A Comparative Study of Different Hydrate Prediction Models

Gas hydrates are clathrate physical compounds where the gas molecules are embedded within crystalline water structures.  There are currently three well known hydrate structures, namely Type I, II, and H, that are known to form at low temperature and high pressure up to 100 MPa.   These conditions are characteristic of operating conditions in oil / gas wells and pipelines.  Hydrate plugs can damage gas transport systems; consequently, the petroleum industry spends more than $2 million each day to prevent hydrate formation in wells and pipelines.   A key strategy in preventing hydrate formation involves being able to design robust systems that operate at conditions which do not promote hydrate formation.  This paper evaluates various thermodynamic models, employed by commercial simulators, to predict hydrate formation.  It appears that more sophisticated models, such as those that account for strong molecular association due to water, provide more accurate predictions.   Also, model predictions regarding the use of hydrate inhibitors are also examined in this work.