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5 September 2008 Concept of Drill Pipe development for UDD (Ultra Deep Drilling)
5 September 2008
Concept of Drill Pipe development for UDD(Ultra Deep Drilling)
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Contents•Understanding of UDD’s problem
deep water problem
•Requirements to Drill Pipe
General requirements
Opinions in papers
Concrete specification issued by oil company
•Response from Drill Pipe manufacture
Investigation of delay fracture
Sour service performance
Fatigue resistance
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Undersatnding to UDD
Difference required in Drill Pipe between ERD and UDD
• ERD…High torque required but low tension。
TSH wedge type connection will be candidate.
max. dogleg severity is 6 degree/100feet in rotary drill pipe.
• UDD… Moderate torque required but high tension and fatigue (riser-less drilling)
Definition: THD/TVD＜0.25
NK-DSTJ-ST series is candidate.
Grade: S150 World record：34189 ft (10420m) at KNOTTY HEAD WELL/Gulf of Mexico
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Deep water problems• Unstable see bed
Sand base, leaning
• Low temperature at sea bedInfluence to pipe, device and equipments
• High load to well headDesign factor, reliability for Engineering
• Operation supports by submarine in sea bedSubcontract it to modernized and reliable company
• Difficulty for vertical drilling by currentNecessity of drilling riser
• Influence of currentFatigue of drill pipe vibrated in current.
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General requirements• Reduction of Drill Pipe weights
• Low friction factor of hardfacing for Tool Joint
• High torque Tool Joint
• High friction factor dope
• High strength Drill Pipe
• High toughness Drill Pipe
IMPL(3/4 size、－20Ｃ)： >59 ft-lbs
• Fartigue resistance Drill Pipe
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Opinions in papersKey factors to be solved in UDD
• Maximum capacity of suspending a string at Rig
• Collapse resistance in BOP
• Maximum shearing force in BOP in emergency
• Difficulty of installation of risers to sea bed device and/or riser less drilling difficulty by current
Referenced papers
SPE 104827 and 105792 indicating difficulty of UDD、Oil Company specification.
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High strength Drill Pipe
Yield strength : ＳＭＹＳ１５０ ksi & １６５ ksi
range shall be 20 ksi.
Charpy test
－4Ｃ IMPL (ft-lbs) Hardness
Each Ａve. HRC
Sub size of pipe 150 ksi ３２ ４０ 42
165 ksi ３５ ４４ 43
Full size of T/J 135 ksi ３３ ４４ 316-375 HB
One specification issued by oil company
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Additionally,ＫＩｓｃｃ（Delay fracture），Fatigue test、SSC test
Condition
ＰＨ２Ｓ ０．５psi balanced with CO2 gas
ＰＨ３．５－４．０
Criterion for SSC test
90% SMYS
One specification issued by oil company
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Response from drill pipe manufacture
• Drill Pipe
Challenge to high strength
Delay fracture
SSC resistance
toughness at welds
• Tool Joint
Influence to external shoulder from bending force under high tension
Influence to external shoulder from vibration due to fast current caused by riser less drilling.
Current ｘｘNott
Univ. joint angle ｘｘdegree
Univ. joint angle ｘｘdegree
２０００－３０００ｍ
０ｍ
８０００ｍ
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Delay fractureWhat we need to consider of in designing of high strength materials
is delay fracture phenomimum is one of the hydrogen brittlement.Hydrogen gas induced by corrosion invade into steel material structure and accumulate and pressurize at certain areaeventually induce fatal cracks. This is called as delay fracture.
It is not managed not to occur by controlling atmosphere, as ithappen in salt water.
Test method is as follows.
After sample is prepared as a drawing then created fatigue crack by fatigue tester, samples with various values of KI calculated by mechanical properties and fatigue crack length are tested to seek no failed sample which has the biggest KI value, which is called as KISCC value.
Test duration: 500 hr
Test facility: next page
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1.Delay fracture test Specimen
Weight
Cell
Solution circulation pump andTemperature controller
3.5%NaCl30 degC
75
150
15
100.15
1.5
1.5
Wire saw notch
Fatigue precrack
Test specimen
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2.Test result
0
50
100
150
200
250
300
350
400
450
1000 1100 1200 1300 1400
T.S.(MPa)
KIｓｃｃ
(kgf
/mm
3/2)
170ksi
Ultimate tensile strength
API S135
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Condition to use S135 in sour service
• PH<10 in accordance with API speｃ.7
But it is difficult to control in Under balanced drilling and High PCO2.
Temperature Profiles
0
5000
10000
15000
20000
250000 50 100 150 200 250 300 350 400
Temperature (deg F)
Mea
sure
d De
pth
(ft)
DP Circ. Temp. Annulus Circ Temp Static Temp
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Product Designing
Grade pipe: YS 105 ksi, T/J material: 110 ksi
SSC Criterion
pipe: 85% SMYS, T/J material: 70% SMYS
Even though delay fracture test would have been succeeded, it isrequested that SSC test conditions and the criterion in accordance with IRP shall be re-considered due to no realistic test method.
Therefore total coordination for drill pipes considering of assorts of full string drill pipes, size, grade and connection.
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Sour service of drill pipePipe Body IRP 1.8 SS105 API G105 NK C105S
type lNK C105S
type ll G/P XD-105
Tensile property Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.YS(Ksi) 105 120 105 135 105 120 105 120 105 120TS(Ksi) 115 140 115 - 115 - 115 - 115 -
EL 17% as per API as per API as per APIHardness(HRc) Min. Max. Not Required Min. Max. Min. Max. Min. Max.
Max. Average - 28.0 - 29.0 - 28.0 - 30.0Reading 21.0 29.0 - - - - - -
freq. per heat, heat treat lot, orevery 200 tubes. Not defined
J ft-lbs J ft-lbs J ft-lbs J ft-lbs J ft-lbs
Min. Single 80 59 38 28 108 80 120 89Min. Ave. - - 43 32 - - - -
85% Not Required 80% 85% 70%
freq. Not defined
Grain size 6 Not Required Not defined Not Required
Steel code U26MMM J61V.J(1.0Cr-0.5Mo)
J97VBL(1.0Cr-0.7Mo)
Not defined
Special compositonsare requested
per heat, heat treat lot
per heat, heat treat lot,or every 200 tubes.four
quadrants.
Toughness(3/4size at room temp.)
SSC(720h NACE-method A)
per heat, heat treatlot, or every 200
tubes.
API
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Sour service T/J material Tool Joint IRP 1.8 SS105 API G105 NK C105S
type lNK C105S
type ll G/P XD-105
Tensile property Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.YS(Ksi) 110 125 120 - 110 125 110 125 105 120TS(Ksi) 125 145 140 - 125 - 125 - 115 -
EL 15% 13% 13% 13% 13%RA 35% Not defined Not defined Not defined Not defined
Hardness(HRc) Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.Max. Ave. - 30.0 - 30.0 29.0 30.0
Reading - 32.0 HB 285(HRc30)
- - - - - - -
freq. per heat,heat treat lot
Suface HA freq. every T/J every T/J
J ft-lbs Not Required J ft-lbs J ft-lbs J ft-lbs
Min. Ave. 90 66 108 80 130 96
freq.
65% Not Required 65% 70% Not Specified
freq.
Grain size 6 Not Required Not Required Not Specified
Steel code J1235F J97VBL(1.0Cr-0.7Mo)
Not defined
per heat, heat treat lot, orevery 200 T/J
per heat, heat treat lot
Special compositonsare requested
per heat, heat treat lot, orevery 200 T/J
per heat, heat treatlot, or every 200 T/J
SSC(720h NACE method A)
per heat, heat treatlot, or every 200 T/J
Toughness(full size at room temp.)
per heat, heat treatlot, or every 200 T/J
API
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Tool Joint fatigue resistanceIn general, fatigue failure for drill pipe is considered as follows.
Failure mode:
I. circumferential fatal crack occur at 1 to 2m from the ends of tool joints.
II. root of threads in tool joint due to stress concentration in external shoulder opened.
Failure process ( internal coated drill pipe):
I. Pitting corrosion at external surface and/ or slip marks at external surface
Fatigue crack initiated from a bottom of pits and propagated.
Fatigue crack reached inside of pipe then leakage started from int.
to ext. surface.
Pressure dropped and/or led to spitted.
II. High fatigue stress from Drill pipes supported by outer casing due to high
bending and light compression to tool Joint is shifted. Once external shoulder started to
detach, stress concentrate at a bottom of threads.
Corrective actions:
I. Cleaning and cleaning drill pipes.
II. Stress relief groove is applied.
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Fatigue analysis by FEM
axial force
amplituded force
Cantilever fatigue tester
no compression compression
Elastic deformation under compression
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Fatigue analysis by FEM
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Fatigue analysis by FEM
of 50%YSno tension
6850%168108110
26%31%31%36%%4130%10486496
1351059575YS2720%6324324
35332927FRF2015%5243243
SGXEgradeFR
Amplitude of vibration
max. surface stress
Bending forceDogleg severity
ksirequired fatigue resistanceAPIksi%ksilbsdegree
EDCBA
5A
inch5ID
inch0.316WTlbs/ft23.4NW of drill pipe
inch5.5OD drill pipe
ksi135Grade
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OthersReduction of Drill Pipe weights
• FRP,Titan alloy, Alminum alloy、
All industrial products but prices are ten times more expensive than low alloy Drill Pipe. And other key issue is strength.
Alminum alloy : maximum yield strength 69 ksi
Titan alloy: maximum yield strength 120 ksi
Low alloy: maximum yield strength 150 ksi
If 160ksi material in low alloy exists, the same string weight would be achieved.
• Under investigation of influence of heavy load of string
Based on a result of FEM, it shall be reflected to a modification of T/J design.
