Oil/Gas Separator Sizing
Size two-phase and three-phase production separators
Input Parameters
Enter production and fluid properties
Separator Sizing Results
Enter parameters and click Calculate
Typical Retention Times
- Light oil (API > 35): 1-2 minutes
- Medium oil (API 25-35): 2-3 minutes
- Heavy oil (API < 25): 3-5+ minutes
- Water (clean): 3-5 minutes
- Emulsion: 10-30 minutes
Formula Reference
Gas Capacity Constraint (Souders-Brown)
Maximum Gas Velocity:
Vmax = K * sqrt((rho_l - rho_g) / rho_g)
Where:
K = 0.35 for horizontal separators (no mist extractor)
K = 0.167 for vertical separators
rho_l = Liquid density (lb/ft3)
rho_g = Gas density (lb/ft3)
Minimum Diameter (gas capacity):
D = sqrt((4 * Qg) / (pi * Vmax * 60))
Where:
Qg = Gas flow rate (ft3/min at conditions)
Liquid Capacity Constraint
Required Liquid Volume:
V_oil = Qo * t_o / 1440 (bbl)
V_water = Qw * t_w / 1440 (bbl)
Where:
Qo = Oil rate (bbl/day)
Qw = Water rate (bbl/day)
t_o = Oil retention time (min)
t_w = Water retention time (min)
For horizontal separator:
D^2 * L = (V_total * 5.61) / (0.5 * pi/4) (50% liquid level)
Stokes' Law Settling
Droplet Settling Velocity:
V_settle = (g * d^2 * (rho_l - rho_g)) / (18 * mu)
Where:
g = Gravity (32.2 ft/s2)
d = Droplet diameter (ft)
rho = Density (lb/ft3)
mu = Gas viscosity (lb/ft-s)
Standard Separator Sizes
| Diameter | Typical L/D | Capacity Range |
|---|---|---|
| 24" | 3-4 | 500-2,000 bbl/d |
| 30" | 3-4 | 1,000-4,000 bbl/d |
| 36" | 3-4 | 2,000-6,000 bbl/d |
| 42" | 3-4 | 3,000-10,000 bbl/d |
| 48" | 3-5 | 5,000-15,000 bbl/d |
| 60" | 3-5 | 10,000-30,000 bbl/d |