湖相细粒沉积岩颗粒微观力学特征及类型划分——以鄂尔多斯盆地上三叠统延长组7段页岩为例  

Micromechanical characteristics and classification of the grains of lacustrine finegrained sedimentary rocks:A case study of shales in the 7^(th) member of the Upper Triassic Yanchang Formation,Ordos Basin

作　　者：解馨慧 邓虎成[3] 胡蓝霄 李勇[1] 毛金昕 刘佳杰 张鑫 李柏洋 Xie Xinhui;Deng Hucheng;Hu Lanxiao;Li Yong;Mao Jinxin;Liu Jiajie;Zhang Xin;Li Boyang(College of Geophysics,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Postdoctoral Mobile Station,College of Geophysics,Chengdu University of Technology,Chengdu,Sichuan 610059,China;College of Energy,Chengdu University of Technology,Chengdu,Sichuan 610059,China)

机构地区：[1]成都理工大学地球物理学院,四川成都610059 [2]成都理工大学地球物理博士后流动站,四川成都610059 [3]成都理工大学能源学院,四川成都610059

出　　处：《石油与天然气地质》2024年第4期1079-1088,共10页Oil & Gas Geology

基　　金：国家自然科学基金面上项目(42072182)。

摘　　要：细粒沉积岩蕴藏着丰富的油气资源,为了研究细粒沉积岩颗粒微观结构及力学特征,以鄂尔多斯盆地上三叠统延长组7段细粒沉积岩为例,开展了扫描电镜观察和纳米压痕实验分析,据此研究细粒沉积颗粒的几何特征和微观力学性质。研究认为:用粒径、扁平度、棱角性、硬度和弹性模量5个特征参数,可将细粒沉积岩划分为粒度+棱角型、扁平度+棱角型、扁平度+棱角+弹性模量+硬度型、弹性模量+硬度型、棱角+弹性模量+硬度型和粒度+棱角+弹性模量型6种主要颗粒类型;接着,根据颗粒类型的相对含量,进一步将颗粒类型划分为5种组合类型;最后,分析了细粒沉积颗粒类型与矿物类型之间的耦合关系。细粒沉积岩颗粒微观分类方案的建立,有助于理解细粒沉积岩微观结构特征,预测地质“甜点”空间分布,对细粒沉积岩的油气资源评价和效益开发具有重要的理论和科学意义。Fine-grained sedimentary rocks contain abundant hydrocarbon resources.To examine the microscopic structural and micromechanical characteristics of their grains,we explore such rocks in the 7th member of the Upper Triassic Yanchang Formation(also referred to as the Chang 7 Member)in the Ordos Basin.Using scanning electron microscopy(SEM)and nanoindentation experiments,we delve into the geometric characteristics and micromechanical properties of the grains of these rocks.The results indicate that based on five characterization parameters,namely grain size,flatness,angularity,hardness,and modulus of elasticity,the fine-grained sedimentary rocks in the Chang 7 Member can be categorized into six major grain types:grain size and angularity predominating;flatness and angularity predominating;flatness,angularity,modulus of elasticity,and hardness predominating;modulus of elasticity and hardness predominating;angularity,modulus of elasticity,and hardness predominating,and grain size,angularity,and modulus of elasticity predominating.Five types of grain assemblages can be further identified based on the relative contents of the six types of grains.Additionally,the coupling relationships between the grain types and mineral types of the fine-grained sedimentary rocks are determined.The proposed scheme for microscopic grain classification of finegrained sedimentary rocks assists in understanding the microscopic structural characteristics of fine-grained sedimentary rocks and predicting the spatial distributions of geological sweet spots,thus holding great theoretical and scientific significance for the hydrocarbon resource assessment and efficient hydrocarbon exploitation of fine-grained sedimentary rocks.

关 键 词：扫描电镜 纳米压痕 分类方案 细粒沉积岩颗粒 页岩 延长组7段 鄂尔多斯盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]