Velarde solution gas oil ratio correlation

Brief

Velarde correlation is ...

Math & Physics

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

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

where:

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

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

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

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

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

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

Discussion

Why the Velarde correlation?

Nomenclature

$A_1..A_{4}$ = coefficients

$B_1..B_{4}$ = coefficients

$C_1..C_{4}$ = coefficients

$\rho_r$ = reduced density, dimensionless

$P$ = pressure, psia

$P_{pc}$ = pseudo critical pressure, psia

$P_{pr}$ = pseudoreduced pressure, dimensionless

$SG_g$ = gas specific gravity, dimensionless

$T$ = temperature, °R

$T_{pc}$ = pseudo critical temperature, °R

$T_{pr}$ = pseudoreduced temperature, dimensionless

$Y_{oil_API}$ = oil API gravity, dimensionless

$z$ = gas compressibility factor, dimensionless