Optimization of activator for oil reservoir microorganisms by response surface methodology

In order to select optimal activator formula for indigenous microbial enhanced oil recovery in Well 93# of Karamay oilfield, the influence of soluble starch concentration, KNO3 concentration, and K2HPO4 concentration on indigenous microorganisms enhance oil recovery has been researched by adopting response surface methodology combined with crude oil degradability and viscosity decreasing index. The results show that the three factors all have significant adverse effect on indigenous microbial enhanced oil recovery, and the relationship between every material level and response value was well illustrated by the regression model. At the same time, the optimal activator formula were as following: soluble starch concentration was 10.9 g/L, KNO3 concentration was 3.2 g/L, and K2HPO4 concentration was 0.9 g/L. Under this condition, the predicted crude oil degeneration rate and viscosity degeneration rate was 65.04% and 42.03%, respectively; whereas the experimental value was 69.27% and 45.17%, which means the error was only 4.23% and 3.14%. The activator formula selected by response surface methodology was very credible, which provide reference for further field application research.