Measurements of the Density, Speed of Sound, Viscosity, and Derived Thermodynamic Properties of Geothermal Fluids

Volumetric (density), acoustic (speed of sound), and transport (viscosity) properties of natural geothermal fluids from south Russia Geothermal Field have been measured over the temperature range from (278 to 343) K and at atmospheric pressure. The measurements were made using the Anton Paar DMA4500 densimeter and Stabinger SVM3000 viscometer for four geothermal fluid samples from the hot-wells. A sound-speed analyzer (Anton Paar DSA 5000 M) was used to measure the speed of sound and the density of the same geothermal samples. The combined expanded uncertainty of the density, viscosity, and speed of sound measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be as follows: density, 0.0005% (for DMA 4500), 0.02%, or 0.5 kg·m^–3 (for the SVM 3000 viscodensimeter) and 0.01% (for the DSA 5000 M sound-speed analyzer); viscosity, 0.35% (for SVM 3000); and speed of sound, 0.1% (DSA 5000 M). Measured values of density and speed of sound were used to calculate other very important derived thermodynamic properties of the geothermal fluid samples. Measured values of density, viscosity, and speed of sound were used to develop correlation models which reproduced the measured values of density, viscosity, and speed of sound within 0.03%, 2.55%, and 0.06%, respectively. The measured properties at atmospheric pressure have been used as reference values for the prediction of high pressure properties.