Research On Water Flooding Sweep Law Of Ultra-low Permeability Reservoir In Changqing Typical Oilfield

With most of waterflooding oil field in our country having entered high water cut period,study on improving oil recovery of middle-late stage water flooding reservoir has become one of the hotspot of petroleum science and technology research fields.Aiming at conventional water flooding reservoir development effect,it is necessary to establish the quantitative evaluation of water drive reservoir sweep efficiency in order to quickly and accurately predict waterflood sweep range,optimize water injection development effect,and provide theoretical guidance for conventional water flooding reservoir development plan design.Based on other people's research results,this paper makes use of reservoir engineering and numerical simulation method to make an improment on the evaluating method of plane sweep efficiency for ultra-low permeability reservoir with two methods.On the same time,the influencing factors of plane sweep efficiency are analysed.Based on the exploration data of Changqing ultra-low permeability reservoir BM oilfield,the evaluating of sweep efficiency as well as the exploitation contradiction are determined.As for Changqing BM oilfield,the improving potential for vertical sweep efficiency is not that big,and the exploitation contradiction is focused on plane sweep efficiency.In the mean time,on the basis of the exploitation characteristic and current situation of Changqing BM oilfield,several sweep efficiecy improving measures,such as profile control,separate layer water injection,patching holes,converting injection well,vertical well encryption and so on,are researched in order to analyze the improving effect of plane and vertical sweep efficiency.