Applying 3D Seismic Technique for Gas Hydrate Investigation Offshore Southwestern Taiwan

• Main Authors: Shih-Wei Liao, 廖士瑋
• Other Authors: Char-Shine Liu
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/68734685469393986963

碩士 === 臺灣大學 === 海洋研究所 === 98 === Gas hydrate as a potential new energy resource has been noticed worldwide in recent years. However, rapid dissociation of gas hydrate may cause serious environment problems such as submarine landslides and global warming. Offshore southwestern Taiwan, clear bottom simulating reflector (BSRs) and strong reflection amplitude anomalies have frequently been observed on 2D seismic profiles. In this study, we try to get detail in a small area by 3D seismic techniques. The study area is located in the southern part of the Yung-An Ridge and adjacent slope basins offshore southwestern Taiwan. The 3D seismic data were collected using a single source and single streamer (thus, a 2D seismic system) shooting in E-W direction across the survey area with line spacing as close as 100 m. We built a 3D geometry from these closely spaced 2D seismic profiles. The 3D data volume contains 92 E-W trending in-lines with 100 m spacing, and 1431 N-S trending crosslines with 12.5 m spacing, the 3D volume covers an area about 180 km2. From this 3D data volume, we can see that BSR appears almost throughout the entire study area. Base on the seismic characteristics typically associated with gas hydrate and structures and sedimentary features, we separate the study area into 5 small zones. They are from west to east, the Penghu canyon, the buried channel area, the Yung-An ridge, the western part of the intra-slope basin, and the eastern part of the intra-slope basin. Each zone has it own fluid migration mechanism, and all mechanisms are controlled by either structure associated or sedimentary processes.