沉积环境对细粒沉积岩微观结构的影响——以鄂尔多斯盆地延长组7段页岩为例
Effects of sedimentary environment on microstructures of fine-grained rocks:a case study of the Yanchang Formation 7 Member shale in the Ordos Basin as an example
解馨慧 1邓虎成 2胡蓝霄 2毛金昕 2刘佳杰 3夏宇 4王园园 5张鑫3
作者信息
- 1. 成都理工大学地球物理学院,四川成都 610059;成都理工大学地球物理博士后流动站,四川成都 610059
- 2. 成都理工大学能源学院,四川成都 610059
- 3. 成都理工大学地球物理学院,四川成都 610059
- 4. 中海石油(中国)有限公司天津分公司,天津 300459
- 5. 中海石油(中国)有限公司海南分公司,海南海口 570100
- 折叠
摘要
细粒沉积岩微观结构特征是岩石的基本属性,影响细粒沉积岩的物理化学行为.以鄂尔多斯盆地延长组7段页岩为例,根据多尺度多视域扫描电镜拼接和图像识别技术,分析细粒沉积颗粒的几何形貌特征,探讨沉积环境对细粒沉积颗粒几何形状和排列结构特征的影响.结果表明:研究区半深湖-深湖相细粒沉积颗粒为细颗度(2～3 μm)、扁平和棱角形,颗粒沿某一段连续区间呈定向分布,强度分布呈扁平的仿锥状,定向排列程度好;浅湖相细粒沉积颗粒为中细颗度(2～8 μm)、扁平和棱角形,颗粒沿某一区间呈尖状分布,规律性不明显,定向排列程度中等;三角洲相细粒沉积颗粒为细粒度(8～12 μm)、似圆形,颗粒分布杂乱无章,强度分布呈似圆形或椭圆形.颗粒周长棱角性指数和扁平度越好,越有利于定向排列结构的形成;颗粒各向异性率和粒度越大,越不利于定向排列结构的形成.该结果有助于了解细粒沉积岩的微观结构特征,建立岩石微观结构和宏观结构的联系.
Abstract
The microstructure characteristics of rocks are the internal basic properties of fine-grained rocks,which affect their physicochemical behavior.This paper takes an example as fine-grained grains in the Yanchang Formation 7 Member of Ordos Basin.First,the geometric morphology characteristics of fine-grained grains are analyzed quantitatively by field scanning electron microscope and image recog-nition technology.Then,we characterized the influence of the sedimentary environment on the geomet-ric shape and orientation arrangement of fine-grained grains.Results show that the grains in the deep-semi-deep lacustrine facies take the characteristics of fine grain size(2-3 μm),flat and angular shape.The grains are directionally distributed along with a continuous interval.The intensity of the distribu-tion shows a flat quasi-cone shape and well-directional orientation.The fine grains in shallow lake facies are medium-fine grains(2-8 μm),flat and angular type.Besides,the grains show a sharp distribution a-long with a certain interval with no obvious regularity,which has a moderate orientation arrangement.The fine grains in delta facies are fine-grained(8-12 μm)and quasi-circular type.This type of fine-grained rock has an irregular distribution.The intensity distribution of fine grains is circular or ellipti-cal.The circumferential angularity index and flatness of grains can promote the formation of oriented ar-rangement structure of grains.By contrast,the anisotropy rate and grain size are unfavorable for the formation of an oriented structure.The results are helpful to understand the microstructural characteris-tics of fine-grained rocks and establish the relationship between microstructures and macrostructures of rocks.
关键词
细粒沉积岩/微观结构/几何特征/定向排列/扫描电镜/页岩/延长组7段/鄂尔多斯盆地Key words
fine-grained rock/microstructure/geometric features/orientation arrange/scanning elec-tron microscope/shale/Yanchang Formation 7 Member/Ordos Basin引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
万方数据