9309595 Sloan This projects concerns phase equilibrium studies for systems containing water and hydrocarbons at intermediate and high pressures and temperatures in the vicinity of the ice point where hydrates are formed. In particular, this project investigates sH hydrates. A statistical thermodynamic model for sH phase equilibria using van der Waals' and Platteeuw's (1959) model is proposed. In a parallel, feedback model with model development , the project investigates such a model via sH phase equilibria measurements of large molecules like those of interest to the hydrocarbon industry (in Items B and C above) but with a second smaller molecule, Xe, and with CH4 both above and below the ice point. The investigators plan to use the model to generate an entire model phase diagram for multiphase fluid-hydrate equilibrium, via analogs to our previous phase diagram work on other hydrate structures. The model will be tested against unusual conditions of the phase diagram, for example with measured co-existence points of sH+sI+gas+H2O+liquid hydrate phase equilibria, obviating the need for many years of experimental research, analogous to that done on sI and sII hydrates since their 1934 discovery in pipelines. ***
