Abstract:

When oilfields begin to assume tertiary oil recovery phase in the east part of China,physical properties and electric properties of pay zones will be uncertainly altered to a great extent due to the iniection of polymer.In order to ascertain the changes of reservoir properties which have been affected by the polymer,the core experiments have been designed according to there servoir behaviors in the period of tertiary oil recovery.Based on the core experiments from polymer in jection region,this paper has identified that core porosity and permeability haven't changed,film potential has dropped off,porosity structural index has increased,the index of saturation of Archie's equation has focused on1.4-1.7,and the resistivity changes are in the shapes of letters s and L.After polymer displacement,reservoir porosity and pemeability can be calculated by conventional logging method.The values of film potential before polymer displacement are apparently bigger than that of after polymer displacement,so the application of spontaneous potential should be noticed after polymer displacement.During polymer displacement,the law of resisitivity change is similar to that of salinity water driving oil.So the method of saturation appraisal of waterflood can be directly used in logging assessment.

Key words: polymer displacement, resistivity, porosity, permeability, film potential