Reservoir Heterogeneity And Remaining Oil Distribution Of HCS Area

After years of development,oil layers of Yan8-yan9,Yan' an formation in HCS area of Ordos basin have moved to a stage of medium-high water-cut.During exploitation,there is a sharply increase on the moisture content and quantity of the liquid,poorer effect on whole water flooding,and it is difficult to describe the occurrence state and the location of residual oil.It means enrich regions of the remaining oil need to be predicted and provide scientific basis for the following development work.This thesis mainly obtained following achievements:First,a Refined reservoir geological model has been set up.They include:l.Yan9 formation could be divided into three layers,and Yan8 could be divided into four layers;2.The oil layers mainly distribute Y84,Y91 and Y92,which occupy 80%of pay thickness;3.There are two vertical independent reservoirs which are both edge water and bottom water reservoir;4.The structural form is westward monoclinic dumping,which keeps consistent with Ordos basin,and there are some low amplitude structures appear on partial area,such as nasal eminence structural highness and small anticline.Second,in-layer,inter-layer,and plane heterogeneity have been studied by using routine parameters.The heterogeneity of upper reservoir is strong,and lower is weak.Main reservoirs with homogeneous rhythm and small interlayer inside are benefit to water drive.Interlayer heterogeneity is medium,and inter layer interference is not strong when multiple-layer produce is applying.Plane heterogeneity would induce water breakthrough.Third,the main character of remaining oil is regional scarceness and local enrichment at high water-cut stage.This thesis clarifies reservoir micro-structure,reservoir heterogeneity and dynamic production control the distribution of remaining oil.There are four Remaining oil patterns:structure high parts,water blocking remaining Oil,excluded oil in the original development program and the oil remained in the retentio n area of the contracted layers.Fourth,the enrichment areas of remaining oil are suitable for new infill wells,which have been proposed.