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Prediction of reservoir quality through chemical modeling, AAPG Memoir 49
0016-7037/91/$3.00
Gawhimica PI Cosmoc%mica Acla Vol. 55, II. 2705 Copyni&htO 1991 Pergamon Ptwplc.Printed in U.S.A.
+ a0
BOOK REVIEWS
Numerical Adventures n& Geochemical Cycle.~by James C. G. Walker. Oxford Univetity Press, 1991,ix -t 192p., U.S. $39.95 (ISBN O-19-504520-3). T/zevr$eed on thaaghtsthat vofuntarvFM?QC? Harmonious numbers . . simulation has become an indispensable part of geochemistry. Those who cannot do it have to find others to do it for them. This little book will bring it within the reach of anyone who wants to try. It begins with a linear differential equation (for carbon dioxide in the a~osph~~) solved by finite differences and shows how numerical stability is assured by using the reverseEuler method. This simple introduction establishes the general approach to simulation and sets the pedagogical tone of the rest of the book. Mass balance between several interconnected reservoirs is illustrated by phosphate in the ocean basins, for which the transfer equations form a matrix that is solved by Gaussian elimination and back substitution. (The results could bear some discussion: deep Pacific water ends up with three times the phosphate ~ncent~tion of deep Atlantic water, in direct proportion to the respective inputs from rivers.) A nonlinear system, the redox balance of the deep sea, is treated next, essentially by “tuning” the time step so that nonlinear terms in the dependent variable are kept small. The remainder of the book applies methods teamed in the Hurst four chapters to more complex global systems: the carbon cycle (including distribution between ocean and atmosphere ofcarbon dioxide from fossil fuels); stable isotope fractionation (with carbon as an example); climate, for which a versatile set of models based on a chain of reservoirs (latitude bands), each connected only to its next-door
NUMERICAL
Predictionof Reservoir QualityThrough Chemical Modeling edited by I. D. Meshri and P. .I. Grtoleva. AAPGMemoir 49, The American Association of Petroleum Geologists, 1990, 17Sp., (members) US $46.00. (nonmembers) US $69.00 (ISBN O-g918l-327-6).
neighbors, simulates the annual average temperature distribution (and the seasonal variation). as well as the effects of cloud cover, permanent and seasona ice, atmospheric carbon dioxide, and continental drift. A diffusion model ofc~~nate d&genesis, using the same prkcipte fin this case the reservoirs are sediment layers) completes the book. The programs are written in BASIC, and are agreeably concise: they will all run on a personal computer. (The author uses an IBM PS/2 MODEL 5OZwith a math coprocessor and the BASIC compiler and says that none of the programs requires more than half an hour.) The emphasis is on understanding the physical systems being modeled and on simpl~f~ng the programs as much as possible. “Let the machine do the work” is a friendly admonition on p. 41. “Watch the calculation as it happens,” we are told on p. 60, and to this end are supplied helpful subroutines that produce graphical displays. Fi-d&f&delo-del. This charming book sings like Milton’s wakeful bird as it leads us through the dark thickets of numbers, tuning its nocturnal note and letting fly an occasional aside (b&one yval anf) at importunate fatma; introducing us to the programs, called, like artisans of oId, after their craft: ISOT, DAV, SEES, and to subrou~~ with such names as SLOPER, GAUSS, and SWAPPER, as reassuringly sonorous as those of ancient Boston law firms. For aging illiterates like myself who think, omegudl never learn this stuff, here is the answer. A graduate student here said every geology department ought to have a course in geochemical modeling based on this book. f SEDSQZ. Bepurtmmt a~~ea~agicff~ Sciences WrightState University Dayton, OH 45435, USA
C. Bryan Gregor
Notable contributions to this volume include chapters 5,6, and 7 by H. Machel, K. L. Nagy et al., and W. Chen et al,, respectively. In summary, these chapters address the most problematic issue of simulating diagenetic conditions, which is that most natural systems are in a state of disequilibrium and the rates of reaction depend upon the extent of d~~uilib~um. Each chapter attempts to resolve the differences between observed petrological features of reservoir rocks and the paragenesis of mineral phases predicted by chemical models. Chapters 8 and 9 are slanted &ward the application of mathematical modeling and simulation of mineral phase transformations and porosity development. Both chapters contain numerous graphical plots, whose qualities and/or purpose are not always clear to the reader. The final chapter contains a specific and important application of chemicaI modeling for the prediction of changes in reservoir properties during steam lIood operations. These types of studies provide excellent test beds for the development of chemical models (although one might expect the reaction kinetics to be different from those of burial diagenetic conditions). If you are actively involved in the search for hydrocarbon deposits and are committed to a quantitative understanding ofgeochemical phenomena that affect reservoir quality, then predictive chemical modeling is going to be a key facet of your work. This book provides a good starting point for those wishing to learn more. Owning this book would complete your library if you are a dedicated chemical modeler, otherwise this reviewer recommends borrowing a copy and photocopying the articles of interest for your particular research or educational purposes.
~REDfCffVE CHEMICAL modeling for the purpose of predriiiing assessment of reservoir quality in frontier basins is just now entering into an embryonic stage. AAPG Memoir 49 offers glimpses of the various approaches that are being used to track this highly complex field of research. The book is organized into 10 chapters, each chapter being an independently authored article. Included is a review by 1. D. Meshri (Chapter 3) on the current modeling approaches, in which the limitations of early speciation and psuedo-kinetic, reaction progress models that are premised upon equilibrium conditions are properly noted. More realistic kinetic models that couple reaction and transport are now being employed. Unfortunately, these newer models are limited by a paucity of kinetic rate data, much of which may be inappropriate because it has been obtained under far from equilibrium conditions. Near equilibrium steady-state rate data are even scarcer. Chapters I, 2, and 4 attempt to provide evidence for chemical changes in reservoir rocks, arguably the most important aspect for constraining modeling efforts, S~iEcaiIy, studies of erosional unconformities and depositional facies and their roles in controlling diagenetic facies (emphasizing porosity occlusion/enhancement) are presented. The articles are a product of an AAPG symposium dedicated to aspects of rock-water interactions, and although this reviewer did not attend the meeting, some of the chapters appear to be annotated versions of the figures presented at the meeting, As a rest& portions of this book lack enough detail to be very u&X, and considering the price a buyer might Feel a little shortchanged.
Paul A. Schroeder
2705
Gawhimica PI Cosmoc%mica Acla Vol. 55, II. 2705 Copyni&htO 1991 Pergamon Ptwplc.Printed in U.S.A.
+ a0
BOOK REVIEWS
Numerical Adventures n& Geochemical Cycle.~by James C. G. Walker. Oxford Univetity Press, 1991,ix -t 192p., U.S. $39.95 (ISBN O-19-504520-3). T/zevr$eed on thaaghtsthat vofuntarvFM?QC? Harmonious numbers . . simulation has become an indispensable part of geochemistry. Those who cannot do it have to find others to do it for them. This little book will bring it within the reach of anyone who wants to try. It begins with a linear differential equation (for carbon dioxide in the a~osph~~) solved by finite differences and shows how numerical stability is assured by using the reverseEuler method. This simple introduction establishes the general approach to simulation and sets the pedagogical tone of the rest of the book. Mass balance between several interconnected reservoirs is illustrated by phosphate in the ocean basins, for which the transfer equations form a matrix that is solved by Gaussian elimination and back substitution. (The results could bear some discussion: deep Pacific water ends up with three times the phosphate ~ncent~tion of deep Atlantic water, in direct proportion to the respective inputs from rivers.) A nonlinear system, the redox balance of the deep sea, is treated next, essentially by “tuning” the time step so that nonlinear terms in the dependent variable are kept small. The remainder of the book applies methods teamed in the Hurst four chapters to more complex global systems: the carbon cycle (including distribution between ocean and atmosphere ofcarbon dioxide from fossil fuels); stable isotope fractionation (with carbon as an example); climate, for which a versatile set of models based on a chain of reservoirs (latitude bands), each connected only to its next-door
NUMERICAL
Predictionof Reservoir QualityThrough Chemical Modeling edited by I. D. Meshri and P. .I. Grtoleva. AAPGMemoir 49, The American Association of Petroleum Geologists, 1990, 17Sp., (members) US $46.00. (nonmembers) US $69.00 (ISBN O-g918l-327-6).
neighbors, simulates the annual average temperature distribution (and the seasonal variation). as well as the effects of cloud cover, permanent and seasona ice, atmospheric carbon dioxide, and continental drift. A diffusion model ofc~~nate d&genesis, using the same prkcipte fin this case the reservoirs are sediment layers) completes the book. The programs are written in BASIC, and are agreeably concise: they will all run on a personal computer. (The author uses an IBM PS/2 MODEL 5OZwith a math coprocessor and the BASIC compiler and says that none of the programs requires more than half an hour.) The emphasis is on understanding the physical systems being modeled and on simpl~f~ng the programs as much as possible. “Let the machine do the work” is a friendly admonition on p. 41. “Watch the calculation as it happens,” we are told on p. 60, and to this end are supplied helpful subroutines that produce graphical displays. Fi-d&f&delo-del. This charming book sings like Milton’s wakeful bird as it leads us through the dark thickets of numbers, tuning its nocturnal note and letting fly an occasional aside (b&one yval anf) at importunate fatma; introducing us to the programs, called, like artisans of oId, after their craft: ISOT, DAV, SEES, and to subrou~~ with such names as SLOPER, GAUSS, and SWAPPER, as reassuringly sonorous as those of ancient Boston law firms. For aging illiterates like myself who think, omegudl never learn this stuff, here is the answer. A graduate student here said every geology department ought to have a course in geochemical modeling based on this book. f SEDSQZ. Bepurtmmt a~~ea~agicff~ Sciences WrightState University Dayton, OH 45435, USA
C. Bryan Gregor
Notable contributions to this volume include chapters 5,6, and 7 by H. Machel, K. L. Nagy et al., and W. Chen et al,, respectively. In summary, these chapters address the most problematic issue of simulating diagenetic conditions, which is that most natural systems are in a state of disequilibrium and the rates of reaction depend upon the extent of d~~uilib~um. Each chapter attempts to resolve the differences between observed petrological features of reservoir rocks and the paragenesis of mineral phases predicted by chemical models. Chapters 8 and 9 are slanted &ward the application of mathematical modeling and simulation of mineral phase transformations and porosity development. Both chapters contain numerous graphical plots, whose qualities and/or purpose are not always clear to the reader. The final chapter contains a specific and important application of chemicaI modeling for the prediction of changes in reservoir properties during steam lIood operations. These types of studies provide excellent test beds for the development of chemical models (although one might expect the reaction kinetics to be different from those of burial diagenetic conditions). If you are actively involved in the search for hydrocarbon deposits and are committed to a quantitative understanding ofgeochemical phenomena that affect reservoir quality, then predictive chemical modeling is going to be a key facet of your work. This book provides a good starting point for those wishing to learn more. Owning this book would complete your library if you are a dedicated chemical modeler, otherwise this reviewer recommends borrowing a copy and photocopying the articles of interest for your particular research or educational purposes.
~REDfCffVE CHEMICAL modeling for the purpose of predriiiing assessment of reservoir quality in frontier basins is just now entering into an embryonic stage. AAPG Memoir 49 offers glimpses of the various approaches that are being used to track this highly complex field of research. The book is organized into 10 chapters, each chapter being an independently authored article. Included is a review by 1. D. Meshri (Chapter 3) on the current modeling approaches, in which the limitations of early speciation and psuedo-kinetic, reaction progress models that are premised upon equilibrium conditions are properly noted. More realistic kinetic models that couple reaction and transport are now being employed. Unfortunately, these newer models are limited by a paucity of kinetic rate data, much of which may be inappropriate because it has been obtained under far from equilibrium conditions. Near equilibrium steady-state rate data are even scarcer. Chapters I, 2, and 4 attempt to provide evidence for chemical changes in reservoir rocks, arguably the most important aspect for constraining modeling efforts, S~iEcaiIy, studies of erosional unconformities and depositional facies and their roles in controlling diagenetic facies (emphasizing porosity occlusion/enhancement) are presented. The articles are a product of an AAPG symposium dedicated to aspects of rock-water interactions, and although this reviewer did not attend the meeting, some of the chapters appear to be annotated versions of the figures presented at the meeting, As a rest& portions of this book lack enough detail to be very u&X, and considering the price a buyer might Feel a little shortchanged.
Paul A. Schroeder
2705