Velarde solution gas oil ratio correlation

Velarde solution gas oil ratio correlation

Velarde correlation is an empirical correlation for the solution gas oil ratio published in 1997.

Velarde solution gas oil ratio correlation in the PVT Software

Math & Physics

$R_s = \frac{R_{sr}}{R_{sb}}$

$R_{sr} = \alpha1 \times P^{\alpha2}_r + (1 - \alpha1) \times P^{\alpha3}_r$

where:

$P_r = \frac{P-0.101}{P_b}$

$\alpha1 = A_0 \times SG^{A_1}_g \times Y^{A_2}_{oil_API} \times {(1.8 T- 459.67)}^{A_3} \times P^{A_3}_b$

A0 = 1.8653e-4
A1 = 1.672608
A2 = 0.929870
A3 = 0.247235
A4 = 1.056052

$\alpha2 = B_0 \times SG^{B_1}_g \times Y^{B_2}_{oil_API} \times {(1.8 T - 459.67)}^{B_3} \times P^{B_4}_b$

B0 = 0.1004
B1 = -1.00475
B2 = 0.337711
B3 = 0.132795
B4 = 0.302065

$\alpha3 = C_0 \times SG^{C_1}_g \times Y^{C_2}_{oil_API} \times {(1.8 T - 459.67)}^{C_3} \times P^{C_4}_b$

C0 = 0.9167
C1 = -1.48548
C2 = -0.164741
C3 = -0.09133
C4 = 0.047094

Example. Calculation of the solution gas oil ratio

Example source

Input data

$R_s$ = 60 sm3/sm3

$SG_o$ = 0.85 or 35 API

$SG_g$ = 0.75

$T$ = 90C or 363K

$P_b$ = 11.65 MPa

Calculate solution gas oil ratio at p = 10 MPa?

Solution

Pr = 0.8493
a1=0.1545
a2=1.8812
a3=0.5431
Rsr=0.8874
Rs=53.24 sm3/sm3

The solution is available in the online PVT calculator software at www.pengtools.com

Application range

$2.35 \le R_s \le 322$

$0.754 \le SG_o \le 0.989$

$0.555 \le SG_g \le 1.245$

$21.1 \le T, C \le 160$

Nomenclature

$API_{oil}$ = oil specific gravity, °R

$A_0..A_{4}$ = coefficients

$B_0..B_{4}$ = coefficients

$C_0..C_{4}$ = coefficients

$P$ = pressure, MPa

$P_b$ = bubble point pressure, MPa

$P_r$ = reduced pressure, MPa

$R_s$ = solution oil gas ratio, sm3/sm3

$R_{rb}$ = solution oil gas ratio at bubble point pressure, sm3/sm3

$R_{rs}$ = reduced solution oil gas ratio, sm3/sm3

$SG_g$ = gas specific gravity, dimensionless

$SG_o$ = oil specific gravity, dimensionless

$T$ = temperature, °K