Effect of Diagenesis on the Formation Effective Reservoirs in Volcanic Rocks of Xujiaweizi Faulted-Sag

Abstract

The volcanic reservoir of Yingcheng Formation in Xujiaweizi Faulted-Sag of Songliao Basin was systematically studied by analyzing the data of the core and cast thin slice. It was founded out that all effective reservoir underwent six diagenetic stages. That is why porosity evolution and physical property of those rocks were different from each other. The organic acid dissolution and CO2-bearing acidulous water dissolution,was the most useful diagenesis to the formation of effective reservoirs, secondary porosity developed mostly in the silicic volcanic rocks, which were easily dissolved by organic acid. Primary porosity system, faults and fractures, top/bottom unconformity surfaces of volcanic rocks are the key factors to dissolution.