南海東北部大陸邊緣揭陽凹陷新生代構造演化之研究及斷坳油氣資源特徵
Abstract
南海東北部大陸邊緣在新生代時期為被動大陸邊緣，形成珠江口盆地和臺西南盆地，揭陽凹陷位於這兩大盆地的過渡區。臺西南盆地西南部揭陽凹陷區域位於深海區，亦處於臺灣海峽中間地帶，遠離華南陸塊和臺灣島，自2011年兩岸石油公司（中國海洋石油公司和臺灣中油公司）合作開始，才第一次採集了震測剖面資料。
本研究利用新採集的高解析度震測資料，以層序地層學理論為指導，結合構造分析與平衡剖面技術，以及地層水準和垂直方向變化量、速度和加速度計算，完成研究區內地層發育、窪陷結構特徵、新生代構造演化過程及油氣資源特徵的分析總結。
分析認爲：揭陽凹陷是由東北-西南走向的向陸方向傾斜的深大斷裂控制的斷坳，控窪拆離斷層最深處最後彙聚在滑脫面上。張裂初始不整合面(rift-onset unconformity)、破裂不整合面(breakup unconformity)和碰撞不整合面(collision unconformity)把揭陽坳陷新生代地層分隔成了裂谷期(rift)、漂移期(drift)、被動大陸邊緣期(passive margin)三個構造時期。揭陽凹陷具備形成石油天然氣的基本地質條件，陸坡區域顯示的震測似海底反射(BSR, Bottom Simulating Reflector)特徵和火成岩性油氣儲層揭示了非常規油氣藏潛力。
The northeastern continental margin of the South China Sea was a passive continental margin in the Cenozoic. It formed two Cenozoic basins, the Pearl River Mouth Basin and the Southwestern Taiwan Basin. Jieyang Depression is located in the transitional area of these two basins, in the deep sea region in the middle of the Taiwan Strait, which is far away from the South China Continent and Taiwan Island. In 2011, two petroleum companies in Mainland of China and Taiwan, namely, China National Offshore Oil Corporation (CNOOC) and CPC Corporation, Taiwan (CPC), began their cooperation. Since then, high-quality seismic profiles have been collected for the first time. Based on newly acquired high resolution seismic data, under the guidance of sequence stratigraphy, by using the technology to interpret seismic section and balanced section, and calculating the amount, velocity, acceleration changes of the formation in horizontal and vertical directions, This study made a summarization on stratigraphy, tectonic framework and evolution, and potentials of oil and gas resources. The results suggest that Jieyang Depression is a fault depression dominant by a NE-SW major deep fracture inclined to the continent. The deepest part of the detachment fault finally converged on the detachment surface. The rift-onset unconformity, the breakup unconformity, and the collision unconformity divide the Cenozoic strata of Jieyang Depression into three tectonic stages of rift, drift, and passive margin. Jieyang depression has the basic geological conditions for the formation of hydrocarbon. The Bottom simulating reflector (BSR, Bottom Simulating Reflector) characteristics shown on the seismic sections and possible igneous reservoir revealed the potential of unconventional oil and gas resources.
The northeastern continental margin of the South China Sea was a passive continental margin in the Cenozoic. It formed two Cenozoic basins, the Pearl River Mouth Basin and the Southwestern Taiwan Basin. Jieyang Depression is located in the transitional area of these two basins, in the deep sea region in the middle of the Taiwan Strait, which is far away from the South China Continent and Taiwan Island. In 2011, two petroleum companies in Mainland of China and Taiwan, namely, China National Offshore Oil Corporation (CNOOC) and CPC Corporation, Taiwan (CPC), began their cooperation. Since then, high-quality seismic profiles have been collected for the first time. Based on newly acquired high resolution seismic data, under the guidance of sequence stratigraphy, by using the technology to interpret seismic section and balanced section, and calculating the amount, velocity, acceleration changes of the formation in horizontal and vertical directions, This study made a summarization on stratigraphy, tectonic framework and evolution, and potentials of oil and gas resources. The results suggest that Jieyang Depression is a fault depression dominant by a NE-SW major deep fracture inclined to the continent. The deepest part of the detachment fault finally converged on the detachment surface. The rift-onset unconformity, the breakup unconformity, and the collision unconformity divide the Cenozoic strata of Jieyang Depression into three tectonic stages of rift, drift, and passive margin. Jieyang depression has the basic geological conditions for the formation of hydrocarbon. The Bottom simulating reflector (BSR, Bottom Simulating Reflector) characteristics shown on the seismic sections and possible igneous reservoir revealed the potential of unconventional oil and gas resources.
Description
Keywords
南海, 大陸邊緣, 減薄陸殼, 伸展速度, 伸展加速度, 揭陽凹陷, South China Sea, continental margin, continental crust thinning, extension rate, extension acceleration, Jieyang Depression