However , working out means of extracting the gas proved difficult for an earlier company Amity Oil in 2004 .
Discovered over 30 years ago , the field is estimated to be over 4 trillion cubic feet in size .
Working out means of extracting the gas proved difficult for an earlier company Amity Oil in 2004 .
Discovered over 30 years ago , the field is estimated to be over 4 trillion cubic feet in size .