煤系地层中储层基本特征与优质储层的形成与分布

通过对鄂尔多斯盆地和四川盆地煤系地层中发育的优质储层分布规律研究，发现优质储层主要受层序界面、有利沉积相带、有机酸性水的溶蚀作用等因素控制。一般来说，优质储层主要分布在三级层序的中下部、三角洲平原或前缘多期分流河道叠置的部位。它们在有机酸性水大量形成时期保留了较多的原生孔隙，酸性水容易进入并溶解其中易溶的碎屑颗粒，产生大量次生溶蚀孔隙，从而形成相对优质的有效储集层。因此，优质储层纵向上与不整合面或层序界面密切相关；平面上受沉积有利相带或断裂带的控制。

General Feature of Reservoir in Coal-bearing Formation and Distribution of the Favorable Reservoir

Though studying distribution of favorable reservoir in coal-bearing formation of upper Permian Shihezi formation in Ordos basin and upper Triassic Xujiahe formation in Central Sichuan basin,it is found that the favorable reservoir is controlled by sequence boundary,sedimentary facies and dissolution of organic acid water.Generally speaking,the favorable reservoir develops in the middle or lower parts of III level sequence,and stacking channels of delta plain or delta front.When organic acid water generates,these sandstones contain lots of primary porosity and organic acid water goes into these sandstones dissolving feldspar or lithic fragments to form lots of secondary porosity.And then it forms favorable reservoir.Therefore,the favorable reservoir in coal-bearing formation is controlled vertically by unconformable plain or sequence boundary and horizontally by favorable facies or fracture belts.