3 a Bit Life

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2008 ReedHycalog,L.P. AllRightsReserved.1

Bit Life

Concepts and Calculations

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Range of Bit Life

Application 8 1/2 EHP Bearing

Results

Middle East 140 HoursS. England 60 Hours

Norway 25 Hours


Factors Affecting Bearing Life

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Factors Aff ecting Bearing Life

Formation Parameters Mud Reaming Direction Vibration

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Formation

Rock Strength

Heterogeneous or Homogenous

Abrasiveness

6

Mud

Mud WeightIncrease

Mud Chemistry

EncouragesHigh W.O.B. Seal Integrity

Reduces R.O.P. Attacks Seal

Mud Solids& Sand

Reduced Life.

Seal ErosionBearing Erosion

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Reaming

Normal Drilling

Different Loading Environments

How much?How difficult?

Reaming

Backreaming

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Direction

Bent Motor Housing or Bent Sub Bend Angle Bit to Bend Distance

Percentage Sliding or Rotating Number of transitions Hole Angle Build Rate/Turn Rate Dog leg severity

9

Vibration

DamagesCutting Structure

Impact Damageto Bearing

AcceleratedBearing Wear Damages Gauge

Uneven bearingload

AcceleratedBearing Wear

Exposes Seal

Reduced Bearing Life

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Parameters

W.O.B.

Direct - loads bearing Indirect - wears/damages cutting structure

Wear versus W.O.B.

0102030405060708090

0 20 40 60 80 100 120

W.O.B.

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WOB and RPM


Measuring Bit Li fe

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Range of Bit Life

Application Horizontal Motor 8 1/2 EHP Bearing

Soft Carbonate

Medium Sandstone

Hard Sandstone

Results Hrs BearingMiddle East 140 Hours E

S. England 60 Hours E

Norway 25 Hours E

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Measures of Bit Life

Hours run

5 8 0 0 00

Total revolutions - Krevs

BPR - Billion Pounds

RevolutionsWOB x RPM x Minutes

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Measures of Bit Life

0

20

40

60

80

100

120

140

M. Ea st Wy tc h Fa rm No rw a y

Run Length - Hours

0

200000

400000

600000

800000

1000000

1200000

1400000

M . E as t Wyt ch F ar m N or wa y

Run Length - KRevs

0

5

10

15

20

M. E as t Wy tc h F ar m No r w ay

Run Length - BPR

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Drilling Hours

Example:12 TD44 in directional wellBit life (effective bearings) in this specific

application typically 70 75 hrs

Activity Multiplier

Drilling 1.0

Reaming .5 - 2.0

Back-Reaming .5 - 3.0

Circulat ing open hole 0 - 0.5

Ci rculat ing casing 0.25 - 2.0

Previous bit severely undergauge

Ream 8 hours

Drill fifty two hours

Backream 6 hours

One lost cone two failed bearings

In sixty six hours

Good bit - - Bad Bit ? ?

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Drilling Hours

12 TD44 in directional wellBit life (effective bearings) in this specific

application typically 70 75 hrs

Activity Multiplier

Drilling 1.0

Reaming .5 - 2.0

Back-Reaming .5 - 3.0

Circulat ing open hole 0 - 0.5

Ci rculat ing casing 0.25 - 2.0

Ream 8 hour s = 15 hour s

Drill fifty two hour s = 52 hour

Backream 6 hours = 16 hours

Good bit - - Bad Practices

Total = 83 hour sTotal = 83 hour s


Estimating Bit Life

Some Practical Methods

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Estimating Bit Life

Pragmatic Estimate Single shot High Risk

Ideal

Cautious, conservative

Step-by-step

Low Risk

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Estimating Bit Life

Ideal Set benchmark performance level

What causes variations in this bitlife?What is the best measure ?

Examine the run and dull bit Adjust length of next run Repeat process

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0

10

20

30

40

50

60

70

1 4 7 1 0

1 3

1 6

1 9

2 2

2 5

2 8

3 1

3 4

Bit Runs

H o u r s

R u n

All runs, ordered by hours

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All runs, ordered by Total Revolutions

0

100

200

300

400

500

600

700800

1 4 7 1 0

1 3

1 6

1 9

2 2

2 5

2 8

3 1

3 4

Bit Runs

K R e v s

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0

100200

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10 11

High RPM runs : rpm g reater than 250

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Estimating Bit Life

Pragmatic

Purchase a book on Chaos Theory and understand itsapplication to Bearing Life!

Characterise the application

Recognise the differences

Adjust projected life on the basis of these differences

Identify a similar application

Lithology

Interval Length

Directional Objectives

Directional Means

Mud System

Other (Drill out, vibration)

Lithology Similar

Interval Length 15% longer

Directional Objectives Greater holeangle

Directional Means 1.15 v 1.5 degbend angle

Mud System Same

Other (Drill out, vibration) Similar

Lithology Similar -0-

Interval Length 15% longer -0-

Directional Objectives Greater holeangle +10%

- 5%

Directional Means 1.15 v 1.5 degbend angle +10%

Mud System Same -0-

Other (Drill out, vibrat ion) Similar -0-

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Bearing Reliability Curves

12 1/4" TC11P - Motor assemblies

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

Krevs

R e

l i a

b i l i t y

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12 1/4" TC11P -Reliability - Motor ass eemblies

0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20 25 30

BPR

R e

l i a

b i l i t y

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12 1/4" TC11P USA Motor

0

20

40

60

80

100

120

0 5 10 15 20 25 30

Effective

Failed Seals

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Cutting Structure Life

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Uncertainties in Cutting Structure Life

MICE

MM icroscopic II ncremental CC atastrophic EE vents

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Vibration

DamagesCutting Structure

Impact Damageto Bearing

AcceleratedBearing Wear Damages Gauge

Uneven bearingload

AcceleratedBearing Wear

Exposes Seal

Reduced Bearing Life

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Bit Life Indicators

How to spot a failed bearing

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Bit Li fe Indicators

Cutting Structure Rate of Penetration Drops Rate of Penetration Stops

Fixed Cutter and Roller ConeFixed Cutter and Roller Cone

Gauge Torque increases

Evidence of stabiliser hang up

R.O.P .

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Bit Life Indicators

Bearing Rate of Penetration Drops Torque increases Steering character changes MWD/LWD signal quality deteriorates MWD/LWD Shock levels increase

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Misleading Indicators

Many factors may affect these indicators Formation

WOB/RPM

Mud weight Change in hole angle Cutting Structure

Wear

6400

6600

6800

7000

7200

7400

7600

0 10000 20000 30000 40000 50000

6400

6600

6800

7000

7200

7400

7600

9 10 11 12 13 14

Mud Weight

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Torque Indicators

Torque increases Torque becomes erratic Torque spikes occur

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Directional Indicators

Qualitatively the steering character of the bit changes insome way

Qualitative Subjective Subtle (Perhaps) Real

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Conclusion

Bit Life Estimates At tainable Goal - Complex Path

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Bit Life - Complex Solution

Therefore, Analyse relevant offset data

carefully systematically

Monitor indicators attentively as the bit is run Diligently evaluate all aspects of successive runs


Questions?

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Questions?

A subtitle, date or details may be added here


Administ rat ive Slides


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Version History

Version 1.0 This presentation was created in its initial form in 2000 by IanMcMillan for a NExT Drilling Engineering Course

Version 2.0 This was adapted in Q1 2001 for use on D & M Directional Driller Induction Courses

Version 2.1 Notes text and illustrations were added to it in connection with a BBSrequest from Bilal Salman in May 2001

Version 2.2 Additional text and new introduction following peer review May 9 2001 Version 2.3 Minor adjustments to animations, Sept 3 2001 Version 3.0 Reduced to bit life determination only, March 2005 Version 3.a NOV format Feb 2009

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Acknowledgemen ts

Version 2.2 My thanks to Mark Jordan for reviewing this material and to Corin

Lewsey and Pawl Victor for acting as guinea pigs for a test run of thepresentation. All three offered valuable suggestions.

Version 3.0 Review and suggestions by Mark Jordan.

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Contact Information

If you have any questions concerning this presentation contact:Ian McMillanReed-Hycalog,Unit 10, Kirkton Avenue,Pitmedden Industrial Estate,

Aberdeen, AB21 0BF

Office: +44 (0)1224Mobile: +44 (0) 7850 924 932Home: +44 (0) 1467 681 451e-mail: [email protected]


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3 a Bit Life