DIAGENESIS OF TIGHT STANDSTONE AND THE INFLUENCE ON RESERVOIR

The sandstone reservoirs of Shan1-He8 member are tight quartz sandstones with many syn-depositional volcanics in upper palezoic sandstone of Wushenzhao-Tongwangcheng area,there is a tight relation between deposition-diagenesis and pore evolution.On the basis of the sedimentary facies research,according to the data of X-diffraction,scanning electron microscope and more than 300 rock slides from 20 wells,it is pointed out that the main diagenesis of sandstone reservoirs are hydrate reaction,compaction,alteration of detrital material,metasomasis,cementation and dissolution in the sandstone reservoirs of He8,Shan1 member.The digenetic series are hydrate reaction - compaction - secondary growth of quartz - (carbonatation of volcanics,kaolinization of volcanics and feldspar,silication of volcanics) - dissolution - cementation of authigenous quartz - cementation of kaolinite - cementation of calcite.Compaction is main destructive diagenesis,while dissoluion is main constructive diagenesis,both of them impact reservoirs a lot.