碩士 / 國立臺灣海洋大學 / 應用地球科學研究所 / 96 / An integrated multi-channel seismic (MCS) and ocean-bottom seismometer (OBS) survey was conducted for exploring gas hydrates west of Kaoping Canyon off SW Taiwan in April, 2006. The total number of OBS stations is 35 with the spacing of about 500-1000 m. We used arrivals of the head wave, refraction and reflection on four-component OBS records to invert the P-wave velocity and interface of the hydrate-bearing sediments. Above the bottom-simulating reflector (BSR), the hydrates with a high P-wave velocity of 1.8-2.04 km/s and a thickness of about 100-150 m are imaged. Beneath the BSR, the free gas with a low P-wave velocity of 1.4-1.72 km/s and a thickness of about 30-110 m can be observed. In particular, the higher velocity (2.04 km/s, implying high saturation) of the hydrate layer and the lower velocity (1.4 km/s, implying large amount) of the free gas layer are seen below stations with strong geochemical signals. P-S and S-P reflected waves converted at BSR and seafloor were picked on two horizontal components of OBS data for inverting the Poisson’s ratios of hydrate and free gas layers. The lower Poisson’s ratio (0.447, implying high saturation) of the hydrate layer across a thrust fault and the higher Poisson’s ratio (0.5, implying large amount) of a free gas zone south of the thrust fault are imaged. According to the OBS models of P-wave velocity and Poisson’s ratio, we suggest that the high saturations of gas hydrates and free gas have been found in two anticlines formed by two basement rises, and gas hydrates may have migrated through two thrust faults north of these anticlines.
| Identifer | oai:union.ndltd.org:TW/096NTOU5135005 |
| Date | January 2008 |
| Creators | Chih-Hsien Chen, 陳志賢 |
| Contributors | Tan-Kin Wang, 王天楷 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 67 |
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