Page 364 - Air and Gas Drilling Manual

Chapter 8: Air, Gas, and Unstable Foam Drilling 8-47
1
= 
f
i1
0 319 
.
114
    2 log  0 00015  + .      2
  . 
f i1 = 0 016
.
Equations 6-67 and 6-68 become, respectively,
a i1 = 10 .
53 36
.
.
a i1 = 0 019
and
.
2 635)
.
b = 0 016  53 36  2 (. 2
i1  10  2
π
(
232 2 . ) .   5
0 319)
 4  (.
,
b i1 = 2 486
Equation 6-72 becomes
  2 (. 0 019 ) ( , 6 650 )   . 05
 (,540 ) 2 + ( , 2 486 ) (537 .66 ) 2 e  537 .66 −  1 
32
    

P in =   2 (. 0 019 ) ( , 6 650 )  
 537 .66 
 e 
 
2
P = 30 590 lb/ft abs
,
in
P in
p in =
144
.
p = 212 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. This is the approximate injection at the top of the drill string required to