渤海湾盆地庙西北地区古近系沙河街组三段源-汇系统重建  

Reconstruction of source-to-sink system of the third member of Paleogene Shahejie Formation in Miaoxibei area,Bohai Bay Basin

作　　者：冯斌 黄晓波 何幼斌[1] 李华[1] 罗进雄[1] 李涛[1] 周晓光 FENG Bin;HUANG Xiaobo;HE Youbin;LI Hua;LUO Jinxiong;LI Tao;ZHOU Xiaoguang(School of Geosciences,Yangtze University,Wuhan 430100,China;Tianjin Branch of CNOOC,Tianjin 300452,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]中国海洋石油总公司天津分公司,天津300452

出　　处：《岩性油气藏》2024年第3期84-95,共12页Lithologic Reservoirs

基　　金：国家自然科学基金“内蒙古乌海地区奥陶系深水复合型及迁移型重力流水道形成机理”(编号:42272115)资助。

摘　　要：基于钻井岩心和三维地震资料,从物源岩性、分水岭和古水系、搬运通道3个方面对渤海湾盆地庙西北地区物源特征和沉积相展布进行了分析,并通过沉积区古地貌恢复和剥蚀物源区古地貌回溯重建了古近系沙河街组三段(沙三段)沉积时期的源-汇系统。研究结果表明:(1)渤海湾盆地庙西北地区古近系沙三段发育一个完整的近源搬运型源-汇系统,庙西北凸起为物源区,渤东凹陷为主要沉积区;庙西北凸起物源岩性包括中生界花岗岩、下元古界石英片岩及下元古界角砾岩;主分水岭沿凸起长轴呈近南北向展布,古水系散布其间,搬运通道主要为5个古沟谷和2个古断槽;渤东凹陷沙三段主要发育快速堆积的扇三角洲—湖泊相沉积,岩性主要为含砾砂岩、细砂岩及泥岩,分选性和磨圆度均较差,岩石成分及矿物组合均与庙西北凸起石英片岩及花岗岩较为匹配,扇三角洲沉积体呈近东西向展布,在渤东凹陷北部以连片朵状扇三角洲为主,南部为孤立朵状。(2)沙三段沉积期,庙西北凸起剥蚀作用具有“西强东弱”的特征,古分水岭逐渐向西迁移,凸起中部及北部物源面积大、垂向高差大,物源供给能力更强;渤东凹陷沙三段厚度为100~600 m,具有东南薄、西北厚的特征,沉积中心位于区域北部,且北部地层剥蚀作用更强,向东部延伸长度可达3.2 km;扇三角洲的发育位置受控于物源区搬运通道,其发育规模则受控于物源区域面积,渤东凹陷北部及中部扇三角洲沉积体规模更大,是勘探有利区。Based on drilling cores and 3D seismic data,the provenance characteristics and sedimentary facies distribution in Miaoxibei area in the Bohai Bay Basin were comprehensively analyzed from three aspects:source lithology identification,reconstruction of watershed river paleo-system and transport pathways,and the sourceto-sink system for the third member of Paleogene Shahejie Formation was reconstructed through the restoration of both paleo-geomorphological features within the sedimentary area and those within the denudation source area.The results show that:(1)A complete source-to-sink system of the third member of Paleogene Shahejie Formation has developed in Miaoxibei area,Bohai Bay Basin,with the provenance area located at Miaoxibei uplift and Bodong sag serving as the main sedimentary area.The source lithologies in Miaoxibei uplift comprise Mesozoic granite,Lower Proterozoic quartz schist,and Lower Proterozoic breccia.The primary watershed is distributed from south to north along the long axis of the uplift,with ancient water systems scattered within it.The main transport pathways consist of five ancient valleys and two ancient fault troughs.Fan delta-lacustrine facies deposits of the third member of Paleogene Shahejie Formation in Miaoxibei area are mainly characterized by rapid accumulation,mainly composed of gravel-bearing sandstone,fine sandstone and mudstone,with poor sorting and grinding degree.Rock composition and mineral association relatively match those found in quartz schist and granite located in Miaoxibei uplift.In northern Bodong sag,contiguous fan-shaped deltas dominate while isolated ones prevail in its southern part.(2)The denudation during the sedimentary period of Sha 3 member was pronounced in western Miaoxibei uplift and comparatively weaker in the eastern region,resulting in a gradual westward migration of the paleo-divide.The central and northern parts of Miaoxibei uplift exhibited a larger provenance area,significant vertical elevation differences,and a stronger supply capacity from the p

关 键 词：源-汇系统 分水岭 古水系 古地貌恢复 扇三角洲 古沟谷和古断槽 沙河街组三段 古近系 庙西北地区 渤海湾盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]