Research On The Interlayer Of The Shallow Water Delta Front Reservoir

With the development of Bozhong 34-1 oilfield becomes more mature and enters its middle and later periods,the water flooding displacement efficiency is reduced.It is difficult to meet the standards that fine exploitation needs to depend on geological reservoir model that based on the small layers.Meanwhile,both the connectivity of single underwater distributary channel sand body and the seepage flow barriers and differences that caused by intercalations in the reservoir cause the distribution of the remaining oil.Therefore,in order to improve the precision of oilfield development and the water injection efficiency,the identification,on the basis of the single layers division and contrast,to the characteristics of reservoir configuration unit and the distribution law of the intercalation layer of reservoir is needed.In this paper,based on the theoretical guidance of Sequence Stratigraphy,Reservoir Geology,Sedimentology and Development Geology,we have established the fine isochronous stratigraphic framework combined with the core data,logging data,seismic data and the production dynamic data.The Nm? oil series can be divided into nine small layers and twenty two single layers.We identified configuration units of the four main layers:Nm?-1?Nm?-2?Nm?-3?Nm?-5,and analyzed vertically the overlapping relationships of single layer.Finally,to identify the interlayer of reservoir and analyze its expanding characteristics after observing the core and studying the reservoir architecture.Results show that:Bozhong 34-1 oilfield is shallow water delta deposit,and Nm? oil series,the target layer,is data front.The sedimentary microfacies mainly include the underwater distributary channel and the bay mud between distributary channels.The vertical superimposition can be divided into three types:isolation type,superimposed type and cut pile type.The main vertical composition of the architecture element in the study area is the superimposed type,the isolation type is followed,and the cut pile type is not developed.The single layer underwater distributary channels of the main small layer are striped and branched from the southwest to the northeast,from the northeast to the southwest,and from the east to the west.The underwater distributary channel graph of each single layer in the target layer is finished,according to the study of the sedimentary microfacies plane spreading in small layers.The argillaceous interlayer,the argillaceous sandwich and the calcareous sandwich in the single sand layer are three types in the study area.The argillaceous interlayer is widely and stably distributed.It is thin or missing in the middle but becomes thicker in both sides of the superimposed area and the end of the underwater distributary channel.On the contrary,for the middle single channel sand,the gross thickness is greater but the frequency distribution of the argillaceous sandwich is minor;for the two sides of the single channel and the end of the underwater channel front,the gross thickness is decreased and the frequency distribution is increased.The calcareous sandwich is less developed.