石柱复向斜及周缘小河坝组致密砂岩储层控制因素

Controlling factors of tight sandstone in Silurian Xiaoheba Formation of Shizhu synclinorium and around area on the eastern edge of Sichuan Basin,China

选取了4个地区相同沉积微相(三角洲前缘水下分流河道)中的样品,从砂岩粒度、压实作用、胶结作用、溶蚀作用及(微)裂缝发育状况等方面分析了四川盆地东缘石柱复向斜及周缘志留系小河坝组致密砂岩储层发育的控制因素。从砂岩粒度对储层的影响来看,在沉积微相的尺度上,并不能完全界定沉积物先天条件的优劣性。强烈的压实和胶结作用及严重的非均质性是导致小河坝组储层致密的主要原因,而溶蚀和破裂作用则是该区优质储层形成的关键。尽管储层普遍致密,但在有利因素的叠加区可以形成较好的储层。

The authors chose the samples from four different sections in the same sedimentary micro-facies（sub-channel branch of delta front）in the Shizhu synclinorium and the around area on the eastern edge of Sichuan Basin,and analyze the controlling factors of the tight sandstone in the Silurian Xiaoheba Formation in terms of grain size,compaction,cementation,dissolution and the upgrowth of fractures.According to the analysis of the grain size,people don＇t think the sedimentary micro-facies can decide the character of the reservoir.Strong compaction and cementation are the main reasons that cause the reservoir tight,whereas dissolution and breakage can improve the physical property of the reservoir and they are the key factors for the high quality reservoir.Although the reservoir is tight in common,high quality reservoirs can still form in some favourable places.