Page 440 - Practical Well Planning and Drilling Manual

Section 3 revised 11/00/bc 1/17/01 12:00 PM Page 416

[ ] Practical Wellsite Operations
3.6.6

two digits); BT would be more important. (See Table 3-3 for bit codes.)
The fourth digit shows the location of this characteristic.

Table 3-3 Bit Codes for IADC 8 Point Grading Scheme

Dull Bit Characteristic Codes Dull Bit Characteristic Codes
BC Broken cones LN Lost nozzle
BF Bond failure (PDC bits) LT Lost teeth or cutters
BT Broken teeth or cutters OC Off center wear
BU Balled up bit PB Pinched bit
CC Cracked cone (note cone number[s]) PN Plugged nozzle or fluid passage
CD Cone dragged (note cone number[s]) RG Rounded gauge
CI Cone interference RO Ringed out
CR Cored bit SD Shirttail damage
CT Chipped teeth or cutters SS Self-sharpening wear
ER Erosion TR Tracking
FC Flat crested wear WO Washed out
HC Heat checking WT Worn teeth or cutters
JD Junk damage NO No dull characteristics
LC Lost cone (note cone number[s]) RO Ringed out

Roller Cone Bits Location Codes Fixed Cutter Bits Location Codes
N Nose row C Cone
M Middle row N Nose
G Gauge row T Taper
A All rows/all areas S Shoulder
#1 Cone 1 G Gauge
#2 Cone 2 A All areas
#3 Cone 3

Digit five (bearings/seals condition). Enter an X for fixed cutter bits
since this digit is not applicable to PDCs, diamond bits, or other fixed
cutter types.
For nonsealed bearing bits, attempt to judge how many eighths of
bearing life are gone. Enter as a number from 0 to 8, with 0 reflecting
no wear and 8 reflecting no life left (cone skidded, locked, or lost).

416