西湖凹陷中下始新统宝石组沉积相研究

Sedimentary Facies of Middle-Lower Eocene Baoshi Formation in Xihu Sag, East China Sea Shelf Basin

李昆 周兴海 吴嘉鹏 万丽芬 谢春雨

LI Kun ZHOU Xinghai WU Jiapeng WAN Lifen XIE Chunyu

中国石油化工股份有限公司上海海洋油气分公司勘探开发研究院, 上海 200120; 中国石油长城钻探工程有限公司解释研究中心, 北京 100101

Institute of Exploration and Development, SINOPEC Offshore Oil & Gas Company, Shanghai 200120, China; Geoscience Centre of Great Wall Drilling Company, CNPC, Beijing 100101, China

西湖凹陷是东海陆架盆地主要的含油气凹陷，2001年B1井首次揭示了宝石组。宝石组沉积于早中始新世，为凹陷强烈断陷期的产物。由于其埋藏深度大，钻井资料少，对沉积相带分布与沉积特征认识尚处于起步阶段。此文从地震和钻井两方面入手，探讨了宝石组沉积相带分布格局，明确了宝石组总体属半封闭浅海的沉积环境。在凹陷西侧发育三角洲、扇三角洲及潮坪沉积、东侧发育小规模的扇三角洲沉积，凹陷中央以局限浅海沉积相为主。研究结果为西湖凹陷新领域油气勘探提供地质依据。

Xihu Sag is a hydrocarbon-rich sag in the East China Sea Shelf Basin. Well B1, drilled in 2001, revealed the existence of Baoshi Formation in Xihu Sag for the first time. Baoshi Formation, deposited in early-middle Eocene, is the product of strongly fault depression period. Due to the deep burial and the scarcity of drilling data, the understanding of the sedimentary facies distribution and sedimentary characteristics is still at the starting stage. Based on the seismic data and information of drilling wells, this paper discusses the distribution pattern of sedimentary facies in Baoshi sedimentation period, confirms it was generally belonged to the semi-closed shallow sea environment. It is suggested that delta, fan-delta and tidal flat deposits were developed along the west flank of the sag, small-scaled fan-delta deposits along the east flank, and the deposits of semi-closed shallow sea in the middle of the sag. It provides geological basis for the exploration of oil and gas in the frontier of Xihu sag.

https://doi.org/10.3969/j.issn.1008-2336.2017.01.016