Bits

(1)

CASING

(2)

Objectives

At the end of this training session, you will be able to:

List the different type of bits

Describe the different rock failure mechanism

Describe the IADC (International Association of Drilling

Contractors) bit coding and dull bit grading

Describe the effect of change in weight on bit, rpm, hole size,

mud weight and solids content on bit performance

(3)

Introduction

Drilling bits selection is crucial to the performance of all drilling

projects.

Understanding the different types of bits and their respective

applications is a pre-requisite to bit selection.

Not only the right bit in the right application but also running it with

the right operating parameters.

Well engineers must stay abreast of the latest developments to

ensure optimum bit selection.

(4)

Bit Types

(5)

Bit Types

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

T S P _BearingRoller _BearingJournal

(6)

PDC (Polycrystalline Diamond

Compact)

Drill Bits Fixed Cutter Roller Cone

Use artificially made

diamonds

Run successfully with

downhole motors

Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(7)

PDC bit: Elements

1. synthetic diamond

cutters

2. support structures for

the cutters

3. gauge protection

1

3

2

5

2

Courtesy of

3. gauge protection

inserts

4. Depth of cut limiters

5. nozzles.

(8)

PDC bit: Body Material

Steel body in

one piece

⇒

High precision

⇒

_{simple repair}

⇒

no weld

Tungsten

Carbide matrix

on steel shell

⇒

Erosion resistant

(9)

8 mm

11 mm

13 mm

16 mm

19 mm

PDC bit: Cutting Elements

BLADE

Courtesy of

PDC CUTTER

(10)

Natural Diamond

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(11)

Diamond Bit Profiles

Shallow cone

Parabolic

Taper or Double cone

Soft formation=>

=>

=> Hard formation

(More diamond coverage)

Low ROP

(12)

Diamond bit : Design

Size and spacing of diamonds determines its use

Widely spaced diamonds : large pieces of soft sand and shale

Medium spacing of large diamonds: wide range of sand, shale ,

limestone

Smaller diamonds set in close pattern: hard formations

(13)

Natural Diamond bit: Elements

Natural Diamonds =

hardest mineral

But brittle and Temp

dependant

Fluid circulation

important

Courtesy of

No cone , operates like

a single unit

Sensitive to shock and

(14)

TSP (Thermally Stable Polycrystalline)

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

T S P _BearingRoller _BearingJournal

(15)

Cutting Elements - TSP

TSP

(16)

Impregnated Diamond

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(17)

Impregnated Diamond: Blades

Formation: medium

hard to very hard,

ABRASIVE!

Impregnated cutting

element.

Distributed in a

tungsten carbide

matrix.

Bit Blade

Matrix

Courtesy of

matrix.

During heating

(furnace) the

Segments are bonded

to the bit body.

(18)

Cutting Elements - Impregnated

Impregnated Diamond Blades

(19)

ROLLER CONE

Alternative Names

Rock Bit

Drill Bits Fixed Cutter Roller Cone

Rock Bit

Tri-Cone™

Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(20)

Basic Types Of Roller Cone Bits

Insert Bits

Tungsten Carbide Bits

Button Bits

Tooth Bits

(21)

Cone #3

Shirttail

Heel Row

Gauge Row

Cone #1

Cone #2

Inner Row

Nose

Roller Cone Components

Pin

Shirttail

_Lug

Bit Body

Nozzle

(22)

Roller

cone

bits: Nozzles

SHROUDED

TYPE

STANDARD

TYPE

(23)

Mill Tooth Bits

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(24)

Cutting Elements – Mill Tooth

Teeth and Hardfacing

(25)

Insert Bits

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

(26)

Cutting Elements - Insert

Tungsten Carbide Inserts

(27)

Tricone Bit - Roller Bearing

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

T S P _BearingRoller _BearingJournal

(28)

Roller Cone Bearing Systems

Main Bearings Retention Bearings Seals

Journal

Bearing

Bit

Roller

Bearing

Bit

(29)

Tricone Bit - Roller Bearing

Retention Bearing

Main Bearing

Courtesy of

Thrust Bearing

Pin Bearing

(30)

Tricone Bit - Journal Bearing

Drill Bits Fixed Cutter Roller Cone Insert Mill Tooth Diamond P D C Natural Diamond Impregnated Diamond

T S P _BearingRoller _BearingJournal

(31)

Retention Bearing

Main Bearing

Tricone Bit - Journal Bearing

Thrust Bearing

(32)

Rock Failure Mechanisms

(33)

Failure Mechanisms

Shear Failure

CONTINUOUS

PDC BIT

SHEARING

Compressive

ROLLER CONE BIT

CYCLIC COMPRESSION

Compressive

Failure

(34)

Drilling Mechanisms

Shear/Compressive

Failure

NATURAL DIAMOND

OR IMPREG BIT

CONTINUOUS

CRUSHING

& ABRASION

Courtesy of

(35)

Drilling Mechanisms vs Bit Type

Scraping

Mill Tooth

Chipping and Crushing Insert

Shearing

PDC

Shearing

PDC

Ploughing / Grinding

Natural/Impregnated Diamond

(36)

IADC Bit Classification

(37)

IADC Classification – Roller Cone

517G

Soft Formations w ith Low Compressive

Strength and High Drillability

1

Medium to Medium Hard Formations w ith

High Compressive Strength

2

Hard Semi-Abrasive and Abrasive

3

STEEL TOOTH BITS

Cutting Structure Series

Cutting Structure

Type (1 to 4)

1 refers to the softest formation in a particular Series and

4 refers to the hardest formation

within the Series

Bearing/Gauge

Description

Standard Roller Bearing

1

Roller Bearing Air Cooled

2

Roller Bearing

3 Features

Available

(Optional)

A - Air Application B - Special Bearing Seal C - Center Jet

D - Deviation Control E - Extended Nozzles G - Gauge/Body

Protection

Ref: SPE 23937 The IADC Roller Bit Classification System

8-1/2” EHP 51

and Abrasive

Formations

3

Soft Formations w ith

Low Compressive Strength and High

Drillability

4

Sof t to Medium Formations w ith Low Compressive Strength

5

Medium Hard Formations w ith High Compressive Strength

6

Hard Semi-Abrasive and Abrasive

Formations

7

Extremely Hard and Abrasive Formations

8

INSERT

BITS

within the Series

Gauge Protected

3

Sealed Roller Bearing

4

Sealed Roller Brg - Gauge Protected

5

Sealed Friction Bearing

6

Sealed Frction Brg Gauge Protected

7

Protection H - Horizontal Steering Appl. J - Jet Deflection L - Lug Pads M - Motor Application S - Standard Steel Tooth T - Two Cone Bit

W - Enhanced Cutting

Structure

X - Predominantly Chisel

Tooth Insert

Y - Conical Tooth Insert Z - Other Shape Insert

(38)

IADC Classification – Fixed Cutter

12-1/4” DS66H

M432

Body Material Steel or Matrix.

Cutter Density PDC: 1 to 4, diamond bits: 6 to 8

(the lower the number, the lighter set the bit).

Cutter Size/Type For PDC cutter, 1 indicates >24 mm, 2

is between 14 and 24 mm, 3 is between 8 and 14 mm

and 4 is smaller than 8. For diamond bits, 1 represents

Ref: SPE 23940 Development of a New IADC Fixed Cutter Drill Bit Classification System

Profile The final digit indicates the general body style

and varies from 1 (flat profile) to 4 (long flanked

turbine style).

Fixed cutter IADC codes are intended only to provide a means for characterizing the general

physical appearance of fixed cutter drill bits. Unlike the IADC classification for roller bits, these

codes do not represent an application guideline.

and 4 is smaller than 8. For diamond bits, 1 represents

natural diamond, 2 is for TSP, 3 is a combination of

(39)

Soft

IADC Codes

Tooth

2

1 1-1

Hard

2

3 1-3

2-1

(40)

Soft

4 Tooth

Insert

IADC Codes

2

1 4-1

Hard

8

7

6

5

2

3 8-3

(41)

Soft

1

4 Tooth

Insert

2

1 PDC

IADC Codes

Hard

8

7

6

4

5

2

3

(42)

Soft

4 Tooth

Insert

IADC Codes

2

1 PDC

Hard

8

7

6

4

5 Diamond

2

3

(43)

Soft

1

4 Tooth

Insert

2

1 IADC Codes

PDC

Hard

8

7

6

4

5

2

3 Impregnated

_Diamond

Diamond

(44)

IADC Bit Dull Grading Code

(45)

IADC

Bit Dull Grading Code

The International Association of Drilling Contractors has

developed a standard methodology for describing used

bits. This information is essential for detailed bit

performance analysis.

The methodology is composed of an 8 character code

that describes bit wear and the reason why the bit was

pulled.

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

(46)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

Fixed Cutter Bits

The cutting structure is graded from 0 to 8 depending on the proportion of

cutting structure lost (0 = Intact, 8 = 100% worn).

Roller Cone Bits

0

1

2

3

4

5

6

7

8

Inner Cutting

Structure (All Inner Rows) Outer Cutting Structure (Gauge Row Only)

0

1

2

3

4

5

6

7

8 Cone 2

Cone 3

Cone 1

(47)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

BF - Bond Failure BT - Broken Cutters BU - Balled Up CT - Chipped Cutters ER - Erosion *BC - Broken Cone BF - Bond Failure BT - Broken Teeth/Cutters BU - Balled Up Bit *CC - Cracked Cone LN - Lost Nozzle LT - Lost Teeth/Cutters OC - Off-Center Wear PB - Pinched Bit

PN - Plugged Nozzle/Flow Passage

Fixed Cutter Bits

Roller Cone Bits

ER - Erosion HC - Heat Checking JD - Junk Damage LN - Lost Nozzle LT - Lost Cutter NR - Not Rerunable PN - Plugged Nozzle RG - Rounded Gauge RO - Ring Out RR - Rerunable

SS - Self Sharpening Wear TR - Tracking

WO - Washed Out Bit WT - Worn Cutters NO - No Dull Characteristics *CC - Cracked Cone *CD - Cone Dragged CI - Cone Interference CR - Cored CT - Chipped Teeth/Cutters ER - Erosion

FC - Flat Crested Wear HC - Heat Checking JD - Junk Damage *LC - Lost Cone

PN - Plugged Nozzle/Flow Passage RG - Rounded Gauge

RO - Ring Out

SD - Shirttail Damage SS - Self Sharpening Wear TR - Tracking

WO - Washed Out Bit WT - Worn Teeth/Cutters NO - No Dull Characteristic * Show Cone under Location 4

Note that this is for the Primary dull characteristics.

(48)

Fixed Cutter – Main Wear Characteristics

NO WEAR

(NO)

WORN

CUTTER

(WT)

BROKEN

CUTTER

(BT)

LOST

CUTTER

(LT)

EROSION

(ER)

POST OR STUD

CUTTERS

BOND

FAILURE

(BF)

NO WEAR

(NO)

WORN

CUTTER

(WT)

BROKEN

CUTTER

(BT)

LOST

CUTTER

(LT)

CYLINDER

CUTTERS

BOND

FAILURE

(BF)

Courtesy of

(49)

Dull Characteristics – Some Examples

BF - Bond Failure BT - Broken Cutters BU - Balled Up CT - Chipped Cutters ER - Erosion HC - Heat Checking JD - Junk Damage LN - Lost Nozzle LT - Lost Cutter

Fixed Cutter Bits

LT - Lost Cutter NR - Not Rerunable PN - Plugged Nozzle RG - Rounded Gauge RO - Ring Out RR - Rerunable

WO - Washed Out Bit WT - Worn Cutters

NO - No Dull Characteristics

_{BU - Balled Up}

(50)

*BC - Broken Cone BF - Bone Failure BT - Broken Teeth/Cutters BU - Balled Up Bit *CC - Cracked Cone *CD - Cone Dragged CI - Cone Interference LN - Lost Nozzle LT - Lost Teeth/Cutters OC - Off-Center Wear PB - Pinched Bit

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

CT - Chipped Teeth/Cutters ER - Erosion

WO - Washed Out Bit WT - Worn Teeth/Cutters NO - No Dull Characteristic

* Show Cone under Location 4

BU – Balled Up Bit

(primary)

CD – Cone Dragged

(secondary)

(51)

Dull Characteristics – Some Examples

Fixed Cutter Bits

_{CT – Chipped Cutter}

(52)

Dull Characteristics – Some Examples

Fixed Cutter Bits

LT – Lost Cutter

(53)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

BT – Broken Teeth/Cutters

(54)

Dull Characteristics – Some Examples

Fixed Cutter Bits

RO – Ring Out

(55)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

JD – Junk Damage

(56)

Dull Characteristics – Some Examples

Fixed Cutter Bits

WT – Worn Cutters

(57)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

SD - Shirttail Damage

(58)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

(59)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

SS – Self Sharpening Wear

(60)

RO - Ring Out

Roller Cone Bits

Dull Characteristics – Some Examples

CR - Cored

ER – Erosion

(61)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

Fixed Cutter Bits

_{Roller Cone Bits}

N - Nose Row

M - Middle Row

G - Gauge Row

Cone 1, 2 or 3

C - Cone

N - Nose

T - Taper

S - Shoulder

G - Gauge

G - Gauge Row

A - All Rows

(62)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

Fixed Cutter Bits

Roller Cone Bits

This box is for roller cone

bits. Fixed cutter bits will

always be designated by "X".

A linear scale estimating

_{bearing life used. (0 -No life}

Non Sealed Bearings

bearing life used. (0 -No life

used, 8 - All life used, i.e., no

bearing life remaining.)

Sealed Bearings

E - Seals Effective

F - Seals Failed

N - Not Able to Grade

(63)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

For all Bits

The letter “I” is used to designate bits that are in gauge.

If the bit is under gauge, the amount is recorded to the nearest 1/16” of

an inch. For example, if the bit is 1/8” under gauge, this is reported as

2/16 or often only as 2.

(64)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

BF - Bond Failure BT - Broken Cutters BU - Balled Up CT - Chipped Cutters ER - Erosion *BC - Broken Cone BF - Bone Failure BT - Broken Teeth/Cutters BU - Balled Up Bit LN - Lost Nozzle LT - Lost Teeth/Cutters OC - Off-Center Wear PB - Pinched Bit

Fixed Cutter Bits

Roller Cone Bits

This is for the Secondary dull char. and it uses the same codes as for the Primary dull char.

ER - Erosion HC - Heat Checking JD - Junk Damage LN - Lost Nozzle LT - Lost Cutter NR - Not Rerunable PN - Plugged Nozzle RG - Rounded Gauge RO - Ring Out RR - Rerunable

WO - Washed Out Bit WT - Worn Cutters NO - No Dull Characteristics BU - Balled Up Bit *CC - Cracked Cone *CD - Cone Dragged CI - Cone Interference CR - Cored CT - Chipped Teeth/Cutters ER - Erosion

PB - Pinched Bit

RO - Ring Out

(65)

IADC Bit Dull Grading Code

INNER

ROWS

OUTER

ROWS

DULL

CHAR

LOCA-TION

BRNG/

SEALS

GAUGE

1/16”

OTHER

CHAR

REASON

PULLED

Cutting Structure

B

G

Remarks

For All Bits

BHA - Change Bottom Hole Assembly

DMF - Down hole Motor Failure

DSF - Drill String Failure

HP - Hole Problems

HR - Hours

PP - Pump Pressure

DSF - Drill String Failure

DST - Drill Stem Test

DTF - Down hole Tool Failure

RIG - Rig Repair

CM - Condition Mud

CP - Core Point

DP - Drill Plug

FM - Formation Change

PP - Pump Pressure

PR - Penetration Rate

TD - Total Depth/Casing Point

TQ - Torque

TW - Twist Off

WC - Weather Conditions

WO - Washout -DrillString

(66)

Key to Dull Bit Grading: Grade a Lot of Dulls !

(67)

BIT RECORD

Well :

BIT RECORD

Date :

Bit Data

BHA Bit Size Bit type Serial IADC Nozzles Depth Depth Drilling ROP Bit krevs WOB Rot Flow Press Inc Mud Total Total Total Dull

No. No. (inch) & maker Number Code (1/32") IN (m)OUT (m) Time (m/hr)(drilling) (Klbs) (RPM) (GPM) (psi) (deg) SG mtr hrs krevs I O D L B G O R

Run Data Bit life Grading

To be filled up at wellsite

No. No. (inch) & maker Number Code (1/32") IN (m)OUT (m) Time (m/hr)(drilling) (Klbs) (RPM) (GPM) (psi) (deg) SG mtr hrs krevs I O D L B G O R

1 1 16 T11C L15264 115 3 x 18, 1

x 16 15 420 18.04 22.45 151.50 10-25 120 820 1450 0 1.07 405 18.04 152 0 1 WT A E I NO TD 2 2RR 12 1/4 DSX113 204556 PDC 8 x 13 420 422 0.50 4.00 1.22 2-10 60 680 1000 0.00 1.15 2 0.50 1 0 1 WT S X I CTBHA 4 2RR2 12 1/4 DSX113 204556 PDC 8 x 13 1408 1714 16.54 18.50 119.09 25-35 120 820 1900 1.00 1.19 308 17.04 120 1 3 WT A X I PN TD

•BHA nb does not always = bit nb

•Drilling time = bit time on bottom (

←

Mud loggers)

(68)

Drilling Parameters vs Bit

Performance

(69)

Bit performance

Main function: ROP and longevity

Drilling fluid is circulated through passageways in the bit

to remove cuttings and apply hydraulic power to improve

ROP

ROP is a function of WOB, RPM, mud properties and

(70)

Chip Formation

Tooth load overcomes rock compressive strength,

generates crater

Scraping helps to remove chips from craters.

Cutter

Formation

Borehole pressure causes

chip hold down effect

(71)

ROP vs Overbalance

Data based on 7-7/8” bit with 30 klbs at 60 RPM

(72)

Chip Removal

Removal of chips is required to

allow for new chip formation

Cutter

Hydraulics help to remove chips

Formation

Cutter

(73)

CHIP CREATION

CHIP REMOVAL

WOB (Weight on Bit) Response

R

O

P

WEIGHT on BIT

0

Courtesy of

(74)

CHIP CREATION

CHIP REMOVAL

RPM Response

R

O

P

RPM

0

Courtesy of

(75)

Effects of Offset or Skew

– 0º - 2º

– Reduced Gage Scraping

– More Durable

– Slower Drilling

– Abrasive / Hard Formations

Reduced Offset

– 3º - 5º

– Increased Gage Scraping

– Less Durable

– Faster Drilling

– Soft / Sticky Formations

Increased Offset

(76)

Cone Profiles

Flat Cone Profile

– Minimum Bottom Scraping

– More Durable

– Slower Drilling

– Abrasive / Hard Formations

Round Cone Profile

– Increased Bottom Scraping

– Less Durable

– Faster Drilling

(77)

Tooth Cutter Design

Faster Drilling

Less Durable

Slower Drilling

More Durable

(78)

Insert Cutter Design

HP83

HP51

Faster Drilling

Less Durable

Slower Drilling

More Durable

(79)

Cutting Structure Comparisons

HP83

EHP41H

Faster Drilling

Less Durable

Slower Drilling

More Durable

(80)

Tooth & Insert Cutter Designs

Soft Formation

• Fewer Teeth

• Longer Teeth

• Bigger Teeth

• Sharper Teeth

Hard Formation

• More Teeth

• Shorter Teeth

• Smaller Teeth

• Duller Teeth

• Sharper Teeth

• Sharp Profile

• Fracture-Resistant Tooth

Material

• Faster Drilling

• Less Durable

• Rounded teeth

• Flat Profile

• Wear-Resistant Tooth

Material

• Slower Drilling

• More Durable

(81)

Bit Selection

(82)

Bit Application Spectrum

P

e

n

e

tr

a

ti

o

n

R

a

te

PDC

Mill Tooth

Insert

DP

Formation Compressive Strength

P

e

n

e

tr

a

ti

o

n

R

a

te

Insert

Impreg

& Natural

Diamond

Courtesy of

(83)

Bit Selection Process

Which

One ?

Courtesy of

(84)

Bit Selection - PDC

Advantages

Very Fast ROP

Long Life Potential

Considerations

Impact Damage

Abrasiveness

Stability

Courtesy of

(85)

Bit Selection – Tooth Bit

Advantages

Fast ROP

Good Stability

Economic

Considerations

Tooth Wear Rate

Bearing Life

(86)

Bit Selection – Insert Bits

Advantages

Cutting Structure Durability

Range of Formations

Interbed Tolerance

Steerability and Stability

Considerations

Slower ROP

Bearing Life

(87)

Bit Selection – Natural & Impreg

Diamond Bits

Advantages

Very Durable

Hard Rock Capability

Low Junk-in-Hole Risk

Considerations

Slower ROP

RPM Sensitivity

High Cost Applications

(88)

Gauging Procedures for 3-Cone Bits

Smith 3-Cone Bits are designed to have minimum gauge contact. By use of suitable gauge cutting structure design and materials, the “minimum gauge” configuration improves penetration rates whilst maintaining full size hole. Only the cutting elements (teeth or inserts) contact, while the cone shell steel is held away from the hole wall. This means that unless the gauge cutting elements are “lined up” with the gauge contact point on any gauge ring, the bit will measure slightly smaller than it actually is. This is particularly true of aggressive insert bits which have a lighter set gauge and large offset.

Gauging a 3-cone bit, either sharp or dull, requires some care and should be carried out as follows:

1. Only use a calibrated 3-cone gauge ring measuring the nominal bit size.

2. Turn the bit on its pin and rotate all the cones to their “maximum gauge point” so that a gauge tooth or insert lines up at this point.

3. Place the gauge ring over the bit at the maximum gauge points. 4. Pull the ring gauge tight against the gauge elements on two cones.

5. Measure any gap at the free cone. This is not the the correct value for gauge wear.

6. To calculate the actual gauge wear you must multiply the gap distance by 2/3 (‘two thirds’). For example: if measured gap is 3/16” then multiply by 2/3 giving 2/16” under-gauge.

7. Record the bit as being either in gauge or the amount under-gauge. Although IADC say to use

Gap

7. Record the bit as being either in gauge or the amount under-gauge. Although IADC say to use an “I” for in gauge, we recommend using a 0 (zero) to avoid the confusion between an I and a 1.

Maximum gauge point

API Sizes for New Bits API Roller Cone Bit Tolerances Bit Size Actual Size Bit Size Tolerance

Min. Max. 26” 26.000” 26.094” 3-3/8” to 13-3/4” +1/32”, -0” 23” 23.000” 23.094” 14” to 17.5” +1/16”, -0” 17.5” 17.500” 17.562” 17-5/8” and larger +3/32”, -0” 16” 16.000” 16.062” 12.25” 12.250” 12.281” 8.5” 8.500” 8.531” 6” 6.000” 6.031”

Important points to note:

A 3-Cone bit can be built larger than nominal size because of the plus tolerance allowed, but a new bit can never be undergauge (due to the required cutting structure clearances).

To gauge a new bit you must use a 3-cone ring gauge that measures the nominal bit size plus API tolerance (see table). YouCANNOT use a PDC ring gauge to gauge a 3-cone bit and vice versa.

On those Smith 3-Cone bits that feature the ‘OD’ diamond enhanced heel row inserts (e.g. MSDGHOD), these bits are designed and built so that these inserts actively cut gauge at the maximum gauge point.

Therefore, if the gauge cutting elements are worn and undergauge, then re-gauge the bit on the heel row inserts.

The manufacturing locations of Smith 3-Cone bits are all ISO Certified (ISO 9001).

(89)

Gauging Procedures for PDC Bits

Gauging a PDC bit, either sharp or dull, requires some care and should be carried

out as follows:

1. Only use a calibrated PDC “No-Go” gauge ring. 2. Turn the bit on its pin.

3. Place the No-Go gauge ring over the bit - it should stop at the gauge skimmer/gauge pads

4. If the No-Go PDC gauge ring will not pass over the entire gauge area of the bit then the bit is in gauge.

5. If the No-Go gauge ring will pass then place the ring gauge at the gauge pads and pull hard to one side.

6. Measure the gap in 1/16” at the point opposite the point of contact between ring gauge and gauge pad.

7. Record the bit as being either in gauge or the amount under-gauge. Although IADC say to

PDC

Bit

No-Go gauge ring pulled hard against gauge pad.

No-Go ring gauge

7. Record the bit as being either in gauge or the amount under-gauge. Although IADC say to use an “I” for in gauge, we recommend using a 0 (zero) to avoid the confusion between an I and a 1.

API PDC Bit Tolerances Bit Size Tolerance

6 3/4” and smaller -0.015” to + 0” 6 25/32” and including 9” -0.020” to + 0” 9 1/32” and including 13 3/4” -0.030” to + 0” 13 25/32” and including 17 1/2” -0.045” to + 0” 17 17/32” and larger -0.063 to + 0”

Important points to note:

A PDC bit can be built slightly smaller than nominal size because of the negative tolerance allowed, but a new bit should never be overgauge.

To gauge a bit you must use a PDC “No-Go” ring gauge that measures the nominal bit size minus API tolerance (see table). You CANNOT