Calculation of critical points of geological fluids: revival of the 'Dutch School'

摘要

The properties of fluids of geological relevance can be described with equations of state, in which a mathematical relation between temperature (T), pressure (p), volume (V), and composition (x) is defined. These equations also define the boundary between heterogeneous and homogeneous fluid systems, which is of major interest to fluid inclusion studies. In addition, the equations allow the calculation of fluid phase equilibria, which are required to interpret microthermometric data. Microthermometry remains one of the most important tools to analyse fluid inclusions. The outline of the mathematical formula is usually based on best-fit criteria, which originated in the hyperbolical behaviour of an isotherm in a P-V diagram.rnMacroscopic measurable fluid properties (like p, T, V and x) can be related directly to fundamental chemical/physical interactions of molecules and atoms through statistical thermodynamics. However, this theoretical background is only applicable by other simplifying best-fit mathematical equations. Chemistry and physics are the designing disciplines, whereas mathematics makes it work. In other words, mathematical equations simplify the conceptual and computational work.