Dull Bit GradingDull Bit GradingIntroductionIntroduction

IADC DULL GRADINGIADC DULL GRADING

IntroductionIntroduction

•Modern IADC dull grading system created in 1987.

•Expansion of the “T-B-G” system.

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The Old I.A.D.C. System1

• T2 B4 In

• T5 B2 4

• T2 B8 6

• T7 B2 In

• T3 B3 2

Three Part System

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The Old I.A.D.C. System 2

Tooth Condition

Bearing Condition Gauge Wear

TBG

T0-8

B0-8

Fractions of 1 inch3/6”, 1/8 etc

IntroductionIntroduction

•Modern IADC dull grading system created in 1987.

•Expansion of the “T-B-G” system.

•Dull grading system revised in 1992.

•Roller Cone Dull Grading: IADC/SPE 23938

•Fix Cutter Dull Grading: IADC/SPE 23939

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Objectives Of Dull Bit GradingObjectives Of Dull Bit Grading

Improve Rock Bit Selection

Enhance Drilling Performance

Improve Bit Pulling Procedures for Minimum Cost Drilling

Improve Historical Data for Application and Design

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Goal Of Dull Bit Grading SystemsGoal Of Dull Bit Grading Systems

Develop a system for roller and fixed cutter bits to “Paint a Mental Picture” of the worn bit’s physical condition.

System must be convenient enough that the drilling community will use it.

IADC 1992 Dull Bit GradingIADC 1992 Dull Bit Grading

1 Inner Cutting Structure (All Inner Rows)

2 Outer Cutting Structure (Gage Row Only)

3 Dull Characteristic (Use Codes, Cutting Structure Only)

4 Location (Where Dull Characteristic Occurs)

5 Bearing / Seals (Condition of Roller Cone)

6 Gage (What is the Final Gage Diameter)

7 Other Dull Characteristic (Use Codes, not limited to CS)

8 Reason Pulled (Use Codes, Termination of Bit Run)

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

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1 Inner Cutting Structure (All Inner Rows)

2 Outer Cutting Structure (Gage Row Only)

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

“A measure of combined cutting structure reduction due to lost, worn and/or broken inserts/teeth.”

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Outer Inner

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Tooth Height Grading 3

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Dull Codes - Worn Teeth 2

WT = Worn Teeth

Worn Teeth – Roller Cone

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Grading Uneven Wear

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Dull Codes - Worn TeethWorn Teeth – Fixed Cutter

WT = Worn Teeth

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3 Major Dull Characteristics (Use only Cutting Structure Related Codes)

*BC - Broken Cone

BF –Bond Failure

BT - Broken Teeth/Cutters

BU - Balled Up Bit

*CC - Cracked Cone

*CD - Cone Dragged

CI - Cone Interface

CR - Cored

CT - Chipped Teeth/Cutters

ER - Erosion

FC - Flat Crested Wear

HC - Heat Checking

*LC - Lost Cone

LN - Lost Nozzle

LT - Lost Teeth/Cutters

NR – Not-Rerunnable

OC - Off Center Wear

PB - Pinched Bit

PN - Plugged Nozzle/Flow Passage

RG - Rounded Gage

RR –Re-Runnable

SD - Shirrtail Damage

SS - Self SharpeningWear

TR - Tracking

WO - Washed Out Bit

WT - Worn Teeth/Cutters

NO - No Dull Characteristics

* Show Cone #’s under Location (4)

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

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These codes should not be used in the dull characteristic field. They go in the “other dull characteristic” field.

LN – Lost Nozzle(s)

PN – Plugged Nozzle(s)

WO – Wash Out

PB – Pinched Bit

NR – Not Rerunnable

RR – ReRunnable

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When using these codes the cone(s) number should be displayed in the location field.

BC – Broken Cone(s)

CC – Cracked Cone(s)

CD – Cone(s) Drag

LC – Lost Cone(s)

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Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

LOCATION

Roller Cone Fixed CutterN – Nose row C – ConeM – Middle row N – NoseG – Gage row T – TaperA – All rows S – Shoulder1 – Cone #1 G – Gage2 – Cone #2 A – All areas3 – Cone #3

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Gage Middle

Nose

Identifying Cones On A Roller Cone BitIdentifying Cones On A Roller Cone Bit

To identify the cones on a roller cone bit:

- Find the cone that has the insert or tooth that is closest to the direct center-line of the axis of rotation of the bit

- That is Cone #1

- Count in a clockwise rotation to find Cone #2 and then Cone #3

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Identifying Cones On A Roller Cone BitIdentifying Cones On A Roller Cone Bit

Cone #1

Cone #3 Cone #2Cone #2Cone #3

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Identifying Blades On A PDC BitIdentifying Blades On A PDC Bit

To identify the blades on a PDC bit:

- Find the blade that has the cutter that is closest to the direct center-line of the axis of rotation of the bit.

- That is Blade #1 (Blade #1 is also the one that has the most cutters).

- Count in a clockwise rotation to find blade #2 and then blade #3, etc.

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Blade #1

Blade #2

Blade #3

Blade #4

Blade #5

Blade #6

Identifying Blades On PDC BitIdentifying Blades On PDC Bit

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5 BEARINGS / SEALS

Non-Sealed Bearing Sealed Bearings

0 - No Life Used E - Seals Effective 8 - All Life Used F - Seals Failed

X - Fixed Cutter BitN - Not Able to Grade

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

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6 GAGE Measure in fractions of 1/16”

I - In Gage 2/16 - 1/8” Out of Gage

1/16 - 1/16” Out of Gage 4/16 - 1/4” Out of Gage

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

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Two Thirds RuleTwo Thirds Rule

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Measured distance

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Gauge ToleranceRoller Cone Go Gauge

Roller Cone No-Go Gauge

Fixed Cutter Go GaugeFixed Cutter No-Go Gauge

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7 Other Dull Characteristics (Use all Related Codes)

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

*BC - Broken Cone

BF –Bond Failure

BT - Broken Teeth/Cutters

BU - Balled Up Bit

*CC - Cracked Cone

*CD - Cone Dragged

CI - Cone Interface

CR - Cored

CT - Chipped Teeth/Cutters

ER - Erosion

FC - Flat Crested Wear

HC - Heat Checking

*LC - Lost Cone

LN - Lost Nozzle

LT - Lost Teeth/Cutters

NR – Not-Rerunnable

OC - Off Center Wear

PB - Pinched Bit

PN - Plugged Nozzle/Flow Passage

RG - Rounded Gage

RR –Re-Runnable

SD - Shirrtail Damage

SS - Self SharpeningWear

TR - Tracking

WO - Washed Out Bit

WT - Worn Teeth/Cutters

NO - No Dull Characteristics

* Show Cone #’s under Location (4)

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8 Reason Pulled Or Run Terminated

BHA - Change Bottom HoleAssembly

DMF - Downhole MotorFailure

DTF - Downhole Tool Failure

DSF - Drill String Failure

DST - Drill Stem Test

LOG - Run Logs

LIH - Left in Hole

RIG - Rig Repair

CM - Condition Mud

CP - Core Point

DP - Drill PlugFM - Formation

ChangeHP - Hole Problems

HR - Hours on Bit

PP - Pump Pressure

PR - Penetration Rate

TD - Total DepthCasing Depth

TQ - Torque

TW - Twist OffWC - Weather

Conditions

Inner Outer Dull Char. Location1 2 3 4 5 6 7 8

ReasonPulled

Cutting Structure Bearings/Seals Gage Other

Dull Char.

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Keys To Dull GradingKeys To Dull Grading

Know What a Sharp Bit Looks Like

Normal Dull Conditions

Sequence of Events

Paint Picture of Dull

Consistency

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Grade Lots of Dulls

Key to Good Dull Grading: GRADE A LOT OF DULLS