Evolution of deepwater sedimentary environments and its implication for hydrocarbon exploration in Qiongdongnan Basin, northwestern South China Sea

作     者：WANG Zhenfeng JIANG Tao ZHANG Daojun WANG Yahui ZUO Qianmei HE Weijun 

作者机构：Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of Geosciences Kochi Institute for Core Sample Research Japan Agency for Marine-Earth Science and Technology 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2015年第34卷第4期

页      面：1-10页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：The National Science and Technology Major Project of China under contract No.2011ZX05025-002-02 the National Natural Science Foundation of China under contract Nos 41476032 and 41372112 

主　　题：deepwater environment Qiongdongnan Basin hydrocarbon exploration central canyon submarine fan 

摘      要：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 evol