东营凹陷古近系砂岩成岩作用与孔隙演化

东营凹陷是重要的油气富集区，在古近系地层发育湖相水下扇沉积、滨浅湖沉积和三角洲沉积等砂岩。砂岩的成岩作用及孔隙演化对储层的储集性能有重要影响。在对大量薄片和岩心进行分析的基础上，运用扫描电镜和X衍射粘土分析等手段，对东营凹陷砂岩储层的成岩作用和孔隙演化进行了研究。研究结果表明，该区压实作用、胶结作用使砂岩孔隙度降低，不稳定矿物的溶蚀作用和碳酸盐胶结物的溶解作用导致孔隙度增大。根据有机质的演化及粘土矿物的变化序列，在不同的构造单元，砂岩成岩作用和孔隙演化随埋深具有明显的规律性，可划分出原生孔隙带、原生次生孔隙带和次生孔隙带3个孔隙演化带，存在着较有利的次生孔隙发育带。

Diagenesis and pore evolution of Paleogene sandstone reservoir in Dongying depression

Dongying depression is one of the most prolific hydrocarbon areas in China. The Paleogene stratum consists of underwater fan, littoral-shallow lacustrine and delta facies sandstones. Diagenesis and pore evolution have exerted great effects on the proporties of reservoir rocks. The study performed by the authors is of significance in finding favorable reservoir zones in Dongying depression. Many thin sections were analyzed by such means as standard petrographic microscope, X-ray diffraction and scanning electron microscope analysis so as to study the selected samples. Diagenetic complexity shows that compaction and cementation lead to decrease in porosity, whereas solution of unsteady minerals and carbonate cements result in increase in porosity. The evolution of organic materials and the sequence of clay minerals suggest that the diagenesis and the pore evolution of the sandstone in different structural belts varied obviously with the increase of the buried depth, and the reservoirs might be classified into three pore evolution zones, namely, the primary shallow pore zone, the primarysecondary transitional pore zone, and the secondary deep pore zone. The sandstones serve as well-developed secondary pore zones.