User LOGMINER needs a lot more grants than are currently documented:

• GRANT EXECUTE ON DBMS_LOGMNR TO LOGMINER;
• GRANT EXECUTE ON DBMS_LOGMNR_D TO LOGMINER;
• GRANT SELECT ON V$LOGMNR_LOGS to LOGMINER;
• GRANT SELECT ON V$LOGMNR_CONTENTS to LOGMINER;
• GRANT SELECT ON V$LOGFILE to LOGMINER;
• GRANT SELECT ON V$ARCHIVED_LOG to LOGMINER;
• GRANT SELECT ON V$ARCHIVE_DEST_STATUS to LOGMINER;