摘要:本計畫為執行中央地質調查所推動之4年期「天然氣水合物資源潛能調查:震測、地熱及地球化學調查」工作,以震測、地熱以及地球化學等探測技術及分析方法在台灣南部與西南海域進行天然氣水合物之調查與探勘研究,一以了解台灣南部過去未曾進行過天然氣水合物調查的海域中是否亦有天然氣水合物的資源潛能,二則以過去在台灣西南海域天然氣水合物調查的成果為基礎,在擇定的探勘好景區內進行天然氣水合物儲集層之資源特性調查。為達成計畫目標,本計畫結合了過去執行中央地質調查所天然氣水合物調查計畫中地球物理與地質、地球化學團隊成員,組成一堅強的調查分析團隊來執行此計畫。除了總計畫負責整個計畫之規劃、協調工作以及維護與擴充天然氣水合物資料庫外,另有8個分項計畫,分別是(1)反射震測與海底迴聲剖面調查研究:負責2維與3維反射震測以及海底聲納迴聲剖面資料之收集、處理、分析與解釋,亦將發展、應用高階的震測資料處理與分析技術來提高震測資料剖面的品質以及其應用價值。(2)海底地震儀對天然氣水合物研究的應用:利用海底地震儀觀測到的震波紀錄,建立地層速度構造,推估地層的泊松比與S波特性,以協助了解地層中天然氣水合物儲集層特性。(3)天然氣水合物賦存區之地熱調查:負責進行調查區之地熱量測與資料處理、分析,提供重要的天然氣水合物分布環境控制及流體移棲資訊。(4)天然氣水合物賦存區流體移棲模式研究:利用地熱、震測、地形等資料建立海床下流體移棲速率及地溫分布模式,協助了解天然氣水合物儲集系統及儲集層特性。(5)天然氣水合物賦存區之地層構造與沉積特徵研究:分析震測剖面資料,建立天然氣水合物賦存區之地質架構及儲集系統,整合地球物理,地質與地球化學等各項資訊,進行天然氣水合物儲集層特性分析,推估天然氣水合物資源量。(6)台灣西南海域海水與沉積物之地球化學組成:採集與分析海水層與海底沉積物標本,建立不同天然氣水合物儲集系統之地球化學特性,探討甲烷氣源及移棲模式等。(7)台灣西南海域沉積物自生礦物之電子顯微分析:負責對採集到的活塞型長岩心標本中的礦物進行高解析度電子顯微分析,瞭解其產狀、結構類型、化學組成、以及其生成環境是否與天然氣水合物相關。(8)台灣西南海域沉積物之磁學性質、年代及微化石研究:負責分析收集到的長活塞岩心標本,量測其磁感率、磁滯曲線、鑑定磁性礦物、分析底棲有孔蟲,進行定年工作等等,以了解沉積環境中是否有大量甲烷逸氣事件發生,並建立沉積物年代。總體而言,本計畫一方面持續調查我國周邊海域天然氣水合物之資源潛能,另一方面在台灣西南海域已證實存在天然氣水合物的探勘好景區中進行精密調查,以建立台灣西南海域各探勘好景區之天然氣水合物儲集系統、仔細評估各儲集系統之能源儲量、掌握各天然氣水合物儲集層之確切分布與特性,並為鑽探驗證做準備。
Abstract: This proposal requests the 1st year support of the 4-year gas hydrate project entitled “Investigation of Gas Hydrate Resource Potential: Seismic, Heat Flow and Geochemical Studies”. Seismic, heat flow and geochemical investigations will be carried in the area offshore south and southwestern Taiwan with 2 purposes in mind: 1. To explore the areas where no gas hydrate investigation has been conducted before to see if there are gas hydrate energy potentials existed in those areas, and 2. To investigate potential gas hydrate reservoir characteristics in the gas hydrate prospects delineated in the previous gas hydrate investigation projects of the Central Geological Survey (CGS). To achieve these goals, a team which consists of 11 scientists/researchers has been formed to carry out this project. The team members are experts in gas hydrate research and all have been involved in the previous gas hydrate investigation projects of CGS. Based on the needs of applying various investigation techniques and approaches, this project will be carried out by one master project and 8 sub-projects. The master project is responsible for the project design and coordination among different sub-projects, also to maintain and continuous developments of the gas hydrate database. The 8 sub-projects and their respective roles in this project are described below: 1. Seismic reflection and chirp sonar investigations. This sub-project will collect both 2D and 3D seismic reflection data and chirp sonar data, and will process, analysis and interpret them to provide sub-strata information for gas hydrate investigation. Advanced seismic data processing and analysis techniques will be developed and applied to improve the quality and values of the acquired seismic data. 2. Ocean bottom seismometer investigation. This sub-project utilizes seismic data recorded by the ocean bottom seismometers to derive velocity information of the substrata, and to extract other important geophysical properties of the substrata. 3. Heat flow investigation of the gas hydrate province. This sub-project will conduct heat flow measurements in the area where gas hydrate exit. Geothermal data will be analyzed and interpreted to provide information regarding the gas hydrate stability zone and factors affecting geothermal structures, such as fluid flows and gas hydrates. 4. Fluid migration modeling of the gas hydrate provinces. This sub-project will build 3D fluid migration models of the gas hydrate prospects using heat flow, seismic and bathymetry data. This modeling approach will help us to better understand the properties of possible gas hydrate reservoirs. 5. Stratigraphic analyses and sediment deposition characters of the gas hydrate prospects. This sub-project will integrate all the available geophysical and geological data to refine the gas hydrate systems proposed in the previous CGS gas hydrate investigation projects, and will estimate the gas hydrate energy potentials in the investigating prospects. 6. Geochemical composition of sea water and sediments offshore SW Taiwan. This sub-project will collect and analyze the sea water and seafloor sediment samples to understand various geochemical characters of gases in the sub-strata, and to establish fluid migration models based on the observations and analysis results. 7. Electronic microscopic analyses of authigenic minerals in the sediments offshore SW Taiwan. This sub-project will conduct petrographic analyses using electronic microscope to identify special minerals and their distribution, structure, and chemical compositions, this will help us to better understand the deposition environment and if there are interactions with methane gas. 8. Magnetic properties, age and microfossils of the sediments offshore SW Taiwan. This sub-project will measure the magnetic susceptibility, hysteresis curve, identify magnetic minerals and forams, and determine the age of the forams. This study will help us to understand the paleo-environment of sediments and if there were large methane gas eruptions occurred in the past.
Overall, this project will continue to investigate and to better define the gas hydrate prospects in the area offshore SW Taiwan for energy resource potential calculation, and to prepare for future drilling investigation. Also, this project will survey other areas offshore Taiwan to find new gas hydrate prospects