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What is "non-conventional" oil ?

Last modified: January 2012

website of the author : www.manicore.com - contact the author: jean-marc@manicore.com

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That's an easy go: non conventional oil is oil... which is not conventional. What is conventional oil then ? It's oil that went through the complete and regular cycle of oil formation (reading this previous page is strongly advised before proceeding). It was created in a mother rock through pyrolysis of kerogen, then went through primary and secondary migrations, then got trapped in a reservoir rock below the ground, or offshore but with less than 500 metres of water above. In the last case, it is the operating conditions that are non conventional, because the oil found offshore is not different from oil found under other circumstances.

From there, one will deduct that non conventional oil can be :

oil that went through the cycle "formation-migration", but then accumulated just below the surface (in sand for example) where it lost its volatile components. Bituminous sands in Canada correspond to this situation. If the oil accumulated below the surface but still lost a fraction of the lightest molecules, it leads to extra heavy, like in Venezuela (but in Canada the loss of volatile compounds is more important and the "oil" looks more like bitumen),

oil that is located in a "normal" reservoir rock, but with more than 500 metres of water between the platform and the ocean floor,

oil "not quite cooked", that is kerogen partially pyrolised and disseminated in a mother rock. We then have bituminous shale or oil shales that might give, after the pyrolysis is completed in a plant, shale oil.

Sometimes this category also includes:

wells situated in polar regions, that produce conventional oil in non conventional situations,

liquid fuels produced from non conventional gas

A single expression ("non conventional") therefore designates products that can be pretty different one from another::

deep offshore - or polar - enables to get "normal" oil (normal from the refiner's standpoint), but that will be extracted in difficult conditions.

tar sands contain a kind of bitumen. As its name suggests, tar is mixed with sand. When it is close to the surface, this "mixture" can be mined with huge excavators, then brought to a plant that will separate the tar from the sand, with steam that will melt the tar. This steam processing can also be done in situ when the tar sand is located sevel hundred meters below the surface. Steam is then sent into the "sand + tar" seam and the tar melt, then puped up to the surface. The tar is then processed in a refinery of a special kind, because the proportion of hydrogen in the tar is much lower than for an ordinary crude. This hydrogen can be brought directely - a production unit of hydrogen is built next to the plant - or indirectely, by mixing the tar with an oxygen-rich solvent before the whole is distillated at high temperature. In the first case the process requires gas, in the second conventional oil (to get the solvent) elsewhere. Because of the steam production, then the hydrogen production, getting one barrel of this non conventional oil requires 2 to 5 times more energy than for conventional oil.

extra-heavy oil contains a little more hydrogen that tar, and two cases can arise. Either this oil is fluid inside the reservoir rock, and then it can be pumped out, but with the same processes that are used for enhanced oil recovery in a conventional field, because of its high viscosity (steam and solvents are used). Or it can be solid, and then steam must be injected in the field for a while.

Shale oil is obtained through heating the shale that contains kerogen non yet fully pyrolyzed. The net output is negative most of the time: the energy used to heat the shale is greater than the energy content of the oil obtained. Most of the time oil shales cannot be counted as reserves. There is an exception in a baltic country, but it is an exception !

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Where is non conventional oil located ?

Offshore fields are found... offshore. They can be found everywhere: Latin America, Africa, Gulf of Mexico, Sea of China, etc. Tar sands and extra-heavy can be found in various locations, but two places concentrate most of the reserves:

Canada, in the Alberta province, has two thirds of the tar sands in the world (and is the only country to have begun an industrial exploitation),

Venezuela, in the Orinoco belt, has more than 90% of the extra-heavy oil in the world (oil in place).

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What possible production ?

Oil in place is supposed to represent considerable amounts: several hundred billion tonnes (about 500, to be compared to roughly 180 billion tonnes of proven reserves for conventional oil). But:

A large fraction of this oil is not recoverable with a positive yield (it is necessary to spend more than one barrel of oil to recover a barrel of oil, which prevents any production - actually the economic limit is generally two times lower: if more than half a barrel-equivalent of energy is required to extract a barrel, no profitable operation can take place),

this extraction requires more capital than conventional oil, as for CTL: for conventional oil, extracting one barrel per day requires 20.000 $ of capital expenses, when for tar sands, for example, it is rather 200.000 $ which is required to get one barrel per day. Production therefore cannot grow as fast as with conventional oil, because with the same money available the physical flow of oil is 5 to 10 times lower.

As a result, the proven reserves in Canada are presently limited to 23 billion tonnes, when, once again, oil in place is 10 times more important. The two following graphs present possible paths for the production of these resources.

An example of production profile for the Canadian tar sands, in billion barrels per year (the world oil production, in 2010, is about 30 billion barrels per year). To 2015, the production follows the projection of the Canadian Association of Petroleum Engineers, then the growth is maintained to 2030, and after that date it remains flat. In 2100 the cumulated production amounts to 140 billion barrels, that is one third of the ultimate reserves.

Source: « Transport energy futures: long-term oil supply trends and projections », Australian Government, Department of Infrastructure, Transport, Regional Development and Local Government, Bureau of Infrastructure, Transport and Regional Economics (BITRE), Canberra (Australia), 2009.

 

An example of production profile for the extra-heavy in Venezuela, in billion barrels per year. This profile also assumes that production triples to 2030 then remains flat. In 2100 the cumulated production amounts to 60 billion barrels, that is 20% of the ultimate reserves.

Source: « Transport energy futures: long-term oil supply trends and projections », Australian Government, Department of Infrastructure, Transport, Regional Development and Local Government, Bureau of Infrastructure, Transport and Regional Economics (BITRE), Canberra (Australia), 2009.

All this non conventional oil is now generally taken into account in the forecasts regarding future production. The graph below shows the contributions of all kinds of oil, and we can see that non conventional oil allows to shift the peak by 10 years, more or less, but not much more.

Simulation of the world production of "liquids" (oil and all products alike). The vertical bar represents 2010. With this simulation the maximum happens during the 2010 decade. Extra-heavy, deep offshore and coal to liquids add a significant fraction to the total after the peak but do not significantly change the date of the peak. But in 2100 these non-conventional hydrocarbons would represent much more than half the production.

Source: « Transport energy futures: long-term oil supply trends and projections », Australian Government, Department of Infrastructure, Transport, Regional Development and Local Government, Bureau of Infrastructure, Transport and Regional Economics (BITRE), Canberra (Australia), 2009.

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