Study On Sedimentary Facies And Favorable Zones Prediction Of The Arad And Ben Group Formation At M Oilfield In South Sudan

Muglad basin,the most important petroliferous basin in northern Africa,is located in both Sudan and South Sudan.The basin is an intracontinental clastic basin developed above a stable Cambrian basement,having been experienced three times fault depression and three times depression,being always controlled by Central Africa shear zone right-handed shear stress during sedimentary evolution.In this paper,the study area,M oilfield lies in south centralMuglad basin,which is completed the first drilling exploration in 2001.So far the study area only has eight wildcat wells and has no traditional coring.So the degree of exploration and research is low.Based on the stratigraphy,sedimentology,petroleum geology and oil and gas field development geology,combined with previous studies on the Muglad basin,this study is focused on the study of the middle-late CretaceousArad and Ben group of M oilfield.On the basis of exact time-depth conversion and combination of the well-log,seismic and mud loggingdata,applying the method of marker bed control,sedimentary cycle division,adjoining well track and equal formation thickness,the two group is divided into nine formations and seventeen layer and the stratigraphic division and correlation connecting-well profile is set up.Within the isochronous stratigraphic framework,we determine the sedimentary facies of Arad and Ben group.The sedimentary facies of Arad and Ben group formation are meandering fluvial facies and braided fluvial facies respectively,furthermore,the sedimentary microfacies such as point bars,natural levee,flood fan,diara,floodplain are also recognized.Through the analysis of logging facies and seismic facies,logging-seismic-sedimentary facies model is established,and thenthe single well-multi-well –plane sedimentary facies and the distribution of the sand body are evaluated.Based on analysis of the effect of sedimentary facies on source rock-reservoir-cap rock relationship,reservoir type and oil-water distribution characteristics,combined with plane distribution of sedimentary facies and sand body development characteristics,finally the favorable petroliferous zone is successfully predicted,providing a theoretical basis for further exploration and development.