Abstract: The disparity between displacement efficiency and ultimate oil recovery in Chinese waterflooded reservoirs is big.For example,average displacement efficiencies corresponding to 1.0 and 0.98 of water cut are 0.6664 and 0.5045,but average ultimate recovery is only 0.302 for Chinese waterflooded fluvial facies reservoirs.It is shown that the sedimentation types of Chinese oil- fields mostly are continental deposit,heterogeneity is serious and sweep efficiency is still low.So enhancing sweep efficiency is one of two important ways of enhancing ultimate oil recovery.By using the research method of geologic model plus numerical simulation plus reservoir engineering plus mathematical statistics,"Evaluation System for Situ and Area Sweep in Waterflooded Bedded Reservoir" has been established.According to calculated results of this "System",three major rich areas of "large scale" unswept remaining oil in waterflooded bedded sandstone reservoirs have been determined:1.the unswept remaining oil in top of waterflooded positive rhythm reservoire with high viscosity oil;2.the unswept remaining oil in side parts and corners of oil reservoirs;3.the unswept remaining owing to development of non-proportionably each substratums in a series of strata.The determining methods and its developing methods of the unswept remaining oil are now summarized.It is shown that the study of these methods is very difficult and is one of kernel technology of present oilfield development and can be called a difficult century problem of world level.The research of this paper is a little progress solving the difficult problem.

Key words: waterflooded reservoir, unswept remaining oil, rich area

摘要： 我国油田水驱油效率与采收率的差距很大,以河流相储层为例,对应含水率1.0和0.98的平均驱油效率为0.6664和0.5045,而平均采收率仅0.302,说明由于我国油田大都是陆相沉积,非均质性强,使注入水的波及状况仍较差.利用抽象地质模型及相应的典型油层参数加油藏数值模拟加油藏工程加数理统计的研究方法,研究出了“注水多层油藏小层层内与平面波及评价系统”,利用这个系统的计算,确定出了注水多层油藏“大尺度”未波及剩余油的三大富集区:1注水高粘正韵律油层顶部未波及剩余油;2边角影响未波及剩余油;3层系内由于各小层物性差异开采不均衡形成的未波及剩余油.概述了目前确定未波及剩余油的方法及其开采方法,指出这项研究的难度很大,是当前油田开发的核心技术之一,可以称得上是世界级的世纪难题.

关键词: 注水油藏, 未波及, 剩余油, 富集区