西湖凹陷渐新世层序地层格架与沉积充填响应

发布时间：2018-10-23 13:00

【摘要】：东海陆架盆地是中国近海最大的沉积盆地,而西湖凹陷又是其中规模最大的富油气凹陷。多年的勘探实践证明渐新统花港组为西湖凹陷主力产气层段,但其层序地层划分长期存在较大争议。在分析了西湖凹陷盆地结构与构造格局的基础上,依据测井、岩芯以及地震反射特征,将西湖凹陷渐新统划分出5个三级层序与12个体系域,建立了其等时地层格架;并通过大量岩芯的写实性描述,结合沉积构造与遗迹化石鉴别以及地球化学资料分析对沉积环境进行了判识,分析结果认为西湖凹陷渐新统花港组沉积时期发生过两次较大的海侵事件,形成"南海北陆"的沉积格局,并发育了河流、三角洲、潮控河口湾以及无障壁海岸四种沉积体系,其沉积体系类型较多,从南到北变化巨大。西湖凹陷渐新世整体表现为"东西短轴三角洲"、"南部潮汐河口湾"、"东北缓岸滩坝"的沉积体系展布格局。系统分析了沉积相在各层序中的展布特征及其对海平面变化的响应、层序演化过程及其对海平面变化的响应,构建了东海陆架盆地西湖凹陷构造—沉积成因模式,明确了"断坳转换,海陆交替"的盆地构造背景与沉积充填的响应关系。
[Abstract]:The East China Sea shelf basin is the largest sedimentary basin in offshore China, and the Xihu depression is the largest one. The exploration practice for many years has proved that Huagang formation of the Oligocene is the main gas-producing formation in Xihu sag, but its sequence stratigraphic division has been in dispute for a long time. On the basis of analyzing the structure and structure of Xihu sag basin, according to the characteristics of logging, core and seismic reflection, the Oligocene of Xihu depression is divided into 5 third-order sequences and 12 system tracts, and its isochronous stratigraphic framework is established. Through the realistic description of a large number of cores, combined with the identification of sedimentary structures and trace fossils and the analysis of geochemical data, the sedimentary environment is identified. The results show that there were two major transgressive events in the sedimentary period of Huagang formation of the Oligocene in Xihu Sag, which formed the sedimentary pattern of "the North Land of the South China Sea" and developed four sedimentary systems: rivers, deltas, tidal estuaries and unobstructed coasts. There are many types of sedimentary systems, which vary greatly from south to north. In the Oligocene of Xihu Sag, the distribution pattern of sedimentary system is "East-West short axis delta", "southern tidal estuary bay" and "northeast gentle bank bar". The distribution characteristics of sedimentary facies in each sequence and its response to sea level change, sequence evolution process and its response to sea level change are systematically analyzed. The tectonic-sedimentary genetic model of Xihu sag in the East China Sea shelf basin is constructed. The response relationship between sedimentary filling and tectonic setting of "fault-depression transformation, sea-land alternation" is clarified.
【作者单位】：中国地质大学(北京)能源学院;中国石油大学(北京)地球科学学院;中海油上海分公司勘探开发研究院;
【基金】：国家科技重大专项项目(2011ZX05023-001-009) 中国博士后科学基金项目(2015M581269) 国家自然科学基金项目(41572080)~~
【分类号】：P618.13

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