i want to make a 15 wide, 20 high and 60 long tunnel, what dimension does the paper need to be?

You have not said what shape this tunnel in it is obviously not a cylinder.

I'll go for the easiest option. 

A rectangular prism where the bottom is also included.  So it has 4 sides.

Here is the net that you will need.   If you fold this 'peice of paper' you will have your tunnel :))

It would have to be 3rd dimension paper

It wouldnt be paper its not possible

"It would have to be 3rd dimension paper"    That is hilarious.    ROF LOL    ROF LOL

Thanks anon you have made my day.  :)))