Hydrate Formation in Systems Containing Methane, Hydrogen Sulphide and Carbon Dioxide

Experimental data have been obtained on the initial hydrate-forming conditions in systems containing, nominally, 72 per cent and 82 per cent methane, with the balance consisting of various mixtures of hydrogen sulphide and carbon dioxide. The study covered a range in pressure from about 100 psia to 2,200 psia and a range in temperature from about 32°F to 76°F. These data, together with previously published data on systems containing methane and carbon dioxide and methane and hydrogen sulphide, were used to prepare working charts to predict initial hydrate-forming conditions in systems containing about 65 per cent or more methane, with the balance consisting of variable amounts of hydrogen sulphide and carbon dioxide. A comparison was made with results calculated using the concept of solid-vapour equilibrium ratios. The calculated pressures at any given temperature were always higher than the experimental pressures at the same temperature. The average error was about 42 per cent for the 72-per-cent methane mixtures and 52 per cent for the 82-per-cent methane mixtures.