陆相页岩油成藏地质条件及富集高产主控因素——以泌阳凹陷为例

Geologic conditions of continental shale oil accumulation and main controlling factors of enrichment and high production:Taking Biyang Depression as an example

分析总结泌阳凹陷陆相页岩油的特点及勘探成果发现,泌阳凹陷陆相页岩主要分布在深湖—半深湖、浅湖沉积相带、淡水—咸水沉积环境,具备良好的陆相页岩油成藏地质条件。其主要特征为：厚度大,有机质丰度高、类型好,热演化程度适中,储集物性好,含油丰富,保存条件好,可压性好。研究认为,广泛分布的富有机质页岩及其适宜的热演化程度是页岩油富集高产的基础,有利的岩相与较好的物性是页岩油富集高产的关键,裂缝及薄砂层发育是页岩油高产的保障。文中建立了陆相页岩油有利区选择标准：深湖—半深湖相带;页岩累计厚度不小于30 m,其中有利页岩相厚度大于20m;TOC平均不小于2%;Ro在0.5%-1.1%;孔隙度不小于3%;裂缝发育;含油饱和度指数不小于70%;埋深小于3500 m;脆性矿物体积分数大于60%。

Analyzing the continental shale oil characteristics and exploration achievements in Biyang Depression, it is considered that the shale is mostly developed in deep lake-semi-deep lake, shallow lake and fresh water-saline water sedimentary environments. With the characteristics of large thickness, high abundance of organic matter, good type of organic matter, moderate thermal evolution degree, good reservoir of properties, rich oil, good preservation conditions and compressibility, the depression has good geological conditions of continental shale oil accumulation. The research suggests that widely distributed rich organic shale, moderate thermal evolution degree, fracture and thin sand layer development insure shale oil enrichment and high production. Meanwhile, the standard of favorable area for continental shale oil is established： deep lake to semi-deep sedimentary lithofacies belt, shale cumulative thickness less 30 m, favorable shale thickness more than 20 m, TOC not less than 2%, Rofrom 0.5% to 1.1%, porosity not less than 3%,fracture development, oil-bearing saturation index not less than 70%, depth less than 3,500 m, brittle mineral content more than 60%.