The North Sea field could come on stream in 2013 at a cost of ­between Nkr4 billion and Nkr6 billion ($675 million and $1 billion), most likely using a floating production, storage and offloading unit.

Both the timing and cost will depend on whether BG Group can lease an existing floater or ­whether a newbuild will be needed, ­according to a prelimin­ary plan sent to the Oslo government.

BG