Viscosity Models for Hydrocarbons at High Pressure: A State-of-the-Art Review

Viscosity is a fundamental property required in many petroleum reservoir applications, including the estimation of reserves, the calculation of flow rates in porous media or wellbores, and the determination of the mobility ratio of a displacement process. Direct measurements of this property are usually expensive and time-consuming. Therefore, reliable predictive methods are often employed to obtain the viscosity.

In this work, viscosity models for pure hydrocarbons are comprehensively reviewed. The models assessed in this study are suitable for use in reservoir simulators and are capable of estimating the viscosity of multi-component mixtures with changing composition. The performance of several selected viscosity models representative of various predictive and correlative approaches is discussed and evaluated by comparison to experimental viscosity data at ambient and extremely high-temperature, high-pressure (HTHP) conditions up to 300 ^oC and 300 MPa, conditions that are typically encountered in ultra-deep petroleum reservoirs, such as those found beneath the Gulf of Mexico. The applicability of each method is discussed and recommended models and approaches are identified.