Page 480 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

436 Production

Ug .= vg = VJ(1-H,)

For a homogeneous model both phases are assumed to have equal velocities and
each is equal to a two-phase (or mixture) velocity:
VL = vg = v, (6-65h)

H, in Equations S65f and S65g refers to liquid holdup.
Liquid holdup is defied as the ratio of the volume of a pipe segment occu-
pied by liquid to the volume of the pipe segment:

volume of liquid in a pipe segment
H, = (6-66a)
volume of pipe segment
In some cases, e.g., for stratified horizontal flow regime, liquid holdup can be
calculated as follows:

(6-66b)

where 4 = cross-sectional area occupied by liquid (oil and water)
A, = cross-sectional area occupied by gas
Slightly Inclined Pipes (-10' 8 15')

As can be seen from Figure 641, there are four flow regimes of interest: strati-
fied, slug, annular and bubbly; and three flow regime transition zones.
Step 1. Dimensionless Parameters

1. Martinelli parameter-this is the ratio of the liquid and gas phases as if
each flowed alone in the pipe:

(6-670)

According to standard fluid mechanics book

0.O46/Reap if Re = yDv/p > 1,500
f(*) = (6-673)
16/Re if Re c 1,500

2. Gas Froude number (dimensionless gas flowrate):

(6-68)

(*) Calculated separatdy for Is" and "gs."