My understanding is that it takes about three barrels of water to produce one of shale oil and it can be recycled on site. The constraint on the availability of water is purely economic. Water costs about a penny a cubic foot (if that), with about eight cubic feet per barrel. With water at $0.08/barrel and oil at $140.00, I think they’ll be glad to truck it in. (They would, of course, prefer to us available local supplies.)
If you check Shell’s site you’ll find they have been buying water rights.