Measurement and modeling of water content in low temperature hydrate-methane and hydrate-natural gas systems

Trace water content creates potential ice or hydrate blocking risks in low temperature gas processing plants. To evaluate such risks, it is important to know the water content of the gas phase in gas mixtures at low temperature. In this work, new experimental data are reported for the water content of methane and a natural gas in equilibrium with hydrates at a pressure range from (3.45 to 13.79) MPa and temperature range from (273.15 to 238.15) K. The measurements have been made with a high-pressure variable volume hydrate cell using tunable diode laser absorption spectroscopy (TDLAS) technology. The cubic-plus-association (CPA) equation of state is used to model the fluid phases, and the hydrate-forming conditions are modeled by the solid solution theory of van der Waals and Platteeuw. Predictions of the model are in good agreement with the experimental data, supporting the reliability of the developed model.