Experimental Measurements and Modeling of Viscosity for Liquid Hydrocarbons At Pressures Up to 243 Mpa and Temperatures Up to 534 K

Viscosity data are reported for n-octane, isooctane, cyclooctane, n-hexadecane, n-octadecane, and n-eicosane at pressures up to ~243 MPa and temperatures up to ~534 K. These extreme conditions are representative of those encountered in ultra-deep petroleum formations beneath the deepwaters of the Gulf of Mexico. The measurements are taken with a novel windowed rolling ball viscometer designed by our team. The reported viscosity values are in good agreement with the available literature data that cover limited pressure and temperature ranges; but our results extend the database of viscosity to the high temperature-high pressure region where most gaps occur in the literature data. The viscosity results are modeled with the free volume theory model in conjunction with the Tait, Peng-Robinson, and PC-SAFT equations of state. The mean absolute percent deviation (MAPD) values obtained with this model range from 2.0 to 3.5%. The data are also correlated by a nonlinear surface fit as a simultaneous function of temperature and pressure that yields MAPD values less than 0.5% for all hydrocarbons considered in this study.