For instance the ones running for more than 12hours:
select ‘alter system kill session ”’||s.sid||’,’||s.serial#||”’ immediate;’,
s.osuser,s.machine,s.module, CEIL(24*(SYSDATE-t.START_DATE))
from v$session s, v$transaction t
WHERE S.SADDR=T.SES_ADDR
and CEIL(24*(SYSDATE-t.START_DATE))>12;