Page 514 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

470 Production

(text continucd fmm page 464)

0. 046/Reie if Re, =
f, =
(6-82~)
(16/Re, if Reg < 1,500
fwL = I

0,04S/Re,"' if Re, = (y$:Ea) 2 1,500

116/ReL if Re, 1,500 (6-823)

Then the frictional and gravitational pressure gradients given by expression
6-64 are

(6-833)

where L = distance in ft
z = vertical coordinate in ft
S = pipeline inclination from the horizontal in degree

Special Cases for Low and High Liquid Holdup

As H, = 1.0 or 0.0, it becomes difficult to determine the liquid holdup accu-
rately. Small errors in the estimation lead to large errors in the frictional portion
of the pressure gradient by Equation 6-83~; therefore, in such cases as above, it
is recommended that the pressure gradient be calculated by the following
methods. If the liquid holdup H, > 0.99, then

(6-84u)

If the liquid holdup Iz. < 0.01, then