Manual Halliburton

(1)

MANUFACTURING AND SERVICE

The Woodlands, Texas

936-442-4700

Brussels, Belgium

32 2 333 3510

SERVICE CENTERS

Grand Junction, Colorado

970-523-3900

Nisku, Alberta

866-373-2487 / TOLL FREE

Dammam, Saudi Arabia

966 3 812 1179

HALLIBURTON H06243 10/09

(2)

IADC DULL GRADING SYSTEM

In this manual, all causes and recommendations are purely focused on application parameters and conditions. There is no discussion of bit

design. Halliburtons Application Design Evaluation (ADESM_{) specialists}

can analyze the bit dull then optimize the bit design to minimize or eliminate described bit dull features in subsequent runs. The proper evaluation of a dull drill bit is critical to improving bit type selection and identifying those drilling parameters which can be altered to improve drilling performance and obtain maximum bit life.

The IADC Dull Grading System is intended to bring consistency across the drilling industry and to facilitate the creation of a mental picture of the worn bits condition through standardized evaluation of certain bit characteristics. The purpose of this manual is to help create consistency and reduce uncertainty when dull grading drill bits.

THE MECHANICS OF DULL GRADING Roller Cone Drill Bits

The most efficient and accurate dull grading technique is one that is thorough and consistent. The best way to accomplish this is to examine dulls in exactly the same manner every time. In other words, develop a procedure that is repeatable and uses the same system or steps every time you look at a dull. Too many times we get caught up in focusing on one aspect of the dull and miss other factors that contributed to the total dull condition.

The first step is to examine the cutting structure. Start with the number one cone and rotate it as you are examining the cutting structure. Not only will you be able to examine the teeth and cone condition, the rotation of the cone will allow you to determine the seal and/or bearing condition. Examine the gauge row carefully, then the middle rows, and finally the inner rows. Look for worn, broken, chipped, and lost teeth. Examine the cone shell for cone interference, cone erosion, junk marks, off center wear, and tracking. Once you have examined the number one cone in this manner, rotate the bit and examine the number two cone and the number three cone in the same manner. After the cutting structure and all bearings are examined, ring gauge the dull as explained on page 8.

After you have graded the cutting structure of all three cones, return to the number one cone and examine the cone backface, shirttail, and arm. Look for broken and lost compacts, erosion and fluid cuts on the cone backface. Examine the shirttail and arm for wear and junk damage. Examine the ball plug weld and filler plug for weeping of oil from lubricant. Look at the reservoir cap for cap or snap ring damage. Check

Drill Bits & Services

The last thing to examine is the pin and shoulder. Look at the pin for signs of cross threading and pay special attention to the shoulder for any signs of galling. This is an indication of improper make-up torque. Turn the bit up on the cones and look down inside the pin. Look for signs of erosion and washing.

This system sounds complicated, but it is not. It is a simple routine that if followed every time a dull is examined, will ensure a thorough and complete grading evaluation procedure. Start at the cones and work your way to the pin and look at everything in between.

Fixed Cutter Drill Bits

Evaluating a fixed cutter bit follows a similar procedure as for roller cone designs, examining each characteristic in the same order each time. As you consider cutter wear, bear in mind that the IADC Fixed Cutter Dull Grading System grades all PDC cutters based on condition of the visible diamond table of the cutter, regardless of cutter shape or exposure. Therefore, your examination should focus on diamond table wear.

First, examine the inner and outer rows of cutters, looking at cutter wear in terms of remaining visible diamond table, as noted above. For these cutters, you are going to rate the amount of wear, from 0 meaning no wear to 8, meaning no remaining diamond table. Then, based on the overall condition of these cutters, determine the average wear by simply averaging the individual grades for each cutter in the area, as described on page 37.

Next, examine the bit face as a whole to determine the most prominent or primary dull characteristic, and note where on the bit it occurred. You are looking for the most significant physical change from new condition. This may be junk damage, a plugged or lost nozzle, ring out, or worn cutters. If cutter wear is the primary dull characteristic, next determine the type of wear, such as broken, chipped or delaminated cutters. The Dull Grade System gives a full list of wear descriptions for the primary dull characteristic on page 38.

Having determined the primary dull characteristic, next you want to determine average overall wear to the bit. At this point, you are looking for secondary evidence of wear. This may be some clearly identifiable wear to the bit as a whole, such as "erosion, or may relate specifically to the primary cutting structure wear, such as chipped cutter. For example, if lost nozzle is the primary dull characteristic, then the erosion may be the resulting secondary characteristic. Finally, examine the bit shoulder and gauge, and run a no go ring gauge test as described on page 39.

(3)

IADC Dull Grading System Quick Reference Chart 35-36 IADC Dull Grading System Overview

Inner Cutting Structure 37

Outer Cutting Structure 37

Dull Characteristics 38

Location 39

Bearings/Seals 39

Gauge 39

Other Dull Characteristics 40

Reason Pulled or Run Terminated 41

Dull Evaluation (BF) Bond Failure 43 (BT) Broken Cutters 44 (BU) Balled Up 45 (CR) Cored 46 (CT) Chipped Cutters 47 (DL) Delaminated Cutters 48 (ER) Erosion 49 (HC) Heat Checking 50 (JD) Junk Damage 51 (LM) Lost Matrix 52 (LN) Lost Nozzle 53 (LT) Lost Cutters 54

(PN) Plugged Nozzle/Flow Passage 55

(RO) Ring Out 56

(WO) Washed Out 57

(WT) Worn Cutters 58

Broken Blade 60

Reaming Wear 61

Spalling 62

(fixed cutter drill bits)

ROLLER CONE IADC DULL GRADING SYSTEM

QUICK REFERENCE CHART

NEW T1 T2 T3 T4 T5 T6 T7 T8

(5)

INNER CUTTING STRUCTURE (I) (All inner rows)

Used to report the condition of the teeth not touching the wall of the hole.

OUTER CUTTING STRUCTURE (O)

Used to report the condition of the teeth that touch the wall of the hole. These teeth are also called gauge row (gauge condition is important to good bit performance).

Steel Tooth Bits

A measure of lost tooth height due to abrasion and/or damage. 0 - No loss of tooth height

8 - Total loss of tooth height Insert Bits

A measure of total cutting structure reduction due to lost, worn and/or broken inserts.

0 - No lost, worn and/or broken inserts 8 - All inserts lost, worn and/or broken Cutting Structure Wear

Cutting Structure Inner Rows I Outer Rows O Dull Char. D Location L Bearings/ Seals B Gauge 1/16 G Other Dull O Reason Pulled R Remarks T B G Remarks 1 2 3 4 5 6 7 8 1 2 DULL CHARACTERISTICS (D)

Uses a two letter code to indicate the major dull characteristics of the cutting structure. Input only one (two-letter) dull characteristic code and use the standard abbreviation only.

(BC) Broken Cone * (BT) Broken Teeth (BU) Balled (CC) Cracked Cone * (CD) Cone Dragged * (CI) Cone Interference (CR) Cored

(CT) Chipped Teeth (ER) Erosion

(FC) Flat Crested Wear (HC) Heat Checking (JD) Junk Damage (LC) Lost Cone * (LN) Lost Nozzle (LT) Lost Teeth

(NO) No Dull Characteristic (NR) Not Rerunnable (OC) Off Center Wear (PB) Pinched Bit

(PN) Plugged Nozzle/Flow Passage (RG) Rounded Gauge

(RR) Rerunnable (SD) Shirttail Damage (SS) Self-Sharpening Wear (TR) Tracking

(WO) Washed Out (WT) Worn Teeth

* Show cone # or #s under location 4. Cone numbers are identified as follows:

If two cones contain a centermost cutting element, or single insert, the insert with the greatest tilt is designated as cone number one.

Cones two and three follow in a clockwise orientation as viewed looking down at the cutting structure with the bit sitting on the pin.

3

IADC DULL GRADING SYSTEM ROLLER CONE

NEW T1 T2 T3 T4 T5 T6 T7 T8

(6)

LOCATION (L)

Uses a letter or number code to indicate the location on the face of the bit where the cutting structure dulling characteristic occurs. The IADC Dull Grading System chart lists the codes to be used for describing locations on roller cone bits.

Location is defined as follows:

N = Nose Row - the center most cutting element(s) of the bit M = Middle Row - cutting elements between the nose and the gauge G = Gauge Row - those cutting elements that touch the hole wall A = All Rows - all rows

4

Steel Tooth Bit

Insert Bit Nose Row Spear Point (Row 3) Middle Row (Row 2) Gauge Row (Row 1) CONE 3 CONE 2 CONE 1 Nose Row (Row 4) Middle Row (Row 3) Middle Row (Row 2) Gauge (Row 1) Surf Row Groove CONE 1 CONE 3 CONE 2

Cone numbers are identified as follows:

The number one cone contains the center most cutting element; the spear-point on a steel tooth cone and the nose insert on a tungsten carbide insert cone. On certain TCI designs two cones may have a nose insert. In this case the nose insert that is offset is on the number one cone.

Cones two and three follow in a clockwise orientation as viewed looking down at the cutting structure with the bit sitting on the pin.

BEARINGS/SEALS (B)

Uses a letter or number code, depending on bearing types, to indicate the bearing condition of roller cone bits.

Non-Sealed Bearings

A linear scale from 0 - 8 is used to indicate that no bearing life has been used (a new bearing) and an 8 indicates that all of the bearing life has been used (locked or lost).

Sealed Bearings (Journal or Roller)

A letter code is used to indicate the condition of the seal. E = Seals effective

F = Seals failed N = Not able to grade Indication of Failed Seals

Locked cone (not always true sign of failure) Intermitted locking or catching cone

Scratchy and/or grinding feeling while turning cone Ability to rock cone axially

Gaps between cone and arm Signs of grease weeping

Shale packing (not always true sign of failure) 5

(7)

GAUGE (G)

Used to report on the gauge of the bit. The letter I (In Gauge) indicates no gauge reduction. If the bit does have a reduction in gauge it is to be recorded in 1/16ths of an inch.

Dull Three Cone Bits

Obtain a nominal size ring gauge. A nominal ring gauge is one that is exact in size. For example, a 12-1/4 inch ring gauge is 12-1/4 inch exactly.

Rotate all cones so that one of the gauge teeth on each cone is at the maximum gauge point*. (Remember, soft formation bits with large offsets have the maximum gauge points

on each cone located towards the leading side of the cone.) Place the ring gauge over the bit and locate it at the maximum

gauge point.

Pull the ring gauge tight against the gauge points of two cones as shown.

Measure the gap between the third cones gauge point and the ring gauge**.

Multiply this measurement by 2/3 for accuracy. This result is the amount the bit is under gauge. In the illustration, for example, measurement shows 3/8 inch, while the bit is actually 1/4 inch out of gauge.

Report this amount to the nearest 1/16 of an inch. Sharp Bits

When ring gauging a sharp (new) roller cone bit, a nominal ring gauge may not fit over the cones due to the plus tolerances. Obtain the appropriate go and no go gauges for each bit size. The go gauge is manufactured to the maximum roller cone bit tolerance (see API Standard Roller Cone Rock Bit Tolerances) plus its own tolerance +.003 to -0 inches for clearance.

The no go gauge is manufactured to the minimum roller cone bit tolerance, which is nominal bit diameter, plus its own tolerance +0- to -.003-in. 6 1 ** * * +

API STANDARD ROLLER CONE BIT TOLERANCES

BIT SIZE (IN) O.D. TOLERANCE (IN)

3-3/8 to 13-3/4 +1/32, -0

14 to 17-1/2 +1/16, -0

17-5/8 and Larger +3/32, -0

OTHER DULL CHARACTERISTICS (O)

Used to report any dulling characteristic of the bit, in addition to the cutting structure dulling characteristic listed in column 3 (D). Use the same standard two-letter codes as used in column 3. Note that this column is not restricted to only cutting structure dulling characteristics.

(BC) Broken Cone (BT) Broken Teeth (BU) Balled Up Bit (CC) Cracked Cone (CD) Cone Dragged (CI) Cone Interference (CR) Cored

(CT) Chipped Teeth (ER) Erosion

(FC) Flat Crested Wear (HC) Heat Checking (JD) Junk Damage (LC) Lost Cone (LN) Lost Nozzle * (LT) Lost Teeth

(NO) No Dull Characteristic (NR) Not Rerunnable (OC) Off Center Wear (PB) Pinched Bit *

(PN) Plugged Nozzle/Flow Passage * (RG) Rounded Gauge

(RR) Rerunnable (SD) Shirttail Damage * (SS) Self-Sharpening Wear (TR) Tracking

(WO) Washed Out Bit * (WT) Worn Teeth

* Used only in the Other Dull Characteristics column. 7

(8)

REASON PULLED OR RUN TERMINATED (R)

Following are the two or three letter codes used to report termination of the bit run.

BHA - Change Bottom Hole Assembly CM - Condition Mud

CP - Core Point

DMF - Downhole Motor Failure DP - Drill Plug

DSF - Drill String Failure DST - Drill Stem Test DTF - Downhole Tool Failure FM - Formation Change HP - Hole Problems HR - Hours on Bit LIH - Left In Hole LOG - Run Logs PP - Pump Pressure PR - Penetration Rate RIG - Rig Repair

TD - Total Depth/Casing Depth TQ - Torque

TW - Twist Off

WC - Weather Conditions WO - Washout in Drill String

(9)

POSSIBLE CAUSES

Cone interference, where the cones contact each other after a bearing failure causing breakage of one or more of the cones Cutting structure failure (lost, broken or worn) resulting in cone

shell thickness reduction

Bit hitting a ledge on trip or connection Running on junk

Dropped drill string

Hydrogen sulfide embrittlement - a condition of low ductility in metals resulting from the absorption of hydrogen; hydrogen atoms diffuse readily into steel during exposure to hydrogen sulfide; after stressing, delayed brittle fracture may occur, particularly in higher strength steels

Propagation of cracks generated by heat after bearing failure APPLICATION RECOMMENDATIONS

Monitor and reduce bit on bottom hours Review application and bit selection

Check running parameters (WOM, RPM, hydraulics) Check running in hole procedures

POSSIBLE CAUSES

Excessive WOB for application indicated by broken teeth, predominantly on the inner and middle row

Excessive RPM for application indicated by broken teeth predominantly on the gauge row teeth

Highly interbedded formations or conglomerates causing uneven loading across the cutting structure

Improper bit selection Drill string vibrations Bit run on junk

Bit hitting a ledge or hitting bottom suddenly

Improper break-in of bit when a major change in bottomhole pattern is made

Cone interference

Bit tracking and off center wear APPLICATION RECOMMENDATIONS

In some formations broken teeth may be a typical dull characteristic and not necessarily a problem with bit selection. However, if the bit run was of uncommonly short duration, broken teeth could indicate problems in bit selection for the application For harder formations and/or higher energy levels, select a bit

with less offset, and/or less tooth extension, and/or greater tooth count, and/or tougher tooth shape and/or tougher carbide material When drilling torque varies greatly, reduce RPM and/or lower

WOB

Avoid drilling out metal objects in the wellbore with insert type bits; use short tooth steel tooth bits

Some breakage may occur during a run; excessive breakage would indicate changes in drilling parameters or bit type is required

BC BROKEN CONE

BROKEN TEETH BT

A broken cone is described as a bit with one or more cones that have been broken into two or more pieces, but with most of the cone still attached to the bit.

A cutting element is considered broken if more than 50% of the cutting element is clearly broken with an angular or jagged break.

(10)

POSSIBLE CAUSES

Inadequate hydraulic cleaning of the bottomhole

Forcing the bit into formation cuttings with the pump not running Drilling a sticky formation

APPLICATION RECOMMENDATIONS

This dull characteristic occurs primarily on steel tooth bits Review hydraulics parameters (consider center jet, SidePort or

Multi-Port nozzles) Consider control drilling Review mud properties

Consider alternate bit type if necessary

POSSIBLE CAUSES

Cone interference, where the cones contact each other after a bearing failure causing breakage of one or more of the cones Cutting structure failure (lost, broken or worn) resulting in cone

shell thickness reduction

Bit hitting a ledge on trip or connection Running on junk

Dropped drill string

Hydrogen sulfide embrittlement - a condition of low ductility in metals resulting from the absorption of hydrogen. Hydrogen atoms diffuse readily into steel during exposure to hydrogen sulfide. After stressing, delayed brittle fracture may occur, particularly in higher strength steels

Propagation of cracks generated by heat after bearing failure APPLICATION RECOMMENDATIONS

Monitor and reduce bit on bottom hours Review application and bit selection

Check running parameters (WOM, RPM, hydraulics) Check procedures for running bit in hole

Consider advanced hydraulics bit design

BU BALLED UP

CRACKED CONE CC

Balled up is when formation packs off between the cones and/or bit body. This usually prevents the cones from turning resulting in lower ROP and possible impeded cone rotation. Possible signs of balled up bits could be wear flats on cutting structure or indications of cone skidding with effective bearings.

A cracked cone is the start of a broken or lost cone. If any portion of the cone is missing then it is a broken cone.

(11)

POSSIBLE CAUSES

Bearing failure on one or more of the cones Junk lodging between the cones

Pinched bit causing cone interference Bit balling up

Inadequate break-in

APPLICATION RECOMMENDATIONS Reduce energy levels

Use solids control equipment to remove abrasives Increase flow rate; use better bit hydraulics to clean the bit Observe drilling torque continually while drilling out cementing

equipment and pick-up off bottom to avoid wedging pieces between cones if high torque exists

Use proper break-in procedures

POSSIBLE CAUSES

Bearing failure on one or more cones Bit being pinched causing cone interference

(see Dull Characteristic - Pinched Bit) Excessive WOB

APPLICATION RECOMMENDATIONS Reduce energy levels

Use proper reaming guidelines for undergauge hole sections Review application and bit selection

CD CONE DRAGGED

CONE INTERFERENCE CI

This dull characteristic indicates that one or more of the cones did not turn during part of the bit run, indicated by one or more flat wear spots. This should not be confused with flat crested wear. Heat checking might be visible on flattened inserts. Cone interference is described as the cutting structure of at least one cone that has impacted the cone shell of an adjacent cone. This results in cone shell grooving and can lead to cutting element breakage. This can lead to cracked or broken cones.

(12)

POSSIBLE CAUSES

Excessive WOB for application indicated by chipped teeth predominantly on the inner and middle row

Excessive RPM for application indicated by chipped teeth predominantly on the gauge row teeth

Tracking and off center wear

Impact loading due to rough drilling or drill string vibration Running on junk

Improper bit selection Slight cone interference

Rough running in air drilling applications APPLICATION RECOMMENDATIONS

For harder formations and/or higher energy levels, select a bit with less offset, and/or less tooth extension, and/or greater tooth count, and/or tougher tooth shape and/or tougher carbide material Reduce RPM when drilling torque varies greatly and/or lower

WOB

Some chipped teeth may occur during a run; excessive chipping could indicate changes in drilling parameters or bit type is required Control drill through transition sections

Note: In some formations chipped teeth may be a typical dull characteristic and not necessarily a problem with bit selection; however, if the bit run was of uncommonly short duration, chipped teeth could indicate problems in bit selection for the application POSSIBLE CAUSES

Cone shell erosion resulting in lost or washed cutting elements Improper break-in of a new bit when there is a major change in

bottomhole pattern

Improper bit selection (too aggressive) Excessive WOB and RPM

Abrasiveness of formation exceeds the wear-resistance of the center teeth

Junk in the hole causing breakage of the center teeth APPLICATION RECOMMENDATIONS

Avoid drilling on junk/metal debris

Avoid running too much WOB and RPM through hard, interbedded or conglomerate lithologies

Insure proper bottomhole pattern break-in (see Drill Bit Handbook for drilling procedures)

Use diffusing nozzle in center jet assembly to reduce erosion

CR CORED

CHIPPED TEETH CT

A bit is cored when the center most cutting elements are worn, lost, or broken, resulting in cone wear. The center most portion of the cone is usually worn more than the outer sections.

On tungsten carbide insert bits, chipped inserts often become broken teeth. A tooth is considered chipped, as opposed to broken, if more than 50% of the cutting element remains above the cone shell.

(13)

POSSIBLE CAUSES

Excessive hydraulics resulting in high velocity fluid erosion Abrasive formation contacting the cone shell between the teeth,

caused by tracking, off center wear, or excessive WOB Abrasive formation cuttings eroding the cone shell due to

inadequate hydraulics

Abrasive drilling fluids or poor solids control

Use of a center jet may cause inner cutting structure erosion APPLICATION RECOMMENDATIONS

Reduce hydraulic energy by changing flow rate or nozzles on subsequent runs

Improve mud properties and run solids control equipment Review hydraulics parameters (consider center jet, SidePort or

Multi-Port nozzles) Control drill if necessary

Consider use of diffusing center jet

POSSIBLE CAUSES

Low WOB and high RPM, often used in attempting to control deviation

Bit selection too aggressive for hard, abrasive formations Tracking on the drive or heel rows may cause the inner portion

to skid excessively

Adjust to a more abrasion resistant cutting element material grade

Select proper bit type for the formation Review and optimize WOB and RPM

ER EROSION

FLAT CRESTED WEAR FC

Erosion describes the loss of cutting structure material due to the effect of drilling fluid, cuttings or formation against the cones. Loss of cone shell by erosion is a major cause of lost inserts. It can also lead to cone shell cracking which can result in a broken cone.

Flat crested wear is an even reduction in height across the entire face of the cutting elements. This is often considered a typical and desirable dull characteristic when the wear is evenly distributed across the cutting structure.

(14)

POSSIBLE CAUSES

Insufficient cooling due to balling or inadequate hydraulics Cone drag or restricted cone rotation

Reaming an undergauge hole at high RPM

Low WOB and high RPM, often used in attempting to control deviation

APPLICATION RECOMMENDATIONS Increase fluid flowrate

Reduce RPM while reaming hole Review and control WOB and RPM

Alternate cutting element materials such as diamond enhanced inserts

POSSIBLE CAUSES

Junk dropped in the hole from the surface (tong dies, tools, etc.) Junk from the drill string (reamer pins, stabilizer blades, etc.) Junk from a previous bit run (tungsten carbide inserts, ball bearings,

etc.)

Junk from the bit itself (tungsten carbide inserts, etc.) Damage due to contact with casing

Plan on running junk basket with next bit and anticipate reduced bit life

Ensure hole is clean before running bit to drill ahead

Circulate and rotate just above hole bottom to lift junk above bit face prior to drilling

Run a cleanout bit if necessary

HC HEAT CHECKING

JUNK DAMAGE JD

Heat checking happens when an insert is overheated due to dragging on the formation and is then cooled by the drilling fluid over many cycles. It is often associated with inserts on the gauge and drive rows (resulting in larger contact areas) but can occur anywhere on the cutting structure.

Junk damage is typified by irregular grooves or scraped indentations in the cone steel or bit body. Typically, inserts or teeth would also be broken.

(15)

POSSIBLE CAUSES

Any of the conditions that lead to a cracked or broken cone may eventually result in the loss of the cone

Excessive hours after bearing failure causing the cone retention system to fail

Review and adhere to recommended operational parameters Monitor drilling parameters during run and react properly to

indications of a potential problem, such as erratic or increased torque values

POSSIBLE CAUSES

Missing or damaged O-ring and/or improper nozzle installation Mechanical or erosion damage to nozzle and/or nozzle retaining

system

Improper nozzle selection for hydraulic conditions Junk in the hole can damage nozzle or nozzle retention APPLICATION RECOMMENDATIONS

Insure O-ring is in place and confirm nozzles are properly installed (refer to Drill Bit Handbook for nozzle installation procedures) Review nozzle selection and hydraulics parameters

Check for unusual bit damage and use proper procedures to deal with junk in the hole

A lost nozzle causes a pressure decrease which may require the bit be pulled out of the hole

LC LOST CONE

LOST NOZZLE LN

Lost cone is described as a condition when one or more cones are lost from the bit arm. This may include the loss of the journal or bearing portion of the arm with the cone.

Lost nozzle describes one or more missing nozzles. While lost nozzle is not a cutting structure dull characteristic, it is an important Other Dull Characteristic that can help describe a bit condition.

(16)

POSSIBLE CAUSES

Insert breakage causing excess cyclic loading on adjacent inserts Improper bit selection

Cone shell erosion reducing insert retention Excessive hours on bit

Tracking or insert burial too deep into formation causing cyclic loading, twisting and insert hole enlargement due to movement Cone steel residual stress relieved due to cone cracking or major

insert breakage

Hydrogen sulfide embrittlement cracks APPLICATION RECOMMENDATIONS

Adjust energy levels in interbedded and hard lithologies Change to a more durable bit type

Review hydraulic parameters or running procedures to avoid excessive cone erosion (see dull characteristic under Erosion) Reduce operating hours

POSSIBLE CAUSES

Bent drill collar or other BHA tool Steerable motor or rotary steerable system

Inadequate stabilization resulting in possible bit whirl/vibration Insufficient WOB for formation and bit type

Change drilling parameters to optimize ROP using drill-off tests Proper stabilization which enables directional control and optimum

bit performance should be discussed prior to running bit Increase WOB to engage cutting structure

Review BHA condition and components

LT LOST TEETH

OFF CENTER WEAR OC

Lost teeth is a characteristic described as tungsten carbide inserts that are missing from the cutting structure. The loss of an insert increases loading on the adjacent inserts and can result in a series of lost or broken inserts.

Off center wear occurs when the geometric center of the bit and the geometric center of the hole do not coincide. Off center wear can be recognized by wear on the cone shells between the rows of teeth, more wear on one or more cones on the cone shell, gauge, arm and by a less than expected ROP. Wear may or may not occur on the cutting elements.

(17)

POSSIBLE CAUSES

Bit being forced into an undergauge hole

Roller cone bit being forced into a section of hole drilled by fixed cutter bits, due to different API O.D. tolerances

Forcing a bit through casing that does not drift to the bit size used Bit being pinched in the bit breaker

Bit being forced into an undersized blowout preventer stack Improper break in of new bit type due to bottomhole profile

differences

Trip in hole with care and wash and ream tight spots Use proper bit size for the casing set; check API casing charts

and ensure bit is under the listed drift diameter

Use correct and undamaged bit breaker; use proper procedures for bit make-up (refer to Drill Bit Handbook)

Exercise caution when reaming undergauge hole

Use proper break-in techniques (refer to Drill Bit Handbook)

POSSIBLE CAUSES

Solid material going up the drill string through the bit on a connection and becoming lodged in a nozzle when circulation is resumed

Solid material pumped down the drill string and becoming lodged in a nozzle

Improper nozzle selection

Debris from failed or failing drill string components (such as rubber from a motor) plug nozzle openings

Jamming the bit into fill with the pump off APPLICATION RECOMMENDATIONS

Run in hole carefully; break circulation 60ft from bottom and wash and ream to bottom

Consider running a float valve

Avoid mixing nozzle sizes which differ by more than 2/32 Insure no debris is pumped down drill string

When a nozzle plugs while drilling there will be an obvious sudden rise in standpipe pressure - monitor hydraulic parameters during running for signs of standpipe pressure increase

PB PINCHED BIT

PLUGGED NOZZLE/FLOW PASSAGE PN

A pinched bit occurs when one or more cones have been mechanically forced together to a less than original gauge diameter. Pinched bits can lead to bearing/ seal failures, broken teeth, chipped teeth, cone interference, dragged cones and many other dull characteristics.

This characteristic is described as one or more nozzles being obstructed. This problem can lead to reduced hydraulics and may require a trip out of the hole due to excessive pump pressure.

(18)

POSSIBLE CAUSES

Drilling an abrasive formation with excessive RPM Reaming an undergauge hole

Running on a steerable motor or rotary steerable system Formation too abrasive for selected bit type

Reduce RPM and increase flow rate to cool and clean more effectively

Select a bit with more durable gauge protection Consider using diamond enhanced gauge protection

POSSIBLE CAUSES Junk in hole

Reaming undergauge hole

A pinched bit causing the shirttails to be the outermost part of the bit

Improper hydraulics

High angle or horizontal wellbore

Gauge rounding or breakage causing undergauge hole condition Rotary steerable (push-the-bit) system

Review procedures for running in hole (refer to Drill Bit Handbook) Insure hole is free of debris or junk (see dull characteristic Junk

Damage for application recommendations) Exercise caution if reaming undergauge hole Evaluate running parameters and hours on bit Consider using enhanced shirttail protection

Improve cutting structure gauge protection (see dull characteristic Gauge Rounding for application recommendations)

RG ROUNDED GAUGE

SHIRTTAIL DAMAGE SD

Rounded gauge is

described as the outermost tip of the gauge cutting element that has rounded over in a way that it is not cutting nominal gauge. Rounded gauge will decrease the ROP and can increase torque.

Shirttail damage is a condition where damage due to wear, erosion or junk occurs in the shirttail area. Shirttail damage is not a Cutting Structure Dull Characteristic, although it can be affected by the condition of the cutting structure. Shirttail wear can contribute to bearing system failures.

(19)

POSSIBLE CAUSES

Abrasion from engagement with formation

In many applications, self-sharpening wear is a desirable characteristic on the cutting structure

Review bit design and selection criteria if self-sharpening wear is a concern for the specific application

POSSIBLE CAUSES

Formation changes from brittle to plastic

Hydrostatic pressure that significantly exceeds the formation pressure (overbalanced drilling)

Improper weight/RPM combination APPLICATION RECOMMENDATIONS

Optimize ROP for each formation change using drill-off tests Reevaluate hydrostatic versus formation pressures to manage

overbalanced drilling Lower mud weight if possible

Tracking can sometimes be alleviated by using a softer bit to drill the formation

Review bit selection

SS SELF-SHARPENING WEAR

TRACKING TR

Self-sharpening wear is a dull characteristic that occurs when teeth wear in a manner such that they retain a sharp crest shape but are reduced in height.

Tracking occurs when the teeth mesh like a gear into the bottomhole pattern. The tooth or insert wear on a bit that has been tracking will be on the leading and trailing flanks. The cone shell wear will be between the teeth in a row. Slower than expected ROP may be an indication of tracking.

(20)

POSSIBLE CAUSES

Very abrasive particles in the mud system or poor solids control High flow rates coupled with elevated mud weights

Bit damage occurring during the bit run due to impact with bottom or ledges on connections

Dropping the drill string Excessive flow rates

O-ring missing when nozzle installed APPLICATION RECOMMENDATIONS

Review drilling mud parameters (Hematite or abrasive muds) and adjust bit running procedures accordingly

Use proper running procedures when tripping in hole and making connections (refer to Drill Bit Handbook)

Spend extra time ensuring nozzles are correctly in place prior to running in the hole; check O-ring for rips or tears and replace

POSSIBLE CAUSES

Bit selection is incorrect for application Energy levels may be excessive

Applying excessive energy in transition zones Tracking

APPLICATION RECOMMENDATIONS Review bit selection

Review WOB and RPM applied

Adjust energy levels when drilling through transition zones and formation changes

Monitor bit performance and review bit pulling procedures

WO WASHED OUT

WORN TEETH WT

Bit washout occurs

when the drilling fluid erodes a passage from the internal area to the exterior of the bit. It is not exclusive to welds. This is not to be confused with the dull characteristic Lost Nozzles. This characteristic is used only in the Other Dull Characteristics column.

Worn teeth is used to describe the reduction in the height of the cutting elements due to the drilling action, which is a normal and expected wear mode. When worn teeth (WT) is indicated on steel tooth bits, it is appropriate to note sharpening (SS) or flat crested (FC) wear.

(21)

CUTTING STRUCTURE INNER OUTER DULL BEARINGS/ OTHER DULL REASON ROWS ROWS CHAR. LOCATION SEALS GAUGE CHAR. PULLED 12 34 x 67 8

INNER CUTTING STRUCTURE OUTER CUTTING STRUCTURE A measure

of

lost,

worn

and/or

broken

cutting structure. Linear Scale: 0-8 0

-No lost, worn and/or broken cutting structure

8

-All of cutting structure lost, worn and/or broken DULL CHARACTERISTICS BF -Bond Failure BT -Broken Cutters BU -Balled Up CR -Cored CT -Chipped Cutters DL -Delaminated Cutters ER -Erosion HC -Heat Checking JD -Junk Damage LM -Lost Matrix LN -Lost Nozzle LT -Lost Cutters NO -No Dull Characteristics NR -Not Rerunnable PN -Plugged Nozzle/Flow Passage RO -Ring Out RR -Rerunnable WO -W ashed Out WT -W orn Cutters LOCATION C -Cone N -Nose T -Taper S -Shoulder G -Gauge A -All Areas X GAUGE I -In Gauge 1 -1/16 Out of Gauge 2 -1/8 Out of Gauge 4 -1/4 Out of Gauge

OTHER DULL CHARACTERISTICS (Refer to column 3 codes) REASON PULLED OR RUN TERMINATED BHA

-Change Bottom Hole Assembly CM -Condition Mud CP -Core Point DMF

-Downhole Motor Failure

DP

-Drill Plug

DSF

-Drill String Failure

DST -Drill Stem T est 1 2 3 4 5 6 7 8

Inner Area 2/3 Radius Outer Area 1/3 Radius

Gauge Shoulder Nose Taper Cone No W ear W orn Cutter Lost Cutter Delaminated DTF -Downhole T ool Failure FM -Formation Change HP -Hole Problems HR -Hours LIH -Left in Hole LOG -Run Logs PP -Pump Pressure PR -Penetration Rate RIG -Rig Repair TD

-Total Depth/Casing Depth

TQ -Torque TW -Twist Off WC -W eather Conditions WO -W

ashout - Drill String

Halliburton Drill Bits and Services fixed

cutter bits are tip ground to exacting tolerances at gauge O.D. per API spec 7. Depending

on the specific design and application, as much as .080 of an inch

of the cutter diameter may be ground flat. This can be mistaken for gauge wear if unfamiliar with our products. Please

ensure that dull bits are in gauge with a calibrated PDC No Go ring gauge.

FIXED CUTTER IADC DULL GRADING SYSTEM

QUICK REFERENCE CHART

(22)

INNER CUTTING STRUCTURE (I)

The first 2/3 of the radius represents the inner rows (Figure 1). Using a linear scale from 0-8, a value is given to cutter wear in the inner rows of cutters (Figure 2). Grading numbers increase with amount of wear, with 0 representing no wear, and 8 meaning no usable cutters left. A grade of 4 indicates 50% wear. For surface set bits, the scale of cutter wear is determined by comparing the initial cutter height with the amount of usable cutter height remaining. PDC cutter wear is measured across the diamond table, regardless of the cutter shape, size, type or exposure. For example, when the cutter is worn flat with a bit blade, a grade of 4 is given.

OUTER CUTTING STRUCTURE (O)

The outer row of cutters represents the last third of the bit radius. Using a linear scale from 0-8, a value is given to cutter wear in the outer rows of cutters (Figure 2). Grading numbers increase with amount of wear, with 0 representing no wear, and 8 meaning no usable cutters left. A grade of 4 indicates 50% wear. For surface set bits, the scale of cutter wear is determined by comparing the initial cutter height with the amount of usable cutter height remaining. PDC cutter wear is measured across the diamond table, regardless of the cutter shape, size, type or exposure.

Cutting Structure Inner Rows I Outer Rows O Dull Char. D Location L Bearings/ Seals B Gauge 1/16 G Other Dull O Reason Pulled R Remarks T B G Remarks 1 2 3 4 X 6 7 8 1 2

IADC DULL GRADING SYSTEM FIXED CUTTER

DULL CHARACTERISTICS (D)

The most prominent or primary physical change from the new condition of the bit is recorded in the third space. Otheror secondary dull characteristics of the bit are noted in the seventh space. If this primary dull characterization is a PDC type failure, then the PDC failure mode box in the header must match. (BF) Bond Failure (BT) Broken Cutters (BU) Balled Up (CR) Cored (CT) Chipped Cutters (DL) Delaminated Cutters (ER) Erosion (HC) Heat Checking (JD) Junk Damage (LM) Lost Matrix (LN) Lost Nozzle (LT) Lost Cutters

(NO) No Dull Characteristics (NR) Not Rerunnable

(PN) Plugged Nozzle/Flow Passage (RO) Ring Out

(RR) Rerunnable (WO) Washed Out

3

Impregnated bits use a ratio of remaining blade height to original blade height (Figure 3). If the original blade height was .5 inches and the remaining blade height is .25 inches, the grading would be a 4 (50% wear). Always measure the blade height vertically and not perpendicular to the blade profile.

Inner Area 2/3 Radius Outer Area 1/3 Radius 1₂ 3 4 5 6 7 8 0 4 8 0 Original Waterway Depth No Waterway Remaining

Figure 1 Figure 2

(23)

OTHER DULL CHARACTERISTICS (O)

Used to report any dulling characteristics of the bit, in addition to the cutting structure dulling characteristic listed in column 3 (D). Such evidence may relate specifically to cutting structure wear, as recorded in the third space, or may note identifiable wear of the bit as a whole, such as erosion or broken blade. Many times, this secondary dull grade identifies the cause of the dull characteristic noted in the third space.

Note that if the primary failure is bit related failure (broken blade, erosion, nozzle failure, etc.), and the secondary failure is a PDC type failure (spall, chipped cutter, delamination, etc.), then this secondary characterization box must match what is entered into the PDC failure mode box in the header.

(BF) Bond Failure (BT) Broken Cutters (BU) Balled Up (CR) Cored (CT) Chipped Cutters (DL) Delaminated Cutters (ER) Erosion (HC) Heat Checking (JD) Junk Damage (LM) Lost Matrix (LN) Lost Nozzle (LT) Lost Cutters (NO) No Dull Characteristic (NR) Not Rerunnable

(PN) Plugged Nozzle/Flow Passage (RO) Ring Out

(RR) Rerunnable (WO) Washed Out (WT) Worn Cutters

7 LOCATION (L)

The fourth space is used to indicate the location of the primary dull characteristic noted in the third space. Locations are designated as: C Cone

N Nose T Taper

BEARINGS/SEALS

This space is only used for roller cone bits. It will always be marked X for fixed cutter bits.

GAUGE (G)

Used to report on the gauge of the bit. The letter I (In Gauge) indicates no gauge reduction. If the bit does have a reduction in gauge it is to be recorded in 1/16ths of an inch.

Any fixed cutter bit should be ring gauged prior to running in the hole. Stabilizers should also be calipered or gauged to verify they meet API-approved outside dimension tolerances as shown in the following table. Fixed cutter bits should not be larger than the nominal diameter.

A no go gauge is used to ensure a bit is not smaller than allowed and, as the name implies, it should not go or slip down the entire length of the bit. A go gauge ensures a bit is not larger than allowed and should slip down the entire bit.

6

API STANDARD FIXED CUTTER BIT TOLERANCES

BIT SIZE (IN.) O.D. TOLERANCE (IN.)

6-3/4 and Smaller -0.015 to +0.00 6-25/32 to 9 -0.020 to +0.00 9-1/32 to 13-3/4 -0.030 to +0.00 13-25/32 to 17-1/2 -0.045 to +0.00 17-17/32 and Larger -0.063 to +0.00 5 GAUGE SHOULDER TAPER NOSE CONE GAUGE SHOULDER TAPER NOSE CONE GAUGE SHOULDER TAPER NOSE CONE GAUGE SHOULDER NOSE CONE S Shoulder G Gauge A All Areas 4

(24)

REASON PULLED OR RUN TERMINATED (R)

Following are the two or three letter codes used to report termination of the bit run.

BHA - Change Bottom Hole Assembly CM - Condition Mud

CP - Core Point

DMF - Downhole Motor Failure DP - Drill Plug

DSF - Drill String Failure DST - Drill Stem Test DTF - Downhole Tool Failure FM - Formation Change HP - Hole Problems HR - Hours LIH - Left In Hole LOG - Run Logs PP - Pump Pressure PR - Penetration Rate RIG - Rig Repair

TD - Total Depth/Casing Depth TQ - Torque

TW - Twist Off

WC - Weather Conditions WO - Washout Drill String

8 NOTES

(25)

POSSIBLE CAUSES Incorrect bit selection Improper WOB

Inadequate bottomhole pattern break-in

Excessive impact load / improper drilling practices Interbedded formations

Bit vibration

Utilize SPARTA software to identify and locate interbedded formations and the relative rock strength

Optimize drilling parameters FEATURE RECOMMENDATIONS

Secondary cutting structure such as R1 and MDRs Impact arrestors

Increase cutter density Less aggressive cutter profile

Bit vibration Junk damage Dropped bit

Running in hole too fast and encountering ledges or obstructions APPLICATION RECOMMENDATIONS

Increase cutter density Less aggressive cutter profile Decrease cutter size

BF BOND FAILURE

BROKEN CUTTERS BT

Bond failure is a characteristic that describes where the braze joint between the PDC cutter and the bonded extension shears or breaks off.

A cutting element is considered broken if more than 1/3 of the cutter is broken and the break occurs in both the diamond layer and the tungsten carbide substrate.

(26)

POSSIBLE CAUSES

Drilling formations with hydratable clays or soft carbonates Inadequate hydraulics

Improper nozzle selection

Inadequate cleaning of the hole after making a connection APPLICATION RECOMMENDATIONS

Optimize bit hydraulics Increase flow rate

Optimize drilling fluid properties Increase RPM

FEATURE RECOMMENDATIONS

Consider use of a steel body bit with anti-balling coating Lighter set bits fewer blades

POSSIBLE CAUSES

Damage during drilling out float equipment Junk damage

Erosion

Significant change in bottomhole profile from previous bit run Improper break-in

Excessive WOB Bit vibration

Formations too hard for bit type selected Bit run following a core bit run APPLICATION RECOMMENDATIONS Confirm PDC drillable float equipment Optimize operating parameters FEATURE RECOMMENDATIONS Increase blade standoff in cone Optimize nozzle placement Increase cutter density in cone

BU BALLED UP

CORED CR

Balled up occurs when cuttings are packed around the cutters and/or blades. This condition can limit drilling rate, possibly decrease drilling torque and increase pump pressure.

Cored is defined as loss of cutting structure extending all the way to the center of the bit.

(27)

Bit vibration

Increase cutter density Less aggressive cutter profile Decrease cutter size Increase cutter chamfer size

Optimize cutter type with regards to impact resistance

POSSIBLE CAUSES

Excessive heat that degrades the diamond layer Incorrect bit selection

Improper WOB

Bit vibration

Increase cutter density Less aggressive cutter profile Decrease cutter size Increase cutter chamfer size

Optimize cutter type with regards to impact resistance Optimize Thermal Mechanical Integrity (TMI) cutters

CT CHIPPED CUTTERS

DELAMINATED CUTTERS DL

A chipped cutter is

characterized as a cutter that has minor breakage and less than 1/3 of the cutter has been broken. Chipping of diamond tables generally occurs in the outer most edge of a cutter.

Delaminated cutters is a condition in which the diamond layer, or a predominant portion of the layer, has cleanly come off the tungsten carbide interface.

(28)

POSSIBLE CAUSES

Excessive HSI amplified by abrasive mud and formation High velocity fluid creating turbulence and impingement on the

blades and cutting elements

Excessive level of low gravity solids in the mud Plugged nozzles

APPLICATION RECOMMENDATIONS Reduce jet velocity / HSI

Decrease low gravity solids in the mud Optimize nozzle placement

Utilize matrix body bits

POSSIBLE CAUSES

Cyclic excessive frictional heating and cooling Inadequate bit cooling

Improper drilling parameters, particularly excessive RPM for the application

Reaming hole at high RPM APPLICATION RECOMMENDATIONS

Consider bit design with improved hydraulic distribution Increase cutter density to decrease wear rate

Use a more wear-resistant PDC cutter

ER EROSION

HEAT CHECKING HC

Erosion is used to describe the loss of material on the cutting structure and bit body due to drilling fluids, solids and cuttings flowing against the drill bit.

Heat checking is characterized by many small cross-hatched pattern microcracks on any surface showing abrasive wear, such as cutter wear flats and gauge areas.

(29)

POSSIBLE CAUSES

Junk dropped in the hole from the surface (tong dies, tools, etc.) Junk from the drill string (reamer pins, stabilizer blades, etc.) Junk from a previous bit run (tungsten carbide inserts, ball bearings,

etc.)

Junk from the bit itself (tungsten carbide inserts, etc.) Damage due to contact with casing

Plan on running junk basket with next bit and anticipate reduced bit life

Circulate and rotate just above hole bottom to lift junk above bit face prior to drilling

Run a cleanout bit if necessary

Ensure hole is clean before running bit to drill ahead

POSSIBLE CAUSES

Impact - junk in hole, excessive torque

Intentional spudding of the bit or tagging the bottom too hard Dropping the drill string

Hitting ledges while tripping into the well Exceeding recommended WOB parameters APPLICATION RECOMMENDATIONS

Ensure hole is clean before running bit to drill ahead Review drill string handling procedures

Optimize drilling parameters

Trip into hole at reduced rate when ledges are suspected

JD JUNK DAMAGE

LOST MATRIX LM

Junk damage is described as a condition where the bit has drilled objects other than formation, causing indentations, cutter damage and broken blades. It is to be used in the remarks Other Dull Characteristics column.

Lost matrix is a condition in which a section of the blade and or bit body has chipped or broken off the bit.

(30)

POSSIBLE CAUSES

Missing or damaged O-ring and/or improper nozzle installation Mechanical or erosion damage to nozzle and/or nozzle retaining

system

Improper nozzle selection for hydraulic conditions Junk in the hole can damage nozzle or nozzle retention APPLICATION RECOMMENDATIONS

Insure O-ring is in place and confirm nozzles are properly installed (refer to Drill Bit Handbook for nozzle installation procedures) Review nozzle selection and hydraulics parameters

Note: A lost nozzle causes a pressure decrease which may require the bit be pulled out of the hole.

POSSIBLE CAUSES

Braze bond fails to retain the carbide in the cutter pocket Junk in the hole

Extreme downhole vibration

Fluid erosion of surrounding blade material APPLICATION RECOMMENDATIONS Optimize drilling parameters

Run BHA analysis and identify critical rotary speeds See recommendations under Erosion

LN LOST NOZZLE

LOST CUTTERS LT

Lost nozzle describes one or more missing nozzles. While lost nozzle is not a cutting structure dull characteristic, it is an important Other Dull Characteristic that can help describe a bit condition.

Lost cutter is a condition in which a cutter is completely gone from the cutter pocket. Lost cutters can be damaging to the remainder of the cutting structure. The loss of one cutting element can increase the workload for the adjacent cutting elements, and poten-tially decrease bit life.

(31)

POSSIBLE CAUSES

Foreign material such as pump parts or mud motor parts in drill string

Lost circulation material Cement cuttings during drillout

Cuttings moving into the bit through the nozzles during a connection plugging the nozzle when circulation is resumed

Running the bit back to bottom without turning on the pumps APPLICATION RECOMMENDATIONS

Use pipe screens Use nozzle strainers Run float

Increase nozzle size if possible

Insure pumps are on when approaching bottom As a rule of thumb, avoid mixing nozzle sizes which differ

by more than 2/32

POSSIBLE CAUSES

Improper bottom hole profile break-in Junk in the hole

Fluid erosion of surrounding blade material Improper bit selection

Excessive WOB for the application Formation change

Ensure hole is clean before running bit to drill ahead Use proper break-in procedures

Optimize hydraulics

Optimize drilling parameters

See recommendations under Junk Damage FEATURE RECOMMENDATIONS

Increase cutter density to decrease wear rate Use a more wear-resistant PDC cutter Secondary cutting elements

PN PLUGGED NOZZLE/FLOW PASSAGE

RING OUT RO

Plugged nozzle/flow passage is a condition where one or more of the nozzles are blocked. This problem can lead to reduced hydraulics efficiency and may require a trip out of the hole due to excessive pump pressure. This characteristic is used only in the "Other Dull Characteristics" column.

Ring out is described when a circular ring of cutting elements are worn down, typically to the blade top. It is often accompanied by the dull characteristic Heat Checking due to the extreme heat build-up which may have occurred.

(32)

POSSIBLE CAUSES

Excessive loading in which a crack may occur during the bit run Improper nozzle installation

Excessive hydraulic energy, predominately in steel bodied bits Damaged API threads or mud seal

Improper make-up torque APPLICATION RECOMMENDATIONS

Insure O-ring is in place and confirm nozzles are properly installed (refer to Drill Bit Handbook)

Optimize hydraulics

Follow proper make-up procedures (refer to Drill Bit Handbook)

POSSIBLE CAUSES

Abrasive formation or formation change Incorrect bit selection

Inadequate hydraulics for application Excessive RPM for application APPLICATION RECOMMENDATIONS Optimize hydraulics

Reduce RPM

Utilize SPARTA software to identify correct bit type FEATURE RECOMMENDATIONS

Use premium PDC cutters Increase cutter density Secondary cutting elements

WO WASHED OUT

WORN CUTTERS WT

Washout occurs when drilling fluid has eroded a passage from an internal flow area to the exterior of the bit. This characteristic is used only in the Other Dull Characteristics column.

Worn cutters are a normal characteristic that describes PDC wear with an even wear flat. The diamond layer is, for the most part, without major chips, spalling or cracks along the worn edge.

(33)

The following pages show additional descriptions for dulling fixed cutter bits that are not IADC standard, but help in identifying areas that are not listed under the standard IADC codes.

POSSIBLE CAUSES

Severe impact such as from hitting a ledge during trip in or a dropped drill string

Severe bit whirl or slip stick Junk in hole

Extreme change in formation, excessive torque APPLICATION RECOMMENDATIONS

Review drill string handling procedures

Run BHA analysis and identify critical rotary speeds See dull characteristic under Junk Damage

BROKEN BLADE

Broken blade is

described when an entire blade has broken off of the bit. The fracture must have been located between the body and 1/2 the height of the blade.

(34)

POSSIBLE CAUSES

Excessive WOB/RPM during reaming

Insufficient gauge cutting structure for application Excessive heat

APPLICATION RECOMMENDATIONS Increase flow rate

Refer to Drill Bit Handbook for reaming procedures Select a bit with higher cutter density on gauge

POSSIBLE CAUSES Excessive heat

High impact due to stick slip, bit whirl, junk or interbedded formations

APPLICATION RECOMMENDATIONS Increase cutter density

Optimize drilling parameters to reduce vibration FEATURE RECOMMENDATIONS

Use impact arrestors

Use secondary cutting structure such as R1 and MDRs Less aggressive cutter profile

Decrease cutter size Increase cutter chamfer size

REAMING WEAR

SPALLING

Reaming wear is characterized by extreme wear on the gauge and/or shoulder area which can lead to an undergauged bit.

Spalling is where areas of the diamond table have chipped off in thin layers or chips; however, the chips and fracturing of the diamond layer are never deep enough to reach the tungsten carbide interface.

Manual Halliburton

MANUFACTURING AND SERVICE

The Woodlands, Texas

936-442-4700

Brussels, Belgium

32 2 333 3510

SERVICE CENTERS

Grand Junction, Colorado

970-523-3900

Nisku, Alberta

866-373-2487 / TOLL FREE

Dammam, Saudi Arabia

966 3 812 1179

TABLE OF CONTENTS

ROLLER CONE IADC DULL GRADING SYSTEM 

QUICK REFERENCE CHART

IADC DULL GRADING SYSTEM  ROLLER CONE

BC  BROKEN CONE

BROKEN TEETH  BT

BU  BALLED UP

CRACKED CONE  CC

CD  CONE DRAGGED

CONE INTERFERENCE  CI

CR  CORED

CHIPPED TEETH  CT

ER  EROSION

FLAT CRESTED WEAR  FC

HC  HEAT CHECKING

JUNK DAMAGE  JD

LC  LOST CONE

LOST NOZZLE  LN

LT  LOST TEETH

OFF CENTER WEAR  OC

PB  PINCHED BIT

PLUGGED NOZZLE/FLOW PASSAGE  PN

RG  ROUNDED GAUGE

SHIRTTAIL DAMAGE  SD

SS  SELF-SHARPENING WEAR

TRACKING  TR

WO  WASHED OUT

WORN TEETH  WT

FIXED CUTTER IADC DULL GRADING SYSTEM 

QUICK REFERENCE CHART

IADC DULL GRADING SYSTEM  FIXED CUTTER

BF  BOND FAILURE

BROKEN CUTTERS  BT

BU  BALLED UP

CORED  CR

CT  CHIPPED CUTTERS

DELAMINATED CUTTERS  DL

ER  EROSION

HEAT CHECKING  HC

JD  JUNK DAMAGE

LOST MATRIX  LM

LN  LOST NOZZLE

LOST CUTTERS  LT

PN  PLUGGED NOZZLE/FLOW PASSAGE

RING OUT  RO

WO  WASHED OUT

WORN CUTTERS  WT

BROKEN BLADE

REAMING WEAR

SPALLING

ROLLER CONE IADC DULL GRADING SYSTEM

IADC DULL GRADING SYSTEM ROLLER CONE

BC BROKEN CONE

BROKEN TEETH BT

BU BALLED UP

CRACKED CONE CC

CD CONE DRAGGED

CONE INTERFERENCE CI

CR CORED

CHIPPED TEETH CT

ER EROSION

FLAT CRESTED WEAR FC

HC HEAT CHECKING

JUNK DAMAGE JD

LC LOST CONE

LOST NOZZLE LN

LT LOST TEETH

OFF CENTER WEAR OC

PB PINCHED BIT

PLUGGED NOZZLE/FLOW PASSAGE PN

RG ROUNDED GAUGE

SHIRTTAIL DAMAGE SD

SS SELF-SHARPENING WEAR

TRACKING TR

WO WASHED OUT

WORN TEETH WT

FIXED CUTTER IADC DULL GRADING SYSTEM

IADC DULL GRADING SYSTEM FIXED CUTTER

BF BOND FAILURE

BROKEN CUTTERS BT

BU BALLED UP

CORED CR

CT CHIPPED CUTTERS

DELAMINATED CUTTERS DL

ER EROSION

HEAT CHECKING HC

JD JUNK DAMAGE

LOST MATRIX LM

LN LOST NOZZLE

LOST CUTTERS LT

PN PLUGGED NOZZLE/FLOW PASSAGE

RING OUT RO

WO WASHED OUT

WORN CUTTERS WT