That's 'all in' cost. You're including sunk costs of acquiring drilling rights, drilling, etc. The marginal cost of production is a larger determinant of whether or not oil shale wells get shut in. I've seen articles stating that the marginal costs are around $20/bbl, +/- $5.
I've also read that shutting in oil shale wells are more problematic, as there are greater costs to restart them than conventional wells.
Oil shale producers are more interested in keeping the doors open and to do that, it's all about cash flow. As long as they can sell their oil for more than $25/bbl, they're not likely to start shutting in wells.
While I love all of the cloak and dagger suggestions in this thread, my thoughts are that we've seen 1) supply increase, 2) demand decrease, and (most importantly) 3) risk premiums decrease significantly. There's now less concern about ISIS blowing up wells, especially since they've been selling oil on the world markets. If you want to point to a single reason for oil's price collapse, my money would be on the news that ISIS is selling oil. Definitely a risk premium killer.
The steep contango is signaling that oil prices will continue to fall. Piezoe, you've got to be nuts to even ponder playing the forward curve with contango this steep. Not to mention that the trading is extremely thin on the forward curve.
As I write this, front month WTI (feb15) is 54.18
Jun15 is 56.50
Dec15 is 60.25
Dec16 is 69.11
And the spread widens the further out on the curve you go. Right now, the oil storage trade is thriving because of oil being in contango.
Disclaimer: I'm short oil future on the forward curve.