The Origin of the Deep-burial High-quality Reservoir and the Model of Diagenetic Evolution in Kela 2 Gas Field, Kuqua Depression

Key words: 
• secondary porosity /
• calcite dissolution /
• Cretaceous /
• Kuqua depression

Abstract: Based on the influencing factors of diagenesis and the reality in Kuqua dep ression, in this paper, the research on the origin of the secondary porosity has been performed for the deep-buried high quality reservoir. The mineral and rock fragment components of the sandstone carbonate cement formed under the past climate and their effects on the secondary porosity have been described. The overp ressure, crevice, authigenic mineral assemblage and their origins, characters, effects on the diagenetic environment and secondary porosity have measured to evaluate the feld-spar and calcite dissolution condition, the rep lacement of dolomite to calcite, the effects of compaction and cementation of the sandstone and so on. Lots of information suggests that the dissolution of calcite cement be responsible for the porosity abnormity at deep depth. Furthermore, on the basis of the study of fluid inclusion and all the worksmentioned above, we established the model of diagenesis and porosity evolution in this area.