| As the main means of secondary development,the effectiveness of water flooding has always been a concern of oilfield developers.The research of conventional experiments mainly focuses on the relationship between injection rate and recovery degree.It is often difficult to visually characterize the use of remaining oil in different levels of pores by water flooding.The three-dimensional distribution characteristics of oil and water in the same position inside the core at different displacement stages can be captured by CT scanning,which can effectively quantitatively evaluate the effectiveness of water flooding remaining oil,thus providing a reliable theoretical basis for improving the efficiency of water flooding remaining oil.For the indoor small core test,generally presents after water washing efficiency and injection multiple logarithm is a good linear relationship,namely different reservoir water injection multiple is the same,but the oil washing efficiency is very different.Based on CT scanning technology,this paper designs microscopic displacement experiments of limit water flooding,polymer flooding after water flooding and ASP flooding after water flooding with different permeability to obtain three-dimensional fluid distribution in cores at each displacement stage.The occurrence state and location of remaining oil distribution in limit water flooding,polymer flooding after water flooding and ASP flooding after water flooding are quantitatively studied,and the effects of three displacement methods with different permeability cores and displacement speeds on remaining oil distribution are compared.By comparing the cores with different permeability,the ultimate displacement experiment under the same displacement speed shows that with the increase of permeability,the final oil washing efficiency of ultimate displacement increases.The analysis of different types of remaining oil can be concluded that in the process of water flooding to 0.5PV to 3PV at the same displacement speed,the utilization of membrane remaining oil is better than that of columnar remaining oil,and the columnar remaining oil is better than the porous remaining oil.In the chemical agent flooding after water flooding,polymer flooding increased by 12.5 %.The analysis of different types of remaining oil shows that after polymer flooding,the utilization of various types of remaining oil has been effectively improved,among which the utilization of polymer flooding after membrane oil-water flooding is the most obvious.The oil washing efficiency of ASP flooding increased by 27.2. |
