| WANG Zhenfeng,JIANG Tao,ZHANG Daojun,WANG Yahui,ZUO Qianmei,HE Weijun. 2015. Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea. Acta Oceanologica Sinica, 34(4):1－10 |
| Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea |
| 南海西北部琼东南盆地深水沉积环境演化及其油气勘探意义 |
| Received:June 25, 2014 Revised:September 28, 2014 |
| DOI：10.1007/s13131-015-0645-4 |
| Key words:deepwater environment Qiongdongnan Basin hydrocarbon exploration central canyon submarine fan |
| 中文关键词: deepwater environment Qiongdongnan Basin hydrocarbon exploration central canyon submarine fan |
| 基金项目: |
| Author Name | Affiliation | E-mail | | WANG Zhenfeng | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | JIANG Tao | Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China
Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi 783-8502, Japan | taojiang@cug.edu.cn | | ZHANG Daojun | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | WANG Yahui | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | ZUO Qianmei | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | | | HE Weijun | Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited, Zhanjiang 524057, China | |
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| Abstract: |
| Over the past several years, a number of hydrocarbon reservoirs have been discovered in the deepwater area of Qiongdongnan Basin, northwestern South China Sea. These oil/gas fields demonstrate that the evolution of the deepwater sedimentary environment are controlling the formation and distribution of large-scale clastic reservoirs. Integration between seismic and borehole data were necessary to best clarify the distribution and quality of these deepwater reservoirs. Geochemical and paleobiological evidence from discrete samples was also applied to document specific information regarding the sedimentary environment. Results show that the Qiongdongnan Basin has existed as a thriving marine environment since Oligocene, when several rifting depressions developed throughout the entire Qiongdongnan Basin. Triggered by the faults activities, several distinct provenances supplied the coarse sediments, transporting and depositing them in deep parts of the rifting depressions. A fan delta system then formed nearby the source in the deeper area of these rifting depressions. The sedimentary environment of Qiongdongnan gradiationally became deepwater since early Miocene. Consequently, abundances of sediments were transported from Hainan Island and Southern Uplift, and then sunk into the basin center. The submarine fans revealed by many boreholes in this area verified them as good reservoir. Because the area reached its lowest sea level at late Miocene and the Southern Uplift subsidenced under sea level, not providing any sediment, so that the carbonate mesa and biorhythms characteristic of this area also developed during this period. In the west part of Qiongdongnan Basin, sediments transported from Vietnam increased in response to the Tibetan Uplift. Consequently, a central canyon developed along the center of Qiongdongnan Basin, which has been confirmed by several boreholes as a favorable hydrocarbon reservoir. The clarification of the deepwater sedimentary environment's evolution is potentially highly beneficial to future hydrocarbon exploration in the deepwater area of Qiongdongnan Basin. |
| 中文摘要: |
| 近几年来,在南海西北部琼东南盆地深水区已经发现了许多油气田.这些油气田的发现表明,该区深水沉积环境的演化控制了这些大型碎屑沉积体的形成和分布.因此,通过钻井和地震的综合研究去更好地阐明这些深水油气储层的特征和分布显得十分迫切.尤其是来自于岩心和岩屑样品中的古生物和地球化学证据能够更好地确定其所处的具体沉积环境.研究结果表明,琼东南盆地自渐新世就已经存在海相环境,该时期盆地内发育了数个裂陷期的凹陷.受构造活动控制,临近的数个分散的物源区提供了大量粗碎屑沉积物以扇三角洲的形式充填在这些凹陷中.早中新世,琼东南盆地逐渐转变为深水沉积环境,来自于海南岛和南部隆起区的大量沉积物充填在盆地中心形成海底扇,这些海底扇已经被钻井证实能够作为良好油气储层.晚中新世,由于强制性海退以及南部隆起区已经沉没于水下,盆地中心总体缺乏碎屑沉积物的供给,发育了碳酸盐岩台地和生物礁.而在盆地西部,受青藏高原隆升影响,来自越南崑嵩隆起物源供给量增加,导致了沿盆地轴向分布的中央峡谷的形成,这也已经被钻井证实能够作为良好油气储层.总之,澄清该盆地深水沉积环境的演化将对琼东南盆地深水区进一步的油气勘探中深水储层的落实具有重大意义. |
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