Application of Seismic Methods to Methane Hydrate Delineation
Masami Hato(1), Takao Inamori(1), Shoshiro Shimizu(2), Kazuhiko Yamaguchi(3) and Toshifumi Matsuoka(3)
(1) Japan Petroleum Exploration, Japan. (2) Japan National Oil Corporation, Japan. (3) Kyoto University, Japan.
Contacts: mhato@japex.co.jp (Masami Hato)
Abstract
On the RAEG held in 2002, we reported the result of the interval velocity analysis on the seismic data acquired Nankai Trough area offshore Japan where methane hydrate (hereafter called ¡ÆMH¡Ç) exists. That result showed us possibility of interval velocity as a delineation tool for MH bearing zone and related low velocity zone (hereafter called ¡ÆLVZ¡Ç) below MH bearing zone. Following the past result, we have tried other types of seismic methods to be applied to the same data in order to find more effective delineation methods for MH bearing zones and LVZ. Those that we have tried are the migration velocity analysis using pre-stack depth migration (hereafter called ¡ÆPSDM/MVA¡Ç), seismic impedance inversion and AVO analysis. In this presentation, we show some results of those analyses. As a current result, the PSDM/MVA method has not always given the result of finer delineation of them than that by the traditional stacking velocity analysis method. At present time, we think one of the reasons comes from geological complexity of MH bearing zones and LVZ at Nankai Trough area. On the other hand, the result of the seismic impedance inversion showed us more detailed velocity-equivalent structure than those from PSDM/MVA and stacking velocity analysis method even though only two closely-located wells exist on the seismic line. As for the AVO analysis, the results of the analysis showed a possibility of gas existence below MH bearing zones. Those results described here gave us high motivation to continue to develop powerful and effective seismic tool for delineating MH bearing zone.
raeg2003@tansa.kumst.kyoto-u.ac.jp
Last modified: Tue Nov 5 18:12:34 2002