select
        thread#,
        to_char(first_time,'dd hh24:mi:ss')         first_time,
        round(24 * 60 * (
                lead(first_time,1) over (
                        partition by thread#
                        order by first_time
                ) -
                first_time
           ),2)                                 minutes
from
        v$log_history v
where
        recid >= 117
order by
        thread#, recid
;    

   THREAD# FIRST_TIME     MINUTES
---------- ----------- ----------
         1 03 21:06:25     473.83
         1 04 05:00:15     962.68
         1 04 21:02:56     380.22
         1 05 03:23:09     937.87
         1 05 19:01:01     477.12
         1 06 02:58:08    1083.63
         1 06 21:01:46     384.72
         1 07 03:26:29     214.55
         1 07 07:01:02    1186.35
         1 08 02:47:23     571.88
         1 08 12:19:16
         2 02 18:25:20    1954.57
         2 04 02:59:54     1968.3
         2 05 11:48:12    1570.95
         2 06 13:59:09     1799.1
         2 07 19:58:15