STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

Hoisting System 609
to supply an excess of drilling line over that required to string up, and to slip
this excess through the system at such a rate that it is evenly worn and that the
line removed by cutoff at the drum end has just reached the end of its useful life.
Initial Length of Line. The relationship between initial lengths of rotary lines
and their normal service life expectancies is shown in Figure 4-83. Possible
savings by the use of a longer line may be offset by an increased cost of handling
for a longer line.
IC
w
c)
9
a
2 7
W
v)
f 6
0
a
w ' 5
a
-
3 4
w
>
5 3
w
a 2
I
1000 2000 3000 4OOO 5OOO 6000 7000
ROTARY LINE INITIAL LENGTH,FT.
Figure 4-83. Relationship between rotary-line initial length and service life [11].*
*Empirical curves developed from general field experience.