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Transcript of Drill Pipe
© Robert Gordon University and Owen S. Jenkins Ltd. 2010
ENM201 WELLSOil & Gas Well Drilling Part 2.
Prepared and presented by Owen Jenkins, BA, MA, CEng,
CMarEng, FEI, MIMarEST.
2© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Introduction to Drill Stem Design
●We’ve already seen some of the basic tools that make up the drill stem
●Let’s see how we use them.
3© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
The Work of Drilling – Remember?
●What makes drilling work?●Weight – gravity●Weight-On-Bit (WOB)●Rotation
■ Torque■Speed of rotation of the bit
●Energy stored in the rocks■Pore pressure
●A means of clearing away the debris
4© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
The Drill String● Identification of Drill String
Credentials●Basic Functions●Yield, Tensile & Torsional
Strength●Rotary Shouldered Connections ●Buoyancy ●Overpull●Collapse & Burst Pressures● ‘Neutral Point’●Buckling●Friction Effects in Directional
Wells●REMEMBER – IT’S NORMALLY
IN TENSION
5© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Identification of Drill Pipe
●Data normally stamped on drill pipe to API, ISO and NORSOK standards:
●1 = Company owning pipe (e.g. KCADeutag)
●2 = Month welded (e.g. 2 = February)●3 = Year welded (e.g. 01 = 2001)●4 = Pipe manufacturer and API licence
number●5 = Drill Pipe Grade (e.g. “S”)●Range Length●API pipe will also normally bear the API
monogram
6© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Basic Functions
●Transmit and support axial loads●Transmit and withstand torsional loads●Transmit fluid under high pressure to
■Clean the hole■Cool the bit ■Power the MWD pulser and mud motor (if
used)● It must withstand potential fatigue damage
■ ‘Leak before break’ principle
7© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Stress/Strain Curve
0 0.2 0.5%
Elasticregion
Elastic limit – Yield Point
0.2% Proof stress
0.5% Strain
0.2% strain offset line, parallel to elastic region
Plastic strain region
8© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Yield Strength per API Spec 5D
Grade Total Extension of Gauge Length,
%E-75 0.5
X-95 0.5
G-105 0.6
S-135 0.7
●Many sources get this wrong
● They state that API specifies the 0.2% offset
● API Specs 7 and 7-1 use the 0.2% offset method for tool joints and BHA components, notdrill pipe bodies.
9© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Torsional Strength
10© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Drill Pipe Grades -Manufacture
API Grades Min Yield (lbs/in2) Symbol
E-75 (*) 75,000 EX-95 (*) 95,000 X
G-105 (*) 105,000 GS-135 (*) 135,000 S
SS-95 95,000 SS-95
G-120 120,000 G-120
Some ProprietaryGrades
Min Yield (lbs/in2) Symbol
V-150 150,000 VNote: (*) denotes commonly used grades of drill pipe
11© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Drill Pipe Class -Inspection
●●Per API RP7GPer API RP7G Recommended Practice for Drill Stem Design and Operating Limits (Includes Errata dated May 2000, andAddendum dated November 2003) 16th Edition August 1998
Class Number & Colour of Bands OD Wear Effect / Remaining Pipe Wall
Thickness1 (New) One White ≥87.5% nom wall
Premium Two White 80%
2 One Yellow 70%
3 One Blue <70%
Reject One Red N/A
12© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Which Joint is the Reject?
13© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Pipe Selection
●When designing the drill string for a well, plan on using PREMIUM PIPE.
●Even if pipe is new, once it is inspected in service, the highest classification used is PREMIUM, even if the pipe meets Class 1 (new) dimensions.
●Only use pipe of lower class in shallow, non-critical wells.
●We do not use anything less than Premium Class in the North Sea.
14© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tensile Strength Example● What’s the yield strength of 5” Grade G
19.5 lb/ft Premium Class Drill Pipe?● First: Pipe dimensions● From tables - API RP7G or other
source, e.g. Wilson website (see link later)1. Find the I.D. or wall thickness of the tube2. 5” x 19.5 ppf – nominal wall thickness =
0.362”,so: I.D. = 5 – (2 x 0.362) or 4.276”
3. O.D.: 20% WT reduction allowable: soMin. O.D. = 5” – (0.362” x 2 x 0.2) = 5” – 0.01448” = 4.8552”
ID
Class 1 New OD
Min. Premium
OD
15© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tensile Strength Example● What’s the yield strength of 5” Grade G,
19.5# Premium Class Drill Pipe?● Second: Cross Sectional Area of Steel =
(π/4)(OD2-ID2) = (π/4)(4.85522 – 4.2762) = 4.1538 sq.in.
● Grade G pipe has a Minimum Specified Tensile Yield Stress of 105,000 psi, so:
● Yield Strength of Pipe = 105,000 x 4.1538 = 436,149 lbf.
● Or 436,000 lbf. rounded to nearest 1,000.
Area of pale blue –CSA of 5”19.5# Premium Pipe = 4.1538 sq.in.
16© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Design Factor (or Safety Factor)
● Such tensile strengths are theoretical values based on minimum areas, wall thickness, and yield strengths
● Yield strength (as defined in API specs) is not the specific point at which permanent deformation of the material begins but the stress at which a certain total deformation has already occurred
● This deformation includes all of the elastic deformation as well as some plastic (permanent) deformation
17© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Design Factor (or Safety Factor)
●So: if the pipe is loaded to the extent shown in such tables, it is likely that some permanent stretch will occur;
●Moreover, there are variations in wear and wall thickness, eccentricity etc.
●To allow for these, a design factor of 85% to 90% of the tabulated value is used
●The Operator will define the SF or DF he chooses to use.
18© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Design Factor (or Safety Factor)
● It may be expressed as:-● A percentage e.g. 85%● A decimal number e.g. 0.85
■ So the Max. allowable stress = Yp x 0.85● Or a figure >1 e.g. 1.18
■ In which case you DIVIDE the component’s nominal yield strength by the factor to get the maximum allowable load = Yp/1.18
● Our design is always based on a percentage of yield strength, NOT ultimate tensile strength.
19© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tensile Strength Example● Is that answer good enough?● That is pure tensile load.●What about torque?●What about torque + tension?●What about internal and external yield due to
pressure differences?●What about bending?●What about real life?● A combination of several of the above, most
of the time.
20© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Torsional Yield Strength
● Defined as the resistance of the tube to failure by a twisting torque or force.
● The torsional yield strength is based on the shear strength equivalent to 57.7% minimum yield.
● Considering pipe failure in pure torsion (zero tensile load):
● API RP7G gives us this formula:-Q = 0.096167JYm / D
■ Where Q = Min torsional yield strength, ft-lbs (i.e. lbf-ft)
■ Ym = Min unit yield strength, psi■ J = Polar moment of inertia: (π/32)(D4-d4)
21© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Torsional Yield Strength
●For our 5” 19.5 lb/ft grade G premium class pipe this is
●Q = 0.096167JYm / D = 0.096167 (π/32)(D4-d4) x 105,000 ÷ D
= 0.096167 x.098175(4.85524 – 4.2764) x105,000 ÷ 4.8552
= 45,200 lbf-ft. ● (or, as it so often called, erroneously, “foot-
pounds”)
22© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Combined Torque and Tension –Pipe Body
● API RP7G gives us this formula for combined torsion and tension:-
2
22096167.0AP
DJQ Y mT −=
● Where■ QT = minimum torsional yield strength under tension, ft-lb (sic!)■ J = polar moment of inertia■ D = outside diameter, inches■ d = inside diameter, inches■ Ym = material yield strength (sic), psi■ P = total load in tension, lbs.
and■ A = cross-sectional area, sq.in.
)(098175.0
for tubes )(32
44
44
dD
dDJ
−=
−=π
23© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Combined Torque and Tension –Pipe Body
●Let’s see what this means for our grade G, 5” premium class pipe body
24© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Combined Torque and Tension – Pipe Body5" G-105 19.5# New, Premium and 90% WT Tube Capability 1.00 SF
0
100000
200000
300000
400000
500000
600000
0 10000 20000 30000 40000 50000 60000 70000
Torque lbf.-ft.
Tens
ion
lbf.
19.5 # G-105 PremiumTube
19.5 # G-105 NewTube
19.5 # G-105 90% WT
25© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tool Joints
●Drill pipe is connected together with TOOL JOINTS
●These usually conform to API Spec. 7●Standard material: 120,000 psi MSYS –
0.2% offset method.
26© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Stress/Strain Curve (Again)
0 0.2 0.5%
Elasticregion
Elastic limit – Yield Point
0.2% Proof stress
0.5% Total Strain
0.2% strain offset line, parallel to elastic region
Plastic strain region
For tool joints and BHA
components
For Grades E and X drill pipe. 0.6% for G
and 0.7% for S.
27© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tool Joint – Box Connection
Tong space
Image edited from FPUK original
28© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Tool Joint – Box Connection
Image edited from FPUK original
Hardbanding (optional)
Tong space
Box Tool Joint
Friction weld External upset
Internal upset
Pipe body
Thread
Rotary Shoulder
18° tapered load shoulder (for elevators)
29© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Rotary Shouldered Connections
● Normal drill stem connections are Rotary shouldered connections
● The shoulder serves to seal the connection face-to-face and to transmit torque
● The threads are tapered and normally conform to API standards
● There are also proprietary threads and connections, but we shall stay with API for the time being.
30© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Connection Strength● Torque to yield a rotary shouldered connection
per API RP7G.
deg. thread,of angle included ½ 0.08) astaken (normally surfaces matingon friction oft coefficien
in. thread,of (pitch) lead
smaller. is whicheveror box,or pin of area sectional-cross psi. ),(stress!strength yield maximum material
ft.-lbf yield to torqueWhere
cos212
===
==
=
⎟⎠⎞
⎜⎝⎛ ++=
θ
θπ
fp
AAAY
T
fRfRpAYT
bp
m
y
stm
y
31© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Connection Strength
box. of area sectional-cross )]([4
grooves relief with )(4
or grooves, relieft pin withou of area sectional-cross ])[(4
in. point, gaugeat threadofdiameter pitch shoulder theof radius effective the)¼(
in. pin, oflength
thread theof radius effective the4
])625.0([:Continuing
cos212
22
22
22
121
EQODA
IDDA
IDBCA
CQODR
L
tprLCCR
fRfRpAYT
cb
RGp
p
cs
pc
pct
stm
y
−−=
−=
−−=
=+=
=
××−−+=
⎟⎠⎞
⎜⎝⎛ ++=
π
π
π
θπ
32© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Connection Strength
in. in. e,counterborbox in. diameter, outside
in/ft. taper,in. ation,root trunc thread
in. ted,not truncaheight height thread
in. thread, theofheight effectivemean the 2
2
in. diameter, inside :Continuing
cos212
121
83
121
81
××======
××+⎟⎠⎞
⎜⎝⎛ −=
=
⎟⎠⎞
⎜⎝⎛ ++=
tprEQODtprSH
tprSHB
ID
fRfRpAYT
c
rs
rs
stm
y θπ
33© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Rotary Shouldered Connection
From API RP7G
34© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Connection Strength
● I’m sure you’ve all memorised that!●So, that was easy, now
35© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Make-Up Torque (MUT)
● It is most important that a connection is done up tight enough.
● It is unusual to have too much torque applied at the surface when making-up connections.
● It is very easy to under-torque a connection
● If you do, it may well try tightening itself down-hole (“downhole make-up”)
36© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Box Failure From Downhole Make-up
Courtesy of FPUK Ltd.
37© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Make-Up Torque
●You memorised the rest earlier, didn’t you?■You didn’t?!■Hock and Shorror!
psi. level, stress up-make drecommende
SRGs. without sconnectionpin on based be shall
smaller. is whicheveror box,or pin of area sectional-cross
ft.-lbf torqueup-make Where
cos212
=
=
=
⎟⎠⎞
⎜⎝⎛ ++=
S
A
AAA
T
fRfRpSAT
p
bp
st
θπ
38© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Allowable Stress●Maximum make-up stress recommended
by API RP7G in rotary shouldered connections, in weaker of box or pin:
●Tool joints: 60% of minimum tensile yield (= 72,000 psi, for API tool joints)
●BHA components: 62,500 psi, except:■ 87,500 psi. for 2 7/8 PAC■ 56,200 psi. for H-90.■With a bit of luck, you’ll never need either of
these awful connections.
39© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Combined Torque and Tension in a Connection
NC 50 Connection, 6-5/8" OD x 2.75" ID
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
0 10000 20000 30000 40000 50000 60000 70000Applied Torsion
App
lied
Tens
ion
Shoulder SeparationPin Yield (2)Pin Yield (1)Box Yield
Recommended Area of Operation
Pin tensile failure
Shoulder separation
Box failure – hoop stress
Pin failure –combined torque and
tension
40© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Combined Diagram for Pipe and Tool Joint
5" G-105 19.5# New, Premium and 90% WT Tube Capability 1.00 SFWith NC50 Connections. 6-5/8" x 2¾".
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
0 10000 20000 30000 40000 50000 60000 70000
Torque lbf.-ft.
Tens
ion
lbf.
19.5 # G-105 PremiumTube19.5 # G-105 New Tube
19.5 # G-105 90% WT
Shoulder Separation
Pin Yield (2)
Pin Yield (1)
Box YieldRecommended Area of Operation
Recommended MUT:38,000 lbf-ft.
41© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Easier Ways
●You can look these things up in RP7G, but it does not include all pipe and connection combinations.
●Try the Grant Prideco Website:●http://www.grantprideco.com/drilling/produ
cts/drilling_products_specsTechs.asp●You will also find details of their
proprietary connections and pipe.
42© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
Useful Links
●Drill pipe data:● http://www.iwilson.com/doc.aspx?fielddoc=prodCatDoc&tabledoc=tb
l_product_category_docs&fieldkey=prodCatDocId&valuekey=8&filetype=application/pdf
● http://www.iwilson.com/doc.aspx?fielddoc=prodCatDoc&tabledoc=tbl_product_category_docs&fieldkey=prodCatDocId&valuekey=10&filetype=application/pdf
43© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
References
●For derivation of drill stem strength formulae:■■ API TR 5C3API TR 5C3 Technical Report on Equations and
Calculations for Casing, Tubing, and Line Pipe used as Casing or Tubing; and Performance Properties Tables for Casing and Tubing (replaces Bull 5C2 and Bull 5C3) 7th Edition, December
2008.
44© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
References & Bibliography● API Spec 5D Specification for Drill Pipe. 5th Edition,
October 2001.● API Spec 7 Specification for Rotary Drill Stem Elements
(Includes Addendums 1, 2 and 3) 40th Edition, November 2001.■ Covers tool joints for drill pipe only.
● API Spec 7-1/ISO 10424-1 Specification for Rotary Drill Stem Elements Petroleum and natural gas industries—Rotary drilling equipment — Part 1: Rotary Drill stem elements (Includes Addendum 1 dated March 2007) 1st Edition February 2006.
45© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
References & Bibliography● API Spec 7-2/ISO 10424-2 Specification for Threading
and Gauging of Rotary Shouldered Thread Connections Petroleum and natural gas industries—Rotary drilling equipment — Part 2: Threading and gauging of rotary shouldered threaded Connections drill-string components. 1st Edition, June 2008.
● API RP 7G Recommended Practice for Drill Stem Design and Operating Limits (Includes Errata dated May 2000, and Addendum dated November 2003) 16th Edition, August 1998.
46© Robert Gordon University© Robert Gordon University and Owen S. Jenkins Ltd. 2010
ENM201 WELLS
Oil & Gas Well Drilling Part 2.
Prepared by
OWEN S. JENKINS LTD.
4, Charlton Avenue, Aboyne, Aberdeenshire, AB34 5GL, Scotland.
Tel. +44 (0)13398 87779. Mobile phone: +44 (0)7803 296779.Email: [email protected] Website: www.osjl.co.uk