白云凹陷恩平组沉积晚期大型三角洲发育特征及其意义  

Development Characteristics and Significance of Large Delta of Upper Enping Formation,Baiyun Sag

作　　者：曾智伟[1,2] 杨香华[1,2] 朱红涛[1,2] 夏晨晨 牛杏[1,2] 陈莹 韩银学 Zeng Zhiwei Yang Xianghua Zhu Hongtao Xia Chenchen Niu Xing Chen Ying Han Yinxue(Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education, China University of Geosciences, Wuhan 430074, China Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China CNOOC Research Institute, Beijing 100028, China)

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国地质大学资源学院,湖北武汉430074 [3]中海油研究总院,北京100028

出　　处：《地球科学（中国地质大学学报）》2017年第1期78-92,共15页Earth Science-Journal of China University of Geosciences

基　　金：国家科技重大油气专项项目(Nos.2011ZX05023-001-015;2011ZX05023-001-001)

摘　　要：白云凹陷恩平组沉积晚期发育大型的辫状河三角洲,但该三角洲的沉积过程、内部发育期次及平面分布规律尚不明确.基于9口钻遇恩三段的钻井资料,开展了砂岩碎屑锆石U-Pb定年及全区覆盖的三维、二维地震资料分析.结果表明恩平组不同沉积时期的主要物源供给方式:恩平组早-中期以白云凹陷四周隆起提供短程物源碎屑为主(母岩类型以中生代火成岩为主),恩平组沉积晚期白云凹陷与北部珠一坳陷开始连通,盆外大型水系携带华南褶皱带物源碎屑沿NW-SE方向进入白云凹陷沉积(母岩类型以古生代-前寒武系变质岩为主),大型三角洲开始发育.地震相及能量半衰时属性分析揭示了白云凹陷恩平组沉积晚期大型三角洲的沉积构成特征,即发育3期不断向东南方向进积的楔状体,其沉积规模由小到大,然后再变小,直至断陷消亡.恩平组沉积晚期三角洲煤系烃源岩及陆源海相烃源岩广泛发育,大型三角洲具备优越的生储盖组合,有利于形成三角洲前缘上倾尖灭油气藏,是白云凹陷深水区古近系油气勘探重要目标.A large-scale braided delta is developed in the late stage of the Enping Formation in the Baiyun sag, but the sedimentary process, the internal development stages and the plane distribution of the delta remain unclear. Based on the nine wells which penetrated the third member of the Enping Formation, the detrital zircon U-Pb dating and the 2D and 3D seismic data analyses were carried out in this paper. The sediment supply patterns of the Enping Formation in different depositional periods were determined. During the first-second members of Enping Formation （SQ1-SQ2）, sediments derived from the paleo-uplih were mainly composed of Mesozoic igneous rocks and are interpreted to have sourced via relatively short-distance transportation. During the third member of Enping Formation （SQ3）, the sediments oriented from South China folded belt （SCFB） which mainly consists of Preeambrian-Paleozoie metamorphic rocks. The sediments which are derived from SCFB and transported long-distance pathways through northwest-southeast orientation have deposited in Baiyun sag and the large-scale delta developed subsequently. Meanwhile, the sedimentary characteristics of large-scale delta of the SQ3 within Baiyun sag are described through typical seismic facies and the energy half-time seismic attribute analysis. The delta developed three stages of progradational wedges continuously to the southeast direction and with increasing scale initially, followed by decreasing scale until the rift hasin disappeared. The resuhs reveal that the deltaic coal bearing and terrigenous-marine source rocks are mainly developed in the SQ3 and thus the large-scale delta has an excellent accumulation condition of source-reservoir-cap rock assemblages. And the delta front sand bodies tend to develop the updip pinch-out reservoir which will become an important target for oil and gas exploration in Paleogene of Baiyun deep-water region.

关 键 词：三角洲 前积反射 物源体系 锆石U-PB定年 恩平组 白云凹陷 石油地质. 

分 类 号：P618.13[天文地球—矿床学]