Abstract

The first oil production at Campos Basin started 35 years ago. However the field conditions changed recently as the water injection caused some souring of the reservoir; now small amounts of H2S associated with CO2, in the range of 0.1 to 0.4%, also have to be considered. Therefore a study to assess carcass corrosion resistance to Sulfide Stress Cracking (SSC) and crevice susceptibility is needed. First production lines in Campos Basin used AISI 304 as carcass material and therefore a test program comprised of this material and 316L was launched. All carcass samples tested came from the flexible lines that had operated in the field. Before the tests, carcass samples were inspected and showed no sign of localized corrosion. According to the results, 304SS carcass presented very good corrosion resistance at 600C, 100,000 ppm of Cl- pH 4 and 10% H2S. At higher temperatures pits and chlorine SCC were observed depending on chloride concentration. These results can be used as technical data to support service life extension of 304SS carcass in Campos Basin. Moreover, according to the tests performed, the 316L SS carcass can operate in sour environments up to 700C, pH 4.5, 60,000ppm of Cl- and 10% H2S with balance of CO2. These limits are beyond the ones defined by MR0175/ISO15156 to 316LSS.

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