榆林气田是鄂尔多斯盆地的重要气田之一,其主力储层为下二叠统山西组2段砂体,但该套砂体的成岩演化过程复杂,受控因素很多,给勘探带来较大困难。为揭示该段砂体孔隙发育的控制因素,在岩石薄片观察的基础上,先用多元逐步回归法对其进行了分析,进而采用变量分离法把影响孔隙的因素分为沉积变量、酸性变量和还原变量,并解释了该区沉积相相同的两段砂体孔隙度不同的根本原因:在沉积条件十分有利的情况下,即无论是否发生溶蚀作用,孔隙都比较发育,其中原生孔隙占有较大比重;在酸性变量较高的区域内,无论沉积条件是否有利,孔隙也都十分发育,但次生孔隙占相当的比重。

Yulin gas field is one of the important gas fields in Ordos basin.Permian Shan 2 member sandstone is the main reservoir,and the diagenesis process of the member was complicated.For uncover the main controlling factors of pore development in this gas field,on the basis of thin section examination of rock,we analyzed Shan 2 member sandstone by multiple stepwise regression,divided the affecting factors of pore growth into three: sediment variable,acidic variable and reductive variable,and discovered the prime.