Appeal No. 97-4183
Application 08/424,128
nozzles is cut off by plug 50 in the case of the embodiment of
Figs. 1, 2 and 5 or by balls 91 in the case of the embodiment
of Figs. 3, 4 and 6. As a result of the flow to the eroded
nozzles being cut off, the upstream pressure increases to the
point where the frangible members 43 or 86 rupture, thus
providing for the flow of drilling fluid to one of the
remaining nozzle systems. By such an arrangement, Miller
provides for new nozzles to be utilized, when the nozzles
previously being utilized become worn or eroded, without the
need to withdraw the bit from the well (see generally, columns
1 and 2).
In addition to the above, as the examiner has noted,
Miller also teaches that:
Moreover, the nozzle dimensions and nozzle
pattern of one system can be different from
those of its paired system permitting the
bit 10 to adapt to different drilling
conditions by merely closing one nozzle
system and opening another. [Column 4,
lines 5-8.]
Accordingly, Miller teaches (or at least would fairly suggest
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