鄂尔多斯盆地东南部上古生界储层岩石学特征

Petrology Characteristics of the Upper Paleozoic Sand Reservoir in the Southeast Ordos Basin

为弄清鄂尔多斯盆地东南部上古生界砂岩储层岩石学特征的差异性,通过大量岩石薄片、扫描电镜、阴极发光和X衍射等分析化验资料,对研究区上古生界主要产气层段砂岩储层的岩石类型、成分特征、平面分布等进行了详细研究。结果表明,盒8段和山1段是以岩屑砂岩和岩屑石英砂岩为主,少量石英砂岩,岩屑主要为千枚岩,其次为石英岩、燧石和变质砂岩;山2段和本溪组则以石英砂岩为主,其次为岩屑石英砂岩,少量岩屑砂岩,其岩屑主要为石英岩,其次为燧石和千枚岩;从盒8段—本溪组的砂岩中碳酸盐和硅质胶结物含量均有逐渐增加的趋势,而高岭石和绿泥石含量逐渐减少。受物源分异的影响,从东部→西部→南部砂岩成分成熟度依次降低。

Petrology characteristics of a reservoir is the main factor determining the reservoir physical properties dur ing diagenesis and porosity evolution processes. The rock types, composition characteristics and plane distributions of Carboniferous Benxi Formation and Permian H 8 Formation in the Southeast of Ordos Basin were studied by ana- lyzing a large number of thin sections and by using scanning electron microscope, cathodoluminescence and X-ray diffraction techniques. The results showed that the main rock types of Shan 1 and He 8 are lithic sandstone, lithic quartz sandstone and a small amount of quartz sandstone, and that detritus are mainly phyllite, followed by quartz- ite, chert and metamorphic sandstone. The results also showed that Shan 2 and Benxi Formations are mainly quartz sandstone, followed by lithic quartz sandstone, lithic sandstone, and that detritus are mainly quartzite, followed by chert and phyllite. From He 8 to Benxi Formations siliceous and carbonate cement in sandstone are gradually in creasing, but the contents of kaolinite and chlorite are gradually reducing. Affected by differentiation provenance, the composition maturity of sandstones reduces from the east part to the west part and then to the south part.