Given the information you have here there are several possibilities:
The distance estimation to resources doesn't take intervening walls etc. into account. So If this is just a few z-levels below the surface and the wood is right above the shop, then the woodworker actually thinks that the surface wood is closer despite having to go the long way around to get it.
If you have any burrows set up then they could exclude the worker from using some resources. However it does not look like you are at a stage where you would have started messing around with burrows.
The workshop could be linked to a stockpile on the surface, if the wood on the surface is in a stockpile.
To fix this you have a few options:
You can set the workshop to only take from the one stockpile you want using the building options, as djsmiley noted.
You could move all the wood down to this wood stockpile.
You could move the workshop next to the stockpile, which would also give time gains on correct hauling.
You could set up a burrow to contain the wood stockpile and the workshop, and anything else the carpenter needs to do(like eat), but not the surface wood, and then assign the carpenter to it.
My personal suggestion would be to move the workshop closer to the correct stockpile.