Improve water flooding efficiency of high pour-point oil reservoir by separate injection at multi stages;

This paper discusses a new concept of multi-level reinjection VSC,its main purpose being a further reduction of the harmonic content,a solution of dynamic voltage balancing for direct series connected switching devices and an improvement of high power converter efficiency and reliability.

Combining typical example,it wasshowed that the right use of multi-stage injection technology was an effective solution for products defects and could improve products qualities.