Continental shales with abundant oil resources often have poor brittleness, which hinders their successful development. To find favorable areas for shale oil development, a comprehensive analysis of the relationships among shale oiliness, fracability, and paleoclimate was conducted for the Biyang depression, where the first breakthrough in the development of continental shale oil in China was made. A number of different analytical techniques were used, including major and trace element analyses, bulk mineralogy, and scanning electron microscopy–energy-dispersive spectroscopy–cathodoluminescence. The results reveal that the paleoclimate during the deposition of the Hetaoyuan Formation can be divided into three stages: arid, semiarid, and humid. In the arid and semiarid paleoclimate stages, water salinity and productivity were high, which resulted in shales with strong hydrocarbon generation abilities and a high degree of oiliness. In addition, the rivers had relatively limited ability to carry terrigenous detrital minerals (clay and feldspar) into the lakes. Authigenic quartz (partly from hydrothermal activity), calcite, and dolomite formation was comparatively high. Thus, the brittleness index values of the shales formed under arid and semiarid paleoclimates are high. In the shales deposited under arid and semiarid paleoclimates, cryptocrystalline/microcrystalline, authigenic quartz can be identified by its morphology, associated minerals, and cathodoluminescence. With increasing depth, the resin, asphaltene, and wax contents of the shale oil decrease and the mobility of the shale oil improves.

中文翻译：

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泌阳坳陷古环境对陆相页岩油富集产能的影响

石油资源丰富的陆相页岩往往脆性较差，阻碍了其成功开发。为寻找页岩油开发有利区，对泌阳坳陷页岩油性、压裂性、古气候关系进行综合分析，实现了我国陆相页岩油开发的首次突破。使用了许多不同的分析技术，包括主要元素和微量元素分析、本体矿物学和扫描电子显微镜-能量色散光谱-阴极发光。结果表明，河桃源组沉积过程中的古气候可分为干旱、半干旱和湿润三个阶段。在干旱和半干旱古气候阶段，水盐度和生产力较高，导致页岩生烃能力强、含油度高。此外，河流将陆源碎屑矿物（粘土和长石）带入湖泊的能力相对有限。自生石英（部分来自热液活动）、方解石和白云石的形成相对较高。因此，干旱和半干旱古气候下形成的页岩脆性指数值较高。在干旱和半干旱古气候下沉积的页岩中，隐晶质/微晶质、自生石英可以通过其形态、伴生矿物和阴极发光来识别。随着深度的增加，页岩油的树脂、沥青质和蜡含量降低，页岩油的流动性提高。