The Sierra Club, The Daily Dead Fishwrapper , and Exxon-Mobile may all say something completely different about drilling in ANWR but here is the OFFICIAL word from the USGS:
The total quantity of technically recoverable oil within the entire assessment area is estimated to be between 5.7 and 16.0 billion barrels (95-percent and 5-percent probability range), with a mean value of 10.4 billion barrels. Technically recoverable oil within the ANWR 1002 area (excluding State and Native areas) is estimated to be between 4.3 and 11.8 billion barrels (95- and 5-percent probability range), with a mean value of 7.7 billion barrels (table 1).
Quantities of technically recoverable oil are not expected to be uniformly distributed throughout the ANWR 1002 area. The undeformed area (fig. 2) is estimated to contain between 3.4 and 10.2 billion barrels of oil (BBO) (95- and 5-percent probability), with a mean of 6.4 BBO. The deformed area (fig. 2) is estimated to contain between 0 and 3.2 BBO (95- and 5-percent probability), with a mean of 1.2 BBO.
At prices less than $13 per barrel, no commercial oil is estimated, but at a price of $30 per barrel, between 3 and 10.4 billion barrels are estimated. Economic analysis includes the costs of finding, developing, producing, and transporting oil to market based on a 12 percent after-tax return on investment, all calculated in constant 1996 dollars.
The amounts of in-place oil estimated for the ANWR 1002 area are larger than previous USGS estimates. The increase results in large part from improved resolution of reprocessed seismic data and geologic analogs provided by recent nearby oil discoveries.
Source: The U.S. Geological Survey (USGS)
See also: ANWR Prospects are Enormous by U.S. Standards
The data are quite clear that the North Slope, and in particular the 1002 area of ANWR, are not only significant, but are without parallel as the best exploratory prospect in the U.S.
The only argument that would change my mind about drilling in ANWR would be the "free market" argument. (I have heard someone argue this) That is, if you opened the place to drilling and no oil company was interested due to such a small reserve that it would not be profitable, then I would say we should not drill there. It certainly should not be subsidized. But by the same token if private enterprise is interested that would indicate a healthy supply of oil and would be a worthwhile investment.
For more free market logic see my previous post.