Guest Post by Willis Eschenbach
There’s a discussion over at Judith Curry’s excellent blog, about peak oil. I find the whole madness surrounding peak oil to be one more example of our human love for warnings of future disaster. Few people want to hear that tomorrow will be OK, that things will work out. Instead, most folks want to hear some terrible story about what tomorrow holds, whether it’s peak oil or climate meltdown or the coming ice age. Go figure.
Figure 1. Conventional oil leaking out of the ground near McKittrick, CA.
One part of the discussion of peak oil that has always bothered me is the division of oil into “conventional oil” and “unconventional oil”. Here’s why I think that division makes no sense with regards to peak oil.
I’ve lived through much of the whole peak oil deal, which near as I can tell has turned into a half-century-long goat roping contest. During the earlier years, people were shouting that the oil would run out, that the top would be very soon now, we’d hit the peak and by gosh, at that point things would turn ugly. Of course, that still hasn’t happened, so the peak oilers were left with the question pondered by failed doomcasters throughout history, viz:
How the heck do I explain the cratering of my position and still maintain some shred of my reputation?
For the peak oil folks, salvation came in the form of “unconventional oil”. Now, we’re assured, oil is still running out, so they were right all along … You see, they say, King Hubbert was right, we’re running out of conventional oil, but as it runs out it is being seamlessly replaced by “unconventional oil”, so we still have oil even though we’re running out of oil. Got it?
The strange part is, when you open a barrel of unconventional oil to see what conventions were broken in its creation, you find it is indistinguishable from conventional oil.
What is unconventional oil? Well, we could start by considering the conventions regarding oil. For literally billions of years the convention was that oil was found in small pools and seeps like you see in Figure 1. Indeed, the discovery of oil in Oil Creek, Pennsylvania, the site of the first US oil well, came about because oil had been seeping out there for untold centuries, and had been known and utilized by the Early Asian Immigrants in the area before the later arrival of the melanin-deficient crowd.
So conventional oil, by ancient hallowed convention handed down through the millennia, is found in tar pits and oil seeps on the surface. Which means that people being so rash as to drill for oil, by definition, would be pumping up “unconventional oil” … but of course, life is not that simple.
As a result, “conventional oil” is not from the conventional method of dipping it up in a bucket from a seep, but by the decidedly unconventional and at that time unheard of method of drilling a hole in the earth to get it to come out …
Things went along just fine like that for years. Then “secondary recovery” methods started to come into use. These were a variety of physical and chemical methods used to squeeze more oil out of existing fields, including fracturing the rock to allow the oil to come out more easily.
Now, about this time, the whole “peak oil” story started to go south, because no matter how much peak oilers howled there was more oil discovered every year. Every year the proved reserves just kept growing. And that process has continued to this very day, with more proved reserves than ever. How were the peak oilers to explain it? Hey, “unconventional oil” to the rescue!

For example, thinner oils were “conventional”, but thicker, more tarry deposits, despite having been utilized by humans for centuries, were “unconventional” oil, so they weren’t counted regarding the peak.
The real laugher, however, the place where you can see the gears stripping, involves the “conventions” about fracturing the rocks to allow more oil to come out, what we call “fracking”. The fracturing technology was developed about forty years ago, and has been used ever since, mostly for secondary recovery. And for all those decades the oil coming from the fractured rocks has been “conventional oil”. But now people have learned to drill wells horizontally and fracture them … and now suddenly after forty years of fracturing the rock, which gave “conventional oil” when it was done from vertical wells, fracking now only delivers “unconventional oil” simply because the drill hole goes horizontally instead of vertically … does this make any sense to anyone?
The classification of oil from fracking as “unconventional oil” shows clearly the ludicrous nature of the dividing line when we are discussing peak oil. Regarding the putative peak, why is oil from a horizontal well “unconventional” and oil from a vertical well “conventional”? It is all gotten by technology, and none of it is any more “unconventional” than the drilling of the first oil well, a most unconventional act …
Calling oil from horizontal wells “unconventional” is crucial for the peak oil folks, however, because if the oil from fracking were classified as conventional oil, the “peak oil” claims and the “peak gas” claims would sink of their own weight …
Look, folks, the ugly truth is that the world is awash with fossil fuels. To start with, The largest single concentration of fossil energy on the planet is the Powder River coal formation in the Northern US. The world has several hundred years worth of coal. The Canadians have huge amounts of oil … of course it too is called “unconventional” oil, because it alone is enough to blow the “peak oil” claims out of the water. Plus now we have the “tight oil”, oil in the rocks that is, of course, unconventional.
Then we have the discovery of the shale gas resources all around the planet. Even Israel finally has some domestic energy resources. How unconventional is that? Australia just announced a huge find. China has massive gas resources. A preliminary assessment says including shale gas we have enough gas for the next couple of hundred years.
And finally, we have the wild card, the methane hydrates, the “ice that burns”. Estimates of the amount of these are all over the map, but all of them share one feature—they are very, very large, on the order of quadrillions of cubic feet. This is rivals the size of the global natural gas resource …

Finally, most of these forms of fossil fuels occur in combination and can be converted into one another. Coal, for example, can be converted to a liquid fuel, or to a gas.
Now, because there never was anyone hollering about “peak coal”, there’s no such thing as “unconventional coal”, despite huge changes in mining technology. Coal mining has changed as much or more than drilling for oil … so why isn’t there “unconventional coal”?
But in that case, since all of the coal on the planet seems to be “conventional” coal, if we convert coal to oil, are we making “conventional oil” or “unconventional oil”? Presumably it would matter whether we converted coal to oil horizontally or vertically …
In summary, once you get past the nonsense of “conventional” and “unconventional”, there’s enough coal and gas for a couple hundred years, and enough oil for a hundred years, just with what we know about now, and that’s not even counting methane hydrates. Which is why I pay no more attention to the peak oil alarmists than I do to the climate alarmists. One group claims we have too much oil and we’re gonna burn it all, the other group claims we’ll soon have too little oil to burn, and I treat those two impostors just the same.
Was the division between “conventional” and “unconventional” oil devised to cover up the failure of the peak oilers? No way. The distinction is useful in a variety of ways for analyzing the world of oil sources. I think that the concept was simply appropriated by the peak oilers because it was very useful to them, since it totally obscured the failure of their peak oil predictions. To me, oil is oil is oil, and if you claim the world will run out of oil, you can’t later say that you have redefined things, and that the oil that proves your prediction wrong is some other special kind of oil that doesn’t count as oil but walks like oil and quacks like oil …
w.
… Oh, yeah, the weather report. Late night again, two AM. The wind has changed and is blowing from the southwest, landcasting the fog and the smells of the ocean. The characteristic sea smells of iodine and dimethyl sulfide in the fog draw my thoughts back, back to the many mornings I spent getting out of bed here on the hill at 4 am and going down to the harbor, rigging the boat and setting out in the dark to have the commercial fishing gear in the water for the dawn salmon bite. Sliding out of Bodega harbor in the half-light with my gorgeous ex-fiancee and my good friend, once again motoring between the rock jetties at the harbor entrance, going out to discuss matters of life and death with the ocean. I love the ocean because it doesn’t give a damn about a man’s position and his power and his pretenses. Knowledge and experience mean nothing to the ocean. After a life at sea, if I put one foot wrong, I get just as wet as the landlubber falling off the dock … I take pleasure in that ultimate equality and justice of the ocean. I know that even if it is a California ocean it would kill me without first asking me to share my feelings, so leaving the safety of the harbor is always sobering moment …
… sneaking out between Bodega Rock and Bodega Head itself, the little shallow passage the fishermen call “between the rock and the hard place”, where once my heart almost stopped with fear, or at least it started with fear, but other emotions got involved. The channel there is shallow, the sport fishing boat “Mary Jane” was capsized in 1986 with the loss of nine souls by a sneaker wave, “full fathom five thy fishermen lie, of their bones are coral made” …
So when I heard a wave break right behind our little fishing boat one afternoon as we were coming in between the rock and the hard place, my first thought was that we were about to join the folks from the Mary Jane.
We spun around, and aaaah, dear heavens, it wasn’t a breaking wave at all, although a wave was breaking, instead it was my old friend Missus Fishbreath breaking the surface just behind the boat, and breaking my heart with the slow-moving stillness of her majestic beauty, a great gray whale dancing her way three thousand miles from the tropics to Alaska. As we turned and gaped, we were looking her right in the eye, and then she rolled our way and opened her blowhole so close to the boat we could almost look down it, it was as big as a dinner plate, we were close, close enough to count the barnacles clinging to her hull, she was the very picture of natural wildness and glorious beauty and unimaginable power, my heart leapt to see it … and she blew out a great cloud of gagging mist, a noxious enveloping adherent miasma reeking of the million vanished piscatorial souls of her most recent month’s meals, a clogging, thick effluvium that enveloped the boat and then drifted away to leeward as the lovely lady disappeared beneath the waves …
… leaving me in the strangest condition imaginable, with the boat wandering off course, my jaw hanging down to my umbilicus, a pulse rate well into the triple digits, adrenalin-shocked, awed beyond words, smelling like the dumpster behind a cheap fish restaurant, blasted by the natural beauty I had just witnessed, and uncertain whether I was going to vomit or not, but tending toward the former.
I’m not jonesing to visit that particular emotional place again, once was enough for any man. And on a cold night like tonight, I’m glad I’m not rolling out at four am. I fished the Bering Sea as well, and these days I’m just as happy to see the bergy bits and watch the Bering ice on the “Deadliest Catch” TV show from the safety of my couch … but ah, dear friends, mostly I’ve just moved my ocean madness to warmer waters, and I wouldn’t have missed it for rubies and pearls …
Sports and gallantries, the stage, the arts, the antics of dancers,
The exuberant voices of music,
Have charm for children but lack nobility; it is bitter earnestness
That makes beauty; the mind
Knows, grown adult.
A sudden fog-drift muffled the ocean,
A throbbing of engines moved in it,
At length, a stone’s throw out, between the rocks and the vapor,
One by one moved shadows
Out of the mystery, shadows, fishing-boats, trailing each other
Following the cliff for guidance,
Holding a difficult path between the peril of the sea-fog
And the foam on the shore granite.
One by one, trailing their leader, six crept by me,
Out of the vapor and into it,
The throb of their engines subdued by the fog, patient and
cautious,
Coasting all round the peninsula
Back to the buoys in Monterey harbor. A flight of pelicans
Is nothing lovelier to look at;
The flight of the planets is nothing nobler; all the arts lose virtue
Against the essential reality
Of creatures going about their business among the equally
Earnest elements of nature.
Robinson Jeffers saw it … when you read those lists of famous last words, nobody ever says “I wish I’d spent more time at the office”. Don’t mail the envelope in, push the envelope, the journey will end long before any of us wish it to. Live your most impossiblessed dreams, my friends, because any other kind is just a dream. Chance the widdershins steps of the tarantella, lift the ancient curses and look under them for old coins and lost loves and dust bunnies with a vest and a gold pocketwatch, opt for an immediate increase in the uncertainty levels, stay away from the world of adrenalin deficit spending, hold your dearest warm under your heart while you dare the icy seas of life, for the night is assuredly coming …
My very best wishes to all, I’m off to sleep.

Willis
I enjoyed reading the article. I think Jeff raised the point about price – which I think is the crux of the issue.
One of the thing the “peak oilers” don’t say is that the argument comes with the implicit caveat that with “given technology, proven reserves and current price then…”.
As you say the world is awash with oil but of course some of it would cost too much to extract – at current prices and technologies. Furthermore, exploration takes a long time to get started in a new – venture – region. We know that there are other big finds out there but the paper work needs to be done first and with political instability in some regions, companies are playing a “wait and see” game.
Your point about conventionals and unconventionals is a good one. But again this is largely a result of economics. In general terms, both have been exploited historically with conventionals winning through due to ease of extraction – why would a company go for the higher fruits first?
And as you say directional drilling has been revelation to both conventional and unconventional reservoirs; improving recovery rates. Other things 3D/4D seismic, microseismic, more stimulation options etc. In short the “peak oilers”, ignore the caveats.
Finally, as demand increases prices go up, if prices go up then marginal fields become economic. Oil companies (particularly private firms) then develop these fields all the while improving the engineering and driving down price.
It’s fun to search for oil production projections in books.google.com. Since the early 1900s there have been predictions that peak production was just a few years away. For over 100 years the peak has been right around the corner.
It really is nice to know that the head of the IPCC, Dr. Rajendra Kumar Pachauri , helped us to prolong our use of dirty, co2 emitting OIL. He set up Glori Oil, now Glori Energy, which is a residual oil extraction technology company. He was its scientific advisor while being head of the IPCC. Al Gore and Pachauri are seeped in oil and are both utter hypocrites of the highest order.
Oil will never run out. This is because by the time reserves get to dangerously low levels we humans would have moved on, like we have always done. There are alternatives which we can’t be bothered with too much at the moment such as Algae fuel.
Further reading:
George Monbiot – Guardian – 2012
“We were wrong on peak oil. There’s enough to fry us all
A boom in oil production has made a mockery of our predictions.”
Business Week
“Everything You Know About Peak Oil Is Wrong“
We’re supposed to have hit ‘peak gold’ too, but I am not buying it.
But I don’t suppose if the temperature levels off, we will get have ‘peak climate’, because that would put alot of alarmists out of work.
Peak oil is a myth.
The average production price of a liter of oil has not risen much.
The cost of producing 1 barrel of oil (about 159 liters) is between US$2.00 and US$15.
While new extraction methods or technology will be more expensive to start off with, they will drop when adopted whole scale.
The price of petrol is a political construct…..
The price of crude oil is not determined by the market but determined by a cartel (OPEC) which sets the bottom price. Price fluctuations are above this bottom price.
http://sovereign-investor.com/2012/12/18/oil-prices-are-headed-higher/
The price of petrol for the end user is also determined by politics.
Governments are heavily dependent on the tax on petrol to fund their election bribes.
Taxes on petrol are also used to subsidize public transport projects. The price needs to be high enough for public transport to ‘compete’.
They are also pressured to keep the price artificially high to appease the ‘environmental’ activists who want to phase out fossil fuels.
For example, some 60 per cent of the pump price in Britain is down to tax and duties.
Petrol is a cash cow.
On top of that, some are wondering if the cost of oil has actually risen at all….
Due to inflation it is very hard to gauge whether oil prices themselves are rising or falling.
Measured in gold, the price seems pretty stable and is currently below average.
Measured in gold, the oil price today is only 82% of its average over the past 41+ years.
http://www.forbes.com/sites/louiswoodhill/2012/02/22/gasoline-prices-are-not-rising-the-dollar-is-falling/
Ed_B says:
February 2, 2013 at 2:31 pm
See, that’s where we’re different. I actually look at the data before making my claims. So when some smug fool comes in to tell me that the world production of oil peaked in 2004, and to gloat unpleasantly about how much wealthier s/he is than us common folks, boasting that s/he has a ton of spare money laying around to purchase “a ton of energy futures”, I just ask her/him to point out the peak …

w.
Why are we skeptics generally such optimists and Warmists tend to be such such doom mongers? They draw a straight line. Let’s look at the peak horsesh!t problem of the late 19th century.
Vrooom, vroooom. Problem solved.
Porpoises leaping through the moon’s track at midnight off the Needles…. I still see it 60 years later.
“Knowledge and experience mean nothing to the ocean. After a life at sea, if I put one foot wrong, I get just as wet as the landlubber falling off the dock”
But after a life at sea, you are surely a lot less likely to put a foot wrong than a landlubber is.
The way I see it, most of this future doomsaying comes about from people making linear extrapolations of current trends. The predictions of doom would come to pass if human beings never changed the way we did things. But we change. Old methods give way to new methods. Discoveries are made. Technologies are invented and the technologies of today fade into irrelevance in the not so distant future. And so the predictions of doom fail to materialize when the future arrives because we adapt and invent. The doomsayers fail to recognize that they can’t predict the future but continue to be given undue importance because they attract a legion of followers.
LOL we reached peak oil in 2004? News to me. I guess those massive reserves of shale in australia are just illusory.
Oil produced from vertical wells is defined as “conventional oil”, but oil produced by rotating the drill 90 degrees (horizontal wells) is something other than conventional oil. Engineers have a term for a 90 degree rotation, which is multiplying by the square root of negative one. Now mathematicians refer to this as “imaginary” components, but engineers prefer the term “complex” component. It looks like any petroleum product gathered from horizontal drilling is either “imaginary” or “complex”. If this is the case, imaginary petroleum when burned makes imaginary CO2 and leads to imaginary global warming. Or if the petroleum is “complex” it leads to complex global warming.
It is fairly easy to postulate that the environmentalists will never be a party to “imaginary” global warming. Noting that the warmists explanations of the mechanism for global warming are so complex no human can understand them now, they will not promote any further addition of complex terms. So the Global Climate Change Alarmists will simply call all petroleum products “dirty oil”.
It isn’t just “peak oil” projections that have repeatedly come a cropper. In the 70’s we were certain we were already into that long slow decline to the next Ice Age. By the 90’s, we were all about to burn up and die. For a quarter century it was illegal to build a natural gas fired power plant in the U.S. because we “knew” that all our natural gas was pretty much used up and we wished to save what was left for higher uses. The list goes on and on and yet here we go with yet another set of confident announcements about the future, all based on what “we know”. It seems to me that this endless cycle of faulty prognostication could be ended if we simply came to appreciate the immense expanse of “what we do not know” and weighed it against the relatively frail body of “what we do know”.
So there’s life around an oil puddle after all…
That’s a rather obtuse question don’t you think?
Good post Willis.
it’s not often mentioned that “fossil fuels” are composed of CO2 that has been taken out of the atmosphere over hundreds of millions of years. If the earth now is experiencing any serious imbalance – it’s the lack of CO2 in the atmosphere.
Willis Eschenbach says:
February 2, 2013 at 4:02 pm
Ed_B, I’m glad you made money and I wish you the joy of it, but before you strain your shoulder patting yourself on the back for your predictive abilities, consider how much money you might have made.

I mean, if only you had incorrectly identified peak oil as being in 1998, instead of incorrectly identifying it as being in 2004, you could have bought in for $17 a barrel instead of $40 dollars a barrel … just sayin’, you wasted a full six years of money-making chances, you financial wizard, you …
Willis writes “I actually look at the data before making my claims.”
And what do you see there Willis? Are you splitting hairs about whether peak is actually 96 million barrels or 97 million barrels per day?
Peak oil is not about and has never been about reserves or technology. Its about peak production and so if you look at the larger picture, the 60s and 70s saw massive growth in the West supported by huge increases in oil usage. The last 20 years has seen massive growth in the East unsupported by the same oil production increases. And what has happened? Prices are increasing faster now and oil usage efficiencies are increasing to compensate both from a “forced” reduced usage per increase in growth and increased production cost points of view.
We may not be precisely at peak oil and we may even flatline or even slightly increase for a while but we’re not going to get large increases like we did in the 60s and 70s and instead we’re going to be doing all we can to keep our heads above water as the conventional sources continue to slow their production rates.
And yes, the data does support that at the moment.
Remember the California gold rush? Well….. http://money.cnn.com/2013/01/14/news/economy/california-oil-boom/index.html
@Willis:
Wasn’t the first fracked well in the USA in 1947 or some such? I make that about 66 years…
If you allow for using explosives instead of hydraulics, I think it goes back to about the Civil War…
Oh,and on Hubbert being “right” in N. America: It is worth pointing out that it is largely due to putting off limits giant tracks of land on all 4 coasts ( Pacific, Arctic, Atlantic, Gulf) and a giant chunk of oil land in Alaska ( the “Naval Reserve”).
Then there is that well in the Gulf of Mexico that keep filling back up from somewhere lower down… and the one where Standard Oil found oil at depths that were theoretically too deep and too hot. Yet the oil is there.
@Alfred Ledner W:
We can make oil. Take CO2, add Hydrogen (often from water) and heat. You can reduce the heat needed with various catalysts (some are Iron based, others us Nickle or Chrome or various mixes; there are even rock based types – Zeolyte) You get various mixes of gasoline, kerosene, Diesel, heavy oils.
Now picture subducting sea floor (say, off California) taking a load of sea bottom mud (with water) and loads of carbonate rock to great depths (magma heated depths). We know what chemical reactions can happen. We admit that in the extreme case it releases the CO2 (why do you think volcanoes behind subduction zones get CO2 vents?) It all “works”.
Yet we staunchly assert that the oil and gas found in the California fields in front of the volcanoes are due to dead critters and not a product of the subducting goo prior to getting fully vaporized.
Now look where lots of oil is found. Tends to be near subduction zones or old plate impact zones. No, not all cases; just a lot of them…
IMHO oil comes from two places. Fermented algae (such as North Sea oil deposits) and subjection / collision of plates (such as California / Saudi). Otherwise California oil doesn’t make much sense. Much of California was only lifted out of the sea recently in geologic terms. It was ‘ocean bottom scrapings’ and not a lot of time for sediment trapping and kerogen breakdown…
So ‘conventional’ theory says dead stuff gets hauled down under rocks and slowly baked to make kerogene then cooked some more to make oil. Too far down it is destroyed, to far up it doesn’t become oil and stays “bitumen sands”. This ignores that wet carbonate rock sucked down to heat and pressure ought to cook out oil…. And when we look around the solar system we find complex hydrocarbons all over the place. No dead animals there….
IMHO the “dead animals” theory only accounts for a minor part of the oil.
http://chiefio.wordpress.com/2012/03/25/did-crude-oil-rain-from-the-sky/
Oh, it is also worth a mention that oil was recently found on the ocean bottom near mid ocean ridges. Loads of it. The stuff is everywhere…
http://chiefio.wordpress.com/2012/09/16/theres-oil-on-that-ocean-bottom/
Oh, and on the “Energy return for energy invested” argument (that inevitably comes up):
One can use very cheap nuclear electricity to raise oil due to the FORM being worth more. We want liquid fuels. If the oil source is cheap than making synthetic from scratch, we will still pump the oil and refine it. (So, for example, if it took 60 kW-hrs to make a unit of synthetic oil but I could raise that oil with 50 kW-hrs it would still be pumped. Even if the energy in that final product were only 40 kW-hr (presuming that 10 kW-hrs is lost in trying to charge / discharge e-car batteries or that I want plastics…) The end result would just be building more nukes so I could put that energy in my gas tank in a convenient form. (This is happening today with the use of Natural Gas to create ‘unconventional oil’ from tar sands. The oil form is worth more than the gas form.)
We can already turn coal and nuclear process heat into ‘oil’ if desired. Make synthesis gas from coal (or trash or chicken feathers) and use nuclear heat to F-T process it into oils and gasoline.
So we will never run out of oil. We will just get it from ever more interesting places. Including our own garbage. (Being done today, BTW.)
Here is something on the history of conventional / unconventional [delete as necessary] small / big oil.
Bitumen and Petroleum in Antiquity
Brill Archive, 1955 – 194 pages
http://tinyurl.com/a7aewhh
Guest Post by Willis Eschenbach: “Few people want to hear that tomorrow will be OK, that things will work out. Instead, most folks want to hear some terrible story about what tomorrow holds, whether it’s peak oil or climate meltdown or the coming ice age.”
===========================================================
Willis, how do you know that about “most folks”? Any scientific evidence?
Is is not that some people invent lies and spread them around as scientific facts and others simply believe the “experts”?
As Jeff L mentioned, the determinant is price that justifies the recovery. I like to think of it as “easy” oil vs. “hard” oil. Most, but not all of the easy oil has been found. There may still be places that have been closed to drilling where easy oil may lurk. But of the places that are open, easy oil is the past tense. If you want to cook oil sands, drill horizontally and frack, drill in deep water, and other things that may become possible in the future, oil can still be retrieved. It will just not be cheap to do so. This is the “hard” oil. Because we are running on harder oil all the time, it will make sense that the price goes up in line the recovery costs. That should be sufficient to limit oil to those things where it is a good choice. Oil/petroleum products are nice to use for plastics, and their energy density and storage characteristics make them nice to use other places. The market will decide the outcome. If not in places like the US, then globally.
TimTheToolMan says:
February 2, 2013 at 4:32 pm
Hmmmm … Tim again. Welcome back, Tim. We’ll see how this works out …
Tim, are you seriously looking at that chart and claiming that oil production peaked in 2004 like Ed_B claims? Because as you correctly point out, peak oil is about one thing only—peak oil production. So let’s look at that, shall we?
We have produced more oil than we did in 2004 every single year since then except 2009, and that was likely due to reduced demand. We have had six years of increasing production since 2004, 2011 production was a full three percent higher than in 2004, and you call 2004 the peak year? What part of the word “peak” are you not understanding?
Again, thanks for providing another example of the degree to which peak oilers will go to “support” their claims, even to the surprising extent of claiming that the year of peak oil production was a year where six of the seven following years had higher production … yeah, that’s the ticket, that’ll show the peak oil doubters, all right …
w.
Willis: I realize you are probably using the terms “conventional oil” and “unconventional oil” facetiously but to a geologist those terms have very specific meanings. When a geologist speaks of “conventional oil” he is describing a system which has a source rock (typically a carbon rich shale), a reservoir rock, (typically a sandstone, limestone or dolostone) into which the oil (or gas) has migrated and a trapping mechanism; This is a means to prevent the oil or gas from escaping to the surface and disappearing These include an impermeable non porous layer (shale) capping domes/anticlines, pinch outs,, fault boundaries. Traps all have one essential feature, They all prevent the migration of oil. In short you have: source rock, reservoir rock and trap.
Unconventional oil (or gas) is different in that “the source rock and the reservoir rock” are one and the same. That is the major difference between the two. The Barnett Shale, The Marcellus Shale, The Athabasca Tar Sands etc. are examples of “unconventional” oil/gas.