A Study On The Diagenetic Environment Of The Carboniferous-permian Tight Sandstone Reservoir In Daniudi Gas Field

Daniudi gas field is a compacted sandstone reservoir,the main gas-bearing strata of which are the Carboniferous Taiyuan Formation,Permian and the Shanxi Formation and Lower Shihezi Formation.Daniudi gas field reservoir giagenetic environment,eapecially in different periods of the nature and distribution of diagenetic fluid to reservoir densification and high quality of reservoir formation control research is still inadequate,restricted the law of high quality reservoir distribution and futher exploration and development.According to the existing problems of tight sandstone reservoir in Daniudi gas field,in this paper,through the analysis of the microscopic feature under the thin section,scaning electron microscopy,combined with other experiment and analysis data shch as laser Raman spectrum,taking the theory of sedimentology and reservoir geology theory as the instruction,discuss the petrology features,the characteristics of diagenesis,and on this basis discuss the diagenetic environment and its evolution of the carboniferous-permian tight sandstone reservoir in Daniudi gas field,this thesis achieved the following understandings and results:The reservoir types of the area is mainly middle-coarse-fine gravel of terrigenous clastic rocks,has high compositional maturity and low texture maturity.Depositional setting of Daniudi gas field is braid river delta sediment systems,develop braid river delta plain and front deposition.The diagenetic stage of revervoirs is devided into early diagenetic stage B,middle diagenetic substage A1 and A2 and middle diagenetic stage B,mainly developed compaction,cementation,metasomatism and dissolution,authigenic clay mineral transformation.By inclusions the microscopic observation,temperature measuring experiment,laser Raman spectroscopy and pH value of the quantitative calculation,analysis the diagenetic environment of the carboniferous-permian tight sandstone reservoir in Daniudi gas field.The area has three periods of quartz,two calcium cementation,level 3 microfracture,and three periods of fluid filling,and overall high pH,form northeast,east to southwest,PH reduce gradually,appear a trend of vasic to acid from southwest.Combined with the comprehensive research of the tectonic movement and the fluid environment in the area of Daniudi,consider has four diagenetic environment stages of tight sandstone reservoir in Daniudi gas field,namely fast compaction stage,the succession of the acid and alkali diagenetic stage,densification and tectonic uplift.