层状页岩微观结构和力学特性的实验研究

Shale gas has become a significant resource in the oil and gas exploration and development in the world. The investigation on the mechanical properties and microstructures of layer shale has also become key scientific problems. At present, some research works have been done through uniaxial/ triaxial rock mechanical testing and SEM observation of the microstructures at home and abroad. But the mechanical properties and microstructures of shale can not fully described only by pressure and surface observation because the shale is in the environment of geostress, earth temperature, drilling fluid, fracturing fluid and shale gas. The experimental techniques are developed on mechanical properties testing and microstructures evolution observation for layer shale under coupling multi-field effect. The parameters of mechanical properties for shale laminated structure and leaf shale, such as Elasticity modulus, Poisson's ratio and compression strength will be given. Crack initiation and propagation in the shale will be analyzed under impact-extrusion effect. Microstructures evolution of internal shale under coupling multi-field effect will be acquired by synchrotron radiation computed tomography techniques. The research activities will reveal the fracturing mechanism, enhanced permeability effect and gas-fluid migration pattern. It will also provide a theoretical support and scientific basis for the exploration and production of shale gas.

页岩气作为一种新的重要能源，已成为全球油气资源勘探开发的新亮点，而与此紧密相联的层状页岩力学特性和微观结构研究成为目前亟待解决的关键科学问题。目前国内外学者开展了单轴、三轴岩石力学实验和扫描电镜观测等相关研究工作。但页岩在钻井和开采过程中处于地应力、地温、钻井液、压裂液、页岩气等多场耦合作用下，单一的压力作用和表面观察难以描述页岩的力学特性和微观结构演化。本项目提出在温度、钻井液、压裂液、气体等多场耦合作用下层状页岩力学性能参数和微观结构演化检测的实验技术和方法，研究页岩复合层压结构及其片状页岩在上述环境下的压缩弹性模量、泊松比和压缩强度；冲击挤压作用下裂缝的萌生和扩展特征；采用同步辐射CT技术获取页岩在多场耦合作用下的微观结构演化及裂缝萌生和扩展规律，揭示页岩气储层的体积压裂机理、裂隙活化增渗效应和气液运移规律。为页岩气勘探开发提供理论支持和科学依据。

页岩气作为一种新的重要能源，已成为全球油气资源勘探开发的新亮点，而与此紧密相联的层状页岩力学特性和微观结构研究成为目前亟待解决的关键科学问题。目前国内外学者开展了单轴、三轴岩石力学实验和扫描电镜观测等相关研究工作。但页岩在钻井和开采过程中处于地应力、地温、钻井液、压裂液、页岩气等多场耦合作用下，单一的压力作用和表面观察难以描述页岩的力学特性和微观结构演化。本项目为此首先研制了一套用于页岩力学特性和微观结构演化的仪器系统，该系统可以进行高温、高压等极端环境多场耦合作用下的材料内部三维微结构及其演化的观测实验；并开展了同步辐射多场耦合力学加载原位实验方法的研究，包括衍射衬度成像方法研究、局部重建和稀疏重建图像处理研究；开展了层状页岩内部微结构损伤演化、力学特性和机理分析研究，揭示了页岩的微结构演化规律。获得了页岩在多场耦合作用下的微观结构演化及裂缝萌生和扩展规律，揭示了页岩气储层的体积压裂机理、裂隙活化增渗效应和气液运移规律。