东海陆架盆地西湖凹陷渐新统花港组河湖交互沉积特征  

Fluvial to lacustrine alternating sedimentary characteristics of the Oligocene Huagang Formation in Xihu Sag,East China Sea shelf Basin

作　　者：秦兰芝 李宁 徐东浩 孙中恒 王维[2] QIN Lanzhi;LI Ning;XU Donghao;SUN Zhongheng;WANG Wei(Shanghai Branch of CNOOC China Limited,Shanghai 200335,China;China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335 [2]中国地质大学(武汉)资源学院,武汉430074

出　　处：《岩性油气藏》2025年第2期178-188,共11页Lithologic Reservoirs

基　　金：国家自然科学基金项目“浅水湖盆河湖交互沉积体系及其成因机理研究”(编号:42172127);中国海洋石油有限公司重大科技专项“东海西湖凹陷大中型气田勘探方向及关键技术研究”(编号:KJZX-2023-0101)联合资助。

摘　　要：根据钻井岩心、测井及三维地震等资料,通过沉积演化序列重建及沉积体系空间展布刻画等方法对东海陆架盆地西湖凹陷中南部黄岩地区花港组浅水湖盆河湖交互沉积特征与控砂机制进行了详细研究。研究结果表明:①东海陆架盆地西湖凹陷黄岩地区花港组自北向南主要发育三大沉积体系:河流-泛滥平原沉积体系、浅水三角洲沉积体系和湖泊沉积体系,可识别出河流相、浅水三角洲相与湖泊相3种沉积相类型。②黄岩地区花港组河湖交互沉积体系可划分为河控主体区、河湖交互区与湖控主体区3个沉积单元,河控主体区发育厚层含砾砂岩,地震相表现为低频弱振幅特征;河湖交互区发育厚层砂岩,泥质夹层增多,地震相表现为中低频、中弱振幅,以隐性前积、叠瓦状前积为主;湖控主体区泥岩较发育,地震相表现为中高频、中强振幅。③研究区花港组沉积期受微地貌与水位幕式升降控制,三级层序等时格架内有3种浅水湖盆控砂模式:洪水期湖泊主体区范围最大,三角洲主体没入水下,孤立砂坝发育;平水期湖平面下降,河湖交互区扩张,砂体在横向上呈席状连片发育,在垂向上砂体被分隔;枯水期主要发育河控主体区,河道萎缩形成网状,河道细砂岩较为发育。④黄岩地区发育多个反转背斜,其翼部具有发育大规模构造—岩性圈闭的潜力,洪水期的优质砂体富集于朵叶侧向叠置部位,枯水期的优质砂体富集于废弃河道处,枯水期的优质砂体富集于河道内部。Based on drilling core,well logging,and 3D seismic data,combined with evolution sequence reconstruction and spatial distribution depiction of depositional systems,the fluvio-lacustrine interactive depositional characteristics and sand-controlling mechanisms of Oligocene Huagang Formation in the shallow lacustrine basin of the Huangyan area,central-southern Xihu Sag of East China Sea shelf Basin were studied.The results show that:(1)There are three major depositional systems,including river-floodplain,shallow delta,and lacustrine systems,primarily developed from north to south in the Huagang Formation of the Xihu Sag.Huangyan area in central-southern region characterized by three sedimentary facies types:fluvial,shallow delta,and lacustrine.(2)The fluvial-lacustrine interaction system of the Huagang Formation in the Huangyan area can be subdivided into three distinct sedimentary units:river-dominated main area,fluvial-lacustrine transitional zone,and lake-dominated main area.The main area of the river control zone is developed with thick layers of gravel sandstone,and the seismic facies exhibit low-frequency weak amplitude characteristics;The interaction zone between rivers and lakes is characterized by the development of thick sandstone layers and an increase in mudstone interlayers.The seismic facies show low to medium frequency and weak amplitude,mainly consisting of implicit progradation and imbricate progradation;The mudstone in the main area of the lake is relatively developed,and the seismic facies are characterized by medium to high frequency and moderate to strong amplitude.(3)During the deposition of the Huagang Formation in the Huangyan area,micro-geomorphology and episodic fluctuations in water levels played pivotal roles.Within the isochronous framework of third-order sequences,three sand-controlling models for shallow lacustrine basins were established:During flood periods,the lake-dominated zone reached its maximum extent,with the main delta body submerged underwater and isolated sandbars developed.

关 键 词：浅水湖盆 河湖交互沉积 浅水三角洲 古地貌 水位幕式升降 河道 花港组 渐新统 黄岩地区 西湖凹陷 东海陆架盆地 

分 类 号：TE122[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]