Volumetric behaviour of (carbon dioxide + hydrocarbon) mixtures at high pressures

• An automated vibrating tube densimeter was implemented for CO2 + hydrocarbon mixtures.
• The technique was successfully checked measuring the test system CO2 + decane.
• Densities of CO2 + dodecane and + squalene were measured at wide temperature and pressure ranges.
• The modified Tamman–Tait equation correlates well the experimental data.

The interest of oil industry in increasing heavy oil production has promoted the use of enhanced oil recovery techniques such as CO2 injection, which produce a decrease of oil viscosity and displacement of heavy oil from reservoir to surface. The design of these processes requires accurate data of densities, viscosities or surface tensions of (CO2 + hydrocarbon) mixtures in order to simulate the behaviour of these mixtures in the reservoir.An automated Anton Paar DMA HPM vibrating-tube densimeter was used to measure densities of this kind of mixtures, and a new mixture injection system, by means of two syringe pumps, was developed for the densimeter. The equipment operates at high pressure, which is controlled through a back pressure valve and a variable volume cylinder with a stepper motor. The estimated standard uncertainty of the density is ±0.9 kg m−3 at temperatures below 373.15 K and pressure range (0.1–140) MPa.In this paper, the densities of the mixtures (CO2 + n-decane), (CO2 + n-dodecane) and (CO2 + squalane) are reported at T = (283.15–393.15) K and p = (10–100) MPa.

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