You can change the ORACLE_SID and ORACLE_HOME without having to change environment variables at the operating-system level. Depending on whether the change is for the source or target database, set the following parameters in the Extract or Replicat parameter files. Then, stop and restart Extract or Replicat for the parameters to take effect.

SETENV (ORACLE_HOME=location)
SETENV (ORACLE_SID='SID')