Research On High Precision Sequence Stratigraphy And Sedimentary Microfacies Of The First Member Of Dainan Formation In Northern Slope Gaoyou Sag

The Second Submember and the Third Submember of the First Member of Dainan Formation of The Northern Slope of Gaoyou Sag are the significant hydrocarbon exploration horizons of Jiangsu Oilfield.However,due to the multiply fault development,lateral tracing correlation is difficult,stratigraphic division and correlation is not enough elaborate,sedimentary microfacies types are various,research is not enough refining,sedimentary facies distribution range is still controversial,which restrict the stratigraphy exploration and development further in this area.Hence,did high-resolution sequence stratigraphy and sedimentary microfacies research,analyzed favorable sand body distribution law and predicted favorable overlap traps development areas in this area.This paper using continental sequence stratigraphy and sedimentary theory as guidance,by core data,analysis assay data,logging data and seismic data,defined high-resolution sequence stratigraphy,divided 1 third-order sequence,5 parasequence sets and 12 parasequence from bottom to top,and considered as tectonic movement and lacustrine level lift control the development characteristics of different position sequence in work area.Based on these,recognized delta-lacustrine sedimentary systems of the Northern Slope Zone and alluvial fan,fan-delta-lacustrine sedimentary systems of the South fault terrace zone,further recognized 10 kinds of subfacies and 20 kinds of microfacies at the Second Submember and the Third Submember of the First Member of Dainan Formation of Gaoyou Sag.And analyzed different periods and different structure position development characteristics and the characteristics of sedimentary microfacies distribution and sand body distribution law.Set up the sand body distribution model of lacustrine level control sand in north,fault terrace zone control sand in south.Finally,according to the development characteristics of each sand set of the first member of Dainan formation overlap position,combined with overlap area microfacies types,sand body distribution characteristics,tectonic geomorphology feature and fault development characteristics,forecast the favorable overlap traps development areas of each sand group,and concluded four overlap trap development models systematically.