(262as) Viscosity and Density of (CO2 + Synthetic Crude Oil) Mixtures at Temperatures from (298 to 423) K and at Pressures up to 100 Mpa

Knowledge of the viscosity and density of CO₂-hydrocarbon mixtures at reservoir conditions is very important for designing and operating enhanced oil recovery processes using CO₂, and also for large-scale carbon storage in depleted hydrocarbon reservoirs. However, very few data have been reported in the literature for the viscosity and density of compositionally-characterized multi-component CO₂-hydrocarbon mixtures. To help address this deficit, we have measured the viscosity and density of a synthetic crude oil mixture with and without dissolved CO₂. The synthetic dead oil was identical in composition to that studied by Al Ghafri et al.¹, who matched the chemical and physical properties of the synthetic mixture to those of a Qatari bottom-hole crude-oil sample. The dead synthetic crude contained 17 components including linear and branched alkanes, naphthenes and aromatics. Live oils with different gas-to-oil ratios were obtained from this dead oil by adding (0.813 CH₄ + 0.126 C₂H₆ + 0.061 C₃H₈) as solution gas. The measurements of viscosity and density were made in the single-phase compressed liquid region at temperatures between (298 and 423) K at pressures up to 100 MPa. The CO₂ mole fractions of the mixtures studied were x₁ = 0.1, 0.2, 0.4, 0.6 and 0.8. The viscosity was measured with a vibrating-wire viscometer while the density was measured by means of a vibrating U-tube densimeter; the viscometer was calibrated with toluene and nitrogen, while the densimeter was calibrated with toluene, water and vacuum following a new calibration method presented by May et al.². Measurements of the viscosity and density of the mixtures are associated with relative uncertainties of 0.2 % for density and 2 % for viscosity. The results for both properties have been correlated as functions of temperature, pressure and the mole fraction of dissolved CO₂.

 

Acknowledgment

We gratefully acknowledge the funding of QCCSRC provided jointly by Qatar Petroleum, Shell, and the Qatar Science and Technology Park, and their permission to publish this research.

References

1. S. Z. Al Ghafri, G. C. Maitland, and J. P. M. Trusler, Fluid Phase Equilibria 365, 2014, 20-40.
2. E. F. May, W. J. Tay, M. Nania, A. Aleji, S. Z. Al Ghafri, and J. P. M. Trusler, Review of Scientific Instruments 85, 2014, 095111.