Well at the beginning I though it will be a difficult task but when you get in to it, you will find out that it's kind of clear task so far ;-)
My plan was to clone my production system to a new server just for the upgrade purpose so I had to do a cloning from multi-node to single node based on note 233428.1 and of course with a great help from sam's post (Multi Node to Single Node Cloning) thank you sam.
After that I started the upgrade journey to R12 I just finished the Database upgrade path acutely I am running the utlrp.sql script while I am writing this post, every thing is clear so far.
I will keep you posted in case of any issue and incase I reach the R12 successfully or not (I hope I will).
I need to major the time needed to do the upgrade and to know if there any issues, my next step will be the upgrade to R12 on my Test servers.