Research On Microscopic Percolation Characteristics And Improvement Of Residual Oil Recovery For High Water-cut Oil Reservoir

With the development of waterflooding,waterflood efficiency is usually very low after entering into the high water-cut period in most all oil fields.So,it is of great significance to study percolation characteristics of water flooding,residual oil distribution and the methods of inproving oil recovery.Glass etching model has been used in this paper to do micro-waterflooding and micro-polymer flooding experiments,the microscopic visualization device made it ture to observe the process of waterflooding and the formation of residual oil.This paper was also focused on the efficiency of wterflooding.The main achievements of this paper are as follows:1.Based on the characteristics of the residual oil,a microscopic quantitative classification criterion of residual oil has been established,and classified the residual oil as droplet residual oil,columnar residual oil,oil slick residual oil,branched residual oil and contiguous type residual oil by doing waterflooding experiments;2.A series of experiments have been done to study the methods of EOR,such as changing water intensity and changing the seepage direction of the injected water,the results show that recovery of residual oil can be improved by increasing the intensity of waterflooding,especially branched residual oil and contiguous type residual oil;3.The relationship between oil viscosity and oil recovery in high water-cut period has been found,micro-polymer flooding experiments and waterflooding on hydrophilic and lipophilic model experiments have been done.Methods to improve waterflooding efficiency of five types residual oil have been found depond on the micro-flooding experiments.In this paper,the results of research has a great significance on the formation and classification of residual oil in high water-cut period,and also can provide guidance for further tap potential of residual oil.