ENVIRONMENTAL FACTORS INDUCED CORROSION OF DOWNHOLE PIPES

The corrosion degree of different downhole pipes varies greatly in the same well although different downhole pipes are in a similar corrosion medium.This results from the environmental factors.The present paper is mainly discusses stray current corrosion,crevice corrosion,galvanic corrosion and stress corrosion.These corrosion phenomena often occur during oil/gas exploitation.There are many different pipes in one downhole well.Severe galvanic corrosion will occur if potential difference in local areas is large.Crevice corrosion occurs in the connection parts.The residual stress may induce stress corrosion,such as in thickened transition zone of drill pipe.