A series of investigations on both outcrops and drilling cores from the front edge of Daba Mountain were carried out.Organic-rich mudstones collected from the Wufeng-Longmaxi formations in Fengjie-Kaixian-Baiquan-Manyue areas were sampled and analyzed.Information was obtained from thin sections and Scanning Electron Microscopy (SEM), and some relevant laboratory tests including organic geochemistry, X-ray diffraction, He-porosity and permeability and Specific Surface Area were made to summarize the basic geological conditions of Wufeng-Longmaxi formations in the study area.The results show that the organic-rich mudstones in the front edge of Daba Mountain were probably formed in a shallow to deep shelf during the Late Ordovician-Early Silurian.The thicknesses of these mudstones range 40-70 m, and the average total organic carbon (TOC) content is more than 2%.The kerogen mainly shows characteristics of type Ⅰ.The thermal maturity of mudstones ranges 0.82%-3.04%, indicating a high to over mature stage.Additionally, the features of low permeability and low porosity as well as several types of pore microstructures were observed in these mudstones.The analyses of typical wells indicate that the preservation of shale gas is a key element for hydrocarbon accumulation.The well-preserved box-shaped anticlines are most favorable for shale gas preservation.%通过大巴山前缘地区五峰-龙马溪组富有机质泥岩的野外露头、钻井、岩心等资料的研究,对一系列岩石样品进行了显微薄片、扫描电镜、有机地化、孔渗性、比表面积、含气性解析等多项实验测试分析,对五峰-龙马溪组页岩气的富集条件进行了综合研究.结果表明:大巴山前缘地区富有机质泥岩总体处在浅水-深水陆棚沉积环境下,其沉积厚度在40~70 m左右,平均有机碳含量大于2%;有机质类型为腐泥型Ⅰ型干酪根,有机质成熟度多数为0.82%~3.04%,达到高-过成熟阶段;低渗透-低孔特征,并发育多种微观空隙结构.典型钻井解剖分析认为,页岩气保存条件是该区富集条件中最为关键的因素;未被断裂破坏的箱状背斜是最为有利的构造保存条件.
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