Experimentally obtained saturated water content, phase behavior and density of acid gas mixtures

The acid gas components H2S and CO2 are separated from hydrocarbons during sour gas processing. Increased environmental restrictions on the flaring of acid gas and a decreased market for elemental sulfur have resulted in disposal of acid gas via injection into underground reservoirs. To effectively design an injection scheme, saturated water contents, phase boundaries and densities of the acid gas mixture over the range of operating temperatures and pressures are required. Extensive experimental data are not available in the literature.;An experimental apparatus and methodology were designed, tested and used to study a matrix of acid gas mixtures over ranges of temperature and pressure relevant to the natural gas industry. Saturated water content, density and phase boundaries of mixtures of H2S, CO2 and light hydrocarbons were measured.;The experimental data compare favourably to available literature data and to predictive models. The models can be used to smooth, interpolate and extrapolate between the experimental data points. The saturated water content data show that under certain conditions, it is feasible to eliminate the need for dehydration by removing the condensed water from the acid gas stream at a pressure corresponding to the minimum water carrying capacity of the gas. Depending on the injection temperature and pressure, liquid or dense gas non-aqueous phases may remain undersaturated with water due to the increased water carrying capacity of the liquid or dense gas at injection conditions compared to the gas at the minimum water carrying capacity.