| Abstract |
Volumetric (density), acoustic (speed of sound), and transport (viscosity) properties of natural geothermal fluids from south Russia Geothermal Field (Dagestan, Caspian seashore) 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 4 geothermal fluid samples from the hot-wells Izberbash (No.68 and 129) and Ternair (No.27T and 38T). A sound-speed analyzer (Anton Paar DSA 5000) 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- density: 0.0005 % (for DMA 4500 densimeter), 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), respectively. Measured values of density and speed of sound were used to calculate other very important for geothermal modeling derived thermodynamic properties such as adiabatic coefficient of bulk compressibility, coefficient of thermal expansion, thermal pressure coefficient, isothermal coefficient of bulk compressibility, isochoric heat capacity, isobaric heat capacity, enthalpy difference, partial pressure derivative of enthalpy, partial derivatives of internal energy (internal pressure) 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 within 0.03 % (density), 2.55 % (viscosity), and 0.06 % (speed of sound), respectively. The measured properties at atmospheric pressure have been used as a reference values for prediction high-pressure properties. |