文档介绍：DRILL STRING DESIGN
© 2008 PetroSkills LLC, All Rights Reserved
Drill String Design
Common gra des o f drill p ipe with
yield strength
Minimum Yield Maximum Yield Tensile Strength
Grade psi psi psi
75,000 105,000 85,000
E
(517 MPa) (724 MPa) (586 MPa)
95, 000 125, 000 105, 000
X
(655 MPa) (862 MPa) (724 MPa)
105,000 135,000 115,000
G
(724 MPa) (931 MPa) (793 MPa)
135,000 165,000 145,000
S
(931 MPa) (1138 MPa) (1000 MPa)
2 © 2008 PetroSkills LLC, All Rights Reserved
Drill String Design
3 © 2008 PetroSkills LLC, All Rights Reserved
Drill String Design
The API recognizes four classes
of drill pipe
¾New
¾Premium Class
¾Class 2
¾Class 3
Pipe is rarely considered new
If it has been run in the hole, it is
considered premi um cl ass
4 © 2008 PetroSkills LLC, All Rights Reserved
Drill String Design
The DSDS--11 standard has an
additional class of drill pipe
¾It is premium class , reduced TSR
¾The tool joints do not meet the
standards for API tool joints and have
a reduce torsional strength
¾PdtiltithPressure and tensile ratings are the
same, but torsional strength is lower
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Drill String Design
Premium class assumes that
there is 80% wall thickness
remaining on the tube and that
the reduction in wall thickness
comes from the outside diameter
of the tube
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Drill String Design
A reduction in outside diameter
removes the most steel and
results in the lowest strength
5” by ” 2
5”, # As = in
2
20% outer wall As = in
2
20% inner wall As = in
” by ” 5” by ”
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Drill String Design
The worn OD can be determined
from the following formula
Dpwpihi= (D − D )× t + D
The worn OD can be used to
calculate tensile strength and
combined torsion and tension
limits
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