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

p y

• 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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g

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 >

50g umberger Public

– 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

rugosecenter

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