Research On Sedimentary Facies Of Paleogene In West Chepaizi Area Of Junggar Basin

Owing to the low exploration of Paleogene in Chepaizi area of Junggar basin,the current learning of sedimentary characteristics of Paleogene in west Junggar basin is not deep enough,nobody systematically summarizes the macro distribution of sand body and also the distribution of favorable reservoir of Paleogene is not clear.According to some questions in the study area,we use the field outcrops,cores,logging,wells,seismics and analysis assay data and then systematically analyze the types of sedimentary system,the distribution and evolution of Paleogene in this area.Further,we predict the development area of favorable reservoir.The area mainly developed two strata in Paleogene:anjihaihe and ziniquanzi formation.Next to the northwest of the Junggar basin in this area,it mainly developed anjihaihe strata including two fourth-order sequence.Each sequence contains two system tracts:transgression system tract and regressive system tract.Depending on the multicyclic feature,it can be divided into six quasi sequence groups which are corresponding to the six sand groups in the study area.The anjihaihe formation of Paleogene mainly developed mudstone and silty sandstone.Meanwhile,there are argillaceous silt,glutenite,fine sandstone,micro conglomerate found in it and so on.Among them,glutenite,argillaceous silt and fine sandstone show oil and gas.Relativily,the sedimentary structure types are simple,as opposed to which,the types of combination of it are various.Horizontal bedding,cross bedding and graded bedding mainly developed in it,Also,scour structure and bioturbation structure are common in study area.Above all,we conclude that the Paleogene in working area belongs to fan delta,sandy beach bar and shore shallow lake.The fan delta mainly developed in lowstand system tract;Sandy beach bar mainly existed in second member of anjihaihe formation;The shore shallow lake widely developed on the edge of lake basinConsidering sedimentary types,origin of pores and diagenetic characteristics of glutenite reservoir,it is pointed out that the reservoir physical properties are mainly influenced by sedimentary environment,and we predict the distribution of favorable reservoir in anjihaihe formation.