川东南五峰组—龙马溪组与黔东南牛蹄塘组页岩储层特征对比分析与差异性探讨

以川东南JY1井五峰组—龙马溪组与黔东南TX1井牛蹄塘组为例，依据矿物学、有机地球化学、孔隙结构、甲烷吸附性、岩石力学和裂缝发育特征等对页岩储层发育特征进行系统对比分析。结果表明：（1）龙马溪组储集空间以迁移有机质（固体沥青）内部有机孔为主，孔径较大，可达微米级；牛蹄塘组有机孔发育程度低，有机孔径普遍小于30 nm，碎粉状有机—无机矿物粒间孔为重要储集空间，裂缝发育程度高，孔隙结构更为复杂，甲烷吸附/解吸能力更强；五峰组孔隙与裂缝发育规模介于龙马溪组与牛蹄塘组之间。（2） TOC含量与脆性的分段式关系使储层孔隙与裂缝发育特征存在显著差异，当w（TOC）<6%时，五峰组—龙马溪组与牛蹄塘组TOC含量、脆性、有机/无机孔与裂缝协同发育；当w（TOC）>6%时，牛蹄塘组塑性增强使裂缝总量降低，但具有擦痕面的滑脱和压扭/张扭性裂缝数量增加，裂缝有效性与储集空间得到显著改善。（3）龙马溪组、五峰组和牛蹄塘组代表不同地质条件下储层演化的阶段性特征：随热演化、成岩和构造（与泄压）作用的增强，有机孔规模逐渐降低，孔隙结构趋于复杂，甲烷吸附/解吸能力增强，无机孔与裂缝对储集空间贡献逐渐增大。

Comparative analysis and discussion of shale reservoir characteristics in the Wufeng-Longmaxi and Niutitang formations: a case study of the well JY1 in SE Sichuan Basin and well TX1 in SE Guizhou area

Wells JY1 in the southeastern Sichuan Basin and TX1 in the southeastern Guizhou were used as examples for a systematic analysis of shale reservoir characteristics of the Wufeng-Longmaxi and Niutitang formations using mineralogy, organic geochemistry, pore structure, methane sorption, brittleness and fracture characteristics. (1) Organic pores with bigger pore sizes that could reach μm in the Longmaxi shale are well-developed in migrated organic matter rather than in in situ organic matter, which are the dominant reservoir spaces. However, organic pores in the Niutitang shale have lower amounts and sizes, commonly lower than 30 nm with more complicated pore structures. The inter-particle pores in the cataclastic organic-inorganic mineral masses are significant reservoir spaces and have stronger methane sorption and desorption capacities. (2) Due to the piecewise correlation between TOC content and brittleness, the developmental characteristics of pore and fracture have significant differences:when the TOC content is less than 6%, the TOC, brittleness, organic/inorganic pores and fractures had positive correlations; when the TOC content is greater than 6%, although the increase of ductility reduces the number of fractures, the lower cohesive strength, internal friction angle and more weak surfaces of interlayer fractures and cataclastic minerals favor to the development of slip fractures, which have significantly improved fracture effectiveness and reservoir space. (3) The Longmaxi, Wufeng and Niutitang shale respectively represent the characteristics of reservoir evolution under different geological conditions, i.e. with the thermal evolution, diagenesis and tectonic deformation and pressure relief, the size, scale and proportion of organic pores gradually decrease, the complexity of pore-fracture structure, methane sorption/desorption capacity and the proportion of inorganic pores and fractures in reservoir space gradually increase.