Synthetic fluid inclusions; X, Experimental determination of P-V-T-X properties in the CO 2 -H 2 O system to 6 kb and 700 degrees C

Abstract

Pressure-volume-temperature-composition (P-V-T-X) relations in the CO2-H2O system have been experimentally determined from 2 to 6 kb and 400°C to 700°C for fluid compositions between 12.5 and 87.5 mole percent CO2 using the synthetic fluid inclusion technique. Molar volumes (MVs) of CO2-H2O mixtures (calculated from densities of fluid inclusions) are used in conjunction with the equations of state of Haar, Gallagher, and Kell (1984) for H2O and Shmonov and Shmulovich (1974) for CO2 to generate an empirical expression that predicts molar volumes of all CO2-H2O compositions over this P-T range. From 2 to 6 kb and 400-degrees to 700-degrees-C, CO2-H2O fluids display very limited departures from ideal mixing with maximum excess volume of +1.31 cm3/mole (4.3 percent) occurring at 6.0 kb, 500-degrees-C, and