利用原子力显微镜研究致密砂岩储层黏土矿物形貌特征  

The Morphological Characteristics of Clay Minerals in a Tight Sandstone Reservoir by Atomic Force Microscopy

作　　者：王坤阳[1] 杜谷[1] 王冠 何佳乐[1] WANG Kunyang;DU Gu*;WANG Guan;HE Jiale(Chengdu Center,China Geological Survey,Chengdu 610081,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《岩矿测试》2025年第2期245-253,共9页Rock and Mineral Analysis

基　　金：国家自然基金青年科学基金项目“华南奥陶—志留纪之交氮循环及古海洋启示”(42102142)。

摘　　要：致密砂岩气作为非常规油气资源的重要组成部分,对其储层矿物学特征的研究一直以来都是非常规油气领域研究热点。黏土矿物作为致密砂岩储层的主要组成矿物之一,目前对其形貌特征的研究主要依赖于电子显微术,但受其表面电荷吸附性及样品表面导电膜二次改造的影响,很难对其表面形貌特征进行准确的精细刻画。然而,致密砂岩储层主体孔径在20~500nm,伊蒙混层黏土、绿泥石、伊利石等黏土矿物为纳米孔隙发育的主要矿物之一,随着致密砂岩储层微纳米孔隙系统的研究深入,黏土矿物纳米形貌特征的研究对于致密砂岩储层评价显得愈发重要,因此,对黏土矿物纳米/亚纳米形貌特征的研究对于储层评价具有重要的意义。本文利用原子力显微镜(AFM)观察到川西须家河组致密砂岩晚成岩阶段中伊蒙混层黏土矿物发育平行阶梯条纹,阶梯的两面凹角处形成了大量的纳米孔隙,是无机纳米孔隙的主要组成部分;绿泥石主要呈面平棱直的理想晶体生长终态,生长层在纵向上有规律地无隙叠置,晶体处于一个稳定的状态;伊利石发育平行阶梯条纹或波纹状阶梯,晶体形态不规则,处于亚稳定状态。其次,川西须家河组晚成岩阶段的黏土矿物构造背景相似、经历的成岩演化序列相同,但是通过AFM观察到川西须家河组晚成岩阶段不同种类黏土矿物晶体形态各异、晶面阶梯发育程度不尽相同,表明黏土矿物的形貌特征与成岩作用之间存在着空间耦合关系。Clay minerals,as one of the main components of unconventional oil and gas reservoirs,have significant implications for the evaluation of unconventional oil and gas reservoirs in terms of their fine characterization of nano/sub-nano morphological features.By using atomic force microscopy(AFM)micro-area analysis technology,the problem of secondary modification of nano-pore structure caused by the conductive film in the pretreatment process of electron microscopy was solved;it made up for the defect that electron microscopy requires the sample to be conductive and can directly observe the morphological characteristics of the sample.Here,it was observed through AFM,that in the late diagenetic stage of the tight sandstone of the Xujiahe Formation in western Sichuan,some clay minerals developed parallel stepped stripes,with a large number of nano-pores formed at the concave angles on both sides of the steps,which were the main components of inorganic pores.Secondly,clay minerals had the same diagenetic evolution sequence,but their crystal morphologies were different,indicating that there was a spatial coupling relationship between their morphological features and diagenesis.

关 键 词：原子力显微镜 致密砂岩 伊蒙混层黏土 绿泥石 伊利石 生长阶梯 川西须家河组 

分 类 号：P575.9[天文地球—矿物学] P618.13[天文地球—地质学]