臺灣西南海域永安及好景海脊區之近表層天然氣水合物賦存潛能

Near-Seafloor Gas Hydrate Potential in the Yung-an and Good Weather Ridges Area, off Southwest Taiwan

邱協棟(S. D. Chiu) ； 陳松春(S. C. Chen) ； 許樹坤(S. K. Hsu) ； 蔡慶輝(C. H. Tsai) ； 王詠絢(Y. S. Wang) ； 劉家瑄(C. S. Liu)

《鑛冶：中國鑛冶工程學會會刊》 59卷2期 (2015/06) Pp. 17-32

https://doi.org/10.30069/MM.201506_59(2).0002

摘要

永安及好景海脊因斷層及褶皺作用，造成一系列的背斜及低地。斷層、破碎帶及地層層面是深部流體移棲到海床的主要通道，地層有廣泛的天然氣水合物賦存指標BSR分布，指示有天然氣水合物賦存。為了解近表層天然氣水合物賦存潛能，進行高解析底拖聲納調查（底質剖面及側掃聲納）、海床觀測調查（TowCam及ROV）及海底電阻等調查。從調查結果顯示有逸氣構造、麻坑、泥火山、崩塌堆積及微斷層分布，崩塌堆積具有高孔隙率特性，適宜天然氣水合物形成。在海脊有自生碳酸鹽礁及氣煙囪分布，顯示有很高的甲烷通量。在麻坑、MD3277岩心站位及微斷層有高電阻率異常。從調查結果顯示，近表層天然氣水合物可能富集在海脊脊部、斷層帶、崩積層、氣煙囪及麻坑等地區。

關鍵字

天然氣水合物 ； 氣煙囪 ； 逸氣構造 ； 麻坑

並列摘要

The area around the Yung-An and the Good Weather ridges is characterized by a series of troughs and anticlinal ridges. The thrusts, fractures and bedding planes provide efficient conduits for fluid to migrate from deep strata to shallower strata and structures. BSRs are widely distributed in the Yung-An and Good Weather ridges area, indicating potential gas hydrate accumulation beneath the seafloor. We conducted deep-towed surveys of sidescan sonar and subbottom profiler, seafloor observations (TowCam and ROV) and resistivity survey to evaluate the near-seafloor gas hydrate potential. Results showed that the study area has gas seeps, pockmarks, mud volcano, mass-transport deposits (MTDs) and minor faults. Because of being highly porous, the MTD is an ideal place for the gas hydrate accumulation. Authigenic carbonates and gas chimneys were observed on the sea seafloor, implying a high methane flux in the area. High resistivity anomalies were found in some pockmarks, MD3277 coring site, and minor faults. The ridges, faults, MTDs, gas chimneys and pockmarks are suitable for near-seafloor gas hydrate accumulation.

並列關鍵字

gas hydrate ； gas chimney ； gas seep ； pockmark