荆门探区五峰组–龙马溪组页岩储层特征及甜点层段评价

为进一步明确荆门探区五峰组—龙马溪组页岩气资源潜力，优选甜点层段，以X井五峰组–龙马溪组一段页岩为主要研究对象，利用干酪根薄片、X衍射、核磁共振、微纳米CT扫描及地化分析等多种测试手段，结合测井解释成果，从岩石学、有机地球化学、矿物组成、孔隙类型及结构、物性及含气性等方面，系统评价五峰组—龙一段各小层储层特征，以优选甜点层段。结果表明:五峰组—龙一段以硅质页岩为主，主要形成于深水陆棚相还原环境，优质页岩段页岩气品质较高，有机地化特征优越；多手段测试孔隙率与渗透率均具有正相关特征，饱和水页岩核磁共振T2谱可分为2类5型，不同类型T2谱所反映的页岩孔径分布特征具有差异性，孤立孔主要存在于小于2 nm的微孔中，占比非常小；基于储层特征评价，优选出龙一$_1^1$—龙一$_1^2$小层为一类储层，五峰组上段和龙一$_1^3$小层为二类储层，龙一$_1^4$小层为三类储层，富碳高硅页岩段的五峰组上段—龙一$_1^3$小层(厚度约17.7 m)为页岩气甜点层段，研究成果可为荆门探区页岩气勘探开发确定水平井的靶体层段提供参考依据。 

Characteristics of the shale gas reservoirs and evaluation of sweet spots in Wufeng Formation and Longmaxi Formation in Jingmen exploration area

In order to further clarify the resource potential of shale gas from Wufeng Formation to Longmaxi Formation in Jingmen exploration area, sweet spots were selected. The shale in Wufeng Formation and 1th Member of Longmaxi Formation of the well X was taken as the research object in this study. Using sliced kerogen, X-ray diffraction, nuclear magnetic resonance, micro nano CT scanning, geochemical analysis and other testing methods, combined with logging interpretation results, based on the petrology, organic geochemical and mineral composition, physical properties, pore types and structure characteristics and hydrocarbon content, the reservoir characteristics of Wufeng-1th Member of the Longmaxi Formation were evaluated, and the longitudinal shale gas sweet spots were optimized. The results show that: (1) Wufeng-1th Member of the Longmaxi Formation is mainly composed of siliceous shale mainly forming the reduction environments in the deep shelf facies. The natural gas in the high-quality shale section has high natural gas quality and excellent organic geochemical characteristics; (2) There is a positive correlation between porosity and permeability measured by various methods. The NMR T2 spectrum of water -saturated shale can be divided into 2 types and 5 types. The pore size distribution of shale reflected by different types of T2 spectrum is different. The isolated pores mainly exist in micropores smaller than 2 nm, which accounts for a very small proportion; (3) Based on the comprehensive evaluation of reservoir characteristics Long $_1^1$- Long $_1^2$ layer were selected as type I reservoir, the upper Wufeng Formation and Long $_1^3$ layers were classified as type Ⅱ reservoirs, and Long $_1^4$ layer as type Ⅲ reservoir. The upper Wufeng Formation-Long₁3 small layer (about 17.7 m thick) namely carbon-rich high silicon shale section is a shale gas sweet spot. The research results can provide a reference for determining the horizontal well target segments for shale gas exploration and development in Jingmen exploration area.