IADC : Dull Bit Grading
Cutting structure Example of bit grading : 2, 4, BT, M, E, X, (CT,WO), DTF.
Bearings seals Gauge Other dull char Reason pulled
Inner Outer Dull Char Location
1 2 3 4 5 6 7 8
1 - Inner cutting structure (All inner rows.) 4 - Location
2 - Outer cutting structure ( Gauge rows only.) Roller cone Fixed cutter
In columns 1 and 2 a linear scale of 0 ---> 8 is used to describe the condition of the cutting
structure according to the following guidelines for specific bit types. N- Nose row G - Gauge row C - Cone S - Shoulder
Steel toothed bits Measure of lost tooth height due to abrasion and / or damage M - Middle row A - All Rows N - Nose G - Guage
0 - No loss of tooth height State cone # or #'s I.e. 1, 2, or 3. T - Taper A - All areas
8 - Total loss of tooth
Insert bits Measures total cutting structure reduction of lost, worn, & or broken inserts 5 - Bearings and seals
0 - No lost worn and / or broken inserts Non sealed bearings Sealed bearings
8 - 0% of inserts and / or cutting structure remaining. A linear scale estimating bearing life is used E - Seals effective F - Seals failed
Fixed cutter bits Measure of lost tooth height due to abrasion and / or damage 0 = No life used ---> 8, 100% bearing life used N - Not able to grade X - Fixed cutter bit
0 - No lost, worn and / or broken cutting structure 6 - Gauge
8 - 100% of cutting structure lost, worn and / or broken x - in gauge 1/16 - 1/16" out of gauge 1/8 - 1/8" ut of gauge 3/16-3/16" out of gauge
3 - Dull characteristics 1/4 - 1/14" out of gauge 5/16 - 5/16" out of gauge 3/8 -3/8" out of gauge 7/16 - 7/16" out of gauge
Note: use only cutting structure related codes 1/2 - 1/2" out of gauge 9/16 - 9/16" out of gauge 5/8 - 5/8" out of gauge etc.
BC - Broken cone * LN - Lost nozzle 7 - Other dull characteristics
BF - Bond failure LT - Lost teeth and cutters Refer to column 3 codes
BT - Broken teeth and cutters OC - Off centre wear 8 - Reasons bit was pulled or run completed
BU - Balled up bit PB - Pinched bit BHA- Change bottom hole assembly HR - Hours on bit
CC - Cracked cone * PN- Plugged nozzle or flow by areas DMF - Downhole motor failure LOG - Run logs
CD - Cone dragged * RG - Rounded gauge DTF - Downhole tool failure PP - Pump pressure
CI - Cone interference RO - Ring out DSF - Drill string failure PR - Penetration rate
CR - Cored SD - Shirttail damage DST - Drill stem test Rig - Rig repair
CT - Chipped Teeth & cutters SS - Shelf sharpening wear DP - Drill Plug TD - Total depth / casing depth
ER - Erosion TR - Cone tracking CM - Condition mud TW - Twist off
FC - Flat crested wear WO - Wash out CP - Core point TQ - Torque
HC - Heat checking WT - Worn teeth or cutters FM - Formation change WC - Weather conditions
LD - Junk damage NO - No dull characteristics HP - Hole problems
LC - Lost cone * * Show cone # or #'s under location 4 LIH - Left in hole
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IADC classification : Rock bits
Series Formation types 1 2 3 4 5 6 7 8
Sealed bearing, Sealed friction
Standard Roller bearing Sealed roller Friction
3 gauge bearing, gauge 8
roller bearing air cooled bearing bearing
protected protection
Milled tooth bits.
1 Soft formations 1. Very soft shale
Low compressive strengths 2. Soft shales
3. Medium soft shale / lime
4. Medium lime shale
2 Medium - Medium hard formations & 2. Medium lime / shale
1.
High compressive strengths 3. Medium hard lime/sand/slate.
3 Hard 1. Hard lime
Semi-abrasive formations. 2. Hard lime/dolomite
3. Hard dolomite
TCI/Insert bits.
4 Soft formations 1. Very soft shale
Low compressive strengths 2. Soft shales.
3. Medium soft shale / lime
4. Medium lime shale.
5 Soft - medium hard formations 1. Very soft shale / sand.
Low compressive strengths 2. Soft shale / sand.
3. Medium soft shale / lime.
6 Medium - hard formations 1. Medium lime / shale.
High compressive strengths 2. Medium hard lime / sand.
3. Medium hard lime/sand/slate
7 Hard semi - abrasive 1. Hard lime / dolomite.
and abrasive formations 2. Hard sand /dolomite.
3. Hard dolomite.
8 Extremely hard & abrasive 1. Hard chert.
& abrasive 2. Very hard chert.
3. Hard granite.
Insert manufacturers bit codes you use in your operational area into appropriate series/formation type
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IADC classification : PDC bits
A B C D
Bit body Formation type Cutting structure Bit profile.
"M" Matrix 1 Very soft 2 PDC, 19mm 1 Short fishtail
"S" Steel 3 PDC, 13mm 2 Short profile
"D" Diamond 4 PDC, 8mm 3 Medium profile
2 Soft 2 PDC, 19mm 4 Long profile
Example 3 PDC, 13mm
M Matrix 4 PDC, 8mm
4 Medium 3 Soft to medium 2 PDC, 19mm
3 PDC 13mm 3 PDC, 13mm
4 Long profile 4 PDC, 8mm
4 Medium 2 PDC, 19mm
3 PDC, 13mm
4 PDC, 8mm
5 no code
6 Medium hard 1 Natural diamond
2 TSP
3 Combination
7 Hard 1 Natural diamond
2 TSP
3 Combination
8 Extremely hard 1 Natural diamond
4 Impregnated diamond
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The 4th Character IADC code.
Manufacturer
Feature and 4th Character Security / DBS Hughes Reed Smith
A Air application (journal bearing with air nozzles) A A A
B Special bearing bit Standard ** ATM*
C Centre jet J4 C* JC C
D Deviation control D* A1
E Extended jets (full length) E T* JX E
G Extra gauge / body protection G*, M*, D, SS* M*, D, G JK G, L, D, OD
H Horizontal / Steering Application Hx*, SS*, MM* M* M*
J Jet deflection JD JD BH*
L Lug pads L P* JL L
M Motor application SS*, MM*, M* MAX* M* M*
S Standard steel tooth model TC* A1
T Two cone 2* D D
w Enhanced cutting structure D
X Predominantly chisel toothed inserts - A
Y Predominantly conical inserts CF
Z Other shaped inserts C*
* Prefix, usually precedes bit number, others are suffices.
** Special HDS seal available as standard feature.
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Total flow area (TFA) of Standard nozzles (ins2)
Number of nozzles
Nozzle size 1 2 3 4 5 6 7 8 9
7/32 0.038 0.075 0.113 0.150 0.188 0.225 0.263 0.301 0.338
3/8 0.110 0.221 0.331 0.442 0.552 0.663 0.773 0.884 0.994
9/32 0.062 0.124 0.186 0.249 0.311 0.373 0.435 0.497 0.559
5/16 0.077 0.153 0.230 0.307 0.383 0.460 0.537 0.614 0.690
11/32 0.093 0.186 0.278 0.371 0.464 0.557 0.650 0.742 0.835
3/8 0.110 0.221 0.331 0.442 0.552 0.663 0.773 0.884 0.994
13/32 0.130 0.259 0.389 0.518 0.648 0.778 0.907 1.037 1.167
7/16 0.150 0.301 0.451 0.601 0.752 0.902 1.052 1.203 1.353
15/32 0.173 0.345 0.518 0.690 0.863 1.035 1.208 1.381 1.553
1/2 0.196 0.393 0.589 0.785 0.982 1.178 1.374 1.571 1.767
17/32 0.222 0.443 0.665 0.887 1.108 1.330 1.552 1.773 1.995
9/16 0.249 0.497 0.746 0.994 1.243 1.491 1.740 1.988 2.237
19/32 0.277 0.554 0.831 1.108 1.384 1.661 1.938 2.215 2.492
5/8 0.307 0.614 0.920 1.227 1.534 1.841 2.148 2.454 2.761
21/32 0.338 0.676 1.015 1.353 1.691 2.029 2.368 2.706 3.044
11/16 0.371 0.742 1.114 1.485 1.856 2.227 2.599 2.970 3.341
23/32 0.406 0.811 1.217 1.623 2.029 2.434 2.840 3.246 3.652
3/4 0.442 0.884 1.325 1.767 2.209 2.651 3.093 3.534 3.976
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Bit calculations
Insert values to view blue results.
Bit cost (£) £ 23,000 Mud weight (ppg) 11 ppg
Rig cost (£/hr) £ 4,000.00 Flow rate (gpm) 950 GPM
2
Trip time (hrs) 18.0 hrs Total flow area (in ) 0.81 sq in
In hole time (hrs) 200.0 hrs Hole size (inches) 12.25 ins
Footage drilled (ft) 3560 ft Hole area 118 sq in
Cost per foot 251.4 £/ft Bit pressure drop 1129 psi
Bit Hydraulic horse power 626 hp
Jet velocity 375 ft/sec
Hydraulic horse power per square inch 5.3 HSI
Rules of thumb
Water based muds: aim for 4-8 HSI, jet velocities 350-550ft/sec
Oil based muds: 3-6 HSI, jet velocities 250-450ft/sec
>17 1/2" holes : minimum jet velocities must be attained
<17 1/2" hole : 35-50% HHP @ bit. (consider formations to be drilled.)
<12 1/4" hole more HSI, up to 65% at bit. (dependant upon formations to be drilled.)
12 1/4" directional hole 800gpm min, 1100gpm max
8 1/2" directional hole 450 - 650gpm.
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Drill off test
Weight on bit optimisation Rotary optimisation
Rate of Rate of
Bit weight Time to drilloff Footage drilled Time to drill 1ft
penetration RPM penetration
(Klbs) 10K (seconds) (ft) (seconds)
(ft/hr) (ft/hr)
50 Klbs 60 secs 0.6 ft 36 ft/hr 140 RPM 120 secs 30 ft/hr
45 Klbs 68 secs 0.6 ft 29 ft/hr 130 RPM 110 secs 33 ft/hr
40 Klbs 73 secs 0.6 ft 27 ft/hr 120 RPM 100 secs 36 ft/hr
35 Klbs 75 secs 0.5 ft 22 ft/hr 110 RPM 108 secs 33 ft/hr
30 Klbs 82 secs 0.5 ft 22 ft/hr 100 RPM 118 secs 31 ft/hr
50 Klbs 62 secs 0.6 ft 35 ft/hr 140 RPM 124 secs 29 ft/hr
Drill off test (WOB) Drill off test (RPM)
40 ft/hr
90 secs
36 ft/hr
82 secs
35 ft/hr
Rate of penetration
80 secs
Rate of penetration
33 ft/hr
33 ft/hr
75 secs
73 secs
31 ft/hr
70 secs 30 ft/hr 30 ft/hr
68 secs 29 ft/hr
62 secs
60 secs 60 secs 25 ft/hr
30 Klbs 40 Klbs 50 Klbs 100 RPM 120 RPM 140 RPM
Weight on bit RPM
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Bit API Reg. Pin Make up *ft/lbs
O. D. (in) Pin connection, size&type Torque (ftlbs)
3-3/4 - 4-1/2 2 3/8 reg 3500 ftlbs
4-5/8 - 5 2 7/8 reg 7000 ftlbs
5-1/8 - 7-3/8 3 1/2 reg 9000 ftlbs
7-5/8 - 9 4 1/2 reg 16000 ftlbs
9-1/2 - 14-1/2 6 5/8 reg 32000 ftlbs
Over 14-1/2 7 5/8 reg 40000 ftlbs
API Roller cone bit tolerances..
Bit size : Nominal ( in inches )
5 5/8" - 13 3/4" + 1 / 32" minus 0
14" - 17 1/2 " + 1 / 16" minus 0
17 5/8" and larger + 3 / 32 " minus 0
API Diamond Bit Tolerances - PDC, Natural Diamond, TSP
Nominal Bit Size O.D. (ins) O.D. Tolerance (inches)
6-3/4 and Smaller +0, - 0.015
6-25/32 to 9, Incl. +0, - 0.020
9-1/32 to 13-3/4, Incl. +0, - 0.030
13-25/32 to 17-1/2, Incl. +0, - 0.045
Recommended drilling parameters, PDC bits.
Weight on
Bit size(inches) Rotary (RPM)
bit (Klbs)
Flow rate (GPM)
5 7/8 100 - 140 15 - 40 160 - 260
6 100 - 140 15 - 40 160 - 280
6½ 100 - 140 15 - 40 220 - 350
6¾ 100 - 140 15 - 40 250 - 350
7 7/8 80 - 120 15 - 40 300 - 400
8½ 80 - 120 15 - 40 300 - 500
8¾ 80 - 120 15 - 40 350 - 550
9 7/8 60 - 120 15 - 40 400 - 650
10 5/8 60 - 120 15 - 40 600 - 800
12 ¼ 60 - 100 15 - 40 650 - 950
Recommended flow rates for diamond bits.
Bit size(inches) Type Stone Size Exp. Flow rate (GPM)
6" MD34 2 n/a 180
MD31 3 n/a 180
MD33 4 n/a 180
8 ½" MD34 1 0.05 380
MD31 4-Mar 0.04 380
MD33 6 0.03 380
MD70 ½ carat 0.45 (appr) 380
12 ¼" MD34 1 0.5 700
MD31 2 0.045 700
MD33 4-Feb 0.045 700
MD 197 1 carat 0.06 500 - 700
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Bit record / hydraulics details. Rig :
Field : Spud Date & time : Mud Pump : Oilwell 12-P-160 RT to Seabed = 379.0 feet.
Well No : TD date and time : Liner size : 5 1/2" Total (In hole) Hrs = 106
Well type : Days spent on well to TD : Pressure rating : 4500 psi. Total rotating Hrs = 70
Bit details Bit hydraulics Depth Feet Total Rot ROP Parameters (Average) Mud details IADC Bit Grade Comments
No Size Mfgr Type Ser No Jets 32'nds TFA HSI ft/sec Out made Hrs Hrs feet WOB RPM TQ GPM PSI Type Wt Vis PV YP I O D L B G O R
6 x cutters on 36" hole opener, reamed hole
1 rr3 26.00 REED Y11 JE2828 20 20 20 20 1.2 0.7 312 638 259 12.5 5.5 47 6 60/90 4/12 1200 800 SW 8.6 ~ ~ ~ 1 1 NO A E I NO TD
due to angle.
2 26.00 REED Y12 JE2828 20 20 20 20 1.2 0.8 286 638 0 2 0.5 0 5/15 60/90 4/6 1100 800 SW 8.6 ~ ~ ~ 1 1 NO A E I NO TD Drill cement.
Riserless, tertiary, reaming hole due to
3 rr2 17.50 Smith MSHOD CER4749 20 20 18 18 1.1 1.7 294 2550 1912 20 12.6 152 5/15 130 2/6 1020 2000 SW 8.6 ~ ~ ~ 1 1 No A E I NO TD
angle.
BT Last 2.5 hrs on bit <100 ft/hr formation
4 12.25 DBS QP19M 5940299 7 x 13 0.9 4.3 306 5761 3211 29 16.9 190 25/55 50/110 2/6 871 3650 WBM 11.8 46 27 23 3 2 LT CN X I FM
WT transition.
EHP
5 12.25 Reed
51HDL
5940299 18 18 18 0 0.7 6.4 374 6148 387 16 14.3 27 35/50 120 2/6 871 3650 WBM 11.8 46 27 26 2 7 LT G12 1/16" BT PR Limestone/Chert, (90% in some samples )
Tertiary Limestone ( TOR, HOD etc. &
6 12.25 BBits BB657 BB404413 2x 12 4x 14 0.8 5.1 336 7070 922 23 19.0 49 15/35 140/170 4/18 860 3600 WBM 11.8 46 28 24 1 1 No A X I No TD
Claystone.)
7 8.50 Bbits BB657 405424RR 6 x 12 0.7 3.7 242 7085 15 3 1.0 15 7580 170 2/6 500 3900 OBM 13.5 70 40 20 Add 4.5hrs drilling cmt plugs etc.
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