四川盆地五峰组—龙马溪组海相页岩具有良好的脆性,页岩经过压裂后可以产生复杂缝网,并成为页岩气产出的有效渗流通道.通过扫描电镜、电子探针和阴极发光等实验,分析了页岩矿物组成、光谱特征等;同时分析了页岩成岩演化过程,发现了海相页岩脆性形成的地质过程,并提出了页岩发生自生脆化的作用机制.研究认为富含有机质的页岩,在向中、高成熟的成岩演化过程中就会发生自生脆化作用,蒙脱石向伊利石转化的过程会产生自生石英,从而提高了页岩的脆性,并形成隐伏性的网状结构,这为后期改造提供了基础.

The marine shale of Wufeng Formation and Longmaxi Formation in Sichuan Basin has a good brittleness. After fracturing, the shale can generate complex fracture network and become effective seepage channels for shale gas production. Taking the marine shale of Sichuan Basin as an example, the composition and spectrum of shale minerals were analyzed by scanning electron microscopy, electron probe and cathodic emission. At the same time, the diagenetic evolution of shale was analyzed, and the geological process of brittle formation in the marine shale was found, and the mechanism of autogenous embrittlement of shale was put forward. It is considered that the shale rich in organic matter will undergo autogenous embrittlement in the process of shale evolution to medium-grade and high-grade diagenesis. The transformation process of montmorillonite to illite will produce authigenic quartz, thus improving the brittleness of shale and forming a concealed reticular structure, which provides a basis for later artificial fracturing.