摘要:臺灣西南海域承接了大量從臺灣造山帶沖積下來的沈積物,形成一個非常適合天然氣水合物形成與賦藏的地區。經濟部中央地質調查所自2004 年開始執行四年一期的臺灣西南海域天然氣水合物調查計畫,至今已進入第三期的工作,而9年間海上調查收集到大量的海洋地球物理、地質與地球化學資料,均顯示臺灣西南海域的高屏斜坡以及南海大陸斜坡處的海底沈積物中應蘊藏了大量的天然氣水合物,推估其天然氣儲量可達2.7 兆立方公尺。然而從研究船調查資料所推估出來的天然氣水合物儲量並不精準,若要對臺灣西南海域天然氣水合物的能源潛力做一較準確的評估,以及能精確推估其可能蘊藏的天然氣儲量,實際鑽井採集天然氣水合物儲集層的岩心標本以及從井下實際量測各地層的物理參數及地質與地球化學特性是極為重要的。本計畫即為天然氣水合物鑽井調查計畫提出規劃,以進行鑽井前的各項準備工作、執行鑽井調查作業、到鑽井採樣後的資料分析與解釋,期望能透過鑽井調查,確實掌握臺灣西南海域海底沈積物中所蘊藏的天然氣水合物賦藏層特性,精確估算其能源潛力與蘊藏量。
本計畫規劃自2012 年12 月1 日開始至2015 年12 月31 日止,分三年執行完畢。第一年的主要工作包括鑽井前的各項準備工作、鑽井地點的擇定、井位的海床精查、井測與岩心標本分析技術的評估與建立、鑽井預定區的天然氣水合物賦藏層模式建立等等。第二年則將安排鑽井時程,簽定鑽井合約,擬訂鑽井作業內容與流程。若該年度有機會進行鑽井調查,則執行鑽井作業;否則規劃於2015 年執行鑽井調查。第二年與第三年的工作均為在鑽井前積極準備鑽井作業與建立鑽井資料分析技術、訓練鑽井資料分析人才;鑽井後則分析資料,完整建立調查區的天然氣水合物賦藏層模式與儲量估算。
本計畫全程完成後,預期能證實臺灣西南海域蘊藏有大量的天然氣水合物,確實掌握海床下含天然氣水合物地層的一些重要特性參數,了解天然氣水合物在賦藏層中的分布與儲量。而在技術方面,我國研究人員當可獲得天然氣水合物深海鑽探作業與鑽井調查所獲得之樣本及資料分析之能力與經驗,且培育年輕學者養成天然氣水合物的調查與資料分析能力。
Abstract: The area offshore of southwestern Taiwan provides a favorable environment for gas hydrate accumulations. Starting from 2004, the Central Geological Survey (CGS) of Taiwan has carried out a multidisciplinary gas hydrate investigation program in that area. Large amount of geophysical, geochemical, and geological data have been collected, and investigation results reveal that enormous amounts of gas hydrate should occur beneath the seafloor offshore of southwestern Taiwan. The estimated gas resources could reach 2.7 trillion cubic meters (Lin, 2011). However, in order to have a more accurate estimation of the gas hydrate energy resource potential and to better constrain the gas hydrate reservoir characters, in-situ observation and sampling through drilling are essential. This project aims to conduct gas hydrate drilling investigation, to better constrain the gas hydrate reservoir characters, and to accurately evaluate and quantify their energy resources potentials.
This project is designed for 3 years. During the first year (from late 1202 to the end of 1203), research works will mainly focus on drilling site selection and preparation, drilling operation information gathering and designing our own drilling operation objectives and procedures; establishing borehole data and sample analyses techniques and design onboard and post-cruise data and sample analyses procedures; and establishing one to two reservoir models from high-priority gas hydrate prospects. In the 2nd year, we expect to negotiate a drilling contract, train our scientists for onboard and lab drilling data and sample analyses works, and continue to prepare drilling sites and drilling targets (reservoir models). If a drill ship is available in 2014, the drilling operation will be carried out in that year. Otherwise, we will carry out the drilling operation in 2015, followed by post-drilling data analyses and gas hydrate reservoir model modification and quantification.
At the end of this 3-year project, we expect to complete the gas hydrate drilling operation, confirm the gas hydrate energy potentials in the investigating areas, obtain a good estimation on the amount of gas hydrate presence in the reservoirs investigated, establish deep water gas hydrate drilling operation and data analysis capabilities, and our young scientists and students will also obtain precious experiences on gas hydrate drilling and reservoir modeling technology.