Page 101 - Air and gas Drilling Field Guide 3rd Edition

92 CHAPTER 4 Downhole Equipment

The factor of safety is determined from Equation (4-4). Equation (4-4) gives
2381940
FS ¼
987613
FS ¼ 2:41
The selected rotary drilling rig has a maximum hoisting capacity of 1334.4 kN lb,
thus using Equation (4-5) the effective MOP is
MOP ¼ 1334400 987613
MOP ¼ 346787 N
The calculations just given show that an additional 349,787 N (above the weight
of the drill string) can be pulled by the hoist system or with the assurance that the
drill string will not fail structurally.

REFERENCES
1. API Recommended Practices for Drill Stem Design and Operating Limits, API RP7G, Sixteenth
Edition, August1998.
2. Drilling Manual, International Association of Drilling Contractors (IADC), Eleventh Edition,
1992.
3. Drilling Assembly Handbook, Smith Services, Division of Smith International, 2006.
4. Roscoe Moss Company, Handbook of Ground Water Development, Wiley, 1990.
5. Bourgoyne, A. T., Millheim, K. K., Chenevert, M. E., and Young, F. S., Applied Drilling
Engineering, SPE, First Printing, 1986.
6. Durrett, E., “Rock Bit Identification Simplified by IADC Action,” Oil and Gas Journal, Vol. 76,
May 22, 1972.
7. Drill Stem Design and Operation, Standard DS-1, Vol. 2, Third Edition, T. H. Hill Associates,
2004.