Advances in estimating water content of natural gases

The aim of this communication is to present advances in predicting water content of natural gases. A semi empirical approach is first introduced for estimating the water content of natural gases in equilibrium with liquid water or ice. This method allows calculating the water content using liquid water/ice vapor pressure and molar volume of liquid water/ ice as well as pressure and temperature of the system. The approach has been developed using experimental water content data of methane at various temperatures and pressures. An analytical correction factor based on the McKetta-Wehe chart is used to take into account the effect of heavy hydrocarbons. In order to extend the capabilities of the new approach to sour gases, an analytical correction factor is introduced for taking into account the effect of acid gases on the water content. The predictions of the developed method are in acceptable agreement with independent data, demonstrating its reliability in estimating the water content of natural gases. With the aim to use a similar semi-empirical approach for predicting the water content of sweet natural gases in equilibrium with gas hydrates, experimental water content data of methane in equilibrium gas hydrates were used to expand the correlation. An analytical correction is then used to take into account the effect of heavier hydrate formers than methane. The predictions of the developed method are in acceptable agreement with the results of a previously recommended but complex method, demonstrating its reliability in estimating the water content of sweet gases in equilibrium with gas hydrates.

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