On the basis of summarizing the researches on indigenous microbial enhanced oil recovery at home and abroad

four activating nutrients were used to activate the indigenous microorganisms selectively.The total number of all bacteria

the numbers of beneficial bacteria and harmful bacteria and the surface tension of Zhan 3 injection water after activation were tested.Then

the physical simulation experiments of indigenous microbial flooding were performed.The results showed that these four activating nutrients could activate the beneficial bacteria successfully;meanwhile

the harmful bacteria SRB were restrained to some degree.Pressure and porous media could influence the growth of microorganisms

especially porous media.KNO3 was better than NH4NO3 in the effect of activation and enhancement of oil recovery.With increasing content of nitrate from 0.1 % to 0.2 %

the change of activation effect was very little.Core flooding experiments indicated that the indigenous microorganisms could improve residual oil recovery by above 6 % after water flooding.