Hii aspirant ,

Coming to your question I would like to tell you that it totally depends on the stream which you get in the iocl that is 

• Marketing 
• Refinery 
• Pipeline 
• Business development

In marketing or pipeline you may get but the duration will be of 3-4 years but in the refinery if you get your posting will be in the outskirts of the main city , and there you will have to live for 6-8 years after that you will be posted to another place ,so mostly the area of the posting depends upon the stream which you get in the iocl.

Hope this helps you ,

Good luck .