The Study On Sedimentary Microfacies Of Lower Member Of Es2 In The First Block Of Shanghe Oilfield

The first area of Shanghe oilfield is located at the north-central of the Shanghe oil field,the east part of the Linyi Sag which is one part of the Jiyang Depression.It contains many oil layers along its vertical direction.And the Lower Member of Es2 is the main oil-bearing reservoir.Since the development,it has long been in the low-yield state due to the limitation of its complexed geological conditions.Taking the first area of Shanghe oilfield as the research area,this paper will focus on establishing an accurate stratigraphic framework and doing a sedimentary microfacies study by using sequence stratigraphy,sedimentology and the underground geology.A conclusion of various subfacies and microfacies identifiers can be expected.Finally,a sedimentary facies mold will be built accordingly.The research area is divided into four sandstone bodies based on the drilling and logging,well logging,seismic data.The four sand group is further divided into twenty sub layers by adopting the cycle-thickness contrast method and equal-height time unit contrast method.A conclusion of various identifiers of subfacies and microfacies is made through observing the core,as well as analyzing the sedimentary facies and the characteristics of the logging curve.The sedimentary subfacies of the delta front from the mainly developed shallow lake facies of the Es2 submemer is identified.And it can also be subdivided into five major microfacies,including subaqueous distributary channel,underwater natural levee,mouth bar,front sheet sandand distributary channels.A detailed summery of the characteristics of various sedimentary micro facies is provided.Using single well phase and mineral facies section as the basis,the paper analyzes the features of the small sand body and sedimentary facies flat sedimentary microfacies distribution based on the contour map drew on the basis of the sand thickness,shale content,Space permeability and logging curve property.The three or four sand group of the Lower Member of Es2 is mainly the development of the mouth bar deposition,one or two sand group mainly developed subaqueous distributary channel.the scale of mouth bar presents an overall declining trend from the top down,and the scale of the riverway keeps enlarging.A sedimentary facies model is established according to the provenance condition and the features and the evolving trend of sedimentary microfacies distribution.