HR: 1340h
AN: OS23A-1047    [Abstracts]
TI: Numerical Simulation of Generation and Migration of Methane and Accumulation of Methane Hydrate in the Eastern Nankai Trough
AU: * Aoyagi, R
EM: ryosuke.aoyagi@mizuho-ir.co.jp
AF: Mizuho Information and Research Institute, 3-1, Kanda-Nishikicho, Chiyoda-ku, Tokyo, 101- 0054, Japan
AU: Fujii, T
EM: fujii-tetsuya@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Yoshikawa, M
EM: minoru.yoshikawa@mizuho-ir.co.jp
AF: Mizuho Information and Research Institute, 3-1, Kanda-Nishikicho, Chiyoda-ku, Tokyo, 101- 0054, Japan
AU: Nakama, Y
EM: yutaka.nakama@mizuho-ir.co.jp
AF: Mizuho Information and Research Institute, 3-1, Kanda-Nishikicho, Chiyoda-ku, Tokyo, 101- 0054, Japan
AU: Kawasaki, T
EM: kawasaki-tatsuji@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Nagakubo, S
EM: nagakubo-sadao@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Takayama, T
EM: takayama-tokujiro@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Kobayashi, T
EM: kobayashi-toshiaki@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Inamori, T
EM: inamori-takao@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AU: Nakamizu, M
EM: nakamizu-masaru@jogmec.go.jp
AF: Japan Oil, Gas and Metals National Corporation, 1-2-2, Hamada, Mihama-ku, Chiba, 261- 0025, Japan
AB: We have developed 2-D numerical simulator "SIGMA-MH" for methane hydrate (MH) accumulation in order to simulate geological/physicochemical phenomena related to MH deposits formation in deepwater sediment and to clarify controlling factors for MH accumulation. SIGMA-MH is a modified version of "SIGMA-2D", basin simulator for petroleum system developed by JOGMEC. SIGMA-MH has models such as microbial methane generation model and MH formation/dissociation model, with which MH accumulation can be simulated. An empirical model is used for microbial methane generation model. In this model, maximum gas generation rate is estimated from organic accumulation rate, which are derived from ODP gas sample analysis. Kinetic reaction model is applied for MH formation/dissociation. MH formation/dissociation rate is expressed as a function of the difference between the fugacity of methane at gas phase and the fugacity of methane at the three- phase equilibrium for MH-water-methane gas. Using SIGMA-MH, case studies were conducted for two sections including boreholes at Tokai-Oki and Daini- Atsumi area where MH concentration is detected. Geological structure used in the simulation was estimated by seismic survey. Rock facies were determined by logging and core sample. Heat flow was calibrated by present temperature measured by geothermometer. Base case, shallow case, and deep case were conducted as a sensitivity analysis for paleo-water depth. As a result, a series of recycling process, that is, methane gas generation, MH formation, MH dissociation, gas migration, and MH formation, was simulated. MH accumulation estimated by simulation nearly corresponds to that of actual borehole. The phenomena that methane gas migrates through permeable sand layers and MH accumulates in them suggests that permeability are a key of MH accumulation. It was found that paleo-water depth plays an important role because it affects on present MH accumulation. For future work, we will conduct sensitivity analyses of quantitative parameters and paleo-water depth and improve SIGMA-MH as a tool for understanding controlling factors of MH accumulation. This study was carried out as a part of Research Consortium for Methane Hydrate Resources in Japan (MH21).
DE: 3004 Gas and hydrate systems
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting