淡水湖相沉积区源储配置模式对致密油富集的控制作用——以四川盆地侏罗系大安寨段为例

四川盆地侏罗系大安寨段为典型的淡水湖相沉积,前期评价致密油资源量高达9×10⁸t,展示出巨大的勘探开发前景。在烃源岩、储层特征分析的基础上,结合大量的生产动态数据,重点解剖了淡水湖相沉积区源储配置关系对致密油富集区的控制作用。通过解剖表明,淡水湖相沉积区源储配置关系受沉积微相控制,可以划分为厚储下薄源上、厚储上薄源下、厚储夹厚源、薄储夹厚源以及源储侧向接触5种类型。实验模拟表明,源储空间配置关系是控制致密油富集程度的关键。典型油田勘探开发实践揭示,滨湖沉积相带下的厚储下薄源上配置类型最好,浅湖沉积相带下的厚储夹厚源配置类型其次,半深湖沉积相带下的薄储夹厚源配置类型相对较差。根据上述源储配置模式和目前的勘探开发实践情况可以得出,滨湖沉积相带是致密油的现实勘探区域,半深湖沉积相带是页岩油气的勘探区域。这一认识可以为四川盆地侏罗系大安寨段致密油、页岩油气的勘探开发评价提供一定依据。

Controlling effect of source-reservoir configuration model on tight oil enrichment in freshwater lacustrine sedimentary area:a case study of the Jurassic Da’anzhai Member in Sichuan Basin

The Jurassic Da'anzhai Member in Sichuan Basin is a type of typical freshwater lacustrine facies, and the pre-evaluated tight oil resources is as high as 9×10⁸ tons, indicating a great prospect of exploration and development. Based on the analysis of source rock and reservoir characteristics in combination with a large number of production dynamic data, this study emphatically analyzes the controlling effect of source-reservoir configurations on tight oil rich area in the freshwater lacustrine sedimentary area. The results show that the relationship between source and storage in this area is controlled by five categories of sedimentary microfacies, i.e., lower thick reservoir-upper thin source, upper thick reservoir-lower thin source, thick reservoir sandwiched with thick source, thin reservoir sandwiched with thick source, and source-reservoir lateral contact. The laboratory simulation shows that the source-reservoir spatial configuration is the key to control the enrichment of tight oil. The exploration and development practice in typical oil fields reveals that the lower thick reservoir-upper thin source under lacustrine sedimentary facies belt is the optimal configuration type, followed by the thick reservoir sandwiched with thick source under shallow lacustrine sedimentary facies belt, whereas the thin reservoir sandwiched with thick source under semi-deep lacustrine sedimentary facies belt is relatively poorer. According to the above source-reservoir configuration models and current exploration and development practice, it can be obtained that the lacustrine sedimentary facies belt is the exploration area for tight oil, while the semi-deep lacustrine sedimentary facies zone is the exploration area of shale oil and gas. The above knowledge lays a solid foundation for the exploration, development and evaluation of tight oil and shale hydrocarbons in this area.