Page 553 - Air and Gas Drilling Manual
P. 553
10-78 Air and Gas Drilling Manual
3
n
s
˙
The theoretical shaft horsepower, W , required by the compressors is obtained from
s
Equation 4-35a. Equation 4-35a becomes
04
(. )
12
,
31 4
() ( . ) (.685 ) 1 500 275 .0 ()( . )
41
4
W ˙ s 1
04
(.) 229 .17 12 .685
W ˙ s 296 .8
Figure 10-7: Back pressure at the top of the annulus as a function of drilling time
(drilling depth) for Illustrative Example 10.2.
The mechanical efficiency, ( , is
m
