TEMPERATURE EFFECT ON DENSITY AND VISCOSITY OF LIGHT, MEDIUM, AND HEAVY CRUDE OILS

Abstract

The density and dynamic viscosity of four light, medium, and heavy (extra-viscous) crude oil samples from Tatarstan Oil Field (Russian Federation) have been measured over the temperature range from (293 to 473) K (for density) and from (293 to 348) K (for viscosity) at atmospheric pressure (101 kPa). The density measurements were made using a new densimeter based on hydrostatic weighing method. The viscosity measurements of the same crude oil samples were made us-ing Brookfield rotational viscometer (DV-II+PRO, LVD-II+PRO). The combined expanded uncertainty of the density, viscosity, atmospheric pressure, and temperature measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated to be 0.16 %, 1.0 %, 1.0 %, and 20 mK, respectively. For validation of the reliability and accuracy of the measured density data and correct operation of the new densimeter, all oil samples were measured using the pycnometric method. The present study showed that the densities measured using the new hydrostatic weighing densimeter (HWD) are agree with the values obtained with pycnometric method within (0.03 to 0.14) %. The measured density and viscosity data were used to develop widerange correlations as a function of temperature and API characteristics. The measured densities were represented using simple function of temperature (polynomial type) with API gravity dependent parameters with an accuracy of AAD within from (0.10 to 0.18) %. The measured viscosity data were also used to develop linear Arrhenius and VTF models. API gravity dependence of the Arrhenius parameters was studied.