Study On Reservoir Heterogeneity In High-resolution Sequence Stratigraphic Framework Of Fuyu Oil Layer In Mu 8 Block In Southern Songliao Basin

Mu8 block is located in the south of Songliao Basin and the northwest of Songyuan City,Jilin Province.It has entered the later stage of oilfield development.The macro heterogeneity of Fuyu reservoir is strong,which leads to poor water injection development effect and seriously restricts the recovery of remaining oil.In the high-resolution sequence stratigraphic framework of Fuyu reservoir,the frequent fluctuation of datum level plays an important role in controlling reservoir heterogeneity,so it is urgent to carry out reservoir heterogeneity research to guide the further exploration of remaining oil.This article is based on high resolution sequence stratigraphy,the oil and gas field development geology theory,using the data of core and well logging data,on the basis of different levels base-level cycle interface signature,inside the fuyu oil layer divided into one long,4 medium,12 short-term base level cycle,and by comparing the short-term base level cycle in fuyu oil layer high resolution sequence stratigraphy framework.In combination with the regional sedimentary background and based on core and logging data,it is clear that there are 1 facies,2 subfacies and 10 sedimentary microfacies in Fuyu oil reservoir,and the logging facies model is established.After analyzing the sedimentary microfacies of single well and connected well in coring well,the distribution of plane sedimentary microfacies in each short-term cycle is carefully studied.According to the depositional evolution law of fuyu reservoir from river controlled shallow water delta plain subfacies to delta front subfacies,the sedimentary model is established and the distribution law of sand body of Fuyu reservoir is summarized.Based on the establishment of sedimentary model,the reservoir heterogeneity of Fuyu oil reservoir in Mu8 block is studied.By analyzing the heterogeneity within,between layers and in plane and calculating the relevant heterogeneity parameters,it is shown that the fuyu reservoir is of medium to strong heterogeneity as a whole,and the reservoir heterogeneity is stronger than that of delta front subfacies in delta plain subfacies.In the high resolution sequence stratigraphic framework of Fuyu reservoir,the degree of reservoir heterogeneity varies with the relative position of datum level.The short-term base-level cycle is located at different positions of the middle and long-term base-level,which controls the types of sedimentary microfacies and affects the reservoir heterogeneity.In the early stage of mid-and long-term base-level rise,the thickness of interlayer is thin,the thickness of vertical sand body is large,and the degree of cutting and stacking is serious.The sand body in plane is widely distributed,with good continuity and weak reservoir heterogeneity.Under the influence of the long-term datum level of Fuyu reservoir rising continuously,the reservoir heterogeneity is obviously enhanced.