PDC Bit Dull Grading

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    19-Oct-2015

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DESCRIPTION

Engineering

Transcript

  • Dull Grading:

    Prepared by:

    Mohd Zulkhairi M Z

  • [outlines]

    PDC bit - overview Dull Grading-overview IADC Dull grading system chart

    Inner/outer row cutting structure Dull characteristics Location Gauge Reason pulled

    Dull grading: example Field application: SMDK-A5/ SMDK-A7 Conclusion

  • PDC Bit overview

    PDC

    Cutters

    Profile

    Gauge

    Bit Breaker

    Slot

    API Threaded

    Pin

    Junk Slot

    TFA Design

    From DBS Bit

    Blade

  • PDC Bit overview

    Blade 3

    Blade 4

    Blade 1

    Blade 5

    Junk

    slot Nozzle

    Blade 6

  • Dull Grading-overview

    IADC fixed cutter dull grading system

    Developed by IADC in 1987- revised 1991

    Applied for all fixed cutter bits

    PDC

    Natural Diamond

    Impregnated Diamond

  • Bit record- in 1984

    Old dull grading system (before 1987)

    [example from Malong SG17.2 appraisal well]

    Not descriptive

    T- teeth B- bearing G- gauge

  • Why??

    To draw a quick view of bit condition by using visual inspection and measuring tool.

    When??

    Primary- just after the bit was pulled out of hole

    Before rerunning back the used bit

    Dull Grading-overview

  • IADC Dull grading system chart

    Applied for both fixed cutter bits and roller cone bits

    First 4 spaces describes cutting structure

    B is for bearing and G for gauge

    Remarks indicate other dull characteristics and reason pulled

    Inner

    Rows

    Outer

    Rows

    Dullcharac-

    teristics

    Othercharac-

    teristics

    Reason

    pulled

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    8-Total lost

    of tooth

    height

    0-No lost

    of tooth

    height

    Grading numbers increase with amount of wear, with O

    representing no wear, and 8 meaning no

    usable cutters left. A grade of 4 indicates

    50% wear.

    [Brandon B.D.et al, IADC/SPE 23939]

    -Round cutter

    - Oval cutter

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    Inner Rows

    Outer Rows

    2 6

    (Does Not include gauge cutters)

  • Typical IADC PDC WEAR GAUGE.

    Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    19 mm @ in

    Diameter

    13mm @ in

    Diameter

    19 mm @ 1in

    Diameter

    38mm @ 1 in

    Diameter

  • Available PDC

    cutting sizes

    8,13,16,19,24 mm

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    BF - Bond Failure

    BT - Broken Teeth/Cutters

    BU - Balled Up

    CR - Cored

    CT - Chipped Teeth/Cutters

    ER - Erosion

    HC - Heat Checking

    JD - Junk Damage

    LN - Lost Nozzle

    NR - Not Rerunnable

    PN - Plugged Nozzle/Flow Area

    RO - Ring Out

    RR - Rerunnable

    WO - Wash Out on Bit

    WT - Worn teeth/Cutters

    LT - Lost Teeth/Cutters

    NO - No Other Major Dull

    Characteristics

    Du

    ll C

    ha

    racte

    ristics

    *Only PDC relevant code are shown

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    Locatio

    n o

    f the p

    rimary

    DC

    G gauge

    S shoulder

    N nose

    C cone

    T taper

    A all areas

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    Code Explanation

    I In Gauge

    1 Undergauge

    up to 1/16

    2 Undergauge

    1/16 to 1/8

    3 Undergauge

    1/8 to 3/16

    4 Undergauge

    3/16 to 1/4

    * Use ONLY PDC gauge ring!!

  • ( 4/16) undergauge

    Measure the

    gap between

    ring gauge and

    gauge cutter

  • Cutting Structure B G Remarks

    InnerRows

    OuterRows

    DullCharact-eristics

    Location BearingSeals

    Gauge(1/16)

    OtherCharact-eristics

    ReasonPulled

    X

    BHA - Change Bottomhole Assembly

    DMF - Downhole Motor Failure

    DSF - Drillstring Failure

    DST - Drill Stem Test

    DTF - Downhole Tool Failure

    LOG - Run Logs

    RIG - Rig Repair

    CM - Condition Mud

    CP - Core Point

    DP - Drill Plug

    FM - Formation Change

    HP - Hole Problems

    PP - Pump Pressure

    PR - Penetration Rate

    TD - Total Depth/CSG Depth

    TQ - Torque

    TW - Twist Off

    WC - Weather Conditions

    WO - Washout Drillstring

    Re

    aso

    n p

    ulle

    d

  • Bond Failure [ BF ]

    Occur when cutter failing along the bond between two carbide substrates

    Formation too hard for the selected bit

    Bit may bouncing due to formation changes

    Dull characteristics

    Broken teeth [ BT ]

    Cutting element is considered broken when 1/3 of the cutting element is broken to the

    substrate

    Caused by lack of bit stability

  • Balled up [BU]

    A condition where formation attached to the blade and bit body/face of the cutters

    May results in reducing ROP

    Create physical damages to bits body

    Rotary torque as the bit balls up

    Dull characteristics

    Washed out [ WO ]

    Occur when drilling fluid eroded a passage from internal to external area

    May results in twist off

    Causes Ppump and ROP

  • Cored [ CR ]

    A bit is considered cored if its centermost cutting elements are worn, broken or lost

    The cone area will show a significant wear from the formation

    Dull characteristics

    Heat checking [ HC ]

    Normally seen as cracks intersecting cutting elements

    Cracks initiated due to thermal shock/fatigue

    Can be seen at all areas: nose, shoulder, gauge

  • Ring out [ RO ]

    A bit is said to have ring out when a circular band of cutting elements are

    worn, broken or lost.

    The blade will show a significant wear from the formation.

    Always associated in Ppump &ROP

    Dull characteristics

    Plugged nozzle/waterway [ PN ]

    A characteristics when one/more nozzles are obstructed

    Always associated in Ppump

  • Worn Teeth [WT]

    A condition where bit height reduces

    due to cutting action

    Exhibit smooth wear

    characteristics

    Dull characteristics

    Lost Nozzle [ LN ]

    Describes a bit that missing one or more jet nozzles.

    Only stated at remarks column as LN

    Caused by improper installation

  • Lost Teeth [LT]

    No portion of cutter remain

    Graded as 8 in cutting

    structure

    Caused by overload

    condition

    Dull characteristics

    Erosion [ ER ]

    Usually occur around cutters

    Caused by several factors: body material, nozzle orientation, mud properties

    Often a secondary characteristics

  • Junk Damage [JD]

    Junk damage when contact with object other than formation

    Caused by foreign object in the hole

    Dull characteristics

    Chipped Teeth/Cutters [ CT ]

    Minor damage to diamond table and substrate

    Caused by impact damage

  • Example A

    R437GN was run in horizontal well

    1st run: drilled 118 m in 8.5 hrs,

    ROP = 13.9 m/hr

    2nd run: drilled 218 m in 13.5 hrs,

    ROP = 16.2 m/hr

    Formation type: n/a

  • R437GN was run in horizontal well

    Drilled 387 m in 30 hrs

    ROP = 13.1 m/hr

    Formation type: brittle to plastic shale/sandstone

    Example B

  • R435SG was run 4 times in North Sea

    Total footage drilled =977m in 166 hrs

    Formation type = salt / anhydrite

    Example C

  • SMDK-A7 12 PDC

    IR OR DC L B/S G O/C R/P

    0 1 CT S X IN NO TD

    Smith

    M75HKLSBPX

  • SMDK A5-8 PDC

    IR OR DC L B/S G O/C R/P

    0 0 NO A X IN NO TD

    Varel VB552-MG2

  • Conclusion/Recommendation

    Dull grading is vital in drilling campaign in order to evaluate the overall bit performance

    A thorough research should be conducted to optimize the bit performance

    For your reading pleasure: www.smithbits.com

    www.bakerhughes.com

    www.varelintl.com

    SPE/IADC papers 16142,16145 and 23939

  • DIMS-Bit record

  • Q & A

  • Thank you

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