Program CSMGem

Sloan et al. (1986,1987)] with corrections by Song and Kobayashi (1994). Apre-diction scheme is discussed in Chapter 5 using the statistical thermodynamics method and included in the program CSMGem. 

Avoidance of the hydrate formation thermodynamic conditions of temperature, pressure, or inhibitor concentration, makes it impossible for plugs to form. The calculations of thermodynamic conditions can be made with acceptable accuracy. Using the methods presented in Chapters 4 and 5 along with the CD program CSMGem provided with this book, the temperature, pressure, and inhibitor concentrations can be calculated respectively, to within 2°F, 10% in pressure and 3% of inhibitor concentration. Since the discovery of hydrate flowline plugs in 1934, such thermodynamic methods have served to provide the major method of flow assurance. 

Includes the software programs CSMGem, which supplies the most recent thermodynamic predictions, and CSMPlug, which provides the time required for hydrate plug removal from a pipeline... 

A new computer program CSMGem, for hydrate thermodynamic calculations... 

Accuracy of CSMGem Compared to Commercial Hydrate Programs... 

The thesis of Ballard (2002) details this calculation method, which includes multiphase systems, solid phases including ice and salts, and thermodynamic inhibition. The CSMGem (the last three initials are the first letters of Gibbs energy minimization ) User s Manual, included in the CD in the endpapers, and the examples of hydrate calculation shown in the Appendix A, enable the reader to use the CD programs. 

A comparison of predictions from CSMGem, the program included in the CD of this work, with the second edition s version (CSMHYD) and three commercial hydrate prediction programs, is given here for all recent hydrate data reported in literature. The five programs (with the last three commercial) compared in this work are... 

Figure 8.14 Temperature changes as a result of depressurization (1) isenthalpic rapid expansion as through a valve, and (2) very slow depressurization, as in a large-volume pipeline. Note that for the rightmost case, a fluid system can be expanded into the hydrate region, as calculated by the methods in Section 4.2.1.1 and the programs of CSMGem on the CD accompanying this book.

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