21-dc - hwdp - nm - flex
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Directional Drilling
Drillstring Components
Sperry-Sun 2004
The contents of this presentation are for training purposes and internal use ONLY and are NOT to be used for customer presentations or external use as it may contain sensitive information.
Directional Drilling
Drill Collars
Sperry-Sun Drilling Services
2004
Drill Collars
Sizes (OD) :2-7/8” – 12”
ID range :1”– 4”
Weights :
19 – 342 lb/ft
Material (σfmin):≤6-7/8” 110 kpsi
≥7” 100 kpsi
Drill Collar Materials
Comparison of properties – 8” OD x 2” ID drill collars :
SG lbs/ft EI = (x 1010 lb-in2)
• Steel AISI 4145H 7.68 160 0.57 • Tungsten Carbide 17.8 326 0.43 • Uranium, depleted 18.4 367 0.90
• Notes :• Tungsten carbide featured memory effect, brittle• Uranium consisted of 2% Mo + 98% U – corrosive,
needed a steel jacket, dangerous material
• SG = Specific Gravity• AISI 4145H as per API Specification 7• EI = Stiffness Coefficient (Young’s Modulus of Elasticity x Moment of
Inertia (l))
Selection of Drill Collars
Issues :
• Weight
• Stiffness
• Hydraulic resistance
Using Drill Collars
• Provides WOB (weight - on – bit) with a stiff tubular
• When keeping neutral point of tension within DC column (use approx. 90% of the DC weight only)
• Minimum effective hole diameter (after Lubinski) :
MEHD = (D bit + D dc) / 2
• Minimum required drill collar diameter (after Koch) :
min DC = 2(Dcsgcoupling) – D bit
MEHDD bit
2
D dc
2
running casing
Stiffness
• Moment of Inertia (l) :
(note: – if you use radius in place of diameter = /4 in place of /64)
(Polar Moment of Inertia (J) = 2 x Moment of Inertia (l) =/32)
Valid for thick wall cylinders, when OD/ID > 1.7
44 IDOD64
I
In4
• Young’s Modulus of Elasticity : Strain (Deformation) = ∫ (σ / E)
(function of (σ = stress) / (E = Young’s modulus of Elasticity))
Valid within the elastic strain region
Values : 29 x 106 psi for common steels (29,000 kpsi) 51.5 x 106 tungsten carbide 10 x 106 aluminium
26 x 106 Monel K500
• Stiffness Coefficient : SC = E x I lb-in2
Triangular Drill Collar for Increased Stiffness
Note : there are rectangular drill collars, too
Spiral Groove on Drill Collar
Drill collars can be spiral grooved to reduce differential sticking (approx. 4% weight loss)
DC Connections• Thread profile : V-038R (V-065 is obsolete)• Preferred connections : REG, NC, FH, H-90 (IF and XH are not preferred but are common in the
oilfield)• Bending Strength Ratio : BSR ~ 2.5 (stiffness of box / stiffness of pin)• Make-up torque : essential • Low- torque connection features• Pipe dope
Stress Reduction on Pins
stress relief groove
Note : not recommended for connections smaller than NC-38
Stress Reduction on Box
Low torque shoulder on the box
Bore - back
Drill Collar Lbs / Ft
Non-Magnetic Drill Collars
• NM drill collars, hang-off collars and hang-off subs - house the survey probes in non-magnetic environment
• NM extension bars – keep the survey probe in the (NM) drill collars far enough away from the steel components to avoid or minimize interference
• NM orienting subs (e.g. UBHO) to reduce interference
• NM string stabilizers, flex collars are available, too
• NM pressure cases and other parts for survey instruments
• Regular steel for drill collars : AISI 4145H (API Spec 7)
• Non-magnetic steels :
– chrome-manganese alloys (P530, P530HS, P550) – chrome-nickel alloys (SMI SM2035, SCF-19)– copper/copper-nickel alloys (MONEL K-500)
• Material strength (σy) :
steel (DC) AISI 4145H 110/100 kpsi (3-1/2” to 6-7/8”; 7” to 11” OD)
nm P530 110/100 P530HS 120/110 P550 140/130
SCF-19 100Staballoy 100
Monel K-500 115 SG 8.44 !
Note : Make-up torque depends on the yield strength, too
Non-Magnetic Materials
Composition of the Most Common NM Alloys
Monel K-500 27-33% Cu + 63% Ni+ (expensive)2.30-3.15% Al + 2.00% Fe
Cr-Ni steel ~ 18% Cr + >13% Ni (tend to gall)
Austenitic Cr - Mn alloys (SCC) used for LWD steel (>18% Mn + 4%Cu-Be)
Be-Cu bronze (expensive)
AUSTENITIC STEELSteel which, because of the presence of alloying elements, such as manganese, nickel, chromium, etc., shows stability of Austenite at normal temperatures.
AUSTENITEPhase in certain steels, characterized as a solid solution, usually off carbon or iron carbide, in the gamma form of iron. Such steels are known as “austenitic”. Austenite is stable only above 1333°F. in a plain carbon steel, but the presence of certain alloying elements, such as nickel and manganese, stabilizes the austenitic form, even at normal temperatures.
NM Drill Collars and Flex Collars
Spiral NM Drill Collars
NMDC End - Without SRG
no SRG
low-torque shoulder
• Problems with non-magnetic LWD and drill collars are:
• Galling on tool joints• Corrosion• Cracking• Frequent re-cutting the tool joints might be needed
(hard on tooling)• Occasionally Hot spots could be developed• Price is high
Non-Magnetic Drill Collars
Non-Mag Galled Threads
Corrosion-Erosion Pitting
Drill Collar Abrasive OD Wear
Non-magnetic Pup Joints
Note the 18° shoulder on tool joints
Directional Drilling
Hevi-Wate Drill Pipe
Spiral-Wate
Sperry-Sun Drilling Services
2004
Hevi-Wate Drillpipes
• Intermediate weight pipes with longer tool joints and additional upset (s) on the pipe body (1 or 3)
• Size range available : 3-1/2” – 4” – 4-1/2” - 5” – 5-1/2” – 6-5/8”
• ID and weights are depending on manufacturer
• Standard, spiral- and non-magnetic versions
• Manufacturers / suppliers : Drilco, Grant-Prideco, Weatherford
• Not covered by API Specification
Comparison of DP to HWDP
• 5” 19.50 lb/ft Grade G NC50 drillpipe approx. wt. 21.92 lb/ft
• 5 x 3” HWDP ( Drilco), standard, adjusted wt. 49.70
• Weight increase 2.27x
• Grant – Prideco standard 5 x 3” 49.3 lb/ft 1 upset
• Drilco - standard 5 x 3” 49.7 1
• - spiral 5 x 3” 54.0 3
• Weatherford - standard 5 x 3” 50.6 1
• - spiral 5 x 3” 53.8 1
Comparison of Hevi-Wate Drillpipes
Hevi-Wate Drillpipes
long TJ
large bore
pipe upset
SRG
HWDP Pin
SRG
HWDP – Pipe Upsets
hardfacing hardfacingupset
HWDP and DP Racked Back
HWDP DP
long TJold API marking :
hi-strength DP
wt and grade codes in slots
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