Corrosion Control Technique for High-sulphur Gas Gathering and Transferring System in Puguang Gas Field

The gathering and transferring system in Puguang gas-field includes a central gas gathering station and 16 substations covering 38 gas wells and 37.78 km pipelines. The content of hydrogen sulfide in the natural gas is nearly 15% and carbon dioxide from 8% to 10%, so the wet high-sour gas makes great corrosion risk to transferring system. Based on tests of electrochemical corrosion, hydrogen-induced cracking (HIC), sulphide stress cracking (SSC), the materials of anti-sulphide-corrosion were studied and selected for pipelines and equipment. And injection technique of corrosion inhibitors is used to prevent the pipes from internal corrosion “pre-coating & continuous injecting”. Also, cathodic protection and intelligent pigging detection are applied as well. Furthermore, corrosion monitoring techniques including corrosion coupon (CC), electro-resistance (ER), linear polarization resistance (LPR) and field signature method (FSM) are introduced to monitor the corrosion development roundly. The monitoring results show that the average corrosion rate of Puguang gathering and transferring system is limited below 0.044 mm/a.