Research On The Outside Surface Corrosion Of Downhole Tubes In Wet Gas Reservoir

This paper sum up and research the corrosion of tube downhole in a gas field group in china. The gas well corrosion phenomena only in China is discovered: the tube outside surface corrosion is serious over 60% in sample gas well of 20 wells in wet reservoir. This corrosion phenomenon of downhole has not yet reported at home and abroad. This paper analyzes theoretically and researches this corrosion phenomenon in laboratory.The analyses show the characteristic of outside surface corrosion of tube that remain of HC1 in acid treat and Cl^-, HCO₃^- in gas fields water are not directly relative. and H₂S, CO₂ in gas induce the outside surface corrosion of tube. But it is not all factors on the outside surface corrosion of tube. Reference to the research results of atmosphere corrosion and top corrosion in pipeline at home and abroad, combined with inner factor and service corrosion factor, comparing the service factor of inner corrosion to service factors of outside surface corrosion of tube, this paper first mentions that the nature of outside surface corrosion of tube is the metal tube corrosion in condensate of nature gas vapor. This corrosion always occurs on the tube downhole without production packer or the packer out of order in wet nature gas reservoir. Some outside surface corrosion of tube is much serious than inside corrosion that is determined by nature of outside surface corrosion of tube. Condensate in the circular space downhole and the corrosive medium, such as H₂S...