DIAGENESIS AND POROSITY EVOLUTION OF THE SANDSTONE OF MEMBER 2 IN SHANXI FORMATION,YULIN GASFIELD
榆林气田山西组2段砂岩成岩作用及孔隙演化

Member 2 in Shanxi formation of Permian system in Yulin gasfield is the mainly gas reservoir,was deposited in a braided river of delta enviroment.The reservoir sandstone mainly is quartzose sandstone, lithic quartzose sandstone and little lithic sandstone,The reservoir sandstone is typical of low porosity and low permeability.This article was based on core observation,and use thin section observation,scanning transmission electron microscope observation,cathodoluminesconce and physical property,takes research and analysis,indicates that the sandstone of member 2 in Shanxi formation in Yulin gasfield went through the compaction,cementation,metasomasis,solution and fillition of clayimpurity during the diagenesis,and now it is in the late diagenesis stage. The porosity of the reservoir sandstone of member 2 in Shanxi formation,its statistical porosity composition being protogenetic intergranular remainder porosity of 44.7%,secondary porosity of 55.3%,which indicates that the diagenesis has the greatest effects in control of the physical property in this aera.The porosity evolution experienced the destruction of protogenetic porosity,the constitution of secondary and the destruction of secondary pore.In that,the compaction and the cemetation were play of mainly destruction,the solution was paly of construction.