# Beggs and Robinson correlation

## Contents

### Brief

Beggs and Robinson is an empirical correlation for the oil viscosity published in 1975 [1].

Oil viscosity in the PVT Tool

### Math & Physics

$\mu_{od} = 10^x-1$

where:

$x = T^{-1.163} \times e^{(13.108-6.591/SG_{o})}$

Saturated oil viscosity (P < Pb):

$\mu_{os} = A \mu_{od}^B$

where:

$A = 10.715\ (R_s + 100)^{-0.515}$
$B = 5.44\ (R_s + 150)^{-0.338}$

Undersaturated oil viscosity (P > Pb):

$\mu_{o} = \mu_{os} (P/P_b)^m$[2]

where:

$m = 2.6\ P^{1.187}\ e^{(-11.513-8.98 \times 10^{-5}\ P)}$

### Application range

Description of the Data Used[1]:

$20 \le R_s \le 2,070$
$0.75 \le SG_o \le 0.96$
$0 \le P \le 5250$
$70 \le T \le 295$

Number of oil systems = 600
Number of dead oil observations = 460
Number of live oil observations = 2,073

### Nomenclature

$A$ = coefficient
$B$ = coefficient
$m$ = coefficient
$P$ = pressure, psia
$R_s$ = solution gas-oil ratio, scf/stb
$SG_o$ = oil specific gravity, dimensionless
$T$ = temperature, °F
$x$ = coefficient
$\mu$ = viscosity, cP

b - bubble point