Sedimentary Diagenesis Of The Dolomitic Reservoir In The Southern Margin Of Lucaogou Formation In Junggar Basin

The Lucaogou Formation dolomite is one of the important tight reservoirs in the Junggar Basin.In recent years,the oil sector has obtained important industrial oil flow in Lucaogou Formation of the Jimsar Sag Area in the southern margin of the basin,resulting in the Lucaogou Formation.The study of dolomite tight reservoirs has become a research hotspot.The previous studies focused on the source rocks in the Lucaogou Formation.Although the formation of the carbonate rocks,the origin of dolomite,the formation of dolomite reservoirs in Lucaogou Formation have been studied,there are different understandings of the densification process.This paper takes the Permian dolomite in Junggar Basin as the research carrier,and analyzes the two measured profiles in the southern margin of the Junggar Basin to study the sedimentary facies and diagenesis of the Permian dolomite reservoir in this area and reveals the densification and controlling factors.of the reservoir in the area.According to the characteristics of the sedimentary structures collected from the measured profiles,it is believed that the Permian Lucaogou Formation in the southern margin of the Junggar Basin is a normal lacustrine deposit,and all types of granular dolomite and stromatolite dolomite formed in the high-energy environment are the main reedgrass sulcus.Group dolomite reservoir rocks.In the vertical direction,the dolomite reservoirs in the Lucaogou Formation are distributed in the upper and middle and lower parts of the Lucaogou Formation.In the plane,the dolomite reservoir dessert section is mainly developed in the deltaic bodies formed by the rivers flowing into the lake.Followed by the delta between the body.According to the observation of the cast thin slices,the dolomite reservoir in the Lucaogou Formation has good initial properties,and the primary and secondary pores mainly develop in high-energy beach facies and reef dolomite.The main diagenesis that promotes the formation of secondary pores is dolomization,atmospheric water-solubility,deep-buried corrosion,and recrystallization during diagenesis.The multi-phase fluid filling causes intense silicification and de-dolomization,causing the primary intergranular pores to be plugged to varying degrees,resulting in a sharp decrease in the face ratio;the densification of the reservoir rock is enhanced,and the primary and secondary pores have been completely or incompletely filled.Destruction and reduction.The study shows that the formation of the dolomite reservoir in the reaaagou formation is mainly controlled by the combination of lithofacies,epigenetic karstification,dolomitization,deep burial karst,silicification and dolomitization,and the key factor for forming high quality and dense reservoir should be the strength of silicification and dolomitization.