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By Robert Rapier on Mar 26, 2012 with 41 responses

Setting the Record Straight on U.S. Oil Reserves

The Difference Between Oil Shale and Oil from Shale Formations

There has been some confusion lately about the overall extent of U.S. oil reserves. Some claim that the U.S. has hundreds of billions or even trillions of barrels of oil waiting to be produced if the Obama Administration will simply stop blocking development. So, I thought it might be a good idea to elaborate somewhat on the issue.

Oil production has been increasing in the U.S., primarily driven by expanding production from the Bakken Shale Formation in North Dakota and the Eagle Ford Shale in Texas. The oil that is being produced from these shale formations is sometimes improperly referred to as shale oil. When politicians speak of hundreds of billions or trillions of barrels of U.S. oil, they are most likely talking about the oil shale in the Green River Formation in Colorado, Utah, and Wyoming. Some have assumed that since we are accessing the shale in North Dakota and Texas, the Green River Formation and its roughly 2 trillion barrels of oil resources will be developed next. But these are very different types of resources.

Even though the oil in the Bakken and Eagle Ford is being extracted from shale formations, the term shale oil is reserved for something entirely different. The oil in these shale formations actually exists as oil, but the shale does not allow the oil to flow very well. This oil is properly called “tight oil”, and advances in hydraulic fracturing (fracking) technology have allowed this oil to be produced. The estimated amount of oil in place (the resource) varies widely, with some suggesting that there could be 400 billion barrels of oil in the Bakken. However, the reserve (the amount that can be technically and economically produced) is a very low fraction of the resource at 2 to 4 billion barrels (although some industry estimates put the recoverable amount as high as 20 billion barrels or so). For reference, the U.S. consumes a billion barrels of oil in about 52 days, and the world goes through a billion barrels in about 11 days.

The Eagle Ford formation in Texas is similar to the Bakken, in that it is oil in tight formations that is being accessed via fracking. The amount of technically recoverable oil in the Eagle Ford is estimated by the U.S. Department of Energy to be 3.35 billion barrels of oil.

Without a doubt, these two formations are a major factor in the current resurgence of U.S. oil production. But the Green River formation is the source of talk of those huge oil resources — larger than those of Saudi Arabia — and it is a very different prospect than the tight oil being produced in North Dakota and Texas. The oil shale in the Green River looks like rock. Unlike the hydrocarbons in the tight oil formations, the oil shale (kerogen) consists of very heavy hydrocarbons that are solid. In that way, oil shale more resembles coal than oil. Oil shale is essentially oil that Mother Nature did not finish cooking, and thus to convert it into oil, heat has to be added. The energy requirements — plus the fact that oil shale production requires a lot of water in a very dry environment — have kept oil shale commercialization out of reach for over 100 years.

Summarizing the Definitions

To summarize, let’s review the definitions for the important terms discussed here:

Oil resource — the total amount of oil in place, most of which can’t be recovered

Oil reserve — the amount of oil that can be recovered economically with existing technology

Oil shale — sedimentary rock that contains solid hydrocarbons called kerogen (e.g., Green River Formation)

Shale oil — the oil that can be obtained by cooking kerogen

Tight oil — liquid hydrocarbons that are obtained by hydraulic fracturing of shale formations (e.g., Bakken Formation and Eagle Ford Formation)

Conclusion: Resources are not Reserves, and Tight Oil isn’t Shale Oil

It is pretty clear that at current oil prices, developments in the tight oil formations will continue. It is not at all clear that even at $100 oil the shale in the Green River formation will be commercialized to produce oil. In order to commercially convert the oil shale into oil, a much less energy intensive method of producing it must be found (or, one would have to have extremely cheap energy and abundant water supplies to drive the process). My prediction is that despite having an oil shale resource that may contain the energy equivalent of 2 trillion barrels of oil, the reserve will continue to be zero for quite some time because there are too many technical hurdles to overcome to realize a commercially viable process.

Link to Original Article: Setting the Record Straight on U.S. Oil Reserves

By Robert Rapier

  1. By rjn3 on March 26, 2012 at 7:31 am

    Thanx Robert for, once again, shining light into a space where the politicians keep turning the lights out.

  2. By Addoeh on March 26, 2012 at 10:56 am

    Whatever happened to Shell’s experiment in the Green River Formation?  They said they needed four more years to determine if they can extract it economically, and that was six years ago.  I would guess that since there has not been much said on it, that it was quietly moved to the back burner.

    • By Glenn Vawter on March 26, 2012 at 4:52 pm

      Shell is still active and has just broken ground on the first of its three BLM Oil Shale Research, Development and Demonstration leases in Colorado.  They have announced success with an ice wall experiment set up to demonstrate one method of mitigating potential ground water impacts.  Another company, American Shale Oil  is in the process of beginning to produce shale oil from its insitu oil shale process also on a BLM RDD lease.  Progress is continuing on several technical fronts on oil shale projects in Colorado and Utah.  

      • By Addoeh on March 27, 2012 at 3:27 pm

        That’s the problem, it is always “just around the corner” but we never seem to reach that corner.  While Shell and AMSO have made a small amount of progress, Chevron recently abandoned their leases in western Colorado.  While AMSO has made a perhaps attainable goal of producing 50,000 bpd by 2025, it would barely amount to a dent in the world consumption (and that’s if it happens).  Of course, Exxon said in 1980 that they will producing 10 million bpd by 2010 from oil shale, only to abandon the project two years later.   

        I hear too many people saying that the Green River Formation is the solution to all our energy problems.   It is, in the absolute best case scenario, a couple decades away from producing anything of real importance.  And there is a really good chance it will never be commercially viable.

  3. By Justin on March 26, 2012 at 11:05 am

    Great post. It covers a few questions I’ve had for a while.

    Are there any other big tight oil formations out there or are Bakken and Eagle Ford the biggest? Also, is tight oil production increasing world wide or just in the United States? My hope was that tight oil would change the price of oil in the same way fracking changed the price of gas. Thanks for the post.

  4. By Muchos Huevos on March 26, 2012 at 12:44 pm

    What the map shows is only one part of the pie, for we have a sea of oil from Texas to Montana and North Dakota, but our tendency to use up anybody else’s oil is really screwing the rest of us, and in the meantime, sending out wealth to our enemies, you figure that out.

    • By armchair261 on March 26, 2012 at 2:40 pm

      Don’t assume that the colored blobs all correspond to recoverable reserves.

      The purple for basins really doesn’t mean too much in terms of reserves: this is just where the right sedimentary rocks exist.

      The pink for play areas corresponds to high graded portions of these basins, but they don’t mean local “seas of oil.” Within each play area, several geological conditions must be met for an oil accumulation to exist, and it’s probable significant percentages of these play areas will not yield commercial production anytime soon. You can’t for example, just pick a random spot on the Niobrara trend in Colorado/Wyoming and expect a fortune. There are dry holes and commercial failures even within these play areas because locally some critical geological elements may be lacking, or insufficiently developed. An example might be shales that locally have total organic carbon content below a critical level.

      Additionally, some of these play areas have yet to be proven commercial. Almost certainly, many will not work at $100 oil.

      Keep in mind the distinction between commercially developable reserves and technically recoverable. If the US has a “tendency to use up anybody else’s oil,” it’s because companies can’t make a profit on a large percentage of the technically recoverable reserves in the US. If a an American company could make an equivalent profit on an American project versus a foreign project, there is no reason why it wouldn’t prefer the American one. Smaller companies would likely prefer the lower political risk, while larger integrated companies, who need to buy about half their crude from foreign sources to keep American refineries humming, would likely prefer to buy locally and avoid the higher transportation costs of foreign crude.

  5. By Jeremy Boak on March 26, 2012 at 1:04 pm

    Thanks for clarifying the distinction between the Green River Formation and the Bakken, Eagle Ford, etc., and for recognizing the priority of use for the term shale oil. The term has been used for more than one hundred years for the product of retorting of oil shale. I feel the terms oil-bearing shale and shale-hosted oil better reflect the rock and the production from the Bakken and Eagle Ford (and the Monterey, and others in the works).  The oil is not tight – the rock is, so the term should be tight-rock oil or tight-reservoir oil, but the press, the public, and even the industry has a problem with three word names.  

    Shale oil production is commercial in Estonia, China, and Brazil, and production with price supports (akin to tax credits for renewables) did occur in the 1980s and 1990s (6 million barrels worth).  Current efforts to bring production on line are occurring both in Utah and Colorado, with first production targeted as early as 2013.  That early date will depend upon permitting for Red Leaf Resources, who have just received a large mine permit.  Enefit American Oil is proceeding on its large land position, and anticipates first production from its latest design retort (part of a long line of commercial technology) in 2019. Shell, ExxonMobil, and Total/Genie are proceeding with experiments on in situ technology in Colorado, but this will take more time.  Expect production to increase by five-fold by the early part of the next decade. 

    Water consumption for shale oil is lower than that for any biofuel that requires irrigation, and comparable to most without.  Energy return on investment estimates depend heavily on modeling assumptions, but is consistently positive, ranging up to 11.  The most recent estimates published in Oil & Gas Journal in 2009 indicate reasonable return on investment at oil prices in the range $38-65, although that price range is affected by cost increases that generally parallel increasing oil price.  Nevertheless, the best estimates show reasonable economic return.  Those interested in oil shale are invited to review proceedings of the last five Oil Shale Symposia at the Colorado School of Mines , and to attend the Symposium this fall (see the link above for information). 

    Jeremy Boak, Co-Chair

    32nd Oil Shale Symposium

    Colorado School of Mines

    Viewpoints expressed are mine, not positions of the Colorado School of Mines

    • By Robert Rapier on March 26, 2012 at 2:17 pm

      Shale oil production is commercial in Estonia, China, and Brazil,…

      But isn’t that primarily just for power production; i.e., they are just burning the shale to produce power?

      Water consumption for shale oil is lower than that for any biofuel that requires irrigation, and comparable to most without.

      But those biofuels aren’t being produced in extremely dry climates. Algae has been envisioned for the desert, but I think the copious water requirements will prevent that dream from being realized.


      • By FG on April 3, 2012 at 10:57 pm

        According to the Wiki, you are correct. It looks like it was never used for as an ICE fuel, only for heat : fixed power, steam locomotives, home heating, etc.

        (The page is surprisingly good :-)

        If the report below is correct (Jacobs’ are not exactly bozos), it’s easy to understand why. The liquids are mostly aromatics, phenolic actually, and 6.1% oxygen. It’s probably very unstable in storage, to boot.

        That being said, if the same report is still correct, the upgrading seems somewhat ‘reasonable’, 34 kg/t H2  It’s a load but I was recently penciling some numbers for upgrading visbroken SDA pitch (*), and 34 kg/t H2  would look positively frugal in this application.

        Now, I would like to see more data on the upgraded oil. Usable but … interesting, I imagine.

        (*) It was just out of curiosity. I’m not a oil guy or a chemist, just playing one on weekends :-)

    • By JoulesBurn on March 26, 2012 at 7:00 pm

      I have a question regarding in-situ methods:  Besides heating the kerogen for awhile to convert it into oil, do you also have to frac the shale to get the oil to flow out, or is the permeability high enough due to the high temperatures?

      Also, I’ve read that shale oil produced from above-ground retorting is generally heavy, requiring specialized refining, whereas that from in-situ approaches is closer to the “natural” shale oil from someplace like the Bakken. Is that true?


      • By Robert Rapier on March 27, 2012 at 4:23 pm

        I know someone working on this, and they said that the oil flows when they heat up in situ. But they are doing small scale experiments. If you look at the nature of oil shale, my guess would be that it doesn’t flow very well and the rock needs to be fractured.

        I have read the same regarding retorting to produce the shale oil, but not sure if the in situ methods would produce a lighter oil. I am not sure why there would be a difference.


  6. By armchair261 on March 26, 2012 at 2:21 pm

    Thanks for posting this. The terminology becomes a problem when, for example (and I’ve encountered this), people oppose hydraulic fracturing because they believe that companies are injecting toxic solvents through well bores into the subsurface to dissolve the kerogen in oil shale, then bring the fluid to the surface and then somehow, voila, oil again. A good reference for the terminology is helpful.

  7. By Benny BND Cole on March 26, 2012 at 2:54 pm

    Yet another excellent post by RR.  

    As usual, RR correctly points the difference between potential and commercial.  

    A lot of sunlight hits the earth, the potential is huge, yet the commercialization remains iffy. 

  8. By Glenn Vawter on March 26, 2012 at 5:00 pm

    Thanks for clarifying what oil shale and shale oil are based on historical terminology.  Here is a simple description developed by the National Oil Shale Association.

    “Oil shale” is a petroleum precursor that requires cooking to get the oil and natural gas out (e.g. Green River oil shale deposits in the Western United States).


    “Tight oil” or “Liquid Rich Shale” is crude oil stored in shale and requires modern drilling and recovery techniques to get it out (e.g. Bakken and Niobrara shale deposits).  Natural gas is also produced from shale deposit.  ·      

    Millions of years ago algae and plankton died and sank to the bottom of lakes and seas.

     As they lay on the bottom of the sea or lake, they were buried under layers of mud and sand.

      Over millions of years more and more mud and sand covered them.

     The layers of mud and sand pushed the dead stuff further into the ground, squashing it under higher pressures and temperatures.

      This heat and pressure squashed the layers of mud together turning it into a special kind of rock called shale, just as the sand was compressed to make sandstone.

      The heat and pressure also turned the dead stuff, squashed inside the shale rock, into oil’s beginnings – kerogen.


    ·       There are some areas where the heat and pressure continued to ‘cook’ the kerogen converting it into crude oil.  Some oil migrated into traditional oil reservoirs.  The oil that remained in the shale is known as “Tight Oil” or “Liquid Rich Shale”.

     There are also areas where the kerogen trapped inside the shale did not get hot enough to ‘cook’ and was not yet crude oil. This is called “Oil Shale”.

    It is possible to extract crude oil from “Oil Shale” also, by finishing off mother-nature’s work by ‘cooking’ the rock faster.

     The crude oil obtained from both sources can be made into high quality products such as gasoline, jet fuel, and diesel to fuel our cars, trucks and planes.

  9. By JoulesBurn on March 26, 2012 at 5:24 pm

    Besides generating a lot of advertising revenue proclaiming that the US has more oil than Saudi Arabia, this semantic controversy is interesting because of how possessive the oil shale folks are regarding the term “shale oil”. I disagree that one must refer to the stuff from Bakken as “tight oil”, or “liquid-rich shale”. “Shale-hosted oil”? Gimme a break. The Bakken stuff was formed in the shale and made into oil there. And it’s still there. Why can’t it be called shale oil? Oil from a whale is called “whale oil”, right?

    Everyone concurs that the stuff in the Bakken and Green River formation has the same early history, no?  The only difference is that the gunk in the latter wasn’t cooked long enough. Ergo, the better correction here would be to start referring to the Green River formation rock as “kerogen shale”, because there is no oil in it (yet). And when you indeed cook it enough, then you may call it “shale oil”.

    But better still would be “fully cooked kerogen formerly hosted in shale“.


  10. By Robert Rapier on March 26, 2012 at 5:47 pm

    The Bakken stuff was formed in the shale and made into oil there. And it’s still there. Why can’t it be called shale oil?

    For the same reason we don’t call a bicycle an automobile. That term already has a long history of usage in a certain context, and when used in a different context it leads to confusion.

    This was also always my beef against gasification processes like Range Fuels calling their process “cellulosic ethanol.” After all, they intended to produce ethanol from cellullose — so why shouldn’t it be called cellulosic ethanol? But terminology is important, and cellulosic ethanol has a history of over 100 years in a specific context.


    • By JoulesBurn on March 26, 2012 at 6:31 pm

      If  someone marketed a bicycle as an automobile, people would laugh at them.

      There is no centralized language police which will take historical context into account. Gas from the Marcellus shale is called shale gas. To the average person, there is no reason not to call a spade a spade.

      Shale Oil in America: Economy Fix of Dangerous Fantasy

      If there were a semantics court, one could argue there that the Oil Shale Industry hasn’t done much with the term over the last 100 years, so someone else should have a chance. But I think the ship has already sailed.

      • By Robert Rapier on March 26, 2012 at 6:48 pm

        If  someone marketed a bicycle as an automobile, people would laugh at them.

        That’s because the average person knows what a bicycle is. But the average person does not know what oil shale is, and therefore they don’t distinguish between the commercialization going on in the Bakken with potential commercialization in the Green River. In fact, I have come across many people who think these are the same types of formations, and they are producing shale oil. I have heard people talk about the kerogen in the Eagle Ford.

        So terminology is important in order to avoid confusion. The average person would not know the difference if I called a pump a compressor (and one can argue by the same logic that a pump compresses), but these things have very different functions and it would be very confusing if I started mixing up that terminology.


        • By JoulesBurn on March 26, 2012 at 7:06 pm

          I agree that there is confusion about this, and that is important to distinguish between the two. But you are arguing that historical usage should take precedence, and I am saying that obvious,  simpler, and logical usage will probably win.

          • By Robert Rapier on March 27, 2012 at 4:27 pm

            But there is already a long history of usage (over 100 years) in a particular context. I mean, we could have called a computer a calculator since it calculates, but a calculator had a history of usage in a particular context. If we started calling a computer a calculator it would have been unnecessarily confusing. Likewise, if we start to change the definitions here, when someone says “shale oil” you don’t actually know what they mean. If you simply call the Bakken oil “tight oil”, confusion averted.


        • By Moiety on March 28, 2012 at 4:27 pm

          You don’t evne have to go outside technical, engineering areas to mix up pumps and compressors i.e. vacuum pumps is an incorrect term that is in the vernacular.

    • By Cyrill Landau on March 27, 2012 at 4:50 pm
  11. By Douglas Hvistendahl on March 26, 2012 at 5:52 pm

    Sulpher eating bacteria are being used to extract metals from poor polymetalic ores. They require water, air, and heat which is produced by the bacteria in giant heaps (like giant compost piles).

    I wonder if someone could find a kerogen eating bacteria that would release light oils? Has anyone been looking? If anything has been found, what conditions would it need to produce effectively?


  12. By ben on March 26, 2012 at 6:18 pm

    Shale energy of various descriptions will demand loads of capital and huge amounts of energy to produce/distribute.   Much of the would-be supply will much too inefficient when viewed through the lens of EROEI calculations and issues of sustainability (not that biofuels are held to the same standards):   Some shale production may help, but it remains more than an expedient balm for a near-term itch resulting from an invidious structural imbalance between world energy supplies and global demand–a situation that ensures a steady escalation of energy costs that promise to outpace the annual growth rate of producer/consumer price indexes by 25 to 50% for the next decade and beyond.  This period of recalibration in the cost of domestic energy will tend toward realignment with the historic costs that were smartly charted by CER’s editor a few weeks ago.   I commend to all a close examination of these charts even as we offer a word of “thanks” to Sam. 



  13. By Jim Takchess on March 27, 2012 at 1:36 pm

    I’m curious what side you would favor in a bill coming up in NH

    I just got a phone call from a call center backed by PSNH referencing the hidden energy tax and urging me to call my state senator .



    • By Robert Rapier on March 27, 2012 at 4:31 pm

      Kind of an odd bill. I don’t know the particular politics there, but I do know that utilities tend to be very powerful and use their political power to squelch competition. So some remedy is probably in order, but I can’t say much about that particular one without hearing both sides.


  14. By Jeremy on March 28, 2012 at 11:13 am


    Almost everyone is talking about oil scarcity but we somehow forget that there is a number of other <a href=””> natural resources we are gradually running out of</a> and their complete depletion would pose a serious threat to some industries and especially to the world of information technology. I am really concerned about whether the scientists will be able to find an effective solution to this problem other than the devastation of one of Earth’s most valuable natural resources – the ocean as suggested in the article.

  15. By Homey Smoothe on April 6, 2012 at 2:09 am

    If the US has a trillion barrels of Kerogen Shale,  why not just have the government  (I know we are broke, but pretend we can keep printing more money)  subsidize the development of the kerogen-to-oil process so that it is commerciably viable?

    Probably a good answer to this, but if the alternative is some massive die off scenario or riding bicycles around, it seems to me this would be the way to go.    CTL and GTL may be more commercial but we don’t need to waste those resources in cars.

    I would rather the government spend money on this than bailing out banks.

    (I realize climate change is  a serious problem too, but I am with Robert absolutely nothing will be done barring some miracle geoengineering strategy).

    Keep up the good work Robert!!!



    • By Thomas Kinoshta on January 24, 2015 at 5:51 pm

      The banks paid all the loans to the USA governments.

  16. By Rob on May 22, 2012 at 8:24 am

    Bull.   There are VAST amounts of recoverable oil throughout the US.  The US and Canada combined will be the single largest oil producers in the world by 2020 and that assumes we do nothing more than is currently being done.  (meaning no keystone pipeline and a political environment that is anti oil production.)

    • By Robert Rapier on May 22, 2012 at 1:04 pm

      There are VAST amounts of recoverable oil throughout the US.

      Technically recoverable is not the same as economically recoverable. That is the point. There is a vast amount of gold in the oceans that is technically recoverable. But it will never be recovered because it is far too costly to recover it.


    • By Thomas Kinoshta on January 24, 2015 at 5:49 pm

      The USA has about 6 years of oil left. If we use 1/2 of our usage each year, it will last 12 years. Canada is not the USA. Canada does have a lot of oil.

      • By Robert Rapier on January 25, 2015 at 2:54 am

        It’s not really like that though. We actually have a larger R/P ratio (the number of “years” we have left at today’s production rate) than we had 20 years ago. “10 years of oil” has lasted us 30 years, and we still have 10 years of oil because of new reserves that have been discovered/developed. That won’t always be the case, but I guarantee you we will still have reserves in 10 years.

      • By snowtrails on February 7, 2016 at 5:02 am

        looks like you were about as wrong as is possible to be wrong.

  17. By Tony on July 26, 2012 at 4:20 am

    Is it not possible to just mine the karogen like it was coal?

    Is it nessesary to convert the karogen to oil and let it flow? The world and US needs energy and not nessesarily oil.

    If there is a large amount of karogen in one place why not build a mine and transport the karogen by rail to a bigger energyplant for electricity production?

    Is coal cheaper than karogen to produce and and how is the energycontent in karogen versus coal?

  18. By Robert Rapier on July 26, 2012 at 12:53 pm

    Is it not possible to just mine the karogen like it was coal?

    Yes, but the energy density is quite low. Yes, you do have to convert it to get to flow. Some countries do use kerogen as a poor man’s coal to produce power, but those are countries that don’t actually have coal.


  19. By Kimo DeV on August 5, 2012 at 6:05 pm
























  20. By snowtrails on February 7, 2016 at 5:00 am

    Well, heres a great example of someone who is eating his words now.

    • By Robert Rapier on February 7, 2016 at 11:36 am

      Not sure if you meant this as a comment on my article, or where trying to respond to someone else. If the former, everything in this article is still totally accurate. The Green River formation wasn’t production oil even when it was $100 a barrel, even though people would talk about the trillions of barrels of oil there. That resource still has never been classified as reserve. Further, a lot of the shale reserves are getting taking off the books now in response to lower prices.

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