Thermodynamics Driven by Hydrates Outside Flowlines

The Russian discovery of hydrates in nature spawned the third wave of advances in hydrate research. Ten major applications and basic research advances occurred in the modem time. 

Kobayashi and co-workers began to use the van der Waals and Platteeuw theory in the 1960s to predict hydrate formation in ternary systems. Parrish and Prausnitz extended the method to prediction of hydrate incipient formation in natural gas systems causing the widespread industrial adoption of the van der Waals and the Platteeuw statistical method. Many academic (e.g.. Holder and co-workers ) and commercial programs (e.g., D.B. Robinson, and Associates ) enabled the gas and oil industry to predict thermodynamic conditions at the incipient formation point, and thereby to prevent hydrate formation in industrial processes. All of the errors in the van der Waals and Platteeuw theory were placed in the solid phase. It may be argued that the theory s unusual success in prediction inhibited motivations for advances in hydrate phase measurements. 

beginning in the 1960s at the Canadian National Research Council (NRC), the group initiated by Davidson and extended by Ripmeester has made the best modem measurements in hydrate science, with particular emphasis on nuclear magnetic resonance (NMR) spectroscopy, neutron diffraction, calorimetry, and molecular modeling. An abbreviated overview of the major advances in hydrate science at NRC is presented in Table 2. 

NMR success motivated other spectroscopic studies to measure the hydrate phase directly. This work represented an experimental departure, because previously only the fluid phases (vapor and liquid(s)) were measured, and any experimental error was incorporated in the solid-phase model of van der Waals and Platteeuw, However, with modem solid-phase measurements, the errors in the van der Waals and Platteeuw model could be clarified and corrected. Raman spectroscopy and diffraction (X-ray and neutron, supplemented by Rietveld analysis ) have been successful the first method to measure the relative occupation of single guest cages, and the second to extend the work to hydrate isothermal, adiabatic, and isobaric compressibilities. As shown in Section 4, these measurements combine with spectroscopic hydrate phase measurements to enable improvements of the model. 

1960-1980 - Dielectric and NMR measurements of hydrate guest and host dynamics many new hydrate si and sll guests identified 

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