Characterization Of Reservoir Sandbody Heterogeneity In River Deposition

By practice of oil field developm ent, there are still some high oil saturation parts even unproducing parts in the channel sandbody reservoir when entering the high water cut stage.Most of oil in these parts is remaining because of the heterogeneity of reservoir. All kinds of channel sandbodies develop in the fluvial-deltaic deposition reservoir in Daqing Lasaxing oilfield,which are varied in scale,shape and genetic type.There are widespread arenaceous braided river sandbodies, wide meander belt sandbodies deposited by high -sinuosity meandering river and narrow straight distributary channel sandbodies. By long-time exploring,geologists in field development has formed a series of mature technological methods for heterogeneity description of different channel sandbodies,and these methods have effectively guided oilfield development plans in the different phases of exploitation. The research is focus on the reservoir in meandering river deposition in Grape Oil Reservoir at the north 3rd zone of Lasaxing oilfield. According to drilling cores and dense pattern logging curves, taking sequence analysis and depositional theories of fluvial reservoirs as guidance,on the base of detailed correlation of single rivers cyclothem, some researches have been done as follows: dividing single meander belt from the composite belts, identifying single point bar,describing single point bar sandbody and establishing three-dimensional geologic model,etc.The research has realized gradual description of channel sandbody reservoir heterogeneity from large to small and has further developed the description of reservoir.Moreover,the study of the three-dimensional characterization of the interbedded stratum in braided river reservoir has also been going on.It may be helpful in further understanding of reservoir based on the former reservoir description,and providing deeper geological basis for this kind reservoir.