Page 333 - Air and Gas Drilling Manual

8-16 Air and Gas Drilling Manual
2
2 019)
0 055
.
b
ac
π
.
.
 10.
2 32 2) (
(
0 656)
(.
 
4
.
b ac = = 674 6 0 656 − 0 375. )  53 36.   2   2 [ (. (. 2 − 0 375) 2 ] 2
Equation 6-57 becomes
  2 (. 0 028 ) ( ,000 )  . 05
10
[

P bh =  ( , 8 309 ) 2 + 674 6 . ) 2 ] e 602 .01 − 674 6 . ) 2 
. (602 01
. (602 01
  

2
,
P bh = 13 450 lb/ft abs
P bh
p bh =
144
p bh = 93 4 psia
.
Using Equation 4-11, the specific weight of the air at bottomhole pressure and
temperature conditions is
0
1
13
(,450 ) ( . )
γ =
bh
(53 .36 ) (618 . )
67
γ bh = 0 407 lb/ft 3
.
The volumetric flow rate of the gas at the bottom of the borehole in the annulus,
Q bh, is
48
0
(.0763 ) (26 . )
Q =
bh
. 0 407
3
Q = 4 964 ft /sec
.
bh
The velocity of the gas at the bottom of the borehole in the annulus, V bh, is
.
V = 4 964
π
  [ 2 2 ]
bh
0 656)
(.
  (. − 0 375)
4