Corrosion Behavior of Deep Water Oil Production Tubing Material Under Supercritical CO2 Environment: Part 2—Effect of Crude Oil and Flow

Abstract

Deep water oil production tubing materials are exposed to high carbon dioxide (CO2) pressure and temperature conditions that can affect the corrosion performance of such materials. The present study evaluated the corrosion behavior of carbon steel exposed to supercritical CO2/oil/brine mixtures at different water cuts (0, 30, 50, 70, and 100%), CO2 partial pressures (8 MPa and 12 MPa), and temperatures (65°C and 90°C) in a flowing 25 wt% sodium chloride (NaCl) solution. Corrosion behavior of carbon steel was evaluated by using electrical resistance (ER) measurements, weight-loss measurements, and surface analytical techniques (scanning electron microscopy [SEM] and energy-dispersive x-ray spectroscopy [EDS]). The corrosion rates of carbon steel increased with increasing water cut. There was no indication of corrosion attack with 0% water cut. At lower water cuts (30% and 50%), the steel surface was covered by iron carbonate (FeCO3), while iron carbide (Fe3C) was present on the steel surface at higher water cuts (70% and 100%) with very high corrosion rates. In addition, the presence of flow prevented the formation of protective FeCO3 at high water cut conditions.