Page 608 - Air and Gas Drilling Manual

11-46 Air and Gas Drilling Manual
1
f
i1
.
2 log 0 319 114 2
.
.
0 00015
.
f i1 0 016
Equations 6-67 and 6-68 become, respectively,
.
10
a i1
.
53 36
a i1 0 019
.
and
2 635)
.
.
0 016 53 36 2 (. 2
b
i1 2
(
232 2 . ) 10 . 5
0 319)
(.
4
b i1 2 486
,
Equation 6-72 becomes
. 05
2 (. 0 019 ) ( , 6 650 )
2
(,350 ) 2 ( ,486 ) (537 .66 ) 2 e 537 .66 1
98
P
in
2 (. 0 019 ) ( , 6 650 )
e 537 .66
2
P 79 693 lb/ft abs
,
in
P in
p in
144
.
p 553 4 psia
in
The injection pressure given above is the flowing air pressure at the top of the
lumped drill pipe body length inside the drill string in the cased section of the
borehole while drilling at a depth of 10,000 ft. This is the approximate injection at
the top of the drill string required to force a volumetric flow rate of 2,400 acfm