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