基于纳米尺度的碎屑岩骨架矿物结构研究

对胜利油田胜坨地区碎屑岩储层岩芯样品和岩石薄晶片分别采用场发射扫描电镜、透射电镜进行镜下观察与能谱测试分析。结果表明:碎屑岩中骨架矿物石英和长石中存在纳米尺度的结构特征;石英镜下可见类蚀像凹坑、雏晶单晶、平行脊线、晶体位错、类包裹体晶内核等5种纳米尺度的结构;长石镜下可见晶面平行凹痕、溶蚀针、纳米级薄层断阶、长石高岭石化、晶体位错和超微包裹体等6种纳米尺度的结构;这些结构大多在几百纳米的尺度范围内,有的甚至只有几十纳米;矿物在纳米尺度上表现出的结构特征与其本身的硬度变化、晶体晶格缺陷、晶体生长过程以及成岩作用的显微表现和显微构造应力改造作用有关。对碎屑岩骨架矿物中纳米尺度结构特征的进一步研究有望为岩石显微变形的应力作用机制和方式以及溶解作用等成岩作用模式做出有效分析,进而为油气勘探开发提供新的探索方式。

Study on Clastic Rock Framework Mineral Structure Based on Nanoscale

The core samples of clastic reservoir and thin crystalloids in Shengtuo Area of Shengli Oilfield were observed and measured by scanning electron microscopy(SEM)and transmission electron microscopy(TEM). The results showed that there were the nanoscale structure characteristic in framework mineral quartz and feldspar of clastic rock; characteristics of the main nanoscale structures developed in quartz were pits similar as erosion, young single crystal, parallel ridge, crystal dislocation and grain kernal inclusion; characteristics of the nanoscale structures in feldspar were parallel dent on the crystal plane, dissolution needle, nanoscale thin layer of broken band, kaolinization of feldspar, crystal dislocation and micro-inclusion; most of them were in several hundred nanometers, and some were even just tens of nanometers; characteristics of the nanoscale structure of mineral were related to the hardness, crystal lattice defects, crystal growth, microscopic manifestation of diagenesis and transformation of microscopic tectonic stress. The further study on the nanoscale clastic rock framework mineral structure could help to find the mechanism and modality of microscopic deformation stress and the diagenesis pattern such as dissolution, and thereby could provide new view for the petroleum exploration.