尼日尔Termit盆地Koulele油田始新统浅水三角洲前缘沉积特征及成因模式  

Sedimentary characteristics and genesis model of the Eocene shallow-water delta front in the Koulele Oilfield,Termit Basin,Niger

作　　者：尹艳树[1] 黄圣斌 黄奇志[2] 谢鹏飞 王立鑫 吴伟[3] YIN Yanshu;HUANG Shengbin;HUANG Qizhi;XIE Pengfei;WANG Lixin;WUWei(School of Geosciences,Yangtze University,Wuhan 430100,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo 454003,Henan,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]中国石油勘探开发研究院,北京100083 [3]河南理工大学资源与环境学院,河南焦作454003

出　　处：《岩性油气藏》2025年第2期12-25,共14页Lithologic Reservoirs

基　　金：国家自然科学基金项目“利用任意二维沉积相剖面重构三维地质模型新方法”(编号:42372137)资助。

摘　　要：尼日尔Termit盆地Koulele油田油气资源丰富,准确预测砂体空间分布可为后续油藏勘探开发提供地质依据。综合利用岩心、测井及三维地震资料,在古地貌和物源供给条件分析的基础上,结合现代沉积对比,总结了研究区始新统晚期浅水三角洲前缘沉积特征并建立了沉积模式。研究结果表明:①尼日尔Termit盆地Koulele油田始新统晚期E1油组沉积期地形平缓、坡度较小、物源供给充足,主要发育浅水三角洲前缘沉积、典型牵引流沉积构造,岩性以粉—细砂岩、泥岩为主。测井曲线形态以箱形、钟形、指形、漏斗形及平直形5种类型为主,其中箱形和钟形占比大于70%。地震切片上呈分支条带状砂体和连片朵状砂体响应特征,剖面上可观察到河道充填的透镜状反射特征,未见明显的前积特征。地震智能融合反演预测出的砂体厚度图表现为单一指状向前延伸,部分呈分支条带状,末端分叉呈朵状连片发育,与现代指状砂坝三角洲形态类似。②研究区不同时期沉积微相的分布与演化特征存在差异。E1油组沉积早期,河道形态多为单一指状,弯曲度低,河口坝在河道末端呈朵状发育,规模较小,宽度小于100m,厚度为2~3m,延伸较近;E1油组沉积中期,河道和河口坝规模变大,河道出现分支现象;E1油组沉积末期,河道和河口坝砂体规模达到最大,河道弯曲度高,呈分支条带状展布,末端分叉,河口坝呈连片分布。③整体上,研究区三角洲内前缘多发育指状河道砂体,外前缘多发育连片朵状河口坝砂体,顺物源方向上河口坝发育规模逐渐增大,河道发育程度减弱,河道下切河口坝,呈“河在坝上走”的样式,垂向上砂体叠置发育。The Koulele Oilfield in the Termit Basin of Niger is rich in oil and gas resources.Accurate prediction of the spatial distribution of sand bodies can provide a geological basis for subsequent reservoir exploration and development.By comprehensively utilizing core,well logging,and 3D seismic data,and based on the analysis of paleotopography and sediment supply conditions,combined with modern sedimentary comparisons,the depositional characteristics of the late Eocene shallow-water delta front in the study area were summarized and a depositional model was established.The results show that:(1)During the deposition period of the E1 oil formation in the late Eocene of the Koulele Oilfield in the Termit Basin of Niger,the terrain was flat with a gentle slope and abundant sediment supply.Mainly shallow-water delta front deposits and typical tractional current depositional structures developed,with lithologies dominated by siltstone to fine sandstone and mudstone.The well logging curves are mainly characterized by five types:box-shaped,bell-shaped,finger-shaped,funnel-shaped,and straight,with box-shaped and bell-shaped curves accounting for more than 70%.On seismic slices,the sand bodies appear as branch-like strips and contiguous lobe-shaped features.Lenticular reflection characteristics of channel fills can be observed on cross-sections,with no obvious progradational features.The sand body thickness map predicted by seismic intelligent fusion inversion exhibits single finger-like extensions,some of which are branchlike strips with bifurcating ends that develop into contiguous lobe-shaped features,similar to the morphology of modern finger-bar deltas.(2)The distribution and evolution characteristics of sedimentary microfacies vary at different times in the study area.In the early deposition stage of the E1 oil formation,river channels were mostly single-finger shaped with low curvature.Mouth bars developed in a lobe shape at the ends of river channels,with a relatively small scale,a width of less than 100 m,a thickness o

关 键 词：沉积特征 浅水三角洲 分支条带状砂体 连片朵状砂体 指状砂坝 始新统 Koulele油田 Termit盆地 尼日尔 

分 类 号：TE122.23[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]