, Daejeon 305-350, Republic of Korea e-mail: [email protected] Y. Kim e-mail: [email protected]
Keywords Seismic data processing Gas hydrate BSR Complex analyses l1 norm deconvolution
Introduction Gas hydrate, a solid-like substance, is composed of a methane molecule at the center and number of water molecules surrounding it. Gas hydrate is formed under conditions of low temperature, high pressure and appropriate natural gas concentration. Previous studies on gas hydrate (Sloan 1998; Riedel et al. 2002; Ryu et al. 2009) have concentrated on: (1) consideration as a new energy resource, (2) a cause of instability on sea floor slope, and (3) as a factor in climate change. The gas hydrate stability zone (GHSZ) occurs naturally beneath the sea bottom or in permafrost areas where the sediment has appropriate temperature and pressure conditions and a high organic carbon concentration in the pore waters. Similar to the petroleum system, the gas hydrate system needs three important geological features, including the in situ or deeper thermogenic generation of methane (source rock), ‘‘clathratisation’’ of a conventional reservoir (reservoir rock), and trapping of gas seepage (trap) (Beauchamp
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