Page 354 - Air and Gas Drilling Manual

Using Equation 8-2, the average absolute surface roughness of this annulus section,
e av5, is
π
π
 
  Chapter 8: Air, Gas, and Unstable Foam Drilling 8-37
0 656)
0 00015)
001)
(.  4  (. 2 + (.  4  (. 2
0 563)
e =
π
π
av5
  2 +   2
0 656)
0 563)
 4  (.  4  (.
e = 0 0058 ft
.
av5
Equation 6-58 becomes
  2
 
f a5 =   0 656 − 1 0 563  
2  log  . .  + .
114

   0 0058   
.
.
f a5 = 0 079
With the above values Equations 6-52 and 6-53 become, respectively,
10  
0 950  
.
a a5 =   53 36    1 +  .  
2 635 
.
 .
.
a = 0 025
a5
and
2 635)
.
.
b a5 = 0 079  53 36  2 2 (. 2
0 656 −
π
.
.
(
2 32 2) ( . 0 563  ) 10    [ 2 2 ] 2
.
0 656)
0 563)
 4  (. − (.
b = 32 210
,
a5
Equation 6-57 becomes
 2 0 025) ( 500)  05 .
(.
[

2 
.
,
(
.
,
(
P =  ( 22 870) 2 + 32 210 601 91) 2 ] e 601 91 − 32 210 601 91 
,
. )
a5
  
