【摘要】 以石英次生加大边、孔隙充填式的石英晶体形式赋存的硅质矿物是鄂尔多斯盆地上古生界储集层砂岩中最为重要的自生矿物之一,平均含量达3.8%,这在众多含油气盆地中是极少见的。对于鄂尔多斯盆地上部地层如石千峰组和石盒子组来说,同期火山物质的蚀变是形成硅质胶结物的主要原因之一;山西组与上部地层石千峰组和石盒子组相比,具较高的硅质胶结物含量且常与高岭石相伴生,同时砂岩中的长石含量很低,这种现象说明,长石等易溶硅酸盐组分在有机酸的溶解下释放的硅提供了形成硅质胶结物的物质来源。早成岩期相对浅埋深条件下形成的硅质胶结物增加了岩石的机械强度和抗压强度,对砂岩储集空间的保存具有积极意义,因而应属于保持性成岩作用,对储集层的影响是中性—正面的。更多还原

【Abstract】 Siliceous cement mineral,occurring in a form of irregular quartz overgrowth,pore-filling quartz crystals or quartz automorphic crystals,is one of the most significant authigenetic mineral in sandstone reservoirs of the Upper Paleozoic in the Ordos Basin,with an average content of 3.8% in volume,giving an unusual case in most petroliferous basins.The siliceous cements are formed largely in early diagenesis stage.In the upper strata of the Upper Paleozoic,i.e.,Shiqianfeng and Shihezi Formations,the siliceous cements were derived from the alteration of volcanic materials.While in the Shanxi Formation,the lower strata of the Upper Paleozoic,the existence of exceptionally high siliceous cement and low feldspar,and the paragenetic relationship of siliceous cement with kaolinite,indicate that the silica cements were supplied by silicon released from soluble components such as feldspar by organic acid.The siliceous cements precipitated during early diagenesis at relatively shallow depth increased the mechanical strength of the sandstone framework,which is favorable for the preservation of reservoir space and belongs to retention diagenetic process,and exerts a neutral-positive influence on reservoir quality to the least extent.更多还原