Corrosion Behavior of Gathering Pipeline Steel in the CO₂/Oil/Water Corrosive Environment

The corrosion behavior of X65 steel in CO₂/oil/water corrosive environment was studied by the methods of orthogonal experiment and weight loss test in a high temperature and high pressure autoclave. The results show that water cut is the major corrosion factor of X65 steel, which can affect the corrosion rate significantly. The grains of corrosion product film were cellular, and their accumulation was uncompacted. The film had loose structure, its protection effect for the matrix was weak. The steel surface was covered by corrosion scales uniformly and exhibited general corrosion morphology with corrosion pits in some local places, the resistance to CO₂ corrosion of X65 steel was comparatively poor. Both at low and high water cut, the corrosion products were basically the same, mainly contained FeCO₃ and Fe.