Research On Sedimentary Characteristics Of Qianfoya Formation Of Jurassic In Bazhong Area, Sichuan Basin

This article is based on the theory of sedimentology,sequence stratigraphy,and on the basis of the research of predecessors,field outcrop,logging and seismic data,and according to the core observation,outcrop reconnaissance,sedimentary structure,paleontology analysis,to recovery the characteristic of the ancient landform during the deposition of Qianfoya Formation in Bazhong Area.It is concluded that the sediments were derived from the Longmen mountains in the early stage,and were controlled by the Daba-Micang mountains in the middle and late stage.By force of contrast the combination of stratigraphic outcrop,logging data,seismic data,systematic stratigraphic division of Qianfoya Formation,and it is divided into one type 1 sequence,three system tracts,nine para-sequence sets.On this basis,establish a high-precision sequence stratigraphic framework.It consider that the up and down of Qianfoya Formation in this area is the deltaic front of delta facies,and the middle of Qianfoya Formation is shore – shallow lake subfacies.Combining sedimentary facies and logging facies analysis,we can know how to divide sedimentary cycles and the progress of sedimentary evolution.According to the sedimentary facies of single well,contrast the correlation profiles of wells,we forecast the available sand body of down of Qianfoya is underwater distributary channel,it mainly distributed in the northeast and northwest area,the available sand body of middle of Qianfoya is beach bar,it mainly distributed in the northwest area,the available sand body of up of Qianfoya is underwater distributary channel,it mainly distributed in the northwast and west area.What's more,we summarize the rule of distribution of high quality sand bodies,and then provide the basis for the prediction of new sand bodies and high-quality sand bodies.