Surprise, Surprise: Oil Boom in the Williston Basin (“the Bakken”)

Resources on the internet about this formation have been revised recently. There appears to be an oil drilling boom going on in eastern Montana and western North Dakota. They are horizontal-drilling and hydro-fracturing for light crude (meaning low viscosity liquid). One of the descriptions says the crude they can recover seems to be just about the same gross physical properties as diesel (density, viscosity).

That's a surprise to me. Two years ago I researched this formation as a "shale unit, very low porosity and microscopic permeability", and everything I read about the hydrocarbons in it said a consistency more like tar. Hydro-fracturing simply would not work on a near-solid resource like that. It would have to be mined, like coal.

What I read now says the Bakken comprises a dolomite layer around 100-140 feet thick, bounded above and below by shale layers. Typically, the shale is the “original” source for the hydrocarbons. The dolomite is listed as 5% porosity and microscopic permeability (1-10 microdarcy's, just almost impermeable). It is in the dolomite layer (not the shale) that they are horizontal-drilling and hydro-fracturing. Estimates vary about how much of the total resource they might possibly recover this way, by over an order of magnitude, depending upon who made the estimate and what agenda they have.

For the Burgess Shale natural gas hydro-fracturing here in Texas, the estimate is that about 3% of the gas down there is actually recoverable. For the liquid in the Bakken dolomite layer, I'd simply guess that factor as 3% or less, which is nearer the 1% end of the estimate range of 1% to 50% that I saw on-line yesterday. Almost-nil permeability just has that effect, hydro-fracturing notwithstanding.

I suspect that there are residual tars left behind in both of the shale units in the Bakken formation, and that the source for the light fractions in the sandwiched dolomite layer is the lower shale member. Somehow, I don't see light fractions migrating downward from the upper shale member, so its lighter fractions are most likely now lost to us.

So, how much recoverable light oil might there be, and how much good might it do, if we can recover around 2% of it?

Oil in the Dolomite Layer:

If you guess that there's something like 500 x 500 statute miles of this formation, averaging 100 ft thick, at 5% porosity, then there might be as many as 6 trillion barrels of light oil down there.

500 mile dimension x 5280 ft per mile = 2.64E6 ft. 500 mi x 500 mi is then 6.97E12 sq ft. Multiply by 100 ft thick to obtain 6.97E14 cu.ft of dolomite rock. The hydrocarbon volume equals the pore space volume at 5% of rock volume, assuming the pores are 100% full. That's 3.48E13 cu.ft of hydrocarbons. Cu.ft volume of hydrocarbons x 7.48 gal per cu.ft is 2.61E14 gal hydrocarbons; divide that by 42 gal/barrel. That's 6.2E12 (about 6 trillion) barrels of hydrocarbon volume down there in the pores of the dolomite layer, supposedly all hydro-fracturable, very light crude.

Assume we can recover 2% of it. That's about 1.24E11 barrels of light oil that could be recovered, or about 124 billion barrels in ordinary terms. That's quite significant. I could be off by a factor of 2-3 in rock volume assumptions, more likely toward the smaller than the larger, so these figures are rather optimistic.

At our 7-8 billion barrels / year consumption in the USA, then potentially, this could power us for about 16-17 years. That really is significant, even if it is optimistic by a factor of 2-3. If it is all light oil. If we really can recover 2% of it. If the rock pores are really full. Lots of "ifs".

Let's say this oil boom lasts 20-30 years (typical for a very large field). The average production rate from the mature field (which takes several years to achieve) might be as much as around 4-6 billion barrels a year, again possibly optimistic by factor of 2-3. That's still a lot, optimistic or otherwise.

Replacing Foreign Imports:

About 1/3 of our consumption is domestic production, about 1/3 comes from Mexico and Canada, and about 1/3 comes from OPEC (which includes Venezuela, along with that idiot running it; and our “friend” Iran, with that insane group of religious fanatics running it). That's about 2.5 billion barrels per year from each source. We might very well be able to replace much of the OPEC oil with domestic from the Bakken dolomite layer, even as the other sources decline. For a little while.

But, no matter how politically expedient, it is still clearly not at all wise to count on it “ending” our dependence on foreign oil. Although, you can bet more than one GOP/Tea Party candidate will run on "why not save ourselves from oil dependence with the Bakken, if the environmentalists and Democrats would just get out of the way?" They did exactly that in '08: remember “drill, baby, drill?”

Even with the new oil boom that I did not expect to see, it’s still a comic-opera puppet-theater issue intended to distract the public from the real truths that threaten us. It’s still just a fake electioneering issue for a bunch of comic-opera buffoon candidates. Beware! I warned you!

About the Tar Shale Layers:

I saw no thickness figures on the two shale units, in the new data that I found this year. I bet they're quite thick, though. You'd have to deep strip mine it, and what I saw said it averages 2 miles down. Figure shale at 0.5% or less porosity, for maybe another handful of trillions of barrels of potentially-recoverable hydrocarbon. This tar shale stuff would be very hard to extract and process, though, and so it would be a supremely expensive product.

And, we would get it for the environmental cost of a permanent crater some 500x500x2 miles in size, which is bigger by far than the volume of Lake Superior. That shale tar is what I was thinking about when I posted what I did about "the Bakken" last year (the 3-14-10 article). That’s still true, oil boom notwithstanding.

Conclusions:

Yep, we need to go get the hydro-fracturable light oil.

Yep, it’ll surely help with imports.

Nope, it will not “save” us.

There is no permanent answer among depletable (fossil) fuels, and never will be.