September 1999

99-09_drillbit-intro.htm (Sep-1999)

A monthly magazine offering industry news, statistics and technical editorial to the oil and gas drilling, exploration and production industry.

September 1999 Vol. 220 No. 9 
Special Report 

Formation Categories
Companies Surveyed
Drill Bit Classifier Tables

Drill Bit Classifier

World Oil offers this comprehensive listing of major manufacturer’s drilling bits to aid drilling supervisors and engineers in field selection. While this listing has been published annually for several years, changes from year to year are significant. Prior to ordering, users should consult the manufacturer to verify availability and specifications.

How to use tables. The following tables are divided into six formation categories. Within these are listed most available drilling/coring bits by type and manufacturer. To use the listings, identify the formation to be drilled, decide which bit type is appropriate, i.e., roller, fixed cutter, steel tooth, insert, diamond, etc., and choose the manufacturer.

Companies were asked to list bit data by: 1) IADC code, 2) readily available sizes (special sizes are often available on request), 3) recommended WOB in lb/in. diameter, and 4) codes for special features and usage, a combination of IADC and World Oil special codes, see Nomenclature.

IADC codes. The Bit Classifier utilizes the International Association of Drilling Contractors’ (IADC) classification system for roller and fixed cutter bits. The standards for these classifications are two technical papers that appear in the IADC Drilling Manual, 11th Edition, Chapter A, Sections 2 and 3. The two papers are "The IADC roller bit classification system," adapted from IADC/SPE Paper 23937, presented Feb. 18—21, 1992, and "Development of a new IADC fixed cutter drill bit classification system," Paper IADC/SPE 23940, presented Feb. 18—21, 1992. All manufacturers were asked to submit data based on these classification systems.

Formation categories. The tables show six formation categories corresponding to the new IADC formation types, as described below. Companies were asked to list any discrete bit in only one formation type, leaving the user to decide about application in harder, or softer, rock. Nevertheless, some duplication of similar bits in multiple formations remains. The formations are:

  • Soft, including soft sticky. Low compressive strength and high drillability, such as clay, marl, gumbo, unconsolidated sand.
  • Soft to medium. Low compressive strength, interbedded with hard layers such as sand, shale, anhydrite.
  • Medium. Hard with moderate compressive strength such as shale, chalk, anhydrite, sand.
  • Medium to hard. Dense with increasing compressive strength but non- or semi-abrasive, e.g., shale, siltstone, sand, lime, anhydrite.
  • Hard. Hard and dense with high compressive strength, some abrasive layers, such as sand, siltstone.
  • Extremely hard. Very hard and abrasive, like quartsite and volcanics.


World Oil shows special features as codes, which include 16 designed by IADC and defined in the above classification papers, plus 10 featured exclusively by World Oil for added descriptions. The codes are:


  A Air drilling application   L Lug pads  
B Special bearing seal M Motor application
C Center jet S Standard steel tooth model
D Deviation control T Two cone bit
E Extended jet (full length) W Enhanced cutting structure
G Gauge/body protection (additional) X Predominatly chisel tooth insert
H Horizontal steering application Y Conical tooth insert
J Jet deflection Z Other shape insert

World Oil

F Face discharge ports P Percussion drilling
I Thermally stable synthetic diamond (TSP) Q Lateral nozzles
K Cross flow hydraulics R Radial flow hydraulics
N Turbine drilling U Cutter density: light (l), medium (m), heavy (h),
e.g., Ul, Um, Uh
O Milling applications V Anti-whirl characteristics.

Companies Surveyed

Company names, as shown in the following listing, were shortened to conserve space.

  Baker Hughes INTEQ Baker Hughes INTEQ   Industrial Industrialexport S.A.  
BBL Brit Bit BBL Brit Bit Ltd. New Tech New Tech Rock Bit Co.
Bit-Tech Bit-Tech RBI/Gearhart RBI/Gearhart
Christensen Products Christensen Products Reed Reed Tool Co.
Crystal Crystal Profor SA RockBit RockBit Industries of Canada
DKG Dunantuli Koolajipari Gepgyar Rt Transdanubian Oil Machine Engineering and Manufacturing Co. Ltd. Security DBS Security DBS, Division of Dresser Industries, Inc.
DPI Diamond Products International Short Short Bit & Tool Co.
GeoDiamond GeoDiamond Smith Smith International Inc.
Hughes Christensen Hughes Christensen TIX TIX Corp., TSK Division
Hycalog Hycalog Tri-Max Tri-Max Industries
Varel Varel Manufacturing Co.
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