16. Coiled Tubing
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Transcript of 16. Coiled Tubing
Slide 1 of 42
PETE 661
Drilling Engineering
Lesson 16
Coiled Tubing
Slide 2 of 42
Lesson 16 - Coiled Tubing
What is Coiled Tubing? Uses of Coiled Tubing Properties of Coiled Tubing Drilling with Coiled Tubing Buckling
Slide 3 of 42
Coiled Tubing - cont’d
• Buckling Modes
• Sinusoidal and Helical Buckling
• Buckling in Horizontal or Inclined Sections
• Buckling in Vertical Section
• Buckling in Curved Wellbores
• Prediction of Buckling Loads
• “Lockup” of Tubulars
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Some Applications of Coiled Tubing
• Cementing• Plug Cementing (e.g. P&A)• Squeeze Cementing
• Logging
• Drilling
• Producing
• Fishing
• Scale Removal
Ref: SPE Reprint Series NO. 38 “Coiled Tubing Technology”
Slide 15 of 42
• No rig required
• No connections - fast tripping
• Fatigue life limit (cycles)
• Pressure and tension
• Diameter and ovality
Disadvantages
Advantages
Slide 16 of 42
Reference:
“Coiled Tubing Buckling Implication in Drilling and Completing Horizontal Wells” by Jiang Wu and H.C. Juvkam-Wold, SPE
Drilling and Completion, March, 1995.
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Sinusoidal Buckling in a Horizontal Wellbore
When the axial compressive load along the coiled tubing reaches the following sinusoidal buckling load Fcr, the intial (sinusoidal or critical) buckling of the coiled tube will occur in the horizontal wellbore.
502 .ecr )r/WIE(F
r
Slide 22 of 42
Consider:
(steel) psi 000,000,30 E
ft
lb2225.0
ft
lb67.2
45.65
6.8107.3 W
ft
lb07.3
231
45.65*12)688.12(
4W
mud gal# 8.6 ID; 1.688" ,OD "2
e
22
in*
502 .ecr )r/WIE(F
Slide 23 of 42
lbf 317.39375.0
2225.0*3869.0*10*302F Then,
in 9375.02
2875.3
2
ODD r
in 3869.0)688.12(64
)IDOD(64
I
5.06
cr
HOLE
44444
Consider:
,
=
r
WIEF e
cr 2
Slide 24 of 42
Sinusoidal Buckling Load
A more general Sinusoidal Buckling Load equation for highly inclined wellbores (including the horizontal wellbore) is:
r
sinEIWF e
cr
2
Slide 25 of 42
Sinusoidal Buckling Load
For the same 2” OD coiled tubing, at = 45o
506
93750
45222503869010302
.o
cr .
sin.*.**F
Fcr = 2,789 lbf
r
sinEIWF e
cr
2
Slide 26 of 42
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Helical Buckling in a Horizontal Wellbore
When the axial compressive load reaches the following helical buckling load Fhel in the horizontal wellbore, the helical buckling of coiled tubing then occurs:
r
WIEF e
hel 1222
93750
222503869010301222
6
.
.*.**Fhel
Fhel = 6,065 lbf
Slide 28 of 42
General Equation
A more general helical buckling load equation for highly inclined wellbores (including the horizontal wellbore) is:
r
sinEIWF e
hel
1222
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Buckling in Vertical Wellbores:
In a vertical wellbore, the buckling of coiled tubing will occur if the coiled tubing becomes axially compressed and the axial compressive load exceeds the buckling load in the vertical section.
This could happen when we “slack-off” weight at the surface to apply bit weight for drilling and pushing the coiled tubing through the build section and into the horizontal section.
Slide 31 of 42
Buckling in Vertical Wellbores:
Lubinski derived in the 1950’s the following buckling load equation for the initial buckling of tubulars in vertical wellbores:
lbf 161F
)2225.0*3869.0*10*30(94.1F
)EIW(94.1F
b,cr
3/126b,cr
3/12eb,cr
Slide 32 of 42
Buckling in Vertical Wellbores:
Another intitial buckling load equation for tubulars in vertical wellbores was also derived recently through an energy analysis:
1) (Table lbf 212F Alternate
)2225.0*3869.0*10*30(55.2F
)EIW(55.2F
bcr,
3/126b,cr
3/12eb,cr
Slide 33 of 42
Helical Buckling in Vertical Wellbores:
A helical buckling load for weighty tubulars in vertical wellbores was also derived recently through an energy analysis to predict the occurrence of the helical buckling:
lbf 461
)EIW(55.5F 3/12eb,hel
Slide 34 of 42
Helical Buckling in Vertical Wellbores:
This helical buckling load predicts the first occurrence of helical buckling of the weighty tubulars in the vertical wellbore.
The first occurrence of helical buckling in the vertical wellbore will be a one-pitch helical buckle at the bottom portion of the tubular, immediately above the KOP.
Slide 35 of 42
Helical Buckling in Vertical Wellbores:
The upper portion of the tubular in the vertical wellbore will be in tension and remain straight.
When more tubular weight is slacked-off at the surface, and the helical buckling becomes more than one helical pitch, the above helical buckling load equation may be used for the top helical pitch of the helically buckled tubular.
Slide 36 of 42
Helical Buckling in Vertical Wellbores:
The top helical buckling load Fhel,t is calculated by simply subtracting the tubular weight of the initial one-pitch of helically buckled pipe from the helical buckling load Fhel,b, which is defined at the bottom of the one-pitch helically buckled tubular:
3/12e
hele3/12
et,hel
)0.14(EIW
LW)EIW(55.5F
Slide 37 of 42
Helical Buckling in Vertical Wellbores:
The length of the initial one-pitch of helical buckling or the first order helical buckling is:
(10) )W/EI16(L 3/1e
2hel
Slide 38 of 42
Helical Buckling in Vertical Wellbores:
From Table 1, it is also amazing to find out that the top helical buckling load, Fhel,t, is very close to zero.
This indicates that the “neutral point”, which is defined as the place of zero axial load (effective axial load exclusive from the hydrostatic pressure force), could be approximately used to define the top of the helical buckling for these coiled tubings.
Slide 39 of 42
Helical Buckling in Vertical Wellbores:
lbf 12F
)2225.0*3869.0*10*30(14.0
)EIW(14.0F
t,hel
2/126
3/12et,hel
Slide 40 of 42
Buckling of 2” x 1.688” CT
Horizontal
crhel FF 122
r
WIEF e
cr 2 = 3,317 lbfSinusoidal:
Helical: = 6,065 lbf
Slide 41 of 42
Buckling of 2” x 1.688” CT
Vertical
Sinusoidal, bottom:
or
lbfWIE.F/
eb,cr 161941312
lbfWIE.F/
eb,cr 212552312
Slide 42 of 42
Buckling of 2” x 1.688” CT
Vertical
Helical, bottom:
Helical, top:
lbfWIE.F/
eb,hel 461555312
lbfWIE.F/
eb,hel 12140312