Is possible do an online snapshot backup , without archive logs at Oracle Database?
Yes, you can do an online backup without archivelogs if you have a storage system or backup tool that can take a point in time snapshot that will be consistent across all your datafiles and control files.  It sounds like you have such a tool and are using it for cold backups.  If that is the case, your documentation will still need to change.  If there is a problem with the system and you need to restore the backup, starting up the restored database will be as though the power plug was pulled a the time of the backup, therefore crash recovery will likely be necessary.  

Given that your documentation needs to change anyway and that you want zero downtime backups, you should probably re-think your resistance to archive logs.  It limits your recovery possibilities greatly.  For example, if due to a disk error you get a bad block in one of your datafiles, and you have older consistent copies of that datafile, you can recover it using archive logs.  With snapshots taken online you would probably end up doing lengthy extracts from multiple snapshots of the system (assuming you can tolerate the downtime) and would probably still loose data.