Replication for Oracle 15.7.1 SP200 now supports Oracle 12c database at the same functional level of Oracle 11g.
The Replication Agent for Oracle Log Reader component with LogMiner requires the GRANT LOGMINING to <pds_username> administrative permission to read from Oracle 12c transaction logs. If the GRANT LOGMINING to <pds_username> permission is granted, do not grant SELECT ON V_$LOGMNR_LOGS and SELECT ON V_$LOGMNR_CONTENTS permissions separately.
See the Replication Agent 15.7.1 SP200 Primary Database Guide.