Fluid Phase Behavior for Conventional and Unconventional Oil and Gas Reservoirs

1.2.7. Oil Viscosity

If an external stress is applied to a part of a fluid, it will cause movement in the direction of the fluid. The affected parts exert a portion of applied stress to nearby portions and make them move with lower velocity. Viscosity is defined as

η=τdvdy

(1.95)

where τ is the external stress and v is the velocity.

Viscosity plays a key role in fluid flow in porous media and pipes. Several correlations for oil viscosity have been developed. Generally, the authors correlated oil viscosity with oil bulk properties such as temperature and API or the composition of the fluid. Some of the more applicable correlations are presented here. ...