莱州湾洼陷带浅层岩性油藏富集机理与亿吨级油田新发现——以垦利10-2油田为例  

Enrichment mechanism of shallow lithologic reservoirs and newly discovered billion-ton oilfield in depression zone of Laizhou Bay Sag:A case study of KL10-2 Oilfield

作　　者：杨海风 石文龙 张中巧 王启明 王航 梁晓 YANG Haifeng;SHI Wenlong;ZHANG Zhongqiao;WANG Qiming;WANG Hang;LIANG Xiao(CNOOC China Limited,Tianjin Branch,Tianjin 300459,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《中国海上油气》2024年第4期23-36,共14页China Offshore Oil and Gas

基　　金：中国海洋石油有限公司“十四五”重大科技项目“地层岩性油气藏高效识别与精细评价技术(编号:KJGG2022-0303)”部分研究成果。

摘　　要：针对莱州湾凹陷深洼带浅层明下段油气成藏与富集机制不明的关键问题,利用钻测井、三维地震资料等综合分析,结合古环境、现代沉积类比、地球化学指标等分析,开展了砂体展布规律、油藏运聚模式研究,揭示了莱州湾凹陷洼陷带明下段沉积古环境与规模性砂体发育机制,建立了岩性油藏油气运移和大面积岩性油藏富集模式。研究表明:(1)明下段Ⅳ油组与Ⅴ油组水生草本植物占比高,化石丰度与分异度介于湖相与河流相之间,为典型的河湖交互沉积环境;测井曲线既有反映河流相砂体的正旋回特征、湖泊作用的反旋回特征,也有正、反复合旋回特征;受河流-湖泊沉积环境频繁交互、快速转换,共同组成了大面积展布、内部广泛连通的“枝蔓式”连片砂体。(2)油气经过陡坡带深层砂体中转站聚集,再通过边界油源断层运移至浅层,最后沿着浅层连片砂体向南部高部位运移;地化指标均具有长距离的运移效应,表现为“迂回式”的成藏特点。(3)明下段岩性油藏富集机制受控于连片砂体展布范围、砂体构型与泥岩封盖能力共同控制;油气先沿河道线状充注,再向湖漫砂体面状调整,形成了浅层砂体“先枝后蔓-枝蔓互联”的大面积连片含油场面;不同期次砂体构型差异控制油气富集程度,其中“枝蔓式”连片砂体保存能力优于孤立河道砂体,最大含油幅度可达117 m。新认识成功指导发现中国深洼带浅层首个大型高产岩性油田--垦利10-2油田,突破了被传统认定为渤海浅层勘探的“禁区”,开辟了渤海湾盆地深洼带浅层大型油田发现的新局面。In view of the key problem of unclear oil and gas accumulation and enrichment mechanism in the shallow lower member of Minghuazhen Formation in the deep depression zone of Laizhou Bay Sag,the sand body distribution rule and reservoir migration and accumulation pattern were studied by conducting a comprehensive analysis of drilling,logging,and 3D seismic data,as well as analysis of paleoenvironment,modern sedimentary analogy,and geological and chemical indexes.The sedimentary paleoenvironment and the development mechanism of large-scale sand bodies in the lower member of the Minghuazhen Formation of the depression zone in Laizhou Bay Sag were revealed,and the oil and gas migration model of lithologic reservoirs and the enrichment model of large-scale lithologic reservoirs were established.The results show that:①There is a high proportion of aquatic herbs in the IV oil group and the V oil group in the lower member of the Minghuazhen Formation,and the fossil abundance and diversity are between lacustrine facies and fluvial facies,which is a typical sedimentary environment featuring river-lake interaction.The well logging curves reflect the positive cycle of fluvial sand bodies,the reverse cycle of lacustrine action,and the positive and reverse cycles.Due to the frequent interaction and rapid transformation of the river-lake sedimentary environment,the“dendritic”contiguous sand bodies with large-area distribution and wide internal connectivity are formed.②Oil and gas accumulate through the deep sand bodies as a transfer station in the steep slope zone,then migrate to the shallow layer through the boundary oil source fault,and finally move southward along the shallow contiguous sand bodies for shallower layers.The geological and chemical indexes all have long-distance migration effects,showing the characteristics of“circuitous”reservoir formation.③The enrichment mechanism of lithologic reservoirs in the lower member of the Minghuazhen Formation is jointly controlled by the distribution range of contiguou

关 键 词：莱州湾凹陷 垦利10-2 明下段 枝蔓式 迂回式 洼陷带 勘探发现 

分 类 号：TE121[石油与天然气工程—油气勘探] P744.4[天文地球—海洋科学]