Patent ID: 7689370

Claim:
A method comprising: flowing fluid through a system, the system comprising a flow meter and at least one additional sensor for measuring at least one additional property determining an absolute viscosity (aV) of the fluid at a section A in the system using the flowmeter; measuring a property of the fluid (P) in the system using at least one sensor for measuring at least one additional property; determining a virtual temperature (T V ) of the fluid at section A using the measured property of the fluid (F) with a relationship that correlates the property of the fluid (F) with the virtual temperature (T V ) of the fluid at section A; estimating a kinematic viscosity (kV) of the fluid from the absolute viscosity (aV) of the fluid at section A; and extrapolating the kinematic viscosity (kV standard ) of the fluid at a standard temperature (T standard ) using the kinematic viscosity (kV) of the fluid, the virtual temperature (T V ) of the fluid, and a relationship that correlates the temperature of the fluid with the kinematic-viscosity of the fluid to determine on-line the kinematic viscosity of the fluid at any temperature.