brocas iadc

Bits and HolemakingIPM

Bits and Holemaking

DRILLING PRACTICES


IADC Bit Classification


IADC Classification – Roller Cone

Ref: SPE 23937 The IADC Roller Bit Classification System

8-1/2” EHP 51

517G

Soft Formations w ith Low Compressive Strength and High

Drillability

1

Medium to Medium Hard Formations w ith

High Compressive Strength

2Hard Semi-Abrasive

and Abrasive Formations

3Soft Formations w ith Low Compressive Strength and High

Drillability

4

Soft to Medium Formations w ith Low

Compressive Strength5

Medium Hard Formations w ith High

Compressive Strength6

Hard Semi-Abrasive and Abrasive Formations

7Extremely Hard and

Abrasive Formations 8

INSERT BITS

STEEL TOOTH

BITS

Cutting Structure Series Cutting Structure Type (1 to 4)

1 refers to the softest formation in a

particular Series and 4 refers to the

hardest formation within the Series

Bearing/Gauge Description

Standard Roller

Bearing1

Roller Bearing Air

Cooled2

Roller Bearing Gauge

Protected

3Sealed Roller

Bearing4

Sealed Roller Brg -

Gauge Protected

5Sealed Friction Bearing

6Sealed

Frction Brg Gauge

Protected

7

Features Available (Optional)

A - Air ApplicationB - Special Bearing SealC - Center JetD - Deviation ControlE - Extended NozzlesG - Gauge/Body ProtectionH - Horizontal Steering Appl.J - Jet DeflectionL - Lug PadsM - Motor ApplicationS - Standard Steel ToothT - Two Cone BitW - Enhanced Cutting StructureX - Predominantly Chisel Tooth InsertY - Conical Tooth InsertZ - Other Shape Insert


Soft

Hard

IADC CodesTooth

2

1

3

1-1

1-3

2-1

IPM


Soft

Hard8

7

6

4

5

Tooth

Insert

IADC Codes

2

1

3

8-3

4-1

IPM


Soft

Hard

1

8

7

6

4

5

Tooth

Insert

2

1

3

PDC

IADC Codes

IPM


Soft

Hard 8

7

6

4

5

Tooth

Insert

Diamond

IADC Codes

2

1

3

PDC

IPM


Soft

Hard

1

8

7

6

4

5

Tooth

Insert

2

1

3Impregnated

Diamond

IADC Codes

Diamond

PDC

IPM


IADC Bit Dull Grading Code


IADC Bit Dull Grading CodeThe International Association of Drilling Contractors has developed a standard methodology for describing used bits. This information is essential for detailed bit performance analysis.

The methodology is composed of an 8 character code that describes bit wear and the reason why the bit was pulled.

INNER ROWS

OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED

Cutting Structure RemarksB G


IADC Bit Dull Grading CodeINNER ROWS

OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED


Fixed Cutter Bits

The cutting structure is graded from 0 to 8 depending on the proportion of cutting structure lost (0 = Intact, 8 = 100% worn).

Roller Cone Bits

Inner Cutting Structure (All Inner Rows)

Outer Cutting Structure (Gauge Row Only)

0 1 2 3 4 5 6 7 8

Cone 2Cone 3

Cone 1

IPM Ref : Reed Hycalog PDC & Roller Cone Product Technology Reference Information



OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED


BF - Bond Failure BT - Broken Cutters BU - Balled Up CT - Chipped Cutters ER - Erosion HC - Heat Checking JD - Junk Damage LN - Lost Nozzle LT - Lost Cutter NR - Not Rerunable PN - Plugged Nozzle RG - Rounded Gauge RO - Ring Out RR - Rerunable SS - Self Sharpening Wear TR - Tracking WO - Washed Out Bit WT - Worn Cutters NO - No Dull Characteristics

*BC - Broken ConeBF - Bond FailureBT - Broken Teeth/CuttersBU - Balled Up Bit*CC - Cracked Cone*CD - Cone DraggedCI - Cone InterferenceCR - CoredCT - Chipped Teeth/CuttersER - ErosionFC - Flat Crested WearHC - Heat CheckingJD - Junk Damage*LC - Lost Cone

LN - Lost NozzleLT - Lost Teeth/CuttersOC - Off-Center WearPB - Pinched BitPN - Plugged Nozzle/Flow PassageRG - Rounded GaugeRO - Ring Out SD - Shirttail DamageSS - Self Sharpening WearTR - TrackingWO - Washed Out BitWT - Worn Teeth/CuttersNO - No Dull Characteristic * Show Cone under Location 4

Fixed Cutter Bits Roller Cone Bits

Note that this is for the Primary dull characteristics.

Ref : Reed Hycalog PDC & Roller Cone Product Technology Reference Information


Fixed Cutter – Main Wear Characteristics

NO WEAR(NO)

WORNCUTTER

(WT)

BROKENCUTTER

(BT)

LOSTCUTTER

(LT)

EROSION(ER)

POST OR STUD CUTTERS

NO WEAR(NO)

WORNCUTTER

(WT)

BROKENCUTTER

(BT)

LOSTCUTTER

(LT)

CYLINDERCUTTERS

BONDFAILURE

(BF)

BONDFAILURE

(BF)

Courtesy of


Dull Characteristics – Some Examples


Fixed Cutter Bits

BU - Balled Up



*BC - Broken ConeBF - Bone FailureBT - Broken Teeth/CuttersBU - Balled Up Bit*CC - Cracked Cone*CD - Cone DraggedCI - Cone InterferenceCR - CoredCT - Chipped Teeth/CuttersER - ErosionFC - Flat Crested WearHC - Heat CheckingJD - Junk Damage*LC - Lost Cone


Roller Cone Bits


BT – Broken Teeth (primary)

CD – Cone Dragged (secondary)

Ref : IADC Drilling Manual – Eleventh Edition




Fixed Cutter Bits

CT – Chipped Cutter





Fixed Cutter Bits

LT – Lost Cutter





Roller Cone Bits


BT – Broken Teeth/Cutters





Fixed Cutter Bits

La

RO – Ring Out





Roller Cone Bits


JD – Junk Damage





Fixed Cutter Bits

WT – Worn Cutters





Roller Cone Bits


SD - Shirttail Damage





Roller Cone Bits


TR - Tracking




Roller Cone Bits


SS – Self Sharpening Wear





Roller Cone Bits


ER – Erosion




OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED



C - Cone N - Nose T - Taper S - ShoulderG - Gauge

N - Nose RowM - Middle RowG - Gauge RowA - All Rows

Cone 1, 2 or 3




OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED



This box is for roller cone bits. Fixed cutter bits will always be designated by "X".

A linear scale estimating bearing life used. (0 -No life used, 8 - All life used, i.e., no bearing life remaining.)

Non Sealed Bearings

Sealed BearingsE - Seals EffectiveF - Seals FailedN - Not Able to Grade




OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED


For all Bits

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

If the bit is under gauge, the amount is recorded to the nearest 1/16” of an inch. For example, if the bit is 1/8” under gauge, this is reported as 2/16 or often only as 2.




OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED





Fixed Cutter Bits Roller Cone BitsThis is for the Secondary dull char. and it uses the same codes as for the Primary dull char.




OUTERROWS

DULL CHAR

LOCA- TION

BRNG/ SEALS

GAUGE 1/16”

OTHER CHAR

REASON PULLED


For All Bits

BHA - Change Bottom Hole Assembly DMF - Down hole Motor Failure DSF - Drill String Failure DST - Drill Stem Test DTF - Down hole Tool Failure RIG - Rig Repair CM - Condition Mud CP - Core Point DP - Drill Plug FM - Formation Change

HP - Hole Problems HR - Hours PP - Pump Pressure PR - Penetration Rate TD - Total Depth/Casing Point TQ - Torque TW - Twist Off WC - Weather Conditions WO - Washout -DrillString



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

Photo courtesy of


BIT RECORD

Well : BIT RECORDDate :

Bit DataBHA Bit Size Bit type Serial IADC Nozzles Depth Depth Drilling ROP Bit krevs WOB Rot Flow Press Inc Mud Total Total Total DullNo. No. (inch) & maker Number Code (1/32") IN (m)OUT (m) Time (m/hr)(drilling) (Klbs) (RPM) (GPM) (psi) (deg) SG mtr hrs krevs I O D L B G O R1 1 16 T11C L15264 115 3 x 18, 1

x 16 15 420 18.04 22.45 151.50 10-25 120 820 1450 0 1.07 405 18.04 152 0 1 WT A E I NO TD

2 2RR 12 1/4 DSX113 204556 PDC 8 x 13 420 422 0.50 4.00 1.22 2-10 60 680 1000 0.00 1.15 2 0.50 1 0 1 WT S X I CTBHA4 2RR2 12 1/4 DSX113 204556 PDC 8 x 13 1408 1714 16.54 18.50 119.09 25-35 120 820 1900 1.00 1.19 308 17.04 120 1 3 WT A X I PN TD

Run Data Bit life Grading

To be filled up at wellsite

•BHA nb does not always = bit nb

•Drilling time = bit time on bottom ( Mud loggers)

•Krevs = 1000 bit revolution ( Mud loggers)


Drilling Parameters vs Bit Performance


DIFFERENTIAL PRESSURE AT BIT

Erosion

Depth of Cut

Wash out

Worn CuttersWOB

Flow Rate

Drilling Problem Identification


CIRCULATING PRESSURE (standpipe pressure with bit off bottom)

Nozzles

Restriction

Wash out

PumpsMud Weight

Flow Rate

Mud Properties

Air in Mud



TORQUE

WOB

Hole Angle

Wash out

FormationMud Weight

Hole Cleaning

Mud Properties

Junk

Bit Related RPM

Reaming Dry Drilling



RATE OF PENETRATION

RPM/WOB

Hole Angle

Wash out

FormationOverbalance

Hydraulics

Bit RelatedJunk



Condition of Dull Bit Possible Causes Possible RemediesExcessive bearing wearExcessive rotary speed

Excessive rotating timeExcessive WOB

Excessive sand in circulating systemUn-stabilised drill collarsImproper bit type

Slower rotary speedReduced rotating hoursLighter WOB

Removal of sand from circulating fluidStabilise drill collars

Use harder formation bit type withstronger bearing structure

Excessive broken teethImproper bit typeImproper break-in procedure used

for new bitExcessive WOB for type used

Use harder formation bit type havingmore teeth

Proper break-in procedure used for newbit

Lighter WOBUnbalanced tooth wearImproper bit type

Improper break-in procedure usedfor new bit

Use of different bit type based upon therows of teeth which are excessively

worn on the dull bitProper break-in procedure used for new

bitExcessive tooth wear Excessive rotary speed

Improper bit typeUse of non hardfaced type

Slower rotary speedUse of harder formation bit type having

a greater number of teethUse of bit type having hardfaced teeth

Fluid cut teeth & coneExcessive circulation rate of fluidExcessive sand in circulating system

Reduction in circulation fluid rateRemoval of sand from circulation fluid

Excessivelyundergauge

Improper bit typeExcessive rotating time

Use of bit having greater gaugeprotection

Reduce rotating hoursSkidded due to balling Excessive WOB

Improper bit typeInsufficient fluid circulation rate

Lighter WOBUse of softer formation bit type having

teeth more widely spacedIncrease fluid circulation rate

ROLLER CONE BITSDrilling Problem Identification


Condition of Dull Bit Possible Cause Possible RemediesPolished diamonds Rotating in a hard formation

without making holeAdd WOB or select a bit withsmaller diamonds/cutters

Shattered diamonds Improper stabilisationAbnormal vibrations

Improper handling

Correct the stabilisationReduce the vibration bychanging the RPMProper handling

Sheared diamonds Improper break-in,Broken nose stones

Clean bottom of hole,Correct break-in procedure

Burned (flattened)diamonds

Inadequate cooling Increase the circulation rate toimprove cooling

Burned bit Overheating as a result ofplugging and/or balling up

Take care of proper hydraulics

Heat checking of PDCsupports or bit body(matrix)

Overheating

Worn throat Fragments of hard formationrolling in the throat

Proper hydraulics

Loss of gauge Long intervals reamed withinsufficient cooling due toclogged junk slots

When reaming minimise RPMand bit weight

Junk damage Junk in hole just ahead of thefirst diamond bit used

Clean bottom on previous bitrun with a junk basket in the

string

FIXED CUTTER BITSDrilling Problem Identification


Bit performance Main function: ROP and longevity

Drilling fluid is circulated through passageways in the bit to remove cuttings and apply hydraulic power to improve ROP

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


Cutting Structure ComparisonsHP83EHP41H

Faster DrillingLess Durable

Slower DrillingMore Durable

42

Tooth & Insert Cutter Designs Soft Formation

Fewer Teeth Longer Teeth Bigger Teeth Sharper Teeth Round Profile Fracture-Resistant

Tooth Material Faster Drilling Less Durable

Hard Formation

• More Teeth• Shorter Teeth• Smaller Teeth• Duller Teeth• Flat Profile• Wear-Resistant Tooth Material

• Slower Drilling• More Durable

43


• Under no circumstances should the cutting structure of fixed cutter bit be allowed to contact any steel surfaces.

• All bits should be gauged with an appropriately sized gauge ring

• Bit serial number should be recorded, together with the bit type and diameter.

• Tricone bits should be made up to the drill string using a correctly sized bit breaker.

• Fixed cutter bits should be “walked” by hand before applying correct torque.

• Natural diamond bits, impregnated bits and TSP bits have a fixed TFA which can not be modified at the rig site.

Bit Handling and Make up


Roller Cone BitsRunning in

• Make the bit up to proper torque.• Lower the bit slowly through ledges and dog legs

• Lower the bit slowly at liner tops• Roller cone bits are not designed for reaming. If reaming is required then it should be undertaken with light weight and low RPM

• Protect nozzles from plugging

Establish a bottom hole pattern• Rotate the bit and circulate when approaching bottom. This will prevent plugged nozzles and clear out hole fill.

• Lightly tag the bottom with low RPM.• Gradually increase the RPM.

• Gradually increase weight on WOB.

Before re-running green bits• Make sure the bit is in gauge.

• Check any bit for complete cutting structure.• Check any sealed bearing bit for effective seals.

• Soak any sealed bearing bit in water or diesel to loosen formation packed in the reservoir cap equalisation ports.• Re-grease l4¾" diameter and larger open bearing bits.

Bit Running Procedures


Fixed Cutter BitsPREPARATION

• Before running a diamond bit into the hole, have a junk basket run on the previous bit.

• After the previous bit is pulled, inspect it for junk damage and other wear, then gauge it.

• If the previous bit appears OK, the bit may be prepared to be run into the hole.

• Check O-ring and install nozzles, if appropriate, using the correct nozzle spanner as supplied by the bit manufacturer.

• Check for cutter damage.

• Check that the bit is within tolerance on diameter and that there is no foreign material inside it.



Fixed Cutter BitsRUNNING THE BIT (ROTARY ASSEMBLY)

• Handle the fixed cutter bit with care. DO NOT set the bit down without placing wood or a rubber pad beneath the diamond cutters.• A correct bit breaker should be used and the bit should be made up to the correct torque as determined by the pin connection size.• Care should be taken in running the bit through the rotary table and through any known tight spots. Hitting ledges or running through tight spots carelessly may damage the cutters or gauge.

• Reaming is not recommended, however, if necessary, pick up the string and run the maximum fluid possible. Rotate at about 60 RPM. Advance bit through tight spot with no more than 4000 pounds weight on bit (WOB) at any time.

• As hole bottom is approached, the last three joints should be washed down slowly at full flow and with 40 to 60 RPM to avoid plugging the bit with fill.• Once the bottom is located, the bit should be lifted just off bottom (0 to 1 foot if possible) and full volume circulated while slowly rotating for about 5 to 10 minutes.

• After circulating, ease back to bottom and establish the bottom hole pattern.• When ready to start drilling, increase the rotary speed to about 100 RPM and start cutting a new bottom hole pattern with approx. 1000 to 4000 pounds WOB.

• Cut at least one foot in this manner before determining optimum bit weight and RPM for drilling.• Determine optimum ROP by conducting a drill-off test.



Fixed Cutter BitsRUNNING THE BIT (PDM or TURBINE)

• Start the pumps and increase to the desired flow rate when approaching bottom.

• After a short cleaning period, lower the bit to bottom and increase WOB slowly.

• After establishing a bottom hole pattern, additional weight may be slowly added.

• As weight is increased, pump pressure will increase, so the differential pressure and WOB must be kept within the recommended downhole motor specifications.

• drillpipe should be slowly rotated to prevent differential sticking.

• All other operating practices are as per standard practices.


brocas iadc

Engineering