Hydrogen Sulphide Scavenging Simulation in HYSYS

In this work, H2S scavenging in oil production was simulated and the effect of gas lift and water production increase were evaluated over the concentration profile of H2S along the production line and the scavenging efficiency. Data from a real production field from Brazil was used. Scavenging kinetics was modelled according to literature concerns. The production line was simulated with the software Aspen HYSYS, from Aspen Technology, Inc. It was observed that lifting gas injection has two important effects upon the system. The first is the anticipation of the meeting point between system's bubble pressure and the line pressure, what means that since the lifting gas injection point there is a gas phase carrying hydrogen sulphide and hydrocarbons from the liquid phase and interfering in the reaction kinetics. The second is the dilution effect of the gas lift. When water production was simulated, at different water-to-oil ratios, it was observed different H2S partitions between the gas and liquid phases, related to the lower solubility of H2S in water. This phenomenon could also affect the scavenging efficiency, because the reaction occurs only in the liquid phase. The authors agree that these observations are very important to the correct modelling of hydrogen sulphide scavenging in oil lines and could be used to support the development of new optimization tools.