The study concerns performance of alkaline formation stimulation metho
d which helps control movement of the injected water front, improves t
he coverage ratio and enhances oil recovery. It has been found that fo
r greater permeability reduction in high water cut zones, alkali shoul
d be injected together with solutions of bivalent metal (Ca or Mg) sal
ts, or well treatment should be repeated using solutions with higher N
aOH concentrations.