Viscosity Modeling of Heavy Crude Oil Using the Friction Theory Combined with PC-SAFT

Small changes in temperature or pressure can lead tocrude oilphase separation and multiple orders of magnitude change in viscosity.The one-parameter friction theory framework using the SARA-based methodwith the perturbed-chain statistical association fluid theory (PC-SAFT)EoS has proven to have high accuracy in viscosity predictions of lightoil. However, it failed for heavy crude oil. In this work, the abovemodel is modified in two aspects to enhance the accuracy of heavycrude oil viscosity prediction: to include the effect of asphaltenepolydispersity and to include the temperature effect to the frictiontheory parameter. The average absolute relative deviation of the fourstudied heavy oils is reduced by 16.81, 24.26, 97.31, and 87.75% comparedto the one-parameter f-theory SARA-based PC-SAFT model. The f-theoryparameter K (c) is modified as a functionof temperature fitted to the viscosity at normal temperature and pressure.Following the simplicity of the expansion of the method, it is recommendedto use this methodology when dealing with heavy crude oils such asthose with viscosity more than 20,000 cP at 25 & DEG;C.