Density, compressibility and phase equilibrium of high pressure-high temperature reservoir fluids up to 473 K and 140 MPa

Experimental measurement of volumetric and phase equilibrium properties of two high pressure - high temperature reservoir fluids was performed in this work. One fluid is volatile oil and the other is gas condensate. The density, isothermal compressibility, saturation pressure, and liquid fraction below the saturation pressure were determined in the temperature range up to 473.15 K by using a high pressure vibrating tube densitometer and a PVT cell. The obtained data were modelled by using equations of state including Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), volume translated SRK (SRK-VT), volume translated PR (PR-VT) and Perturbed-Chain Statistical Association Fluid Theory (PC-SAFT). Among these models, the performance in saturation pressure prediction is system-dependent and it is hard to generalize the observation. PC-SAFT models volumetric properties satisfactorily. Regarding density calculation, it performs similarly to SRK-VT and PR-VT for the two fluids investigated here. Concerning isothermal compressibility, PC-SAFT is slightly better.