Development of double layer metal thermal spray: Novel external corrosion mitigation method for gas well tubing

This paper discussed the corrosion characters and new double layers metal thermal spary technology for gas well tubing in Erdos basin, Changqing field. Some gas wells produce formation brine, also contain low H 2S content and medium CO 2 content. (water/gas ratio lager than 0.2m 3/10 4m 3, and averge total ions strength is 120g/L, Cl - nearly 80g/L). The electric-chemical corrosion causes the workover lifetime of gas well less than 5 years. On the external surface of SSC-resistant carbon steel (80S) tubing, the double metals protection layers of 13Cr and Aluminum were designed and applied by high speed arc spary technology. Physical and corrosive properties were researched at simulation and HT/HP conditions. More than 15 wells were applied by this method in recently 4 years. Before workovering, the lifetime of those wells were not more than 5 years, also lower than regulation workover time of 8 years. At 4 years ago, the corrosion situations of 3 wells which would be workovered were inspected using the multifinger imaging tool and magnetic thickness tool, MID-K logging equipments. By now, those wells were logged (MIT+MTT) again and showing a good condition. Copyright 2012, Society of Petroleum Engineers.