鄂尔多斯盆地南部延长组7段泥页岩储层特征及其控制因素

厘清鄂尔多斯盆地延长组7段泥页岩储层发育特征及其与不同成岩作用的关系,能够为分析页岩气储层储集性能以及“甜点区”预测评价提供指导。本次研究在大量岩石薄片鉴定、扫描电镜、X射线衍射等分析实验基础上,对鄂尔多斯盆地南部延长组7段泥页岩储层的矿物含量变化、组成类型、纵向分布规律、储集空间分布以及成岩作用类型进行研究。结果显示：研究区泥页岩可划分为富伊利石型、富伊利石和伊蒙混层型、含长石富伊蒙混层型、含长石富伊利石型四种类型;纵向上,随着埋深增加,伊蒙混层的含量变化由高到低,伊利石的含量变化由低到高。泥页岩中微观储集空间相对发育,类型多样,发育有压实作用、黄铁矿形成作用、黏土矿物转化作用、溶蚀作用以及有机质生烃等成岩作用,不同成岩作用对储集空间的影响有一定的差异;分析不同成岩作用对储集空间发育的影响,对认识研究区储层特征和进一步勘探均具有重要意义。

Mineral composition characteristics and its controlling factors in shale of Chang 7 member of Yanchang Formation in the south of Ordos Basin

By studying the law of pore evolution and its relationship with different diagenesis in shale of Chang 7 member of Yanchang Formation in Ordos Basin, it can provide guidance for the analysis of shale gas reservoir performance and the prediction and evaluation of "dessert area". Using rock thin section identification, scanning electron microscope observation and X-ray diffraction test, mineral content change, composition type, vertical distribution law, reservoir spatial distribution and diagenesis type are analyzed in shale of member 7 of Yanchang Formation in Ordos Basin. The results show that the shale of member 7 of Yanchang Formation can be divided into four types: illite rich type, illite rich and Yimeng mixed layer type, feldspar rich Yimeng mixed layer type and feldspar rich illite type. With the increase of buried depth, the content of Yimeng mixed layer changes from high to low, and the content of illite changes from low to high. A variety of shale storage spaces can be observed, and the diagenesis is developed, including compaction, pyrite formation, clay mineral transformation, dissolution, and organic matter hydrocarbon generation. The influence of different diagenesis on reservoir space is different; Analyzing the influence of different diagenesis on the development of reservoir space is of great significance to understand the reservoir characteristics and further exploration in the study area.