Simulation of reservoir souring has been a neglected area of corrosion research. The procedure followed herein is to form a sweet corrosion product layer, introduce a low concentration of H2S in the gas phase (<100ppm) and allow the system to continue to evolve. The experimental apparatus used was a 2L glass cell with an impeller in the center and 5 samples spaced evenly around it to allow for in situ corrosion rate monitoring and extraction of specimens for surface analysis. In experiments involving Fe3C residues the general corrosion rate decreased when H2S was added to the system. FeS was detected on the samples with the Fe3C; it is postulated that a thin layer of FeS forms leading to the decrease in general corrosion rate. When the FeCO3 was challenged with H2S, the general corrosion rate increased. FeS was detected on the samples, but no significant change was observed in the FeCO3. However, it was electrochemically determined that the H2S impacted the FeCO3 sufficiently to allow the general corrosion rate to increase.