STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

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Drilling Bits and Downhole Tools 805
Two versions of the profile matrix are presented. One version (Figure 4-158)
is primarily for the use of manufacturers in classifying their bit profiles. Precise
ranges of high, medium and low values are given. In Figure 4-158 gage height
and cone height dimensions are normalized to a reference dimension which is
taken to be the bit diameter for drill bits and the (OD-ID) for core bits. Figure
4-159 provides a visual reference which is better suited for use by field personnel.
Bold lines are drawn as examples of typical bit profiles in each category. Crosshatched
areas represent the range of variation for each category. Each of the
nine profiles is given a name. For example, “double cone” is the term used to
describe the profile in the center of the matrix (code 5). The double-cone profile
is typical of many natural diamond and TSP bits.
The number 0 is used for unusual bit profiles which cannot be described by
the 3 x 3 matrix of Figure 4-158. For example, a “bi-center” bit which has an
asymmetrical profile with respect to the bit pin centerline should be classified
with the numeral 0.
Hydrauric Design. The numbers 1 through 9 in the third character of the fixed
cutter classification code refer to the hydraulic design of the bit (Figure 4-160).
HYDRAULIC DESIGN
CHANGEABLE FIXED OPEN
JETS PORTS THROAT
17/8/91
FACED
ALTERNATE COOES
R RADIAL FLOW
X - CROSS FLOW
0 - OTHER
Figure 4-160. Hydraulic design code for fixed-cutter bits [54]. (Courtesy SPE.)