An Investigation of Internal Corrosion of Oil and Gas Transporting Carbon Steel Pipes in the Niger Delta Area of Nigeria

Internal corrosion of carbon steel pipes of oil and gas Companies in the Niger Delta area of Nigeria using coupons and ER probes is presented. Corrosion mechanisms for the lines vary with the fluid type and operational parameters. Aqueous corrosion with, in some cases CO2 corrosion additive, erosion corrosion and elevated temperature oxidation are corrosion mechanisms implicated in the pipes. No H2S-induced corrosion was observed for all the lines investigated. They act separately or synergistically to exacerbate the corrosion attack. Application of inhibitors of the amine group drastically lowered the corrosion rates. Effective inhibition regime had in an instance markedly lowered the corrosion rate of a line from 42.7080mpy to 1.3447mpy. The ER probes incorporation offered a comparative corrosion monitoring alternative and provided insight into the real time conditions of the lines over prolonged periods of times. The exercise proved very useful in determining the corrosion status of the pipes and helped to determine the lines that should require immediate maintenance intervention to obviate possible ugly incidents of breakouts and ruptures.