Research On Sedimentary Facies Of Guantao Formation In Shanjiasi Area Of Dongying Depression

Through integrated analyses of the core,well log,oil testing,and seismic data,this thesis applies principles of sedimentogy,sequence stratigraphy,and petrolume geology to classify sedimentary facies,construct high-resolution sequence stratigraphic framework,interpret depositional systems,delineate sandstone distribution patterns,and predict potential the distribution range of effective reservoir sand bodies within Guantao Formation in Shanjiasi Area.Within the sequence stratigraphic framework,the Guantao Formation has been divided into four sandstone units,named as Ng1,Ng,Ng3,and Ng4.They have been subdivided into 11 beds,named as Ng1-1,Ng1-2,Ng2-1,Ng2-2,Ng3-1,Ng3-2,Ng3-3,Ng4-1,Ng4-2,Ng4-3,and Ng4-4,respectively.In the study area,the Guantao Formation is composed of pebbly sandstone,sandstone,and mudstone.Overall,Ng1 and Ng2 units have a lenticular sandstone distribution,signifying sandstone surrounded by mudstone.Ng3 units show interbedded sandstone and mudstone.Ng4 unit has a flaser sandstone distribution,signifying mudstone surrouned by sandstone.Sedimentary structures include massive,cross,parallel,planar,and graded bedding,as well as scour surfaces.The compositional and textural maturity of the rocks are relatively low,and they are deposited in alluvial depositional setting.The Ng4 and Ng3 sandstone units are formed by alluvial fan and braided stream systems,including proximal-middle-distal fan,mid-channel bar,and floodplain subfacies.Ng1 sandstone unit is formed by meandering stream systems;and Ng2 sandstone unit is formed by both braided and meandering stream systems,including point-bar,natural levee,crevasse splay,and floodplain subfacies.Guantao Formation consists of multiple vertically stacked thick alluvial-fluvial deposits.The sandstone bodies display a SW-NE oriented ring-like geometry in plane view.Based on the characteristics of sand body morphology,physical properties and sedimentary facies distribution,the distribution regularity of effective reservoirs in the Guantao Formation in the Shanjiasi area was analyzed.The Ng4 sand group in the Guantao Formation of the Shanjiasi area was considered as the potential hydrocarbon target.The palaeogeographic high part of Binxian County is predicted as effective sandy traps.