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

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. (C) 2016 Elsevier B.V. All rights reserved.