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Reviews - June 2008

Reservoir Geomechanics

Res Geomech

Mark Zoback
Published by: Cambridge
First published: 2007
ISBN: 978-0-521-77069-9
List price: £80.00
449 pp



www.cambridge.org

There are relatively few books that cover aspects of structural geology, particularly stress, in an applied sense; so this book is a welcome addition to the literature, especially as it collates a vast amount of material published in a diverse series of journals by the author over a period of 30 years. A major advantage of the book is its interdisciplinary approach, in that it provides an excellent crossover between aspects of structural geology and reservoir engineering - a link that is all too often overlooked. Fluid properties and the causes of overpressure are dealt with, as well as the properties of the rocks themselves. The response of rocks to stress, including failure, and the determination of stresses, are covered in detail. Less familiar to those from a non-engineering background will be the consideration of wellbore stability and the effects of reservoir depletion.

Most readers are unlikely to start at page one and work systematically through to the end, but that does not matter as the book is written in an accessible way that allows the reader to dip in and out of it. The overall layout of the book follows a logical course, although some chapters are more general than others - inevitably, the first part ranges more widely than some of the later, more detailed sections. The diagrams and other illustrations are generally very clear and easy to follow, but some of the colour figures (especially those with stereographic projections) are a little blurred.

It is customary in reviews to have an ‘ah but ...,’ bit towards the end, but I genuinely have very few quibbles with this book. One minor one - for all the mention of faults, and also their sealing potential, there is little mention of the products of faulting, such as cataclasites and clay smears that can have a profound influence on fluid flow.

In conclusion, I would recommend the book to any geologist working in a situation where faults or fractures interact with the present-day stress field. The book should certainly be available to anyone working on fractured reservoirs and dealing with overpressured fields. The price of £80 is not extortionate by present-day standards and so should not, in itself, be a major source of stress.

Tim Needham
Needham Geoscience, Ilkley

        

Impact Structures in Canada

Canada

Richard A F Grieve
Published by: Geological Association of Canada (Geotext 5)
Publication date: 2006
ISBN: 1-895095-11-2 (hbk)
List price: CDN $60.00
210 pp



www.gac.ca/publications

The Foreword of this book relates how studies of terrestrial impact structures in Canada commenced in the 1950s. Through the 1960s the topic remained controversial, and indeed the opposing interpretation of such structures was elegantly championed by K L Currie - who interpreted them as resurgent calderas of volcanic origin. The story of terrestrial impact structures has now swung firmly to worldwide acceptance of extraterrestrial agencies of formation. As I remarked in Geological Society Special Publication 256 (2006) “it is unlikely that this attribution (to impact) will be overturned”.

The 25-page introduction is a very detailed account of the state of knowledge concerning such structures, written in concise and lucid English. Though this is quite excellent, there are some omissions. It does not mention the new evidence of Gerta Keller, based on foraminifera, putting the date of the Chicxulub impact at ~350,000 years prior to the K/T extinction (possibly because this volume was written before this date was firmly established). Strangely, the supposition is that there are no impact structures in the deep ocean, where the crust is repeatedly destroyed by subduction according to the accepted ideas of Plate Tectonics. There is a single remarkable non-craterform structure, the 25km diameter Eltanin structure in the South Pacific Ocean, described by Kyte and others.

The remainder of the volume consists of accounts of each of the 29 structures now recognised in Canada, arranged alphabetically. It is interesting that these are all quite large structures and there are no small, young craters like Wabar, Arabia (D= 0.116km) or Dalgaranga, Australia (D= 0.024km). The smallest in Canada is 2.35km diameter, probably because of the extensive glacial cover. The illustrations are well selected, but each one of these structures has received much fuller illustrated treatment elsewhere. (For example Pye, Naldrett and Gibling produced a 603 page volume on the Sudbury structure in 1984). A reader who wants to learn more should use the pages in this new volume as a lead-in to the full accounts.

The volume is devoid of colour, except for the splendid image of the Carswell Structure on the cover - but black and white seems perfectly adequate.

Joe McCall