Carbon Steel Corrosion on Production Environment, Evaluating the Impact of CO₂ Partial Pressure, BSW and Oil Characteristics on Tubular Life Extend Available to Purchase

The high productivity of pre-salt exploratory wells led to a re-evaluation of Petrobras’ model of offshore oil production and exploration. We present here the study that allowed the conversion of exploratory wells into producers, based on the corrosion resistance of carbon steel in different scenarios of pre-salt field production. The aim of the test program was to evaluate the influence of the produced water content (BSW), CO₂ partial pressure and oil characteristics on the carbon steel corrosion resistance. General corrosion analysis showed that for brine content below 40% corrosion rates ca. 0.05 mm/year for 28-day tests. Higher CO₂ partial pressure did not lead to increased corrosiveness, unlike shear stress. There was localized corrosion in most of the evaluated test conditions, confirming the importance of using laboratory techniques that allow such analysis. Localized as well as generalized corrosion kinetics decrease over time, confirming that laboratory tests, even when replicating field conditions, are more conservative as the operation time of the production columns will be extremely longer than laboratory test times. Based on results of this test program it was possible to extend the operation of exploratory wells adopting as safety criteria for well abandonment the produced water content (i.e. BS&W content) and additionally monitoring the internal pressure of production tubing.