Aiming at the serious casing corrosion of water injection wells,one chemical agent is injected into the annular space of the tubing and casing,and forms a ring-shape elastical seal plug,then the suitable corrosion control agent and bactericidal agent are injected,used as a casing protection fluid.

With regard to the frequent occurrence of abnormal tripping faults of ZKH-3 feeder assembly protection in substation, implements the site-inspection, test and theoretical analysis of the faults, defines the reasons causing the incorrect operation and over-zone tripping of the assembly protection and points out the effective counter-measures.