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October 2009

Geoscientist 19.10 October 2009


An Atlas of Oil and Gas Depletion

Colin J Campbell & Siobhan Heapes
Published by: Jeremy Mills Publishing
Publication date: August 2008
ISBN: 978-1906600-26-6
List price: £110.00
396 pp


www.jeremymillspublishing.co.uk 

O&GDThe world is dependent on oil and gas – currently supplying 50% of total energy needs - so assessing resources and predicting future production are immensely important. No one has probably devoted more effort to this than Colin Campbell. This is his fifth book since 1991, and in 2002 he founded ‘The Association for the Study of Peak Oil and Gas’ (www.aspo-ireland.org). He has two aims: to highlight the importance of ‘peak oil’ and to predict when peak oil and peak gas production may occur.

The bulk of this book comprises chapters on 63 countries each with standardised contents: a table of past and future production and dates for peak discovery and production; graphs of discovery, production and depletion from 1930 to 2007; analyses of past discovery trends to predict ultimate recoverable resources and predicted production to 2030; notes on geology, discovery, production, consumption and history. The new method for predicting future discovery involves a spreadsheet with the above data and eight steps. The critical step utilises graphs showing the discovery trend and the derivative logistic (annual/cumulative vs cumulative production) extrapolated to zero, to give the total produced when production ends; the authors adjust this value based on exploration maturity.

Seven regional sections outline statistics on a further 93 ‘minor’ countries. Concluding chapters summarise the findings for ‘regular, conventional oil and gas’ in the world, briefly review non-conventional oil and gas, set the oil age in perspective and give 900 references on petroleum resources. The book’s conclusions are these: about 50 countries have already passed ‘peak oil’; the most important that have not are in the Middle East–Caspian region; the world ‘peak’ for oil was 2005; two thirds of the countries analysed have not reached ‘peak gas’; the world ‘peak’ for gas will be 2021.

Should we believe these predictions? There are numerous difficulties - predicting from past results cannot reveal new basins / petroleum systems / plays / ideas; excluding polar and deep-water (>500m) finds seems unnecessary; scant attention is given to improved-oil-recovery etc. Nevertheless, this book is the best yet and deserves to be known to all concerned with the geoscience of petroleum resources. I will let the author have the final word: “it is recognised that the page numbers are probably the only accurate ones, such is the state of confusion on public data, but, that said, the general patterns of depletion can be put forward with confidence.”

Anthony Spencer


Planetary Crusts: Their composition, origin and evolution

S R Taylor and S M McLennan
Published by: Cambridge University Press
Publication date: 2008
ISBN: 9780521841863
List price: £70 (US$150)
378 pp


www.cambridge.org 

Planetary CrustsThis is the first book to explain how it is believed that planets and satellites form crusts. This is a brave venture because, unlike stars which form by ‘top-down’ condensation of H and He gas from dense cores in molecular clouds and which are assembled in a systematic fashion, our planets and their satellites were assembled randomly and ‘bottom-up’ from the material left over in the nebular disk in our Solar System. They are consequently distinct mixtures of gases, ices and rock, in any combination.

The main conclusions are:
  1. No planet in our Solar System resembles the Earth sufficiently closely to allow direct comparison. The authors define primary crusts, derived from differentiation and melting after accretion from planetismals in time scales of ~108 years: secondary crusts products of partial melting of mantles in rocky planets, in a rather longer time scale, perhaps >109 years; and tertiary crusts formed by dehydration or melting of secondary crusts - the only example of these, the sialic crust of the Earth, has continued to form probably over 4000,000,000 years.
  2. The Moon provides an excellent example of a combination of primary anorthositic crust (~45km thick), floated dry from a magma ocean which may have embraced the entire early satellite. The secondary crust is the basalt of the Mare, which is thin and forms a miniscule proportion of the dry moon rocks.
  3. Mercury - the authors were hampered by the pre-Messenger date of writing. The plains are probably basalt, but different in character from the very fluid basalts of the Moon because of their low albedo. Little is known about the thin mantle and huge core of this surprisingly dense small planet.
  4. Mars, one tenth the mass of Earth. The crust is ~50km thick and sustains a ~30km relief. It is essentially basaltic, but Orbiter evidence reveals some silicic rocks.
  5. Venus - similar in mass and uncompressed density to the Earth, it probably should have similar bulk composition. However, there the likeness ends, and it is a cautionary model for those seeking Earth-like planets outside our solar system! The crust is estimated at ~50km thick, and supports large volcanoes. It is a one-plate planet with plains covering much of the surface, and some likely rhyolite domes.
  6. Earth – beyond its thin basaltic secondary ocean crust, and sialic tertiary crust, there is no trace of the primary crust. The authors believe that, despite the very old Jack Hills zircons, there was no tertiary crust in the Hadean (>4000Ma). The sialic crust probably started to form soon after that, implying that plate tectonics commenced ~3000Ma or later
  7. The Planetary satellites are even more variable in their crusts than the planets. Of the Galilean satellites, Io is a differentiated planet with an active volcanic crust 20-30km thick, characterised by giant lava flows, lava fountains up to 350km high and large caldera volcanoes. It has no ice and no impact structures. Europa has a thick icy crust riding on a water ocean, while Ganymede has two surfaces – a dark heavily cratered older surface and grooved later surface. Callisto has an ancient cratered surface and the largest multiple ring structure in solar system (Valhalla, 4000km). Titan (Saturn) has sand dunes and methane lakes on its icy surface, while Triton (Neptune) is characterised by a water ice shell 400km thick. There is no mention of Enceladus (Saturn), with water ice plumes from fissures on its surface and a possible buried ocean, or Hyperion, which has a crust resembling Brobdingnagian pumice!

The authors can come to no systematic conclusion, so many are the variables and so random the picture. Splendid book, but not without warts, covering as it does such a broad canvas of speculation, hypothesis, theory and guesswork.

Joe McCall