塔里木盆地西南缘上震旦统上部砂岩的成岩作用研究

在研究薄片的基础上,使用粒度分析、电子探针分析和红外光谱分析资料,已识别了塔里木盆地西南缘上震旦统上部库尔卡克组四、五段及其上覆的克孜苏胡木组一段砂岩的机械压实、压溶和溶解、交代、重结晶以及胶结作用等主要成岩作用,鉴定了每种成岩作用所包含的成岩变化类型,指出了各类成岩作用的分布和鉴定特征,并对其形成机理分别作了探讨。按照上述成岩作用产物间的相互关系,确立了各种成岩变化的形成顺序。继之,将所研究的砂岩成岩阶段划分为海解阶段,早、晚期成岩阶段和后生阶段,阐明了各个成岩阶段砂岩孔隙的相应演变。结合孔隙度低的物性参数,得出了如下结论:在早、晚期成岩阶段发生的胶结作用,尤其是石英的次生加大,充填了砂岩大量的孔隙,是破坏砂体储集空间的主要因素。图3表2参2

A Study on the Diagenesis of the Sandstones in the Upper Part of the Upper Sinian Series in the Southwest Margin of Tarim Basin

Based on the study of thin section, and using the date of particle analysis, electron microprobe analysis, and infrared absorption spectrum, there has been identified a main diagenesis of the sandstones of the members 4 & 5 of Kuerkake formation and the member 1 of Kezisuhumu formation in the upper part of the upper Sinian series. The diagenesis includes compaction, pressure-dissolution and solubilization, replacement, recrystallization and cementing. The distribution and characterictics of the diagenesis are presented. According to the relationship between the diagenetic products, the order of the diagenetic varieties are determined. The diagenetic stages of the studied sandstones are divided into halmyrolysis, early & late diagenetic and anadiagenesis stages. The pore evolution in different diagenetic stages are studied. It is concluded that cementation is a main inflUence on the sandstone porosity in early and late diagenetic stages.