Study On Sedimentary System Of Funing Formation In Northern Jinhu Depression

The northern part of Jinhu Depression is the main exploration area of Jiangsu oilfield.The classification criteria of Funing Formation strata are still controversial.In terms of sedimentary research,the types and distribution characteristics of sedimentary facies developed in Funing Formation（E₁f）in the study area are not clear.The research in view of the problem encountered in the exploration and development,the distribution features of sedimentary facies in the studied area,comprehensive formation distribution characteristics,and analysis of ancient gully slope break belt control action of sedimentary evolution,to establish the funing formation sedimentary period of the model of sedimentary facies in the study area,north to golden lake sag next oil and gas exploration and development to provide theoretical support.According to the identification of the marker layers in each section,the sedimentary cycle and logging curve combination form formed according to the changes of lake level,it is concluded that the stratigraphic distribution of E₁f in the sedimentary period is generally thicker in the middle and thinner in the slope zones on both sides.Among them,the thickness of the E₁f₁sedimentary period is the largest,while in the E₁f₄sedimentary period,the strata at the edge of the study area affected by the later tectonic movement can not be completely preserved.Combined with seismic reflectivity layers（T₃³and T₃⁰）of Funing Formation in the study area,the development types and distribution range of gully slope break zone are analyzed,and it is concluded that the main gully types in the study area are lower cut valleys.The main types of slope break zone are tectonic slope break zone.In seismic section,cliff type,steep slope type and step type slope break zone can be seen.The plane distribution shows the comb,parallel,cross and broom-shaped slope break.On the basis of stratigraphic correlation in the study area,combined with the core observation and logging data and the comprehensive analysis of the core characteristic parameters of palaeogeomorphology,it is concluded that the provenance direction and supply size of each section of Funing Formation in the sedimentary period are different,and the provenance is mainly from jianhu uplift and Zhangbaling uplift in the south.Meandering river delta plain and braided river delta plain were developed in the middle and east of the study area during the sedimentary period of the the E₁f₁sedimentary period;Shallow lake and semi-deep lake subfacies were developed in a large area during the E₁f₂sedimentary period,and sandy beach bar microfacies were developed sporadically due to the late lacustrine current transformation,and banded mixed beach bar microfacies were developed in the western slope area;Delta front subfacies was developed in the east and west of the study area during the E₁f₃sedimentary period,and shallow lake subfacies was developed at the intersection of the two fronts;Delta front subfacies developed in a small area in southwest of E₁f₄member during depositional period.Figure 57;Table 4;Reference 60...