Now, this blog is mainly about sandy topics and explicitly non-controversial. Sand does figure as a bit player in this drama, but sometimes there are topics about which I know a little and that I find so infuriating that, rather than rant at the TV or the computer screen, I will suspend my publishing principles and go to press. This is one of those topics. There is some kind of conspiracy here - one of ignorance, stupidity, and the intellectual feeble-mindedness of the inability, or unwillingness, to question, to check facts.
Almost exactly two years ago, the US Geological Survey (not Service, as the e-mail quotes), published an updated assessment of the potential oil resources of the 350 million year old Bakken Formation in the great pile of sedimentary rocks that is the Williston Basin, long the source of prolific oil and gas production. The USGS follows a rigorous and tested methodology that has been applied around the world to come up with such estimates - estimates being the important term, since these things always come with a health warning about uncertainty - in this particular case, to quote from the USGS Fact Sheet: " there is significant geologic uncertainty in these estimates, which is reflected in the range of estimates for oil." The table of the USGS summary of its results is reproduced below, with the figure of 3.6 billion barrels of oil as the mean estimate highlighted in red.
The "F95" and "F5" numbers refer to a 95% and 5% probability that the numbers are equal to, or larger than, those attached to each estimate; the statistical mean is then summarised (mathematically, the means are the only numbers that can be added together and still preserve the statistical validity). Now, the range of such estimates (F95 versus F5) is normally much larger than this, but in this case the small range reflects the peculiarity of the oil resource that is the Bakken; so, a brief explanation of this peculiarity:
- The Bakken consists of a great pile of shale, extending over a large area and with a sandstone sandwiched in the middle.
- The shale is formed from marine mud and contains a lot of decayed organic matter.
- With burial, pressure, temperature, and time, this organic matter has been cooked to the point where it has been transformed into hydrocarbons - the Bakken shale is a great source rock for oil and gas.
- But a shale, originally mud, is composed mainly of compacted clay, extremely fine-grained rock. The porosity (the empty spaces between the grains that can contain oil,gas, or water), and the permeability (the connectivity of those spaces that allows fluids to flow through the rock) are extremely low.
- Therefore, while some of the oil generated has escaped and migrated into other parts of the sedimentary pile (including the sandwiched sandstone) and provided the production history of the Williston Basin, the laws of physics mean that much of it remains trapped in the shale.
- Unlike conventional oil accumulations where the fluids have migrated out of the source rock and into some geological configuration where they are trapped, the entire Bakken shale is an oil resource - as the USGS define it, a "continuous resource."
- The total volume of the shale and the oil content are relatively straightforward to calculate, and this is why the range of the estimates is not great.
The 3.6 billion barrels are "technically recoverable" by the USGS definition - and here's the critical point. Yes, we have the technology to recover this oil - but at what cost? The USGS estimates explicitly do not address costs or other aspects of economics and commerciality. As others have remarked, yes, we could send a manned mission to Mars - but can we afford it?
Because it's a shale, and its porosity and permeability are so low, the Bakken is extremely unwilling to give up the oil it contains. The required technology involves drilling wells horizontally through the shale and stimulating fracturing of the solid rock, attempting to enhance the natural fractures that increase its permeability. The image at the head of this post (from the full USGS report) shows core samples and microscope images of the Bakken shale - a very solid rock with a few natural fractures along which oil might be induced to flow. All this technology is expensive and the volume of shale around a single well that might be willing to give up its oil is relatively small - a lot of expensive wells are needed and the commercial viability of drilling them is highly sensitive to the price of oil as well as the cooperative (or otherwise) behaviour of the rocks. Today, a number of companies are drilling in the Bakken shale, and production is rising, but another Saudi Arabia it is not.
So where, in the hysterical e-mail, does the figure of 500 billion barrels come from? From an unpublished and un-peer-reviewed 1999 report from a reputable geologist, Leigh Price, who sadly died before the work was completed. His estimate was a mean figure of 413 billion barrels of "potential resources in place." Note the words "in place" - this means the oil that the Bakken potentially contains, not what can be extracted. Those laws of physics, surface tension and so on, that cause oil to stick to the grains of sand in a conventional oil reservoir, mean that recoverable volumes are, even at the best of times, only a fraction of the total of what's there, the in-place oil. This fraction is known as the recovery factor, and in a high quality oil reservoir with great porosity and permeability, a recovery factor of 60% is really good. In a shale, with its miniscule porosity and permeability, even helped by fractures, this number is more like 1%, 5% if you're lucky. So, if you apply these kinds of recovery factors to Price's oil in place, you're in the ballpark of the USGS estimate - for the total resource, not for the economically recoverable volumes.
Where do the trillion barrel numbers come from? Hallucination and distortion on the part of investment snake oil salesmen.
What I have tried to set out here are some facts - that are verifiable by anyone who cares to do so (it's not rocket science). I wrote in my previous post about not taking anything at face value - the proponents of this ignorant and hysterical diatribe clearly have no interest (in spite of the exhortation to "Google it") in following this principle, preferring to believe in a conspiracy: "the environmentalists and others have blocked all efforts to help America become independent of foreign oil!" The e-mail ends with the comment "Now I just wonder what would happen in this country if every one of you sent this to every one in your address book" - it seems as if this has already occurred ; the truth does not emerge from the endless repetition of ignorance.
[A couple of years ago, Brian Romans at Clastic Detritus put up a thoughtful and useful post on this topic, so this is just something of an update. The original USGS Fact Sheet is linked above; their FAQs are also helpful and the full report is available as a somewhat chunky download. There is good commentary at the credible Oil Drum site, Geology.com, FactCheck.org, and, of course, Snopes. Endless entertainment and an astonishing mix of fact and fantasy can be found simply by - as the e-mail exhorts - Googling "Bakken Oil"]