湖相纹层泥页岩有机质富集机理及其与页岩油关系

With the change of composition of international petroleum resources, unconventional petroleum geology has been laid more and more emphasis. The beginning of exploration and development of shale oil is later than shale gas, which is still at the exploratory stage. But the capacity of shale oil rose sharply. Shale oil enrichment rule is closely related to microstructure of shale which controlled the hydrocarbon generation potential and physical property. The applied fundamental study focused on these two controlling factors as one goal is still considerably weak. The results of recent exploration discovered that the enrichment of shale oil has causative relation to the laminite which alternated with deep and light color laminas. Our study proceed from the characteristic and couplets' types of Permian laminated shale in study area Santanghu Basin, then discuss enrichment mechanism of organic matter. By way of organic and inorganic geochemistry analysis, combined with sedimentation mechanism of laminated sediments of Sugan Lake in Qaidam Basin to recover the forming geological conditions of organic-rich laminated shale. Study the diagenesis between deep and light color laminas with the primary migration of hydrocarbon in the evolution process of laminated organic matter, build evolution pattern of shale reservoir space. After that, quantification ally evaluate the relation between laminite and enrichment of shale oil in profile and plane. On these studies, locate the optimum target areas and supply effective academic foundation for the petroleum exploration to the tight source rock reservoir.

随着世界油气资源结构的转变，非常规油气地质的研究越来越受到重视。页岩油的勘探与开发较页岩气起步晚，尚处于探索阶段，但产能增长极快。页岩油的富集规律与母岩的微观结构密切相关，主要受控于泥页岩的生烃潜力与储集性能，但将这两方面作为统一整体进行的应用基础研究还相当薄弱。目前的勘探结果发现，页岩油富集与深、浅色相间的沉积纹层具有重要的联系。从靶区（三塘湖盆地二叠系）泥页岩纹层发育特征、层偶类型出发，研究暗色纹层有机质富集机理，通过有机、无机地球化学分析结果，结合柴达木盆地苏干湖现代纹层沉积机制，恢复富有机质纹层岩形成的地质条件。研究纹层岩在热演化过程中，伴随着油气初次运移的深、浅色纹层间的相互成岩作用，建立烃类赋存形式及泥页岩储油空间演化模式，进而定量化评价纹层岩在平面上、垂向上与页岩油分布、富集的关系，在此基础上优选靶区页岩油富集区，为其他探区的致密源岩内油气勘探工作提供有效的基础理论支持。

富有机质纹层状细粒岩普遍具有较高的含油级别，是最为现实的页岩油/致密油勘探领域。本次研究以三塘湖盆地二叠系芦草沟组为例，通过高分辨率岩心图像扫描、常规薄片、扫描电镜、能谱分析等岩石学研究方法，结合微量元素、生物标志化合物等地球化学手段，对湖相富有机质纹层细粒岩的岩石学特征、沉积成因进行了研究，并分析了其页岩油/致密油勘探意义。研究结果表明，纹层具有硅质碎屑富集层、碳酸盐富集层、凝灰质富集层及有机质富集层四种类型，通过组合可以形成三种层偶类型。有机质则呈纹层状富集或分散状分布于碳酸盐纹层及凝灰质纹层中。缺少陆源碎屑供给的封闭盐湖沉积体系，形成了分层的古湖泊水体，加之湖底的热水活动和季风性气候共同控制了有机质的富集保存及湖相多元纹层状细粒岩的形成。由于该类细粒岩有机质丰度高具有较好的生烃潜力，碳酸盐纹层微孔及纹层间微裂缝发育使其具有丰富的储集空间类型，并由于脆性矿物含量高而易于后期压裂改造，具备形成页岩油/致密油的有利条件，勘探意义重大。