Sedimentary Facies Of The Lower Cambrian Longwangmiao Formation And Its Relationship With Reservoirs In Southwestern Sichuan

Under the guidance of the theory of carbonate sedimentology and carbonate reservoir geology,using a variety of modern testing methods,this thesis takes the early Cambrian Longwangmiao Formation of the Southwest part of Sichuan Basin as the main object,makes a more detailed study on the stratigraphic characteristics,the sedimentary facies and reservoir characteristics and the relationship between them.Finally,this article points out the favorable facies belt for reservoir development,and the vertical distribution of reservoir.According to the research,it is deemed that the stratum of the early Cambrian Longwangmiao Formation in the Southwest part of Sichuan Basin has a clear top and bottom line.The main lithology is particle dolomite,grain dolomite,argillaceous dolomite,and some other dolomite.The stratum thickness thickens gradually from west to east.Combined with the area depositional history and the facies indicators,the analysis of the sedimentary evolution can be made.Longwangmiao Formation in the Southwest part of Sichuan Basin belongs to the restricted platform facies,it can be divided into lagoon and platform inner shoal,furthermore,particle shoal,argillaceous lagoon and some other microfacies.The most beneficial sedimentary facies belt for reservoir formation and evolution is the platform inner shoal.The reservoir of Longwangmiao Formation in the Southwest part of Sichuan Basin is mainly located in the Moxi-Gaoshiti area.The thickness and quality of the upper reservoir is better than the lower part.The most important kind of reservoir is the sand-clastic dolomite.The mainly reservoir space types are intergranular dissolution pores and intercrystal dissolution pores.Crack is the most important percolating space.As a whole,?,? class are the mainly reservoir in the Southwest part of Sichuan Basin,while it's ?,? class in the Moxi-Gaoshiti area.Sedimentation control the reservoir distribution,but the final form of the reservoir is also under the influence of other factors,such as diagenesis and tectonism.