Appeal No. 97-4183
Application 08/424,128
allowed.
We AFFIRM.
The appellants’ invention pertains to a method of
adjusting the flow of drilling fluid through the nozzles in a
drill bit while the drilling operation is taking place.
Independent claim 9 is further illustrative of the appealed
subject matter and reads as follows:
9. A method for adjusting the total flow area of a
drill bit concurrently with drilling with a drilling fluid
having a selected composition, comprising the steps of:
(a) attaching a drill bit to a drill string, the
drill bit including a plurality of nozzles, at least one of
the nozzles being open and at least one of the nozzles having
a closure means thereon to prevent upward or downward flow
through the nozzle, the closure means being adapted to open at
a pre-selected differential pressure;
(b) placing the drill string and bit down a
wellbore and commencing drilling; and
(c) before the open nozzle has eroded or plugged
and while drilling with the fluid of the selected composition,
increasing the differential pressure across the bit so as to
cause the closure means to open, causing an adjustment in the
total flow area of the drill bit concurrent while drilling and
without removing the bit from the wellbore.
The references relied on by the examiner are:
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