編號： 015

題　名：台灣第三紀地層之油氣探勘

The Hydrocarbon Exploration to the Tertiary Strata in Taiwan .

研究者：李長之 ; 丁信修 ; 梅文威 ; 莊恭周 ; 楊耿明 ; 周定芳 Lee, Chang-Jie ; Ting, Hsin-Hsiu ; Mei, Wen-Wei ; Chuang, Kung-Chou ; Yang, Kenn-Ming ; Chou, Ting-Fang

機構名稱：中國石油公司探採研究所 (TPEO)

研究日期： 1995/07 - 1996/06

頁冊數： 258頁

中文摘要：古第三系盆地多由大規模的正斷層活動形成封閉或獨立的構造盆地 ,其沈積相的組合完全視其封閉程度而定。這種盆地不可能堆積大而厚的沈積砂體和生油岩層。因此,決定油氣潛能的因素除了在於該沈積盆地的規模之外,更重要的還在於沈積盆地內地層中有機碳的富集度,在這種獨立的半地塹盆地或者張裂型盆地,生油主要來自陸相的湖泊沈積,所以盆地與外海的連通性高,則反而不利於有機碳聚集和保存。古第三紀留存之三個縱排的構造盆地中,以東引島盆地的規模最大,故其湖相沈積體積也最大,其他依序則為南日島,澎湖盆地。另外在澎湖脊以南到佳里斷層之間,可能在古第三紀形成一個張裂性盆地,有相當厚的疑似始新世頁岩,並含頗高的TOC,應當是一個值得注意的古第三系探勘目標。新第三系盆地與古地三系盆地的最大不同,即其為真正的沈積盆地而非構造盆地,所以幾乎都是海相沈積。這些海相沈積的有機碳富集度並不高,只有煤系地層才能孕育大量的油氣。此外北部煤田可能向北延伸到南彭佳嶼盆地的南半部,因此南彭佳嶼盆地南半部與台西盆地的連通情形、沈積環境變化及北部煤田的伸展狀況都值得再詳細研究,其生油潛能或許不弱於台西盆地的竹苗地區,是第三系探勘值得注意的目標。

英文摘要： Most of the Paleogene basins are isolated and restricted tectonic basins that were formed by large scale of normal faulting and the sedimentary facies in these basins are dependent on how these basins were isolated. In general, vast and thick source beds and reservoir sandstones are not possibly deposited in such kinds of basin. Meanwhile, beside the scale of sedimentary basin, the more important factor that affects hydrocarbon potentiality is concentration of total organic carbons, which is highly related with the lithofacies in the sedimentary basins. This study indicates that source beds were deposited in terrestrial lacustrine environment in such kinds of isolated basin of half-graben or rifted basin; therefore, fair connection between the basins and the adjacent open seas would be disadvantageous to accumulation and preservation of organic carbons. From this point of view, we can better reevaluate the hydrocarbon potentiality in the Paleogene basins. Among the tectonic basins to the west, which lie in longitudinal array, the Tungyintao Basin is the largest in scale and accumulates largest volume of lacustrine deposits. The second and the third largest basins and volume of lacustrine in turn are the Nanjitao and Penghu basins. Besides these basins, there might be another Paleogene rifted basin located containing high TOC have been found in this basin and make this basin highly worthy to be another target for the exploration on the Paleogene basins. The primary difference between the Neogene and the Paleogene basins is that the former are rather merely sedimentary basins than tectonic basins. The concentration of organic carbons is not fair within the marine deposits and only coal beds are the possible source for hydrocarbons produced from these deposits. The coal fields in the northern Taiwan might extend northward into the southern part of the South Pengchiahsu Basin . Therefore, it is worth to study in details the connective situation between the southern part of the South Pengchiayu and the Taihsi basins, the variation in the sedimentary environments and the extent of the northern coal fields; the potentiality of generating hydrocarbon in the southern part of the South Pengchiahsu area might be as fair as that in the Miaoli-Hsinchu areas in the Taihsi Basin, and the area can be another target area for the exploration on the Tertiary strata.