PetengCalculators

PRODUCTION ENGINEERING - CHOKE PERFORMANCE

Flow Through Chokes (2-phase Liquid & Gas)

THEORY & FORMULAE

Gas-Liquid Flow Through Chokes

The three commonly-used methods for predicting the flow rates of 2-phase flow through a choke are:

   - Gilbert's Correlation

   - Ros's Correlation

   - Omaha's Correlation

Gilbert's and Ros's correlations are of the same simple form, requiring three input values.

Omaha's correlation is more complex and it is based on dimensionless variable groups. It requires some 10 input values, and it is restricted to critial flow where the downstream pressure is less than half of upstream. Also, it is is best suited for choke bean sizes of less than [16/64] inch, liquid rate of less than 900 bbl/day and fluid viscosity close to water viscosity.

The equations for each method is given below:

And where:

   q_l = liquid flow rate, STB/day
   p₁ = pressure upstream of choke, psia
    D₆₄= choke diameter (bean size), 64th of inch
   GLR = gas-liquid ratio, SCF/STB
   ρ_l = liquid density, lb/ft
   ρ_g = gas density, lb/ft
   σ_l = liquid-gas surface tension, dynes/cm
   T = temperature upstream of choke, ° F
   Z = gas compressibility factor

BIBLIOGRAPHY

Economides M.J., Hill A.D. & Ehlig-Economides C.; Petroleum Production Systems; PTR Prentice Hall Inc. Englewood Cliffs, NJ, 1994, chap. 10.

Choke diameter		64ths of inch
Gas-liquid ratio		scf/bbl
Wellhead flowing pressure		psia

Liquid density		lb_m/ft³
Gas density		lb_m/ft³
Oil-gas surface tension		dynes/cm
Wellhead temperature		° F
Gas Compressibility

Liquid Flow Rate	bbl/day
♦ Gilbert's Correlation
♦ Ros's Correlation
♦ Omaha's Correlation