STUDY ON THE SEQUENCE STRATIGRAPHY OF THE MEMBER2-MEMBER1 SHAHEJIE FORMA-TION IN THE NORTH-CENTRAL PART OF LIXIAN SLOPE

Based on the comprehensive study on core,seismic and logging data,the sequence stratigraphy framework is built up.The strata of the Member 2 and Member 1 of Shahejie Formation can be divided into two third-order sequences,including six system tracts with three different types:low stand system tract,extension system tract and high stand system tract.And the depositional evolution of the system tracts is analyzed.The braided fluvial delta and sand bar and beach of shallow-shore lacustrine are the main facies.The braided fluvial delta plain distributes on the outer belt of the slope,and along the middle belt of the slope the braided fluvial delta-front is widely developed during the Member 2 of Shahejie Formation.While the Member 1 of Shahejie Formation has experienced the largest transgression from the Paleogene,the delta deposit is obviously decreased.Intermediate stage of the Member 1 of Shahejie Formation,the delta-front is developed only on the belt of Dabaichi,and the rest of the area is covered by source rocks.The braided fluvial delta-front sandbodies which include the sand bar and beach in Yanling and Xiliu,are in direct contact with oil generation depression and are the favorable exploration areas.