Page 491 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Flow of Fluids 447

(text continued f+om pap 437)

p'=(k) (6-73)

where K,, K, = dimensionless gas and liquid flowrates
p p = density of gas and liquid phases in lbm/ft3
v:vs: = superficial gas and liquid velocities in ft/s
= surface tension between gas-oil phases in lbf/ft
3 dimensionless density ration
=
g = acceleration of gravity in ft/s2
Step 2. Flow Regime Map

Once these dimensionless parameters are calculated, then the point with the
coordinates (K,, KJ is located on the flow regime map in Figure 6-44.

Step 3. Flow Regime Selection

The boundary for the appropriate density ratio is located for the transition
boundary between the slug and bubbly flow regimes. Once the appropriate
boundary line is found, then the flow regime is simply bubbly, slug or annular
depending upon the region in which the point falls. This slug to annular
transition applies only if the pipe size D is larger than a critical diameter D,r
given by

(6-744

where

(6-74b)

pL = liquid phase viscosity in lbJ(ft/s)

Usually, the critical pipe size is. about 2 in. for conditions of gas and oil
pipelines so that Figure 644 can be used often. The criterion should be checked
each time, however.-If D < Dc, another method has to be used; see Reference 22,
VOl. 3.

Downcomers (0 = -90")

There are also three possible flow regimes: annular, slug and bubbly. There
are two flow regime transitions to be calculated. Two different maps will be used,
one for transition between annular and slug flow regimes and a second for the
transition between the slug and bubbly flow regimes.