A couple of questions Dermot; 
If Prudhoe Bay were discovered today, considering the size of the resource and the promise of more, would it be a profitable and prudent long range investment for a major oil company to finance building TAPS today? even given current oil prices? 
If the answer is yes, it speaks to the current claim by the three majors in Alaska of a need for huge oil tax subsidies for all "new" oil on legacy leases that under SB21 extend far into the future of the state.   What`s the value of all remaining oil and gas under state lease??