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June 2010

Applied Geostatistics with SGeMS

Nicolas Remy, Alexandre Boucher and Jianbing Wu
Published by: Cambridge University Press
Publication date: 2009
ISBN: 978-0-52151-414-9 (hbk)
List price: £50.00
264 pp plus CD-ROM containing SGeMS

Remy et alAt last! Here is a publisher who has prepared a thoroughly practical and well presented guide to geostatistics, together with software in a form that can be run by most on their own computers. This attractively printed volume includes a brief overview of spatial statistics (geostatistics) before going on to demonstrate how basic data can be treated. The book then develops concepts of modelling including simulation and analysis.

Two decades have passed since the release of GeoEAS (Geostatistical Environmental Assessment Software) by the US Environmental Protection Agency, the first geostatistical package to be made freely available and in a form suitable for teaching as well as basic geostatistical processing. However, it is limited to 2-D data and runs in a DOS environment, and so it is somewhat alien to today’s students. Furthermore, although the source code was later released, it does not readily lend itself to modification by the user. A decade ago GSLIB (Geostatistical Software Library) filled this gap, enabling modules to be compiled and readily rewritten to suit the user’s needs. The source code was suitable for running in a DOS environment but in compiled form was also available for Windows, for those who paid an appropriate registration fee.

Able to read data in similar format, SGeMS (Stanford Geostatistical Modelling Software) has now been released by staff associated with the Centre for Reservoir Forecasting at Stanford University, with the object of providing a basic and adaptable package “for solving problems involving spatially related variables. It provides geostatistics practitioners with a user-friendly interface, an interactive 3-D visualisation and a selection of algorithms”. There are two main groups of algorithm: kriging (ordinary, indicator, cokriging and block kriging) and simulation (variogram-based, such as Gaussian and sequential, and multiple point), together with utilities to facilitate data transformation.

The book will prove a valuable companion to anyone learning to run the software. It is not, however, an introductory text on geostatistics nor is it a software manual per se. The former is already well catered for by published textbooks and the latter can be downloaded from the support website, together with an example data file concerning porosity that is used in the book. The constraints provided by known and modelled outcrops of sand channels produce striking simulations that are likely to be particularly attractive to geoscientists concerned with environmental and hydrocarbon investigations. The accompanying CD-ROM contains the full SGeMS software and there is a web site to support users in their endeavours: The approach will be intuitive to those already familiar with GeoEAS and GSLIB, and hopefully can be readily followed by others.

This book is recommended for those wishing to conduct their own geostatistical modelling and analysis, and is suitable for students and practitioners alike.

Mike Rosenbaum

Introduction to Numerical Geodynamic Modelling

Taras Gerya
Published by: Cambridge University Press
Publication date: 2010
ISBN: 978-0-521-88754-0 (hbk)
List price: £40.00
345 pp

TGGeodynamics seeks to help our understanding of the workings of the solid Earth. Numerical modelling of geodynamic processes has developed rapidly since computing power became widely available in the late 1970s. This book provides an excellent introduction to the subject for anyone wanting to understand more about this important area of geoscience.

The book has a practical focus and is written in user-friendly, straightforward language. A minor criticism is the use of the symbol Δ, both for difference and for the Laplacian operator; however any confusion can be quickly dispelled by a check of units! The material is reinforced by in-chapter exercises that promote active reading and by well structured end-of-chapter exercises. Those working through this book in detail would be advised to have access to MATLAB to develop the appropriate code and, equally importantly, to display the results visually; they will then be able to compare their solutions with those presented by the author on the book’s accompanying website.

The book is structured to cover “mechanical” modelling of deformation and flow, followed by “thermal” modelling of heat transfer. The author then brings these two strands together to consider thermo-mechanical geodynamic models within a variety of plate tectonic settings. The theoretical background to each topic is clearly and succinctly explained in a qualitative way; the relevant equations are then developed by informal proofs that, as the author promises, involve nothing more than algebra and simple calculus. Theory is then followed by the nuts and bolts of numerical implementation, where the appropriate finite difference methodology is clearly explained and illustrated by examples with any pitfalls pointed out. Throughout the book there is useful advice on modelling in general, including a chapter on benchmarking (model validation) and advice on the debugging of errant code.

This is a well produced hardback in a clear type with excellent supporting diagrams. It has been very well proof-read, especially considering the mathematical nature of some of the text. In short, the book provides excellent value for those wanting an introduction to the field. Anyone who works carefully through this book and completes all the exercises should be well prepared for further work in geodynamic modelling.

Duncan C Woodcock
ABB Limited, Warrington