Sedimentary microfacies of the second member of Hetaoyuan Formation in Xia'ermen Oilfield,Biyang Sag,Nanxiang Basin

The reservoir heterogeneity of the second member of Hetaoyuan Formation in Xia'ermen Oilfield is strong and the adjacent well productivity is greatly different.On the basis of the data of core,well logging and grain size,the division and characteristics analysis of sedimentary microfacies of the second member of Hetaoyuan Formation are carried out,and the shape and distribution of the reservoir sand body and the mode of sand body superposition are analyzed.The result showed that Ⅱ—Ⅴ oil-bearing layer of the second member of Hetaoyuan Formation developed braided river delta front subfacies deposit,which can be divided into five sizes of sedimentary microfacies and creeping turbidite sand body.The sedimentary microfacies include subsea distributary channel,mouth bar,distal bar,front sheet sand and distributary interchannel,among which the subsea distributary channel and mouth bar are the favorable facies belts of the study area.