Prediction Of Sedimentary Facies And Favorable Reservoir Facies Belts Of Taiyuan Formation In Western Sulige

There have been many views and understandings on the sedimentary environment of the Taiyuan Formation in the Sulige area.Through the study on the strata,sedimentary environment and reservoirs of the Taiyuan Formation in the western Sulige area,this paper attempts to predict the good reservoir facies belt of the Taiyuan Formation.Sedimentary petrology,logging geology,reservoir geology and related theory as the instruction,with the help of electron microscope and related equipment,use of heavy mineral analysis,image size,pore structure analysis,conventional petrophysical analysis data,and the results for the exploration and development of the Taiyuan Formation provide certain theoretical support.According to the existing stratigraphic division scheme and identification marks,the Taiyuan Formation is divided into two sub-sections,Tai one member and Tai two member.The stratum thickness map shows that the Tai one member section is thicker than the Tai two member section,the northwest section is thicker,and the southeast section is thinner.According to the sedimentary facies identification signs,it is found that Taiyuan Formation is the sedimentary environment of shallow braided river delta-shallow sea.The shallow braided delta can further distinguish the microfacies of distributary channel,distributary depression,peat swamp,underwater distributary channel,estuary dam,distributary bay,and pre-delta mud.The distribution of sedimentary facies is from northwest to southeast,and the distribution of sedimentary facies in northwest is generally delta plain subfacies,characterized by the development of distributary channels,distributary depressions and peat marshes,and the distributary channels are distributed in a northwest-southeast belt.Delta front is mainly developed in central Suliga.Predelta and shallow sea environment are basically developed in southeast Sulige.It is found that coarse quartz sandstone is the best reservoir rock in the study area.The reservoir space includes primary pores,inter-granular dissolution pores,inter-granular solution pores,mold pores and fractures,which is a super low porosity and super low permeability reservoir.The fine sedimentary microfacies in the study area are distributary channels.Sedimentary facies controls the distribution of high quality reservoir sand bodies and is the key to reservoir formation.Finally,two favorable areas were identified by combining the plane distribution of sand body,porosity,reservoir thickness and energy storage coefficient.