Experimental Methods and Measurements of Hydrate Properties

Chapters 4 and 5 were concerned with the fitting and prediction of hydrate thermodynamic data. Those two chapters indicate how hydrate theoretical developments have dramatically changed over their history, particularly due to advances in knowledge of molecular structure, statistical thermodynamics, kinetics, and computing capability. Yet the powerful tools provided by all of these predictive methods are only as good as the measurements upon which they are based. 

In addition to the change in the theoretical methods applied to hydrates, there have been significant advancements and widespread use of meso- and microscopic tools in hydrate research. Conversely, the typical static experimental apparatus used today to measure macroscopic properties, such as phase equilibria properties, is based on the same principles as the apparatus used by Deaton and Frost (1946). In part, this is due to the fact that the simplest apparatus is both the most elegant and reliable simulation of hydrate formation in industrial systems. In Section 6.1.1 apparatuses for the determination of hydrate thermodynamic and transport macroscopic properties are reviewed. 

Thermodynamic data form the basis for future theoretical developments, because the data represent the physical reality and they have been painstakingly obtained. Usually a period of several months (or even years) is required to construct an experimental apparatus and, due to long metastable periods, it is not uncommon to obtain only one pressure-temperature data point per 1 or 2 days of experimental effort. Phase equilibria data are presented in Section 6.3.1 for simple hydrates (Section 6.3.1.1), binary (Section 6.3.1.2), ternary (Section 6.3.1.3), 

Thermal conductivity data are even more difficult to obtain. In the case of calorimetric data of heat capacity and heats of dissociation, the measurements though still reasonably challenging are aided by significant improvements in commercial calorimeters that can operate at high pressures. Thermal property data are presented in Section 6.3.2. 

This chapter deals with macro-, meso-, and molecular-level thermodynamic and transport hydrate properties of natural gas and condensate components, with and without solute. The feasibility of using these tools to measure the kinetics of hydrate formation and decomposition are also briefly discussed, while the results of these measurements have been discussed in Chapter 3. The results for insoluble substances such as porous media are discussed in Chapter 7. 

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Experimental Methods and Measurements of Hydrate Properties Continued... 

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