Dull Grading 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

H06243 10/09 © 2008 Halliburton All Rights Reserved Printed in U.S.A. HALLIBURTON

Dri l l Bi ts & Se r v i ce s 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. Halliburton’s 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 bit’s 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 the nozzle boss for wear, erosion or damage. Examine all welds for any signs of cracking. Again, once you have examined the number one arm, rotate the bit and examine the number two arm and then the number three arm in the same manner.

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. Following these procedures will help ensure proper bit evaluation as you gain experience in dull grading. In the meantime, it is helpful to familiarize yourself with the various dull characteristics of the IADC System and photographs which are included in this manual.

TABLE OF CONTENTS

( ro l l e r c on e dri l l b i ts ) ( fi x e d c u tte r d ri l l bit s)

( ro l l e r c on e dri l l b i ts ) IADC Dull Grading System – Quick Reference Chart

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IADC Dull Grading System – Overview Inner Cutting Structure Outer Cutting Structure Dull Characteristics Location Bearings/Seals Gauge Other Dull Characteristics Reason Pulled or Run Terminated

3 3 4 5 6 7 8 9

Dull Evaluation (BC) Broken Cone (BT) Broken Teeth (BU) Balled Up (CC) Cracked Cone (CD) Cone Dragged (C I) 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 (L T) Lost Teeth (OC) Off Center Wear (PB) Pinched Bit (PN) Plugged Nozzle/Flow Passage (RG) Rounded Gauge (SD) Shirttail Damage (SS) Self-Sharpening Wear (TR) Tracking (WO) Washed Out (WT) Worn Teeth

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

IADC Dull Grading System – Quick Reference Chart

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IADC Dull Grading System – Overview Inner Cutting Structure Outer Cutting Structure Dull Characteristics Location Bearings/Seals Gauge Other Dull Characteristics Reason Pulled or Run Terminated

37 37 38 39 39 39 40 41

Dull Evaluation (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 (PN) Plugged Nozzle/Flow Passage (RO) Ring Out (WO) Washed Out (WT) Worn Cutters Broken Blade Reaming Wear Spalling

43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 60 61 62

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3 DULL CHARACTERISTICS (Use only cutting structure related codes) BC - Broken Cone* BT - Broken Teeth BU - Balled Up CC - Cracked Cone* CD - Cone Dragged*

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

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

2 OUTER CUTTING STRUCTURE (Gauge row only) In columns 1 and 2, a linear scale from 0 to 8 is used to describe the condition of the cutting structure according to the following:

-

PN RG RR SD SS TR WO WT -

CI CR CT ER FC HC JD LC LN LT NO NR OC PB

Cone # 1 2 3

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BEARINGS/ SEALS

Plugged Nozzle/Flow Passage Rounded Gauge Rerunnable Shirttail Damage Self-Sharpening Wear Tracking Washed Out Worn Teeth

Cone Interference Cored Chipped Teeth Erosion Flat Crested Wear Heat Checking Junk Damage Lost Cone* Lost Nozzle Lost Teeth No Dull Characteristic Not Rerunnable Off Center Wear Pinched Bit

4

LOCATION

4 LOCATION N - Nose Row M - Middle Row G - Gauge Row A - All Rows

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CUTTING STRUCTURE OUTER DULL ROWS CHAR.

1 INNER CUTTING STRUCTURE (All inner rows)

1

INNER ROWS 7

OTHER DULL CHAR.

8 REASON PULLED OR RUN TERMINATED BHA - Change Bottom Hole Assembly CM - Condition Mud CP - Core Point DMF - Downhole Motor Failure DP - Drill Plug

7 OTHER DULL CHARACTERISTICS (Refer to column 3 codes)

6 GAUGE (Measure in fractions of an inch) I - In Gauge 1 - 1/16” Out of Gauge 2 - 1/8” Out of Gauge 4 - 1/4” Out of Gauge

Sealed Bearings E - Seals effective F - Seals failed N - Not able to grade

5 BEARINGS/SEALS Non-Sealed Bearings A linear scale estimating bearing life used. 0 - No life used 8 - All life used, i.e., no bearing life remaining

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GAUGE

-

Drill String Failure Drill Stem Test Downhole Tool Failure Formation Change Hole Problems Hours on Bit Left in Hole Run Logs Pump Pressure Penetration Rate Rig Repair Total Depth/Casing Depth Torque Twist Off Weather Conditions

T6

T8

T5

T7

T4

NEW

T3 T1

T2

Cutting Structure Wear

• The number one cone contains the centermost cutting element. • Cones two and three follow in a clockwise orientation as viewed looking down at the cutting structure with the bit sitting on the pin.

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

DSF DST DTF FM HP HR LIH LOG PP PR RIG TD TQ TW WC

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REASON PULLED

ROLLER CONE IADC DULL GRADING SYSTEM – QUICK REFERENCE CHART

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T

1 Inner Rows I

2

B

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G

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Remarks

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Cutting Structure Outer Dull Location Bearings/ Rows Char. Seals O D L B

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8 Remarks Other Reason Dull Pulled O R

Gauge 1/16” G

1 INNER CUTTING STRUCTURE (I) (All inner rows) Used to report the condition of the teeth not touching the wall of the hole. 2 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

T3 T2 T1 NEW

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T4

T5 T6 T7 T8

3 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) (BT) (BU) (CC) (CD) (CI) (CR) (CT) (ER) (FC) (HC) (JD) (LC) (LN) (LT) (NO) (NR) (OC) (PB) (PN) (RG) (RR) (SD) (SS) (TR) (WO) (WT)

Broken Cone * Broken Teeth Balled Cracked Cone * Cone Dragged * Cone Interference Cored Chipped Teeth Erosion Flat Crested Wear Heat Checking Junk Damage Lost Cone * Lost Nozzle Lost Teeth No Dull Characteristic Not Rerunnable Off Center Wear Pinched Bit Plugged Nozzle/Flow Passage Rounded Gauge Rerunnable Shirttail Damage Self-Sharpening Wear Tracking Washed Out 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.

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(r oller con e dr ill b it s )

IADC DULL GRADING SYSTEM – ROLLER CONE

4 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 Steel Tooth Bit Nose Row “Spear Point” (Row 3)

C ON E 2

C ON E 1

Middle Row (Row 2) Gauge Row (Row 1)

Insert Bit CONE 1

Nose Row (Row 4)

C ON E 2

CO NE 3

Middle Row (Row 3)

5 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)

Middle Row (Row 2)

(ro lle r co ne d rill bit s)

CONE 3

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.

Gauge (Row 1) Surf Row Groove

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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 cone’s 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.

7 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) (BT) (BU) (CC) (CD) (CI) (CR) (CT) (ER) (FC) (HC) (JD) (LC) (LN) (LT) (NO) (NR) (OC) (PB) (PN) (RG) (RR) (SD) (SS) (TR) (WO) (WT)

Broken Cone Broken Teeth Balled Up Bit Cracked Cone Cone Dragged Cone Interference Cored Chipped Teeth Erosion Flat Crested Wear Heat Checking Junk Damage Lost Cone Lost Nozzle * Lost Teeth No Dull Characteristic Not Rerunnable Off Center Wear Pinched Bit * Plugged Nozzle/Flow Passage * Rounded Gauge Rerunnable Shirttail Damage * Self-Sharpening Wear Tracking Washed Out Bit * Worn Teeth

* Used only in the “Other Dull Characteristics” column.

(r olle r c on e drill bits )

6 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.

API STANDARD ROLLER CONE BIT TOLERANCES BIT SIZE (IN) 3-3/8 to 13-3/4 14 to 17-1/2 17-5/8 and Larger

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O.D. TOLERANCE (IN) +1/32, -0 +1/16, -0 +3/32, -0

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8 REASON PULLED OR RUN TERMINATED (R) Following are the two or three letter codes used to report termination of the bit run.

-

Change Bottom Hole Assembly Condition Mud Core Point Downhole Motor Failure Drill Plug Drill String Failure Drill Stem Test Downhole Tool Failure Formation Change Hole Problems Hours on Bit Left In Hole Run Logs Pump Pressure Penetration Rate Rig Repair Total Depth/Casing Depth Torque Twist Off Weather Conditions Washout in Drill String

(ro lle r co ne d rill bit s)

BHA CM CP DMF DP DSF DST DTF FM HP HR LIH LOG PP PR RIG TD TQ TW WC WO

NOTES

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B C – B R O K EN CO NE

BROKE N TE E TH – B T

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

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

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

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(ro lle r c on e drill bits )

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.

B U – B A LL ED U P

CRACKE D CON E – C C 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.

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

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.

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

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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

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C D – C O N E D RA G G ED

CON E IN TE RF E RE N CE – C I 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.

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

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

(r olle r c on e drill bits )

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

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.

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C R – C O R ED

CHIPPE D TE E TH – C T

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

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.

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

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(ro lle r c on e drill bits )

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.

E R – E R O S IO N

F LAT CRE STE D WE AR – F C 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.

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

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 APPLICATION RECOMMENDATIONS • Adjust to a more abrasion resistant cutting element material grade • Select proper bit type for the formation • Review and optimize WOB and RPM

(ro lle r c on e drill bits )

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

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.

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H C – H E AT CH ECK ING

JUN K 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.

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

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 APPLICATION RECOMMENDATIONS • 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

(ro lle r c on e drill bits )

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

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.

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L C – L O S T CO NE

LOST N OZ Z LE – L N 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.

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

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

(ro lle r c on e drill bits )

APPLICATION RECOMMENDATIONS • 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

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.

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L T – L O S T TEETH

OF F CE N TE R WE AR – O C 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.

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

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 APPLICATION RECOMMENDATIONS • 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

(ro lle r c on e drill bits )

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

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.

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P B – P INCH ED B IT

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.

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

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 (ro lle r c on e drill bits )

APPLICATION RECOMMENDATIONS • 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)

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.

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R G – R O UND ED G A U G E

SHIRTTAIL DAMAGE – S D 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.

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

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 APPLICATION RECOMMENDATIONS • 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) (ro lle r c on e drill bits )

APPLICATION RECOMMENDATIONS • 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

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.

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S S – S E L F- S H A RPENING WEA R 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.

POSSIBLE CAUSES • Abrasion from engagement with formation • In many applications, self-sharpening wear is a desirable characteristic on the cutting structure

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.

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

(ro lle r c on e drill bits )

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

TRACKIN G – T R

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W O – W A S H ED O U T

WORN TE E TH – W T 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.

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

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

(ro lle r c on e drill bits )

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

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 selfsharpening (SS) or flat crested (FC) wear.

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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.

Delaminated

Lost Cutter

Outer Area 1/3 Radius

Worn Cutter

Inner Area 2/3 Radius

2

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x

BEARINGS/ SEALS

CR CT DL ER HC JD LM LN LT NO NR PN RO RR WO WT -

Cored Chipped Cutters Delaminated Cutters Erosion Heat Checking Junk Damage Lost Matrix Lost Nozzle Lost Cutters No Dull Characteristics Not Rerunnable Plugged Nozzle/Flow Passage Ring Out Rerunnable Washed Out Worn Cutters

3 DULL CHARACTERISTICS BF - Bond Failure BT - Broken Cutters BU - Balled Up

1 INNER CUTTING STRUCTURE 2 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

4

LOCATION

( fi x e d c u tte r d ri l l b i ts )

3

CUTTING STRUCTURE OUTER DULL ROWS CHAR.

No Wear

1

INNER ROWS 7

OTHER DULL CHAR.

-

Taper

Shoulder

Nose

Cone

Downhole Tool Failure Formation Change Hole Problems Hours Left in Hole Run Logs Pump Pressure Penetration Rate Rig Repair Total Depth/Casing Depth Torque Twist Off Weather Conditions Washout - Drill String

Gauge

DTF FM HP HR LIH LOG PP PR RIG TD TQ TW WC WO

8

REASON PULLED

8 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 Test

7 OTHER DULL CHARACTERISTICS (Refer to column 3 codes)

6 GAUGE I - In Gauge 1 - 1/16” Out of Gauge 2 - 1/8” Out of Gauge 4 - 1/4” Out of Gauge

5 X

4 LOCATION C - Cone N - Nose T - Taper S - Shoulder G - Gauge A - All Areas

6

GAUGE

FIXED CUTTER IADC DULL GRADING SYSTEM – QUICK REFERENCE CHART

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IADC DULL GRADING SYSTEM – FIXED CUTTER T

1

2

B

3

4

G

Remarks

X

6

Cutting Structure Outer Dull Location Bearings/ Rows Char. Seals O D L B

Inner Rows I

Gauge 1/16” G

7

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.

8 Remarks Other Reason Dull Pulled O R

0

Original Waterway Depth

4

1 INNER CUTTING STRUCTURE (I)

8

2 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. Inner Area 2/3 Radius

0

Outer Area 1/3 Radius

1 2 3 4 5 6 7 8

Figure 1

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Figure 2

No Waterway Remaining

Figure 3

3 DULL CHARACTERISTICS (D) The most prominent or “primary” physical change from the new condition of the bit is recorded in the third space. “Other”or 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) (BT) (BU) (CR) (CT) (DL) (ER) (HC) (JD) (LM) (LN) (LT) (NO) (NR) (PN) (RO) (RR) (WO) (WT)

Bond Failure Broken Cutters Balled Up Cored Chipped Cutters Delaminated Cutters Erosion Heat Checking Junk Damage Lost Matrix Lost Nozzle Lost Cutters No Dull Characteristics Not Rerunnable Plugged Nozzle/Flow Passage Ring Out Rerunnable Washed Out Worn Cutters Broken Blade Reaming Wear Spalling

( fi x e d c u tte r d ri l l b i ts )

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.

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S – Shoulder G – Gauge A – All Areas

C – Cone N – Nose T – Taper

GAUGE

GAUGE

SHOULDER TAPER CONE

NOSE

CONE

GAUGE

NOSE

SHOULDER TAPER

GAUGE SHOULDER

SHOULDER CONE

NOSE

TAPER CONE

NOSE

5 BEARINGS/SEALS This space is only used for roller cone bits. It will always be marked “X” for fixed cutter bits. 6 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.

7 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) (BT) (BU) (CR) (CT) (DL) (ER) (HC) (JD) (LM) (LN) (LT) (NO) (NR) (PN) (RO) (RR) (WO) (WT)

Bond Failure Broken Cutters Balled Up Cored Chipped Cutters Delaminated Cutters Erosion Heat Checking Junk Damage Lost Matrix Lost Nozzle Lost Cutters No Dull Characteristic Not Rerunnable Plugged Nozzle/Flow Passage Ring Out Rerunnable Washed Out Worn Cutters

( fi x e d c u tte r d ri l l b i ts )

4 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:

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. API STANDARD FIXED CUTTER BIT TOLERANCES BIT SIZE (IN.) 6-3/4 and Smaller 6-25/32 to 9 9-1/32 to 13-3/4 13-25/32 to 17-1/2 17-17/32 and Larger

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O.D. TOLERANCE (IN.) -0.015 to +0.00 -0.020 to +0.00 -0.030 to +0.00 -0.045 to +0.00 -0.063 to +0.00

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8 REASON PULLED OR RUN TERMINATED (R)

NOTES

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

Change Bottom Hole Assembly Condition Mud Core Point Downhole Motor Failure Drill Plug Drill String Failure Drill Stem Test Downhole Tool Failure Formation Change Hole Problems Hours Left In Hole Run Logs Pump Pressure Penetration Rate Rig Repair Total Depth/Casing Depth Torque Twist Off Weather Conditions Washout Drill String ( fi x e d c u tte r d ri l l b i ts )

BHA CM CP DMF DP DSF DST DTF FM HP HR LIH LOG PP PR RIG TD TQ TW WC WO

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B F – B O N D FA IL U RE

BROKE N CUTTE RS – B T

POSSIBLE CAUSES • Incorrect bit selection • Improper WOB • Inadequate bottomhole pattern break-in • Excessive impact load / improper drilling practices • Interbedded formations • Bit vibration APPLICATION RECOMMENDATIONS • 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 MDR’s • Impact arrestors • Increase cutter density • Less aggressive cutter profile

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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.

POSSIBLE CAUSES • Incorrect bit selection • Improper WOB • Inadequate bottomhole pattern break-in • Excessive impact load / improper drilling practices • Interbedded formations • Bit vibration • Junk damage • Dropped bit • Running in hole too fast and encountering ledges or obstructions (f ix e d c u tte r d ri l l b i ts )

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

APPLICATION RECOMMENDATIONS • 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 MDR’s • Impact arrestors • Increase cutter density • Less aggressive cutter profile • Decrease cutter size

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B U – B A LL ED U P

CORE D – C R

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

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

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 (f ix e d c u tte r d ri l l b i ts )

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.

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

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DE LAMIN ATE D CUTTE RS – D L 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.

POSSIBLE CAUSES • Incorrect bit selection • Improper WOB • Inadequate bottomhole pattern break-in • Excessive impact load / improper drilling practices • Interbedded formations • Bit vibration APPLICATION RECOMMENDATIONS • 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 MDR’s • Impact arrestors • Increase cutter density • Less aggressive cutter profile • Decrease cutter size • Increase cutter chamfer size • Optimize cutter type with regards to impact resistance

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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.

POSSIBLE CAUSES • Excessive heat that degrades the diamond layer • Incorrect bit selection • Improper WOB • Inadequate bottomhole pattern break-in • Excessive impact load / improper drilling practices • Interbedded formations • Bit vibration APPLICATION RECOMMENDATIONS • Utilize SPARTA™ software to identify and locate interbedded formations and the relative rock strength • Optimize drilling parameters

(f ix e d c u tte r d ri l l b i ts )

C T – C H I PPED CU TTERS

FEATURE RECOMMENDATIONS • Secondary cutting structure such as R1™ and MDR’s • Impact arrestors • 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

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E R – E R O S IO N

HE AT CHE CKIN G – H C 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.

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 • Reduce jet velocity / HSI • Decrease low gravity solids in the mud • Optimize nozzle placement • Utilize matrix body bits

APPLICATION RECOMMENDATIONS • Consider bit design with improved hydraulic distribution • Increase cutter density to decrease wear rate • Use a more wear-resistant PDC cutter

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(f ix e d c u tte r d ri l l b i ts )

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

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JD – JUNK DAMAGE

LOST MATRIX – L M

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 APPLICATION RECOMMENDATIONS • 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

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

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

Dull Grading Manual

(f ix e d c u tte r d ri l l b i ts )

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.

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L N – L O S T NO ZZL E

LOST CUTTE RS – L T

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

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 potentially decrease bit life.

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 • Check for unusual bit damage and use proper procedures to deal with junk in the hole • Run BHA analysis and identify critical rotary speeds • See recommendations under “Erosion”

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

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(f ix e d c u tte r d ri l l b i ts )

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.

P N – P L UG G ED NO ZZL E/ FL O W PASSAGE

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”

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.

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 APPLICATION RECOMMENDATIONS • Ensure hole is clean before running bit to drill ahead • Use proper break-in procedures • Optimize hydraulics • Utilize SPARTA™ software to identify and locate interbedded formations and the relative rock strength • Optimize drilling parameters • See recommendations under “Junk Damage”

(f ix e d c u tte r d ri l l b i ts )

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.

RIN G OUT – R O

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

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W O – W A S H ED O U T

WORN CUTTE RS – WT

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)

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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.

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 (f ix e d c u tte r d ri l l b i ts )

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.

FEATURE RECOMMENDATIONS • Use premium PDC cutters • Increase cutter density • Secondary cutting elements

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BROKE N BLADE 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.

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.

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

(f ix e d c u tte r d ri l l b i ts )

APPLICATION RECOMMENDATIONS • Review drill string handling procedures • Run BHA analysis and identify critical rotary speeds • See dull characteristic under “Junk Damage”

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R E A M ING WEA R

SPALLI NG

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

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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.

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 MDR’s • Less aggressive cutter profile • Decrease cutter size • Increase cutter chamfer size

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(f ix e d c u tte r d ri l l b i ts )

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

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