鄂尔多斯盆地上古生界构造演化、岩性与裂缝形成关系浅析

发布时间：2018-07-27 19:36

【摘要】：含油气盆地中,松散沉积物在沉降埋藏演化过程中一般会经历塑性压实、弹塑性压缩最后发生破裂。裂缝的形成不但可以构成油气的储集空间和运移通道,同时对油气藏的形成与分布有十分重要的意义。本文以鄂尔多斯盆地上古生界构造演化特征、地层岩性与沉积特征为基础,用砂泥岩声波时差曲线对沉积物沉降埋藏演化阶段进行划分并通过岩心、薄片、X衍射全岩矿物相对含量分析发育裂缝的岩性特征,取得以下主要认识：(1)构造分区及演化特征太原组底面现今构造划分为鄂托克旗—鄂尔多斯、鄂托克前旗—乌审旗一神木、环县—吴起—绥德、庆阳—富县—吉县四个凹隆区。太原组上覆岩层在不同地质时期演化过程中,盆地伊金霍洛旗—苏里格—靖边—子洲以东一直处于今古相似区,除此之外的其它区域处于今古差异区。(2)地层岩性与沉积特征构造凹隆区的低部位发育泻湖、浅湖、潮坪、水下分流河道和分支间流沉积,岩性主要是粘土岩、石英杂岩、粘土杂岩和煤；在凹隆区低部位周缘主要是三角洲平原和三角洲前缘沉积,岩性主要是石英砂岩、长石砂岩和少量杂岩。(3)沉积物沉降埋藏演化阶段划分及裂缝发育的岩性特征鄂尔多斯盆地砂、泥岩沉降埋藏演化过程大致可以划分为三个阶段：塑性压实段、弹塑性压缩段和破裂段,其中塑性压实段深度为1509米,1509～2218米之间为弹塑性压缩段,2218米以下进入了破裂段。破裂段山西组和下石盒子组裂缝普遍发育,其中石英砂岩、粘土岩和煤岩裂缝较发育,杂岩不发育裂缝或发育较差。发育裂缝的岩石主要有以下特征：在岩石成分上,石英、粘土等脆性矿物含量较高；在岩石结构上,颗粒接触紧密、结构较为均质。如果岩石中各种矿物含量较低且相近、结构致密混杂则不发育裂缝或发育较差。(4)鄂尔多斯盆地上古生界裂缝发育规律鄂尔多斯盆地上古生界裂缝普遍发育。裂缝最先开始发育在构造凹隆区的低部位或埋藏深处,并且构造凹隆区的低部位比高部位裂缝发育程度大。
[Abstract]:In petroliferous basins, loose sediments generally undergo plastic compaction during the process of subsidence and burial evolution, and finally fracture occurs under elastic-plastic compression. The formation of fractures can not only constitute the reservoir space and migration channel of oil and gas, but also play an important role in the formation and distribution of oil and gas reservoirs. Based on the structural evolution characteristics, stratigraphic lithology and sedimentary characteristics of Upper Paleozoic in Ordos Basin, this paper uses sonic time difference curve of sand and mudstone to divide sediment subsidence and burial evolution stage and pass through core. The lithologic characteristics of the developed fractures are analyzed by the relative content of the whole rock minerals by thin slice X-ray diffraction. The main conclusions are as follows: (1) the structural zoning and evolution characteristics of the Taiyuan formation are divided into Ortokeban-Ordos at present. Etok Qianqi-Wushenqi-Shenmu, Huanxian-Wuqi-Suide, Qingyang-Fuxian-Ji County four AoLong District. During the evolution of the overlying strata of Taiyuan formation in different geological periods, the basin has been located in the similar area of modern and ancient times to the east of Ekinholuo Banner-Sulige-Jingbian-Zizhou. In addition, the other regions are located in the modern and ancient differential areas. (2) the low part of the tectonic depression uplift area is characterized by lagoon, shallow lake, tidal flat, underwater distributary channel and interbranch flow deposition. The lithology is mainly clay rock and quartz complex. In the lower part of the uplift, the delta plain and delta front are the main deposits, and the lithology is mainly quartz sandstone. Feldspathic sandstone and a few complex rocks. (3) lithologic characteristics of sedimentary subsidence and burial evolution stage and fracture development in Ordos Basin. The burial evolution process of mudstone subsidence can be divided into three stages: plastic compaction section. Elasto-plastic compression section and fracture section, in which the depth of plastic compaction section is 1509 m / 1509 ~ 2218 m and the depth is less than 2218 m into the rupture section. The fractures of Shanxi formation and Xiashihezi formation in the fracture section are generally developed, among which quartz sandstone, clay rock and coal rock fractures are relatively developed, while the complex rocks are not developed or developed well. The main characteristics of the fractured rocks are as follows: the content of brittle minerals such as quartz and clay is relatively high in the rock composition, and in the rock structure, the particles are in close contact with each other and the structure is more homogeneous. If the mineral contents in the rocks are low and similar, and the structure is dense and mixed, the fractures will not develop or develop badly. (4) the Upper Paleozoic fractures in the Ordos Basin are generally developed in the Upper Paleozoic fractures of the Ordos Basin. The fractures first developed in the lower part or buried depth of the tectonic concave uplift, and the lower part of the tectonic concave uplift is more developed than that of the high part.
【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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