Phase Behavior and ThermodynamicsFluid Properties
Logarithmic Crude Oil Viscosity from API Gravity Formula
Logarithmic Crude Oil Viscosity from API Gravity calculates logarithmic crude oil viscosity for fluid properties workflows in phase behavior and thermodynamics.
How engineers use this formula
Use this formula when the listed inputs (a, API) are known and the assumptions behind the cited fluid properties relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, log_mu_o equals 0.275 log10(cP).
adimensionless
1.5
APIdeg API
35
Inputs
a
dimensionlessEmpirical Viscosity Coefficient
API
deg APIAPI Gravity
Outputs
log_mu_o
log10(cP)
Logarithmic Crude Oil Viscosity
a
dimensionless
Empirical Viscosity Coefficient
API
deg API
API Gravity
Source and review
reviewedGas Conditioning and Processing, Campbell, J.M. (1992)
Campbell, J.M. 1992. Gas Conditioning and Processing, Vol. 1, Campbell Petroleum Series, Page 74.
Source