Appeal No. 2002-2203 Page 4
Application No. 09/584,526
throttling device at or near the top of the riser to adjust the mass flow rate out of the top
of the riser and the riser surface pressure to compensate for changes in the riser base
pressure, as called for in claim 1.
Dower discloses using a throttling device (casing pressure regulator 21) near the
top of the riser to control the flow of the return drilling fluid to thereby impose a back
pressure on the drilling fluid to reduce kicks. Dower, however, monitors riser surface
pressure using pressure gage 22 and adjusts the casing pressure regulator 21 in
response thereto.
We agree with the examiner that the combined teachings of Bruce and Dower
are sufficient to suggest use of a throttling device at or near the surface of Bruce’s riser
to adjust the mass flow rate out of the top of the riser and hence the riser surface
pressure. Dower, however, would have suggested adjustment of the throttling device to
compensate for changes in the riser surface pressure, not changes in the riser base
pressure, as called for in appellants’ claim 1. Thus, combination of the applied
references would not yield the invention recited in claim 1. It therefore follows that we
cannot sustain the rejection of claim 1.2
We turn next to the rejection of claim 12 as being unpatentable over Bruce in
view of Calcar. Calcar discloses a method of detecting kicks comprising predicting the
2 It is elementary that to support an obviousness rejection, all of the claim limitations must be
taught or suggested by the prior art applied (see In re Royka, 490 F.2d 981, 984-85, 180 USPQ 580, 582-
83 (CCPA 1974)) and that all words in a claim must be considered in judging the patentability of that claim
against the prior art (In re Wilson, 424 F.2d 1382, 1385, 165 USPQ 494, 496 (CCPA 1970)).
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