(74p) Evaluation of the Methods for Predicting Dynamic Viscosity of High-Temperatures and High-Pressures Deep Petroleum Formations

Ten methods of predicting dynamic viscosity for high-temperatures and high-pressures (HTHP) deep-water petroleum formations are evaluated for ease of implementation and applications for flow assurance modeling, pipeline flow simulation and reservoir simulation of carbon dioxide sequestration in the depleted oil-reservoirs. The evaluated techniques include various versions of the dead-oil viscosity correlation, the Stiel-Thodos viscosity correlation, the Little-Kennedy correlation, the free-volume viscosity theory, the frictional theory for viscosity, the kinetic theory description for viscosity, the Van der Waals transport equations-of-state, the Ely-Hanley corresponding states viscosity methods, the hard-sphere theory of viscosity by Dymond-Assael, the Yarranton-Satyro viscosity correlations and those versions of viscosity methods that are coupled with the modified Tait equation, VDW EoS, CPA EoS and SAFT+ cubic EoS for liquid density estimations at the HTHP conditions. The HTHP dynamic viscosity data used in the evaluation of the methods for predicting dynamic viscosities are reported in the literature by Enick Group at U of Pitt, Caudwell-Trusler-Wakeham Group at Imperial College London and Ducoulombier et al. in France. While all the evaluated methods gave various degrees of uncertainties at HTHP conditions (due to the judicious choice of the inaccurate liquid density correlations), the VDW viscosity equation of state (which does not require liquid densities or volumetric properties as input data) performs better and in agreement with the measured dynamic viscosities at the HTHP conditions of deep-water petroleum formations. It also provides a very suitable mean of predicting viscosity over the entire PVT states of HTHP densities, including dilute, dense-fluids, supercritical, near-critical and at critical viscosity. This article is useful for all type of analyses of flow assurance modeling.

Keywords: cubic equation, viscosity methods, dynamic viscosity, volumetric property, flow assurance