I wasn’t aware of that. What, then, is the tax in question?
There was already a royalties scheme in place (a per barrel fee) as well as an existing state tax on the companies. The new tax was layered on top of it and is pegged to the price of oil per barrel on the global market. The base line is $25/Barrel. Anything above that gets hit with an additional tax. If the price rises above $52/Barrel then an additional 2% per dollar above that point is levied on net profits.
The President of BP Alaska stated publicly that the windfall tax brought the cost of taxes and fees to 75% of revenues. He further stated that the tax was causing his company to cut back Alaskan activity in favor of investing in more business friendly areas.
IOW...just like everywhere else, higher taxes drive business away.