Page 496 - Air and Gas Drilling Manual

Substituting the values for
. 098
Q gbp (. 0 234 ) bp and Q w gives Chapter 10: Stable Foam drilling 10-21
1 . 0 98
3
Q gbp 11 46 ft /sec
.
Using Equation 4-11 the specific weight of the gas (air) upstream of the back
pressure valve can be obtained. This is
0
1
(,275 ) ( .)
4
bp
(53 .36 ) (504 . )
41
0 159 lb/ft 3
.
bp
The weight rate of flow of gas, ˙ w , is
g
˙ w Q
g bp gbp
˙ w (. 0 159 ) ( .46 )
11
g
˙ w . 1 821 lb/sec
g
The volumetric flow rate of the gas at the surface location atmospheric conditions is
w ˙ g
Q g
g
.
1 821
Q g
.
0 0659
3
Q g 27 64 ft /sec
.
q g Q 60
g
q g 1 658 acfm
,

The openhole diameter, D h, is
.
d h 7 875 inches