Keywords: 
• high-resolution sequence stratig raphy /
• base-level cycle /
• stratigraphic framework /
• isochronostratigraphic correlation of small sandbody /
• isochronic microfacies map /
• development of oil and gas reservoir

Abstract: Through the comprehensive analysis of outcrops, cores, well logs and seismic interpretation data, and under the guidance of the theory and technology of the high-resolution sequence stratig raphy initiated by Timothy A-Cross in 1994, the characteristics of the different grade sequence interface and laucstrine flooding surface in the second member of Nadu Formation Eocene in Lun-35 Block of Ziyin Oil Field from Base Basin are studied.According to the identification sign of the sequence interface and flooding sedimentation, four-grade base-level cycle sequences that are divided into 13 ～ 18 supershort-term, 7 ～ 9 short-term, two middle-term, and one long-term cycle sequences are recognized from the formation.On the basis of these studies, the vertical sequence, facies association, lithologic component, structure type and stacking pattern are discussed in detail.Among these sequences, the supershort-term and short-term cycle sequence may be divided into two basic types of st ructure which are up-deepening non-symmetry and symmetry from up-deepening to up-shallowening.The first can be divided further into two subtypes of low or high accommodation and the second can be devided further into three subtypes of non-complete or nearly complete symmetry.These basic sequence types and subtypes are of various stacking and distribution patterns.The structure type and stacking pattern of the middle-term cycle sequence are the same as that of the shortterm cycle sequence.The long-term cycle sequence are of non-complete symmetric st ructure which develop complete depositional sequence of lacust rine transgressive-reg ressive cycle, and thickness of rising half-cycle is larger than the falling half-cycle.According to the high-resolution isochronous stratig raphic correlation of the turnround boundaries of different order base-level including short and middle termcycle sequence, the sequence and time stratigraphic framework can be built that in the scale of supershort-term base-level cycle as an isochronous unit, which are of varied application significance in hydrocarbon exploration and development, such as isochronous stratig raphic correlation of small sandbodies with oil, charting of isochronic microfacies in the large scale, description of sandbody geometry, forecasting reservoir and petroleum accumulation, analy sing reservoir heterogeneity, reservoir modeling and so on.