坝上河-滩坝微相组合特征——以柴北缘南八仙油气田新近系下油砂山组为例  

Characteristics of upper distributary bar and beach-bar microfacies assemblages:a case study of Neogene Xiayoushashan formation in Nanbaxian oil and gas field on northern margin of Qaidam basin

作　　者：张振铎 姚宗全 穆波宇 涂加沙 潘品百 ZHANG Zhenduo;YAO Zongquan;MU Boyu;TU Jiasha;PAN Pinbai(School of Geology and Mining Engineering,Xinjiang University,Urumqi 830047,China;Central Asian Geology and Mineral Information Integration Autonomous Region Key Laboratory(Xinjiang University),Urumqi 830047,China;Exploration and Development Research Institute of PetroChina Qinghai Oilfield Branch,Dunhuang,Gansu 736202,China)

机构地区：[1]新疆大学地质与矿业工程学院,乌鲁木齐830047 [2]中亚地质矿产信息集成自治区重点实验室(新疆大学),乌鲁木齐830047 [3]中国石油青海油田分公司勘探开发研究院,甘肃敦煌736202

出　　处：《中国科技论文》2023年第9期942-955,共14页China Sciencepaper

基　　金：国家自然科学基金资助项目(41902109);天山青年计划项目(2020Q064)。

摘　　要：为了深入评价柴达木盆地北缘南八仙油气田新近系下油砂山组砂体的油气勘探前景以及预测有利勘探区带和勘探目标,在岩心观察和钻测井资料综合分析的基础上,通过岩石学特征、泥岩颜色、粒度特征、沉积构造等沉积相标志综合分析,再结合单井相及连井相对比,精细刻画出南八仙油气田下油砂山组坝上河-滩坝微相组合沉积特征,并剖析了研究区沉积微相平面展布特征。结果表明:新近系下油砂山组属于辫状河三角洲前缘-滨浅湖沉积体系,并主要发育坝上河-滩坝微相组合;坝上河可分为以河为主式、对称式和以坝为主式3种类型,并随着河流作用由强到弱,湖水阻力由弱到强,组合逐渐由以河为主式演变为对称式进而演变为以坝为主式;滩坝区别出有滩无坝及滩坝共生2种类型,其中有滩无坝的远岸滩砂发育规模较小,分布范围局限且较为零散,滩坝共生的近岸砂体面积较大呈席状分布,远岸砂体多孤立呈土豆状分布。最后,根据沉积微相的展布特征建立了研究区辫状河三角洲前缘-滨浅湖的沉积相模式,研究区的水下分流河道、周边的坝上河复合砂体及近岸滩坝是主要的优势储层。研究可为油气田下一步挖潜提供地质依据。This work aims at a in depth evaluation of the oil and gas exploration prospects of the sand body of the Neogene Xiayoushashan formation of the Nanbaxian oil and gas field in the northern margin of Qaidam basin,as well as the prediction of the favorable exploration zone and exploration targets.On the basis of the comprehensive analysis of core observation and drilling and logging data,the combined sedimentary characteristics of upper distributary bar and beach-bar microfacies in the Xiayoushashan formation of Nanbaxian oil and gas field were finely delineated through the comprehensive analysis of sedimentary facies such as petrological characteristics,mudstone color,particle size characteristics,sedimentary structure,lithofacy combination characteristics,etc.,combined with the relative ratio of single well facies and connected wells,and the sedimentary microfacies plane spread characteristics of the study area were analyzed.The results show that the Neogene Xiayoushashan formation belongs to the braided river delta front-coastal shallow lake sedimentary system,and mainly develops the micro-facies combination of the upper distributary bar and the beach dam;the upper distributary bar can be divided into three types:river-based,symmetrical and dam-based.Moreover,as the river action changes from strong to weak,the lake water resistance changes from weak to strong,and the combination gradually evolves from river-based to symmetrical and then to dam-based.Beach dams distinguish between beach without bar and beach dam symbiosis,the development scale of far-shore beach sand with beaches without bar is small,and the distribution range is limited and relatively scattered,the near-shore sand bodies with symbiosis between beach and dam are relatively large and mat-like,and the far-shore sand bodies are mostly isolated and potato-shaped.Finally,according to the spread characteristics of sedimentary microfacies,the sedimentary facies model of the braided river delta front-coastal shallow lake in the study area is established.I

关 键 词：坝上河 滩坝 微相组合 辫状河三角洲前缘-滨浅湖 下油砂山组 沉积特征 

分 类 号：P62[天文地球—地质矿产勘探]