Research On The Reservoir Architecture Of Putaohua Reservoir In Xing6 Area Of Xingshugang Oilfield, Daqing

At present,some problems are becoming more and more prominent in most of oilfields in eastern China,such as high oil production rate,high extraction degree,high water content but low reserve production ratio and low recovery rate.How to improve the recovery efficiency in the late development stage of the old oilfields,is the important problem facing currently and to be solved urgently.After three element composite flooding in PI-3 oil layer of Daqing Oilfield,reservoirs are flooded seriously with a 67.6%recovery degree.Meanwhile,the latest figures from sample analysis indicate that there are still considerable residual oil inside distributary channels,sand sheet and so on.While,due to the complexity of the internal structure and distribution regularities of reservoirs,the laws of internal structure inside sandbody and distribution of remaining oil are not clear.Shallow water delta is usually composed of?underwater?distributary channel,in which estuary dam is rare relatively.Because of the thin and narrow distributary channel sandbody,there are no mature research thinking and methods for hierarchical architecture analysis on distributary channel sandbodies of shallow-water delta facies in China and abroad at present.Therefore,based on core,seismic,log and test data,the paper puts forward a division scheme about reservoir architecture in shallow water delta guided by hierarchical analyzing and model fitting,to characterizate architectural elements in different scale quantitatively and to analyze the control effects of reservoir architecture on remaining oil distribution according to sample test and production data.Results show that?1?8architectural levels are classified for the sandbody of shallow water delta facies in the study area.Response characteristics of interfaces in different scales are different distinctly as far as core,seismic,logging and XRF test.?2?The 5^th architecture elements refer to mainly single distributary channel in various types and sizes.Straight distributary channel underwater is about 213m wide and its W/T ratio is about 78.1.Distributary channel with low sinuosity is 381 m wide with a W/T ratio about 89.4.While,the meandering ones distributed continuously with a large scale.Stable interlayers distribute commonly between distributary channels formed in different periods,which control general effect of waterflood development and interbed remaining oil is prone to form.?3?Different kinds of 4^thh architecture elements distribution characteristics changes greatly in single well and plane.Main channel is over 3m thick and 200⁶50m wide with high porosity and permeability;subsidiary channel is less 2m thick and 120²50m wide;terminal channel is 1.2¹.8m thick and 120²00m wide with a small scale;abandoned channel distributes limitedly with thickness about 2.0⁴.5m and width about 220³00m.Different kinds of 4^th architecture elements distribution characteristics changes greatly in single well and plane,in which remaining oil saturations differ considerably.Main channel and point bar are potential with good properties.Remaining oil are enriched in upper sand in superposed point bar and forks of distributary channels.While,lower parts of the abandoned channel are poor.?4?The 3^rdd elements distribute in multistages.Vertical accretionary body is 0.5²m thick and its surface is horizontal while lateral accretionary body is 110¹30m wide with a gentle occurrence.Its surface is about 5°¹8°and extend far in the end.The 3rd elements distribute in multistages,and the control effects depend on thire scale,properties and well network distribution,etc.