Beggs-Robinson Live Oil Viscosity Calculator
Enter dead-oil viscosity and solution gas-oil ratio in the declared units. The calculator evaluates the Beggs-Robinson coefficients and returns live-oil viscosity in cP.
Calculation context and source notes
The Beggs-Robinson live-oil correlation estimates saturated oil viscosity from dead-oil viscosity and solution gas-oil ratio through correlation coefficients that capture the viscosity-reducing effect of dissolved gas.
Use it for black-oil PVT screening when measured live-oil viscosity is unavailable. Calculate or measure dead-oil viscosity and solution gas-oil ratio on compatible conditions before applying the live-oil relationship.
Solves for
mu_o (cP)
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Formula, variables, and sourceRelated source-backed guides
Formula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns mu_o = 0.54894 cP. Defaults demonstrate the implementation; they are not recommended field values.
2
600
Input definitions
mu_od
cPDead Oil Viscosity
R_s
SCF/STBSolution Gas-Oil Ratio
Output definitions
mu_o
Live Oil Viscosity
A_br_live_oil
Beggs-Robinson Live Oil Coefficient A
B_br_live_oil
Beggs-Robinson Live Oil Coefficient B
mu_od
Dead Oil Viscosity
Engineering use, assumptions, and limits
Use it for black-oil PVT screening when measured live-oil viscosity is unavailable. Calculate or measure dead-oil viscosity and solution gas-oil ratio on compatible conditions before applying the live-oil relationship.
Assumptions
- Dead-oil viscosity and solution gas-oil ratio represent the fluid condition being evaluated.
- The oil behaves within the empirical range represented by the Beggs-Robinson correlation.
- The result is for saturated or live oil on the correlation's published basis.
Limitations
- Empirical PVT viscosity correlations can be inaccurate for unusual crude compositions or conditions outside their development data.
- Measured viscosity or a calibrated fluid model should control when available.
Common mistakes
- Substituting stock-tank viscosity for dead-oil viscosity without checking temperature basis.
- Entering solution gas-oil ratio in the wrong units.
- Applying a saturated-oil relationship above bubble point without the appropriate undersaturated-oil correction.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
Craft, B.C., Hawkins, M. and Terry, R.E. 1991. Applied Petroleum Reservoir Engineering, 2nd Edition, Page 41.
Open source reference