Abstract
摘要:本計畫為執行中央地質調查所推動之4年期「台灣西南海域新興能源-天然氣水合物資源調查與評估:震測及地熱調查」工作,以震測及地熱等地球物理探測技術及分析方法在台灣西南海域進行天然氣水合物之調查與探勘研究,以暸解台灣西南海域探勘好景區內天然氣水合物之資源特性,並利用石油系統分析觀念建立調查區內天然氣水合物儲集系統,評估探勘好景區天然氣水合物可能之能源儲量及其開發潛能,規劃出最適合之鑽探井位。為達成本計畫之目標,本4年期計畫調查工作包括進行長支距多頻道深部地殼反射震測及海底地震儀(OBS)探測以及地熱量測與分析,並在擇定之探勘好景區(鑽探井位規劃區)進行仿3維震測,以協助釐定各個鑽探好景區之鑽井位置與鑽探目標。所有收集來的資料及分析結果均置入台灣西南海域天然氣水合物資料庫。目前此4年計畫已順利完成前三年的工作,即將展開第4年(100年度)的工作。在97年度計畫執行期間,本計畫提出17個鑽探井位,並著重在井位地區之精查。98年度間,租用美國震測研究船,成功完成了長支距深部震測及海底地震儀觀測工作,並根據新收集來之震測與地熱資料與國際學者的建議,調整所提出17個井位之鑽探深度及另外增加1個鑽探井位。99年度間,本計畫協助地調所租用法國研究船R/V Marion Dufresne(簡稱MD)完成長岩心採樣、紅外線影像掃瞄以及地熱量測工作,另成功的收集到一組3維震測資料。本(100)年度計畫由國內9位學者專家合作,進行之調查研究工作重點包括:
1.總計畫:(1)綜合各團隊調查成果,規畫未來調查重點區域及鑽探井位之優先順序;(2)擴充及維護天然氣水合物資料庫,推廣WebGIS的使用,持續改進與維護天然氣水合物資訊網;(3)推動國際合作,邀請至少2位國際知名學者訪台;(4)將水下定位系統(USBL)建置於海研一號研究船上,以提升水下探測儀器定位能力。
2.反射震測與海床聲納剖面子計畫:(1)在台灣西南海域天然氣水合物好景區收集一組總長1,000公里之仿3維震測資料與chirp sonar剖面資料收集;(2)完成仿3維震測資料組之3維資料處理工作,並將這些資料製作屬性資料表及圖檔,置入資料庫;(3)完成chirp sonar海床聲納剖面資料處理與分析,並將這些資料製作屬性資料及圖檔置入資料庫;(4)分析解釋各3維震測區塊,並結合其他地熱、OBS與地質、地化資料,建立各3維震測區塊地區之天然氣水合物富藏層模式,推估其天然氣水合物能源儲量。
3.海底地震儀子計畫之工作重點在於:(1)處理與分析2007年在九龍甲烷礁地區收集之25站海底地震儀資料,建立4條P波速度構造剖面、計算該4條剖面之泊松比值、並推估該4條剖面之天然氣水合物飽和度分布;(2)對MGL0905-05及MGL0905-08線進行移位速度分析,以建立九龍甲烷礁地區的P波速度資料;(3)繼續處理與分析2008年在永安海脊調查區收集之25站海底地震儀資料,建立OBS儀器蒐集S波訊號能力及S波應用在估算天然氣水合物蘊藏量之技術;(4)處理與分析2004年至2009年收集來約80個OBS測站之海底仿擬反射(BSR)反射係數資料,結合地質及地化資料,完成台灣西南海域區域天然氣水合物飽和度分布與蘊藏評估。
4.海域震測與海底地震儀資料處理與分析子計畫:(1)應用上年度發展出之海底地震儀與多頻道反射震測資料處理技術,對MGL0905-08長支距震測剖面進行資料處理以及走時與全波形逆推;(2)應用逆時移位技術處理該剖面,以獲得更清晰的剖面影像;(3)建立網頁提供震測研究團隊技術支援。
5.以地熱及震測資料推估天然氣水合物賦存區流體移棲模式研究子計畫:(1)利用地形、地熱及震測資料,發展2維的地下熱流傳導與對流模式,進一步了解台灣西南海域天然氣水合物之流體移棲模式;(2)結合流體移棲之特性與區域構造間的關聯性,建置出更完整有助於判別鑽探目標的熱流資訊。
6.天然氣水合物賦存區之地熱調查子計畫:(1)在台灣西南海域進行地熱量測,完成5個測站之原地溫度與岩心沉積物之熱導係數量測及拍攝紅外線影像;(2)完成新收集來地熱資料之處理、分析與解釋,並以地溫梯度推估天然氣水合物穩定帶底部(BGHS)深度並比較BSR深度;(3)完成2010 MD航次收集的14根長岩心紅外線掃瞄的影像分析,並依此次經驗建立紅外線掃標準作業流程;(4)整編台灣西南海域所有的地熱測量資料,完成BGHS深度、地溫梯度、熱導係數等資料之等值圖繪製。
7.含天然氣水合物地層的構造與沉積特徵研究子計畫:(1)MD岩心之沈積學研究;(2)長支距反射震測與台南盆地震測剖面解釋;(3)整合MD岩心資料、通過鑽井建議地點的反射震測剖面及地質、地化資料,重新評估各鑽探井位的天然氣水合物富藏系統與天然氣水合物資源量,並排訂各鑽探井位鑽井調查之優先順序。
本計畫並將與天然氣水合物地質及地球化學調查計畫以及底拖調查計畫密切合作,共同完成台灣西南海域天然氣水合物資源評估工作。
Abstract: This proposal requests the 4th year support of the 4-year gas hydrate project entitled “Investigation and evaluation of gas hydrate resource potential in the offshore area of southwestern Taiwan: Seismic and heat flow studies”. Multichannel seismic reflection and chirp sonar profiling, ocean bottom seismometer (OBS) observation and heat flow measurements are carried out to investigate the detailed gas hydrate distribution and energy resource potential in the study area. In order to achieve these goals, this 4-year project will collect large-offset seismic reflection and OBS wide-angle reflection and refraction data, conduct pseudo 3D seismic reflection surveys in selected prospective sites, measure heat flow values, and integrate all the geophysical investigation results to help define gas hydrate prospects. In the past 3 years, 18 gas hydrate prospects were selected as potential sites for future gas hydrate drilling investigation. Intensive high-resolution surveys have been conducted to establish the “gas hydrate system” for the selected prospects. Large offset seismic reflection data as well as OBS data were colleted during the 2nd year of this project, and 2 sets of 3D seismic data were collected and processed to reveal details of the Yung-An Ridge and the southern part of the Fang-Liao Canyon areas. Heat flow measurements and IR scan were performed in the 3rd year during the R/V Marion Dufresne corning cruise. Results from large offset seismic reflection profile data as well as from OBS data analyses provide insights on the velocity structures and gas hydrate saturation estimations.
As this proposal is for the last year work of the 4-year gas hydrate project, major works to be carried out include:
1.To install an USBL system on the R/V Ocean Researchers I for better underwater positioning.
2.To Collect a new set of pseudo-3D seismic reflection survey data in the passive China continental margin near the deformation front.
3.Processing and analyzing the newly collected and existing pseudo-3D seismic reflection data sets to reveal detailed structures and properties of the gas hydrate bearing strata.
4.Selected large-offset deep seismic profiling data over the prospecting areas will be re-processed analyzed to provide a structural framework and seismic characters of the hydrate-bear strata in the region.
5.Processing and analyzing the MCS and OBS data collected in the Jiulong Methane Reef area for better understanding its gas hydrate potentials.
6.All the OBS data collected for the gas hydrate investigation in the past (about 80 of them) will be analyzed to estimate potential gas hydrate saturation values at different places.
7.Special processing techniques on MCS and OBS data will be introduced which include pre- and post-stack processing and inversions.
8.Heat flow data as well as BSR depths information will be used to establish 2D fluid migration rate for selected prospects.
9.New heat flow measurements will be conducted. Heat flow vaules, thermal conductivities and other thermal parameters will be measured or derived.
10.All the heat flow data collected previously in the area offshore southwestern Taiwan will be compiled and analyzed to generate regional heat flow maps.
11.Various geophysical, geological and geochemical data will be integrated to provide bases for revision of the proposed drilling sites.
12.New geophysical, geological and geochemical data will be added to the gas hydrate database, the capability of the GIS-based data management and displaying system will be up-graded and improved. We will also expand the contents of the “gas hydrate information” web page for general education purposes.
13.International cooperative projects will be promoted..
This project will work closely with colleagues conducting geological and geochemical investigation and high-resolution sea floor survey in the study area.
Keyword(s)
天然氣水合物
台灣西南海域
反射震測
海底地震儀
地熱量測
地層構造
沉積環境
Gas hydrate,Offshore southwestern Taiwan,Seismic exploration,Heat flow
Gas hydrate system,Deposition environment