龙马溪组页岩三维缝网重构及分形分析

发布时间：2018-05-06 20:06

本文选题：页岩 + 三维缝网　；参考：《工程地质学报》2017年06期

【摘要】：传统上研究含气页岩宏观缝网特征的方法多是基于小样品开展,通过观察小样品的裂缝展布特征来了解页岩的裂缝发育的宏观特性。但是这类方法因尺度过小,缺乏代表性,不能获取连续面上的裂缝特征,难以分析裂缝发育和地应力方向之间的关系。为获取更详细的大尺度含气页岩的宏观裂缝特征,本文从重庆市涪陵地区石柱县采样获取2m×3m×0.7m完整大尺度岩块,并采用有序标号切割来获取30cm~3规格岩样,在此基础上提取小岩样的表面裂缝并按照大尺度岩样切割的相对顺序构建三维裂缝网络。分析观测大尺度的三维裂缝网络可以发现,含气页岩的裂缝分布具有明显的规律性:水平主应力方向上的裂缝发育度普遍高于最小水平主应力方向;垂直方向上的裂缝与最小水平主应力的夹角为-62°。分维研究表明所有不同面上的裂缝均符合分维特性,说明小尺度裂缝特征和大尺度裂缝特征具有相似的规律性。此外,研究还表明最大水平主应力上的裂缝密度和分形维数最大,缝网结构最为复杂,最小水平主应力方向缝网结构次之,垂直主应力方向的裂缝结构最为简单;水平应力方向上主要以层理裂缝为主,垂直方向上以剪切缝为主,且与最小水平主应力的夹角为-62°。在掌握宏观裂缝分布特征基础上,研究可为页岩显微观测实验提供相应的理论依据。
[Abstract]:Traditionally, the methods of studying the macroscopic fracture network characteristics of gas-bearing shale are based on small samples, and the macroscopic characteristics of shale fracture development can be understood by observing the distribution characteristics of fractures in small samples. However, due to the small scale and lack of representativeness, this kind of method can not obtain the fracture characteristics on the continuous plane, and it is difficult to analyze the relationship between the fracture development and the direction of in-situ stress. In order to obtain more detailed macroscopic fracture characteristics of large scale gas-bearing shale, the intact large scale rock blocks of 2m 脳 3m 脳 0.7m were obtained from Shizhu County, Fuling area of Chongqing City, and the samples of 30cm~3 specifications were obtained by orderly cutting. On this basis, the surface cracks of small rock samples are extracted and 3D fracture networks are constructed according to the relative order of large scale rock samples. By analyzing the large scale 3D fracture network, it can be found that the fracture distribution of gas-bearing shale has obvious regularity: the fracture development degree in the horizontal principal stress direction is generally higher than that in the minimum horizontal principal stress direction; The angle between the fracture in the vertical direction and the minimum horizontal principal stress is -62 掳. The study of fractal dimension shows that all fractures on different planes accord with the characteristics of fractal dimension, which indicates that the characteristics of small scale fractures and large scale fractures have similar regularity. In addition, the fracture density and fractal dimension of the maximum horizontal principal stress are the largest, the crack mesh structure is the most complex, the crack mesh structure in the minimum horizontal principal stress direction is the second, and the crack structure in the vertical principal stress direction is the simplest. The horizontal stress direction is mainly stratified fracture, the vertical direction is shear joint, and the angle with the minimum horizontal principal stress is -62 掳. On the basis of mastering the distribution characteristics of macroscopic fractures, the study can provide corresponding theoretical basis for shale microscopic observation experiment.
【作者单位】：中国科学院地理科学与资源研究所;长安大学地质工程与测绘学院;中国科学院大学;
【基金】：中国科学院战略性先导科技专项(B类)(XDB10030300) 国家自然科学基金国家杰出青年基金项目(41525010);国家自然科学基金创新群体项目“地理时空数据分析”(41421001)资助
【分类号】：P618.13

【相似文献】