The USGS updated their estimate of the amount of oil that is undiscovered, technically recoverable in the Bakken field. Second paragraph of their press release says:
The USGS assessment found that the Bakken Formation has an estimated mean oil resource of 3.65 BBO and the Three Forks Formation has an estimated mean resource of 3.73 BBO, for a total of 7.38 BBO, with a range of 4.42 (95 percent chance) to 11.43 BBO (5 percent chance). This assessment of both formations represents a significant increase over the estimated mean resource of 3.65 billion barrels of undiscovered oil in the Bakken Formation that was estimated in the 2008 assessment.
This means the mid-point (statistically correct phrase: mean) of the total oil that is technically recoverable with current technology is 7.4 billion barrels of oil. Their assessment is that the probability is 95% that there will be at least 4.4B and the probability is 5% that there could be as much as 11.4B.
That’s the standard way they estimate a field’s size – a mean with accompanying estimates at the 95% and 5% level (I think that’s called confidence level, but my recollections of grad school stats class and studying of stats since then are a bit fuzzy).
Million Dollar Way has a good post that accumulates info as it accumulated yesterday: US Government Agency Announces “Another Bakken” Discovered In North Dakota! USGS Doubles Estimate of the Bakken: 7.4 Billion Bbls Of Recoverable Oil; And That’s The Mean; Top Line Is 11.4 Billion Bbls; Both Numbers Considered Conservative By Some
The biggest change in the estimate is including the Three Forks formation, or layer. Previous estimate only included the Bakken formation. As I understand, there are multiple layers of oil bearing shale in the Bakken field. Three Forks is below Bakken. Look at this comment from the USGS report:
Since the 2008 USGS assessment, more than 4,000 wells have been drilled in the Williston Basin, providing updated subsurface geologic data. Previously, very little data existed on the Three Forks Formation and it was generally thought to be unproductive. However, new drilling resulted in a new understanding of the reservoir and its resource potential.
MDW quotes and links to this comment from The Oil & Gas Journal:
The updated assessment represents a two-fold increase from the 2008 estimate of 3.65 billion bbl in the Bakken, it noted. The update includes the Three Forks for the first time.
USGS’s latest assessment found that the Bakken has a 3.65 billion bbl estimated mean resource—unchanged from 5 years ago—and Three Forks has an estimated mean 3.73 billion bbl. The formations’ combined estimate ranges from 4.42 million bbl, with a 95% chance of production, to 11.43 billion bbl, with a 5% chance.
Since 2008, however, more than 4,000 wells have been drilled in the 2 formations producing 450 million bbl of crude, and Three Forks activity has increased significantly, warranting its inclusion in the area estimate, the US Department of the Interior agency said.
Current mean estimate of Bakken Formation is 3.65B. Now we can add to that the Three Forks with mean estimate of 3.73B.
That means another Bakken’s worth of oil is underneath the current Bakken.
I browsed the official assessment which can be found here. Won’t discuss it because it is way over my head. Only thing I really understood is the Three Forks layer had not been included in the previous assessment.
What Peak Oil?
Not that any more nails are needed for the coffin containing Peak Oil, but this is another. A huge amount of oil is officially included in the reserve calculations now which hadn’t been included before because previously the considered opinion was the oil could not be pulled out of the ground.
Now we have 2 Bakkens worth of oil in the Dakotas & Montana.