Alkaline Diagenesis and Reservoir Quality of the Upper Paleozoic Tight Sandstones in Daniudi Gas Field, China

Summary There is a probability that the alkaline formation water occurs during diagenetic evolution. The alteration that alkaline fluid exerts on sandstones is also not negligible. Alkaline diagenesis emphasizes the role of alkaline fluid in the formation of secondary pores, which is the improvement and development of classical diagenesis theory. Based on the dissolution of quartz in the tight sandstone reservoir of Daniudi gas field, this abstract analysed the evidence of alkaline diagenesis and the effect of alkaline diagenesis on reservoir quality. The research includes water-rock simulation experiment, diagenetic minerals analysis, and the role of quartz dissolution on porosity. The water-rock simulation experiments and diagenetic minerals (illite and ferrocalcite) prove the inevitability of alkaline environment. Furthermore, the alkaline dissolution strength is the key to the tight sandstone reservoir in Daniudi gas field.