鄂尔多斯盆地苏里格东三区上古生界沉积相研究

发布时间：2019-04-19 01:07

【摘要】：在借鉴前人研究的基础上,运用沉积学、地球物理学、沉积盆地分析等基本理论,结合区域地质背景、盆地周缘野外露头、岩心观察、测井资料等,对研究区山西组、下石盒子组盒8段进行了地层划分、物源分析,识别出主要的沉积相类型、分析沉积相及骨架砂体的平面展布特征,并建立沉积相模式。通过确定全区稳定分布的2个主要标志层、3个辅助标志层,将山西组、盒8段地层划分为山2段、山1段、盒8下亚段、盒8上亚段四个小层,各小层地层厚度变化不大、整体平缓、分布稳定。综合利用多种分析手段,探讨了苏里格东三区山西组、盒8段沉积期碎屑物质的来源。研究表明,研究区受到北部物源的影响,母岩主要为阴山古陆中部太古界、元古界的中-高级变质岩系。在物源研究的前提下,根据沉积相标志、单井沉积相分析及连井剖面对比,并结合鄂尔多斯盆地北部上古生界宏观的沉积环境,判断研究区山西组发育曲流河三角洲相,北部为三角洲平原环境,向南进入三角洲前缘沉积。山2期,湖岸线大致位于研究区中部,山1期,三角洲前缘亚相范围扩大。盒8段发育辫状河三角洲相,其突出特征表现为(水下)分流河道微相极为发育,受物源方向的影响,整体呈南北向延伸,较盒8下期,盒8上期湖岸线向北迁移,三角洲前缘沉积略有扩大。砂体的展布总体受沉积相带的制约,在主河道及河道的交汇部位形成厚层砂体,区域上为席状展布,其中盒8下段厚砂体最为发育,主要分布在研究区西北部沙尔利-河南、东南部艾好茆-青阳岔-坪桥一带,成为天然气勘探的重点。
[Abstract]:On the basis of the previous studies, using the basic theories of sedimentology, geophysics, sedimentary basin analysis and so on, combined with the regional geological background, field outcrop, core observation and logging data of the peripheral margin of the basin, the Shanxi formation of the study area is studied. The stratigraphic division, provenance analysis, identification of major sedimentary facies types, plane distribution characteristics of sedimentary facies and skeleton sand bodies were carried out in member 8 of Lower Shihehe formation box 8, and sedimentary facies models were established. By determining the stable distribution of two main marker beds and three auxiliary marker beds in the whole area, the strata of Shanxi formation and he-8 member are divided into Shan-2 section, Shan-1 section, box-8 lower sub-section and box-8 upper sub-segment, and the thickness of each sub-layer varies little. The whole is smooth and the distribution is stable. The source of detrital material in Shanxi formation and he-8 member of Suligdong-3 formation is discussed by means of comprehensive analysis. The study shows that the study area is affected by the northern provenance, and the parent rocks are mainly Archean in the middle part of Yinshan Paleocontinent and middle-advanced metamorphic rocks in Proterozoic. On the premise of provenance study, according to the sign of sedimentary facies, analysis of single well sedimentary facies and correlation of connecting well section, combined with the macro sedimentary environment of upper Paleozoic in northern Ordos basin, the meandering river delta facies of Shanxi formation in the study area was judged. The northern part is a delta plain environment, which moves southward into the delta front. The Lakeshore line is located in the middle part of the study area, the mountain stage 1, and the delta front subfacies are expanded. The braided delta facies is developed in member 8, which is characterized by extremely developed microfacies of (underwater) distributary channel, influenced by the provenance direction, extending southward as a whole, and moving northward as a whole compared with the next stage of he 8, and the lakeshore line moves northward in the last stage of he 8, and is affected by the provenance direction. The delta front deposit is slightly enlarged. The distribution of sand body is generally restricted by sedimentary facies zone, and the thick sand body is formed in the main channel and the intersection of river course, and is sheet-shaped in the region. The thick sand body in the lower section of box 8 is the most developed, mainly distributed in the northwest part of the study area, Shalli-Henan, where the sand body is distributed in the north-west of the study area. Southeast Ai Hao Mao-Qingyang Cha-Pingqiao area, has become the focus of natural gas exploration.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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