Study On Braided River Reservoir Architecture Of 8-10 Sand Groups Of Guantao Formation In The West Distract Of Chengdong Oilfield

There is a set of braided river deposits are developed in the 8-10 sand groups of Guantao formation in the west distract of Chengdong Oilfield.The sand bodies are overlaid frequently,the internal structure and the oil-water relationship is complex.At present,it is still in the late stage of high water cut development.In order to further tap the potential of remaining oil and improve oilfield production,it is necessary to study the architecture of braided river reservoir,clarify the internal architecture elements and combination relationship of braided river reservoir,and analyze its influence on remaining oil distribution.In this paper,based on the comprehensive utilization of core,logging and development dynamic data and the guidance of previous studies,the stratigraphic of the study area is finely divided,and the isochronous stratigraphic framework of different orders is established.The architecture interfaces of single well and inter-well are divided and compared,and the architecture units and their combination pattern under the control of 4^th order architecture interface and 3^rd order architecture interface are mainly studied.The influence of reservoir architecture interface and architecture unit combination on remaining oil distribution is analyzed,and the possible enrichment area of remaining oil in the study area is predicted.The result shows that the study area is divided into 6 orders architecture interfaces on a single well.By using 6 kinds of inter-well architecture interface comparison patterns under different orders,the 5^th～3^rd orders interface of inter-well is compared,the combination relationship between the architecture elements of braided river reservoir in the study area and the influence on the distribution of remaining oil are clarified.7 kinds of architecture units under the 5^th～3^rd orders architecture interfaces were identified in the study area,which were composite river channel,overflow deposits,flood plain,braided river channel,channel bar,accretion body and falling silt layer.The combination relationship of 4 kinds of vertical architecture units,4 kinds of lateral contact relationship and 3 kinds of distribution patterns of falling silt layer in the channel bar were summarized,and the architecture unit combination pattern of composite river channel with superimposed channel bar was established.The research results of reservoir architecture are applied to the study of remaining oil distribution,and it is concluded that the remaining oil is blocked by the seepage barrier between the various architecture units in the braided river reservoir,which is mainly distributed in the top and edge of the oil-bearing architecture unit.It is speculated that the remaining oil is mainly enriched in C55-18 well,C55-4 well,C55-3 well,C55-9 well,C24-151 well area in the southeast of the study area and in C32-10 well,C31-10 well,C31-X12 well area in the southwest of the study area.