Appeal No. 2002-0836 Page 3
Application No. 09/264,437
reasons which follow, we conclude that the combined teachings of the applied
references are insufficient to establish a prima facie case of obviousness of the subject
matter of the claims.
Before turning to the prior art, it is critical that we understand the scope of the
claimed subject matter. In this regard, our understanding of claim 1 is that the wellbore
forms part of the claimed “wellbore heater,” with the other recited elements of the
heater disposed within the wellbore as set forth in the claim.
Carpenter discloses an apparatus for tertiary recovery of oil comprising a plurality
of electrodes extending into a plurality of boreholes. Electrical current from an electrical
power source is passed through the electrodes and then through salt water which is
part of the earth formation from which oil is to be recovered. The flow of current
through the salt water causes the salt water to be heated, the salt water then acting as
a heating element to heat up the oil in the formation, thereby lowering its viscosity and
improving the flow characteristics of the formation (column 6, lines 41-59). As
explained by Carpenter in column 8, lines 39-55, it is very desirable that the resistance
of the salt water providing the conductive path between electrodes have a high
resistance compared to the total series resistance of the electrodes, so that power is
dissipated primarily through the salt water rather than across the electrodes.
Accordingly, Carpenter teaches that it may be desirable to use electrodes formed of
aluminum or similar material having a lower resistivity than steel.
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