DIAGENESIS AND POROSITY EVOLUTION OF THE RESERVOIR OF THE MEMBER 3 OF SHAHEJIE FORMATION IN QIAOKOU AREA IN DONGPU SAG

From the analysis of thin slice,The diagenesis of The reservoir sandstone includes compaction,cementation, dissolution and denudation in the Member 3 of ShaHeJie Formation In Qiaokou area,The pores are mainly of secondary pores such as dissolution pores between grains and in grains and cement pores:Based on the X ray diffraction of clay minera,the diagenetic stages here are classified as earlier diagenetic A, later diagenetic A1、A2、B, the cementation and compaction contribute to the massive loss of porosity in the Earlier diagenesis A and B,dissolution plays an important role in improving the pores and Xreated a large number of secondary pores increased in the later diagenetiX A1,Lots of The seXondary pores are reduced because of the cementation of calcite cements in the later diagenetic A2、B:So the early lost of great number of primary porosity,and the late reduce of the secondary pores are the main factors of low porosity and low permeability of sandstone.