Sequence Stratigraphic Framework and Sedimentary System Distribution in the Lishu Rift,Songliao Basin

Based on seismic data,logging,drilling data,cores and characteristic of structure evolution,sequence framework of faulted layer in the Lishu rift is established.The faulted layer of the Lishu rift includes the Late Jurassic-Early Cretaceous strata of Huoshiling,Yingcheng,Shahezi and Denglouku formations,and is subdivided into three second-order sequences(I-III) and seven third-order sequences(SQ1-SQ7).Furthermore,sedimentary facies and sedimentary system are studied within the sequence frameworks.The results show that it mainly developed alluvial fan,fan delta,braided river delta,nearshore subaqueous fan,and lacustrine sedimentary system.Alluvial fan system mainly developed in the SQ2 sequence.Fan delta system mainly developed in the SQ3 and SQ4 sequences.Braided river delta system was found in the SQ5,SQ6 and SQ7 sequences.Nearshore subaqueous fan system mainly developed in the steep-slope zone of the SQ4,SQ5 and SQ6 sequences.The lateral and vertical evolutions of sedimentary systems were controlled by palaeostructure and palaeogeomorphology.The sand bodies of the SQ4 and SQ5 sequences are more favorable exploration area in the Lishu rift.