In order to demonstrate the characteristics of high resolution sequence stratigraphy of XingⅠ Formation in the Du 84 Block

cores and logging data were applied to conduct the research on the sequence boundaries reorganization

sequence analysis on single well profile and cross-well profiles of cored wells

interpretation of different level cycle types.We establish the chronostratigraphic sequence framework in the study area.One long-term sequence cycle(LSC1)and two mid-term sequence cycles(MSC1-MSC2)are identified according to unconformity

scour surface and flooding surface.Meanwhile

four short-term sequence cycles(SSC1-SSC4)are further identified according to the sedimentary transformation surfaces and rhythm conversion surfaces.These SSC are subdivided into three basic types and 7 sub-types according to the stacking patterns of cycles of various levels

planar and spatial distribution of sedimentary facies.The three basic types are deepening upward nonsymmetric type(typeA)

shallowing upward nonsymmetric type(type B)and symmetric type(type C).Type A mainly develops in the MSC and LSC.And the type C develops in the SSC2.The strata in the whole basin belong to retrograding sequences formed during expansion of lake basin

featuring in multi-cycle mostly having only ascending half cycle and zonation in plane distribution during the SSC.The reservoir sands are best deve-loped at the bottom of the ascending half cycle(SSC1-SSC2).They consist of stacked underwater distributary channel sand bodies of different periods

and have good reservoir property

thus are the main targets of remaining oil potential tapping in the future.