schl shocks & vibrations a cause of drillstem failure hayes... · the definition of failure ......
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Schluumberger Public
Shocks & VibrationsShocks & VibrationsA Cause Of Drillstem FailureA Cause Of Drillstem FailureA Cause Of Drillstem FailureA Cause Of Drillstem Failure
Martin HayesMartin HayesSenior Drilling EngineerSchlumberger
An Introduction to Shocks & Vibration ManagementAn Introduction to Shocks & Vibration Management
• Overview of Shock and Vibration Related Failure
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• Causes of Shocks & Vibration• Managing Shocks and Vibrations um
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g g– Design
• Equipment Selection & Modeling– Execution
• Diagnosing & Mitigating– Review
What are Shocks & Vibrations?What are Shocks & Vibrations?
• The dynamic mechanical excitation that may cause a
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dynamic response of a physical system that is exposed tothat excitation
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– In general:• Shocks are an excitation over a relatively short duration
Vibration is an excitation over a relatively long duration• Vibration is an excitation over a relatively long duration
The Definition Of FailureThe Definition Of Failure
• when someone or something does not succeed
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• when you do not do something that you must do or are expected to do um
berger Public• What does this mean in drilling?– Failure to meet the defined drilling objective
• Expected TD depth / run length• Expected Performance (penetration rates, directional, power
use)
Drillstring Dynamic MotionsDrillstring Dynamic MotionsSchluum
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Obvious Shock & Vibration FailuresObvious Shock & Vibration Failures
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More Extreme Shock and Vibration Damage?Schluum
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Other Shock and Vibration Related ‘Failures’Other Shock and Vibration Related Failures
• Low Penetration Rates
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• Failure to acquire evaluation data• Poor wellbore quality um
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q y– Increased Tripping Times– Inability to run & set casing– Torque & Drag
• Directional Control• Fatigue Minimal / No
Bit Whirl Bit Whirl?
Causes of Shocks and VibrationCauses of Shocks and Vibration• Drillstem
Excitation of the drillstem
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• Excitation of the drillstem• Natural Harmonics
• Wellbore umberger Public
• Wellbore– Drillstring – Borehole interaction
• Borehole Geometry and ShapeBorehole Geometry and Shape• Trajectory• Drill stem designg• Mud Properties
• The Drive / Surface Control
Managing Shocks & VibrationsManaging Shocks & Vibrations
• Techniques flow through design into execution phases of a
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well.....and into evaluation
DesignBHA DesignTrajectory DesignParameter Selection um
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DesignReview Program
Parameter Selection
Review & AnalysisContinuous
Review
Control
Revised ParametersRe-Design / MoC
ExecuteReport
Parameter MonitoringResult Reporting
Report
Designing Out ShocksDesigning Out ShocksMechanical design of tools– Make the tools tougher!
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Make the tools tougher!
Protection Of Equipment– Shock Guards (Shock subs, roller reamers, etc, etc) um
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BHA design– Stabilizer type / location
• Full vs Undergauge• Straight blade vs Spiral• Hard facing• Roller Reamers
– BHA size / neutral point location– BHA size / neutral point location• Neutral Point generally cycles even before shocks!• Heavier BHA’s: stiffer, more stable, less prone to buckling• Light BHA’s: flexible, shorter, more directionally responsive
Bit Selection 101Fixed cutter
PDC bits fail rock with torque
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PDC bits fail rock with torque– Required stess to fail rock > torque at bit then
no rotation• Therefore less aggressive or lower DOC bit can um
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Therefore less aggressive or lower DOC bit can be less prone to creating stick slip
– Every reaction has an equal an opposite reactionreaction• PDC bits more prone to whirl if side cutting
action high enough– Longer gauge bits?Longer gauge bits?
Bit Selection 101CRoller Cones
Roller Cone bits are less prone to bit generated
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Roller Cone bits are less prone to bit generated stick slipAxial shocks may cause interference and um
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bearing problems– Cross loading, changes in axial loadingAxial shocks (most) commonly caused by roller Axial shocks (most) commonly caused by roller cones– Soft formation bits in hard formationsOnce bearing are worn increases in torsionalvibrations are common.
Standard Drillstem Design Modelling In Shock & Vib ti& Vibration• Torque and Drag modelling
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– Highlights contact sideforces in the drillstem• Useful in gross identification of torsional changes with axial load
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• Static BHA Modeling (tendency modeling)– Can highlight contact points where potential whirl could occur– Aid for identifying required stabilisation
• Standard modeling can primarily be used to infer potential problems.
Frequency Domain ModellingFrequency Domain Modelling• Static Modeling of BHA contact points
D i d t l f i b d
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• Derived natural frequencies based on static modeling
• User defined excitation factors umberger Public
• No full consideration for interaction between drillstring and borehole wall
Transient ModelingTransient Modeling• Mechanical model stepping forward in time• Better representation of excitation factors
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• Better representation of excitation factors• Captures vibration mechanisms
– Not just inferences from static umberger Public
Not just inferences from static• Computationally Intensive• Specialist Interpretation Required
Model LimitationsModel Limitations• Models are limited by assumptions of potential unknowns, including:
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• Formation properties / heterogeneity• Component Imbalance• BHA Misalignment um
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• BHA Misalignment• Damping• Contact point friction
• The Power of modeling in design is in comparison– A guide to be used with actual drilling data
Example - VerticalityExample Verticality• In a Vertical wellplan little
i li i i b l i
Transient Modelling Sideforces
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inclination imbalance is present
• Modeling planned inputs umberger Public
Modeling planned inputs will not recognise potential lateral force variationvariation
• But with offset analysis it was possible to model p(actual) wear
Monitoring & MitigatingMonitoring & Mitigating
• When applying monitoring and mitigation techniques some
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questions must be defined:– WHO monitors shocks and vibrations?
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– WHY are shocks and vibrations being monitored?– Who makes the decision on HOW and WHEN to mitigate
b d t ?observed measurements?
The Monitoring ProblemThe Data ‘Problem’
S fThe Monitoring ProblemSurface:Hookload
Weight On Bit
T
Indirect measurement
f d h l
Inferred Hole Conditions
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Torque
RPM
Flow
St d i P
of downhole conditions But Better
than No Measurement
Rig FloorMudloggers um
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Standpipe Pressure
Mud Information
Downhole Direct Improved
ggMeasurements Company
Shocks & Vibrations
Drilling Mechanics
Hole Quality Information
Direct measurement of downhole conditions
Improved understanding of hole conditions
Formation Evaluation But needs understanding of measurement
Measurements Company
DiagnosisDiagnosis
Axial Shocks Lateral Shocks Torsional Shocks Eccentric motion
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Surface Sensors
May see visible string / top drive
bounce. Fluctuating SWOB
May see erratic surface torque
Rhythmic cycling of top drive speed / torq. High
sigma torq, cyclical pressure SWOB etc
Can combine the symptoms of stick slip and lateral
shocks umberger Public
Fluctuating SWOB. pressure, SWOB etc.
MWD / LWD
Axial Vibration Measurement (not
Lateral/Transverse Vibration
High torsional vibration measurement, Stick Slip
indicator downhole torque
Initially high lateral/transverse shocks
(may reduce) Possible highLWD always avaliable) Measurementindicator, downhole torque
variation(may reduce). Possible high
stick slip indicator
Bit Grading Damage to inner Hard to diagnose Increased wear to outer gauge with associated
Broken teeth, particularly in the shoulder, guage and Bit Grading
cutters (nose). from bit gradinggauge with associated
heat checkinglower taper. Damage from
behind the teeth.
PDSHKRSK(PDSHKRSK)
0 3.1----
StandpipePressure (SPPA)
2500 5000psi
Bit on Bottom(BONB)
SHKRSK_RT(SHKRSK_RT)
0 3----
MWD Shock Peak(SHKPK RT)
Rate ofPenetration (ROP) Hookload (HKLD)
Avg RotationalSpeed (RPM)
0 300c/min
MWD Collar RPM(CRPM RT) FLWI (FLWI)
(BONB)
-10 1----
ATMP_RT(ATMP RT)
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(S _ )
0 5200ft/s2
AJAM_MWD(AJAM_MWD)
0 2----
e e a o ( O )
100 0ft/h
Block Position(BPOS)
0 150ft
150 650klbf
Surface WeightOn Bit (SWOB)
0 50klbf
STOR (STOR)
0 3000kft.lbf
(C _ )
0 300c/min
STICK_RT(STICK_RT)
0 300c/min
0 1000gal/min
MWD TurbineRPM (TRPM_RT)
0 5000c/min
( _ )
200 300degF
Equiv CirculatingDensity (ECD_RT)
10 12lbm/gal umberger Public
Jul.06-2009 14:00
Jul.06-200916:00
Example DiagnosisExample Diagnosis
Axial Shocks Lateral Shocks Torsional Shocks Eccentric motion
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Surface Sensors
May see visible string / top drive
bounce. Fluctuating SWOB
May see erratic surface torque
Rhythmic cycling of top drive speed / torq. High
sigma torq, cyclical pressure SWOB etc
Can combine the symptoms of stick slip and lateral
shocks umberger Public
Fluctuating SWOB. pressure, SWOB etc.
MWD / LWD
Axial Vibration Measurement (not
Lateral/Transverse Vibration
High torsional vibration measurement, Stick Slip
indicator downhole torque
Initially high lateral/transverse shocks
(may reduce) Possible highLWD always avaliable) Measurementindicator, downhole torque
variation(may reduce). Possible high
stick slip indicator
Bit Grading Damage to inner Hard to diagnose Increased wear to outer gauge with associated
Broken teeth, particularly in the shoulder, guage and Bit Grading
cutters (nose). from bit gradinggauge with associated
heat checkinglower taper. Damage from
behind the teeth.
Was the Diagnosis Correct?Was the Diagnosis Correct?
• Post Run Evidence Confirmed Forward Whirl
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Shock and Vibration MitigationShock and Vibration Mitigation
• Once drilling what can be changed?
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StopStop
• Energy input needs to be stopped
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• The vibration needs to be dampened
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• Practically:– Off bottom and cut rotation– Allow vibrations to stop– Return with varied (?) parameters
– May not be required for stick slip
The problem – couplingThe problem couplingSchluum
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Continuous ImprovementR i & R d iReview & Redesign• Each run with should be analysed to reduce shock &
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vibrations– Improved overall performance
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• Models will improve with calibration• Lessons Learned Recorded
DesignReview Program
– (and applied)Continuous
Review
Review
ControlControl
ExecuteReport
Managing Shocks & Vibrations IsManaging Drillstring Fatigue• Fatigue is the major cause of drillstem failure
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g j• Shock & Vibration Dynamic Motions can:
– Cycle tensile & torsional StressBend drillstring (axially & torsionally) um
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– Bend drillstring (axially & torsionally)– Increase Sideforces– Temporarily increase the applied stress to the
tcomponent– Promote component wear
• These are all contributors to fatigue!
One Step Towards ROP OptimizationOne Step Towards ROP Optimization
• Shock & Vibration Management
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ROP
Shaker CapacityShock & Vibration
Directional Control– Only one part of the jigsaw – Best managed early in process um
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Shock & Vibration
Hole Cleaning
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• But.......getting it right solves many WOBproblems
– Drillstem Failure has many imeanings.....
SummarySummary
Shocks & Vibrations are a negative aspect of
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g pthe drilling process:– Cause direct equipment failure– A contributor to fatigue um
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A contributor to fatigue– Take energy away from drilling– Create tortuosity & spiraling to wellboreC t l f Sh k & Vib ti h ld b b thControl of Shocks & Vibrations should be both:– Reactive: Managing parameters to minimise
shocks– Proactive: Engineering the well & drillstem
to minimise shocks.
Questions?Questions?
Shocks & Vibrations - A Cause Of Drillstring Failure
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Sponsored By EnQuest & Schlumberger umberger Public
Sponsored By EnQuest & Schlumberger
Additional SlidesAdditional Slides
• .
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Schlumberger Drilling & Measurements‘Shock Risk’ Levels
What is 50g? Shock Risk
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g50 x force of gravity (9.81 m/s2)
Imagine travelling at 1765
Shock RiskShock Risk Severity Frequency of shocks >
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– Imagine travelling at 1765 km/hr (1096 miles/hour)
– Now come to a dead stopTh t i 50
0 No risk cps <= 1
1 Low Risk 1 < cps < 5– That is 50g– the human body can only
survive 20-35 g (if applied f h t i d f ti !)
2 Medium Risk
5 < cps < 10
3 High Risk cps > 10for a short period of time!)
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Mitigation & EconomicsMitigation & Economics
But…..sometimes mitigating the shocks reduces the ROP?
SchluQuick economic analysis can show that the cost of failed umberger Public
yequipment is more than a slightly reduced ROP– Also consider the tripping cost due to the failure of downhole
equipment (RSS/MWD/LWD/Bits etc)– There may also be fishing trips (and remedial operation time)– The subsequent casing may not run to bottom.
Axial Vibrations – Bit BouncingAxial Vibrations Bit Bouncing
Top Drive Shaking?
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Top Drive Shaking?
Kelly Bouncing?Whats the problem umberger Public
Down Hole Vibration?
Whats the problem with this image?
PDC Bit?
Tri-Lobing (3 x RPM)Bit Leaving Bottom?
Bit does not physically leave the bottom of the hole – variation in axial loadingaxial loading
Stick Slip – Rotational VibrationsStick Slip Rotational Vibrations
BHA stalling
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BHA stalling
Repeated cycles umberger Public
May be seen on surfaceSurface RPM Variation– Surface RPM Variation
– Surface Torque Variation
Bit/BHA may stop rotating or even spin backwards
Eccentric Motion – Bit WhirlEccentric Motion Bit Whirl
Common in poorly (near
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Common in poorly (near bit) stabilised assembliesCommon in PDC bits with um
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aggressive side-cuttersBit follows an eccentric path with one more lobe path with one more lobe than it has bladesHole is over-gauge and
Path of bit Hole is over gauge and
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Eccentric Motion – BHA WhirlEccentric Motion BHA Whirl
Large frequent shocks
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Large, frequent shocksBHA hits borehole and is flung across by rotation of pipe um
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Whirl may be forward or backward.Energy imparted dependant on Energy imparted dependant on friction and restitution of borehole wallIncrease the bending stress in the string
BHA WhirlBHA WhirlSchluum
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Mode CouplingMode CouplingSchluum
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Other Contributing FactorsOther Contributing FactorsReaming
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– Changes in accelerationDrilling inside casing (cement, plugs etc)H l Cl i
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Hole Cleaning– Increases in friction, solids binding with stabilisersPoorly stabilised assembliesPoorly stabilised assembliesBicenter drill bitsBit BallingBit Balling
Well DesignWell DesignDesigning out shocks and vibrations at the well plan is:
Minimise Tortuosity to minimise Sideforces
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– Minimise Tortuosity to minimise Sideforces• Reduces contact points & forces• But what about geosteering? um
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g g– Design & planning key
Minimise Friction– Minimise Friction• Reduces torque & drag required to move string• Change Friction By:g y
– BHA & Drillstring Design (Handbanding, etc)– Mud system type (Water > Polymer > Oil Based)– Add lubricants (amount depends on lubricant and mud system)Add lubricants (amount depends on lubricant and mud system)
The Rotating Equipment&Top Drives & Rotary Tables
Running at high RPM
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– Lower torques avaliable in high gear– But higher RPMRunning with torque limiters set too low um
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Running with torque limiters set too low• OR too high!
SCR to TDS power variationS ft T / T f db k tSoft Torque / Torque feedback systems– Can help reduce torsional vibrations
• Though must be monitored as certain cases have seen negative effects!
– Now available for AC topdrivesAC Topdrives during stick slip eventsp g p