It is a million dollar question which cannot be answered so simply. Reliance will not put so much money into it for no reason. I think its just the tip of the iceberg what we know in terms of KG-D6 basin which has something huge which is yet to be disclosed to the public & Reliance is waiting for the apt time to do so. They are least bothered in reducing the import bills or benefit to the government but are interested in making the most for themselves !!
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Certain things can not be always judged with returns especially when it comes to self reliance and infrastructure.
But in this case, since itz being from pvt. sector that to ppl. like Reliance, the must hv done their homework on returns.
In oil & gas sector, twenty seven thousand crores s not really big money and evaporate within no tim like diesel and pestol.