Ultra-tight sandstone diagenesis and mechanism for the formation of relatively high-quality reservoir of Xujiahe Group in western Sichuan

Xujiahe sandstone in west Sichuan of China which is not only the important gas reservoir and producing pay, but also the one of he most deeply buried and tightest elastic reservoir rock has developed relatively favorable reservoirs for natural gas accumulation. After burial, this sandstone has experienced a complex change in the process of diagenesis, so that the secondary porosity and primary porosity coexisted in it. Based on the study of petrography, mineralogy, geochemistry and characteristic of diagenesis of this sandstone reservoir, we generalize the reservoir diagenetic features of Xujiahe sandstone in west SiChuan in the condition of deep burial, and then, conclude its formation mechanism of relatively high quality reservoirs.