Page 520 - Air and Gas Drilling Manual

Chapter 10: Stable Foam drilling 10-45
assuming this Reynolds number approximates the flow conditions throughout the
annulus section.
Using Equation 4-11, the approximate specific weight of the gas as it exits this
cased annulus section is determined from P a3. This is
,
.
( 132 346) ( 1 0)
a4
( 53 36) ( 598 79)
.
.
.
4 142 lb/ft 3
a4
The volumetric flowrate of the gas as it exits this openhole annulus section is
w ˙ g
Q ga4
ga4
1 821
.
Q ga4
.
4 142
3
.
Q ga4 0 440 ft /sec
The foam quality as it exits this openhole annulus section is
Q ga4
sfa4
Q ga4 Q w
.
0 440
sfa4
.
.
0 440 0 234
.
0 653
sfa4
Using Equation 10-5, the absolute viscosity of the foam as it exits this
openhole annulus section is
(
.
.
.
0 00002089 1 3 6 0 653)
sfa4
lb sec
0 00006997
.
sfa4 2
ft
The specific weight of the foam as it exits this openhole annulus section is
approximated by