Page 582 - Air and Gas Drilling Manual

11-20 Air and Gas Drilling Manual
3
.
Vol
0 625 ft
c
But the weight inside this new volume is that of the specific weight determined
above. Therefore, the new specific weight of the compressed air in the drill collars
after the stop is
0 976
.
cdci
.
0 625
1 561 lb/ft 3
.
cdci
Using Equation 4-11, the pressure due to the stop action of the air hammer is
1
41
(.561 ) (53 .36 ) (604 . )
P cdci
10
(. )
2
,
P cdci 50 360 lb/ft abs
P cdci
p
cdci
144
.
p cdci 349 7 psia
Geometry Inside the Drill String
Starting at the bottom of the drill string, the total length of the drill collars
length increment, H 5, in the openhole section is
H 5 500 ft
The inside diameter of the drill collars length in this openhole section is
.
d 2 8125 inches
5
d 5
D 5
12
D 0 234 ft
.
5
The total length of the drill pipe tool joints lumped geometry increment, H 4, in
the openhole section is
H 4 125 ft