science

Oil shale reserves

Oil shale reserves is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Oil shale reserves rather than just read about it. In short: Oil shale reserves refers to oil shale resources that are economically recoverable under current economic conditions and technological abilities. Oil shale deposits range from small presently economically unrecoverable to large potentially recoverable resources.

Key takeaways

Oil shale reserves belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oil shale reserves to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oil shale reserves from memory before moving on to harder problems.

Reference excerpt

Oil shale reserves refers to oil shale resources that are economically recoverable under current economic conditions and technological abilities. Oil shale deposits range from small presently economically unrecoverable to large potentially recoverable resources. Defining oil shale reserves is difficult, as the chemical composition of different oil shales, as well as their kerogen content and extraction technologies, vary significantly. The economic feasibility of oil shale extraction is highly dependent on the price of conventional oil; if the price of crude oil per barrel is less than the production price per barrel of oil shale, it is uneconomic. As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. There are more than 600 known oil shale deposits around the world. Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value. Many deposits need more exploration to determine their potential as reserves. Well-explored deposits, which could ultimately be classified as reserves, include the Green River deposits in the western United States, the Tertiary deposits in Queensland, Australia, deposits in Sweden and Estonia, the El-Lajjun deposit in Jordan, and deposits in France, Germany, Brazil, China, and Russia. It is expected that these deposits would yield at least 40 liters (0.25 bbl) of shale oil per metric ton of shale, using the Fischer Assay. A 2016 conservative estimate set the total world resources of oil shale equivalent to yield of 6.05 trillion barrels (962 billion cubic metres) of shale oil, with the largest resource deposits in the United States accounting for more than 80% of the world total resource. For comparison, at the same time the world's proven oil reserves are estimated to be 1.6976 trillion barrels (269.90 billion cubic metres).

Oil shale geology

Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays) or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings). Much of the organic matter in oil shale is of algal origin, but may also include remains of vascular land plants. Three major type of organic matter (macerals) in oil shale are telalginite, lamalginite, and bituminite. Some oil-shale deposits also contain metals which include vanadium, zinc, copper, and uranium. Most oil shale deposits were formed during Middle Cambrian, Early and Middle Ordovician, Late Devonian, Late Jurassic, and Paleogene times through burial by sedimentary loading on top of the algal swamp deposits, resulting in conversion of the organic matter to kerogen by diagenetic processes. The largest deposits are found in the remains of large lakes such as the deposits of the Green River Formation of Wyoming and Utah, USA. Oil-shale deposits formed in the shallow seas of continental shelves generally are much thinner than large lake basin deposits.

Definition of reserves

Estimating shale oil reserves is complicated by several factors. Firstly, the amount of kerogen contained in oil shale deposits varies considerably. Secondly, some nations report as reserves the total amount of kerogen in place, including all kerogen regardless of technical or economic constraints; these estimates do not consider the amount of kerogen that may be extracted from identified and assayed oil shale rock using available technology and under given economic conditions. By most definitions, "reserves" refers only to the amount of resource which is technically exploitable and economically feasible under current economic conditions. The term "resources", on the other hand, may refer to all deposits containing kerogen. Thirdly, shale oil extraction technologies are still developing, so the amount of recoverable kerogen can only be estimated. There are a wide variety of extraction methods, which yield significantly different quantities of useful oil. As a result, the estimated amounts of resources and reserves display wide variance. The kerogen content of oil shale formations differs widely, and the economic feasibility of its extraction is highly dependent on international and local costs of oil. Several methods are used to determine the quantity and quality of the products extracted from shale oil. At their best, these methods give an approximate value to its energy potential. One standard method is the Fischer Assay, which yields a heating value, that is, a measure of caloric output. This is generally considered a good overall measure of usefulness. The Fischer Assay has been modified, standardized, and adapted by the American Petroleum Institute. It does not, however, indicate how much oil could be extracted from the sample. Some processing methods yield considerably more useful product than the Fischer Assay would indicate. The Tosco II method yields over 100% more oil, and the Hytort process yields between 300% and 400% more oil.

Size of the resource The size of the oil shale resources is highly dependent on which grade cut-off is used. A 2008 estimate set the total world resources of oil shale at 689 gigatones—equivalent to yield of 4.8 trillion barrels (760 billion cubic metres) of shale oil, with the largest reserves in the United States, which is thought to have 3.7 trillion barrels (590 billion cubic metres), though only a part of it is recoverable. According to the 2010 World Energy Outlook by the International Energy Agency, the world oil shale resources may be equivalent of more than 5 trillion barrels (790 billion cubic metres) of oil in place of which more than 1 trillion barrels (160 billion cubic metres) may be technically recoverable. A 2016 conservative estimate by the World Energy Council set the total world resources of oil shale equivalent to yield of 6.05 trillion barrels (962 billion cubic metres). For comparison, at the same time the world's proven oil reserves are estimated to be 1.6976 trillion barrels (269.90 billion cubic metres).

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Oil shale reserves

Start with the simplest possible case. Write down what Oil shale reserves claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oil shale reserves before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oil shale reserves ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oil shale reserves

In research: Oil shale reserves appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oil shale reserves in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oil shale reserves is common in secondary-school and first-year university syllabi. It links to neighbouring topics Oil reserves, Oil shale, so understanding it makes those chapters shorter.
In everyday life: Look for Oil shale reserves outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Oil shale reserves in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oil shale reserves means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oil shale reserves out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oil shale reserves in simple terms?

Why does Oil shale reserves matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oil shale reserves?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oil shale reserves.