Sedimentary system characteristics and evolution of the second member of Shahejie formation in Jinzhou 25-1Soilfield in Liaoxi low uplift

Paleogene Shahejie formation of Bohai oilfield is generally developed braided river delta deposit.Its deposited background is complex and the lateral reservoirs change quickly.By taking the second member of Shahejie formation in Jinzhou 25-1S oilfield as an example,through comprehensive analysis of cores,well logging,seismic,paleontology and heavy minerals and other materials,based on sequence stratigraphy theory,a fine layer sequence stratigraphic framework has been established.Based on the sequence stratigraphic framework,a detailed study of sand sedimentary characteristics of the second member of Shahejie formation has been carried out.Studies results show:1 Jinzhou 25-1S oilfield is controlled by double provenance,the secondmember of Shahejie formation can be divided into 3 fourthorder sequence,9 fifth-order sequences;2the sedimentary characteristics at all orders of sequence and evolution regularity have been analyzed,the deposition mode of Jinzhou25-1S Oilfield under isochronous stratigraphic framework has been established;3 by applying the research results so as to provide effective guidance for sequences development strategy of the oilfield.