Reservoir Description On The Aershan Formation Of The A31 Fault-block In Anan Oilfield

With the development of oil field and the continuous improvement of the oil field knowledge,the fine reservoir description of the old oil field is not only a requirement to oil field development but also an effective means to comprehensively understand the reservoir.A31 fault-block is the main block of Anan Oilfield and the reservoir description of the Aershan formation in 31 fault block provides geological basis for productivity construction of oilfield.In this paper,with the comprehensive utilization of drilling records,well logging and seismic data,the studies on reservoir description of Aershan formation in 31 fault block are carried out.Firstly,with the comparison method of sedimentary cycle thickness and on the basis of the identification and comparison of the standard layer,thin layer division and contrast is carried out.Secondly,using seismic data to carry out the structural interpretation and structural characteristics analysis,and through the identification of core facies marks the type of sedimentary microfacies are determined then the study of sedimentary microfacies is carried out.Based on the log data pre-processing,researches are carried out on relationships of the four characters of reservoir,and the well logging interpretation model has been established and the standard of oil and water layer interpretation has been determined.Based on the research above,a fine 3D geological model is established.The research shows that the 10 marker beds are identified of the Aershan formation in 31fault block,and on the basis of marker beds 4 oil-bearing formations and 49 sub layers are devided.The overall structural features of 31 fault block are a broken nose structure,and there are two structural high of nose structures located in east and west.The east high point of structure is controlled by a block of fault block composed of the north to the east and west of the reverse fault,and the west high point of structure is controlled by the nose-like structure formed by north to the east of forward detachment fault.Through the study of sedimentary micro facies,A_I and A_III oil formation of the A31 fault-block is Binshore subaqueous fans,and can be divided into three subphases,the fan end,the fan middle,and the fan top,and the fan middle is the most important subfacies.With the reinterpreted logging curve,the main parameters are calculated which accord with real geology situations.The 3D geological model established on the basis of the above study accords with real geology situations,which can be directly used for reservoir numerical simulation to provide geological basis for adjusting reservoir development plan in late stage.