Stress Field of the Earth s Crust

Transcription

1 Stress Field of the Earth s Crust

2 Stress Field of the Earth s Crust Arno Zang German Research Centre for Geosciences (GFZ) Potsdam, Germany and Ove Stephansson GFZ and KTH Stockholm, Sweden With Foreword by Bezalel Haimson 1 3

3 Priv.-Doz. Dr. Arno Zang GFZ German Research Centre for Geosciences Telegrafenberg Potsdam Germany Prof. Ove Stephansson GFZ German Research Centre for Geosciences Telegrafenberg Potsdam Germany Additional material to this book can be download from ISBN e-isbn DOI / Springer Dordrecht Heidelberg London New York Library of Congress Control Number: Springer Science+Business Media B.V No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Cover illustrations: i) Cube of rock mass in the Earth s crust with open cracks at top, progressively closing cracks in the middle and residual pores at bottom. Principal stresses are indicated by arrows (S V > S H > S h ) forcing a favourable oriented shear crack to slide. ii) Section of the World Stress Map (Heidbach et al. 2007) shows orientations of the maximum horizontal principal stress (S H ). For detailed description see Chapter 11. Cover design: deblik DVD-ROM included inside back cover Printed on acid-free paper Springer is part of Springer Science+Business Media (

4 For my wife Corinna and our children Felix, Charlotte and Marlene. I am grateful to my academic teachers Hans Berckhemer and Gerhard Müller ( ) both at Goethe-University Frankfurt/Main Arno Zang I like to thank my wife Almut for her support and our children Samuel and Naemi for bringing in a good balance between daily life and work. Ove Stephansson

5 Foreword Stress Field of the Earth s Crust is based on lecture notes prepared for a course offered to graduate students in the Earth sciences and engineering at University of Potsdam. In my opinion, it will undoubtedly also become a standard reference book on the desk of most scientists working with rocks, such as geophysicists, structural geologists, rock mechanics experts, as well as geotechnical and petroleum engineers. That is because this book is concerned with what is probably the most peculiar characteristic of rock its initial stress condition. Rock is always under a natural state of stress, primarily a result of the gravitational and tectonic forces to which it is subjected. Crustal stresses can vary regionally and locally and can reach in places considerable magnitudes, leading to natural or man-made mechanical failure. Preexisting stress distinguishes rock from most other materials and is at the core of the discipline of Rock Mechanics, which has been developed over the last century. Knowledge of rock stress is fundamental to understanding faulting mechanisms and earthquake triggering, to designing stable underground caverns and productive oil fields, and to improving mining methods and geothermal energy extraction, among others. Several books have been written on the subject, but none has attempted to be as all-encompassing as the one by Zang and Stephansson. The present book does not limit itself to just providing a detailed description of the known methods of measuring stress in-situ, and of the different stress fields around the globe. It first presents a detailed and thorough description of the concept of stress, the sources of in-situ stress, and rock failure criteria. These first three chapters are the very foundation of rock mechanics, and could be used as a text for an introductory course in this field. The last three chapters go beyond stress measurements, to describe stress profiles through the Earth s crust, regional stress fields, the World Stress Map, and three recent international field projects in which scientists from many countries collaborated, and in which one of the first priorities was the determination of the state of in-situ stress. These are the KTB, SAFOD, and Olkiluoto projects. The book provides excellent summaries of these major projects, the results of which are otherwise scattered over many publications. These case histories are an invaluable resource to researchers, teachers, and students in the Earth sciences. The chapters dealing directly with stress measurements are encyclopedic. Each method listed is presented in some detail, accompanied by an exhaustive list of vii

6 viii Foreword references, so that the reader could dig deep into any of the techniques at the level he/she chooses. The variety of stress measuring methods in practice today is divided logically into borehole- and core-based. Naturally, the more commonly accepted methods, hydrofracturing, overcoring, and borehole breakouts, are given added emphasis, but all methods are treated as equals even if their use at this time is rather rare. PD Dr. Zang and Prof. Stephansson, who are among the top echelon of in-situ stress researchers and consultants, have produced a much needed book on the state of stress in the Earth s crust, one that complements previous texts, which were considerably more restricted in scope. The book thoroughly and convincingly integrates in-situ stress, its sources, measurement, and applications, into the fields of geophysics, geology, geomechanics, and geoengineering. It is therefore that I enthusiastically recommend Stress Field of the Earth s Crust. University of Wisconsin Madison, USA June 2009 Bezalel Haimson

7 Preface Rock stress is a key parameter in solid Earth sciences and technology. Long-term geological processes like plate tectonics are driven by mechanisms that generate different types of stresses in the Earth s crust. These stresses are acting as we extract raw materials from the crust and deposit human altered materials into the crust in boreholes, mines and underground constructions. To better use and save our resources there is an obvious need for a greater understanding of mechanical stresses in the Earth s crust. This book is directed toward graduate students, teachers and practitioners in geology, geophysics and civil, mining, petroleum and rock engineering. The book aims to fill the gap in the existing literature between principles in rock mechanics (Jaeger, Cook & Zimmerman 2007), rock stress measurements (Amadei & Stephansson 1997) and stress regimes in the lithosphere (Engelder 1993). Mechanical stress and rock stress are fictitious terms as stress can never be directly measured. Stresses in rock originate from gravity and tectonic forces and can only be inferred by disturbing the rock by drilling a borehole, making a slot and coring the rock. The drill core can be brought to the laboratory and stresses determined by different physical methods. The complex nature of rocks prevents us from exactly determinating the magnitudes and orientation of the components of the stress tensor and often we have to accept large variability and uncertainties. Stress in rock is usually described in the context of continuum mechanics. To introduce the Stress Field of the Earth s Crust to students in geosciences, one has to adopt methods from a number of otherwise self-supporting disciplines like the theory of elasticity, continuum mechanics, fracture mechanics, structural geology, geophysics, geodesy, experimental physics, rock and petroleum engineering. This book starts by introducing the physical Concept of Stress from continuum mechanics, and continues to describe Rock Failure from classical to strength of material and modern fracture mechanics approaches. The chapter on Rock Stress Terminology, presented from a material sciences and rock engineering viewpoint, is followed by simple physical models describing the variation of stress magnitudes with depth in the Earth s crust. Then a chapter on the Physics of Stress Measurements is presented, where techniques from experimental physics are applied to determine residual stresses using material sciences standard. Methods for determining crustal stresses are separated into Borehole Techniques (e.g., overcoring, ix

8 x Preface hydraulic fracturing, borehole breakouts) and Core-Based Methods (e.g., anelastic strain recovery, Kaiser effect). The focus of the chapter Local Stress Data is to demonstrate facets of integrated stress measuring strategies as applied to scientific deep wells (KTB, Germany), to nuclear waste repository (Olkiluoto, Finland), and to monitor a seismically active fault zone (SAFOD, USA). The chapter Generic Stress Data reports on general trends in stress-magnitude profiles and stress-orientation maps, where stress-state scaling relations are used to find the best estimated stress model. In the last chapter the European and World Stress Map is interpreted in terms of Plate Tectonics by a thermally self-balancing planet Earth. We wrote this as a classical black and white textbook (apart from 8 color figures) taking into account our experience and expertise in the topic. The reader will benefit from the presentation of the material as a textbook combined with DVD movies. Where a movie symbol is found in the margin of the body text of the book, the reader is able to click on the corresponding movie-file of the DVD. The movie material explains complex scientific relationships, demonstrates sophisticated experimental apparatus or field testing equipment for stress determination, and allows filing interviews with experts in rock stress and its measurements. After listening and watching the digital information, the reader returns to the textbook letters. In the case of getting lost while reading or watching, the reader can go directly to the Note-Box at the end of each section. From there, one can work backwards to obtain the full knowledge. The content presented in this book is based on the many years of research and practical work of the two authors. In writing the book, we have made ample references to key publications in related fields and have tried to bring the reader up-to-date about theory, experiments, field tests and stress data compilations and analysis. In doing this, we may have omitted some references and hope the reader will forgive us. The material of this book was first compiled as lecture notes in 1999 when the first author started to teach a course entitled Stress Field of the Earth s Crust at the University of Potsdam for students in geosciences. Potsdam May 2009 Arno Zang and Ove Stephansson

9 Acknowledgements The writing of this book could not have been possible without using the excellent research environment of the Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences. We thank the Chairman of the Executive Board, Prof. Dr. Dr. h.c. Reinhard Hüttl and the Director of Department 3 Geodynamics and Geomaterials, Prof. Dr. Onno Oncken, for agreeing to publish this book and using GFZ resources. We are thankful to the Head of the Sect. 3.2 Geomechanics and Rheology, Prof. Dr. Georg Dresen for supporting this work. We profited from the stimulating discussions and the helpful and open atmosphere among the colleagues of Sect In addition, the writing of the book strongly benefited from the comments and questions asked by Geosciences students at the University of Potsdam while the first author was lecturing in the decade 1999 to The quality of this manuscript was substantially improved by a review process taking into account comments and suggestions of 16 colleagues and one graduate student. We gratefully acknowledge the highly recognized experts in their field who commented on earlier versions of single chapters of the manuscript, namely Prof. Frank Roth, GFZ (Chap. 2); Prof. Teng-fong Wong, State University of New York at Stony Brook, USA (Chap. 3); Prof. John A. Hudson, Imperial College, London, UK (Chap. 4); Prof. Robert W. Zimmerman, Imperial College, UK and Dr. Erik Rybacki, GFZ (Chap. 5); Prof. Hans-Rudolf Wenk, University of California at Berkeley, USA and Dr. Christian Scheffzük, GFZ (Chap. 6); Prof. Fritz Rummel, Bochum University and MeSy GmbH, Prof. François Cornet, Institute Physique du Globe, Paris, France and PD Dr. Sebastian Hainzl, GFZ (Chap. 7); Prof. Rune Holt and Dr. Alexandre Lavrov, SINTEF Petroleum Research, Trondheim, Norway (Chap. 8); Prof. Jörg Erzinger; GFZ and Dr. Martin Brudy, Baker Hughes, Houston, Texas, USA (Chap. 9), Dr. Oliver Heidbach, GFZ and World Stress Map project (Chaps. 10 and 11). Among these experts we asked one eminent authority to comment on the revised book script as a whole. We are grateful to Prof. Bezalel C. Haimson, University of Wisconsin-Madison (USA) for his thorough reading and valuable comments, and for providing the foreword of this book. Last, we thank Katrin Plenkers, GFZ and University of Potsdam for her useful comments from a student s point of view. xi

10 xii Acknowledgements We very much appreciate the expertise and patience of Andreas Hendrich who created and modified most of the viewgraphs. Some illustrations including the draft of the book cover was made available by Manuela Dziggel. Stephanie Teteris helped in finalizing the viewgraphs of Chap. 5. We gratefully acknowledge the excellent work of these three draftsmen located at GFZ. We would like to thank Dr. Diedrich Fritzsche (Alfred-Wegener Institut für Meeres- und Polarforschung Potsdam) for his help in obtaining the copyright permission of the portrait of Alfred Wegener in Fig Dr. Fritzsche helped us in locating Käthe Schönharting (second daughter of Alfred Wegener with his wife Else Wegener; born Köppen) and Käthe Schönharting s son Dr. Günther Schönharting (grandson of Alfred Wegener), who own the portrait of Alfred Wegener sketched by the painter Achton Friis ( ). Friis accompanied Alfred Wegener during his first Greenland (Denmark) expedition in Günther Schönharting provided us the address of the Arctic Institute at Copenhagen, Denmark, from where we received a high-resolution scan of the original drawing and the permission to reproduce the portrait. Ulrich Harms and Thomas Wöhrl, International Deep Drilling Project ICDP, located at GFZ provided two photographs from the German Continental Deep Drilling Program, one cross-section in Fig. 9.1b and the aerial photograph of the drill site in Fig We apologize for the quality of some of the movies. All 17 movies are selfmade documentaries, and therefore the viewer cannot expect Hollywood quality pictures. Raw movie material was processed with the software package MAGIX Video deluxe 2008 Premium by Wolfgang Kunert (wksyspro.de). The DVD movie material was examined in terms of content by the head of GFZ Sect. 3.2 Prof Dr. Georg Dresen and in terms of copyright queries by GFZ public relation manager Franz Ossing. The help of Mr. Otto Grabe in video related queries and using GFZ equipment is grateful acknowledged. Movie M1 contains the introduction of the first author to Stresses in a Body (Book Chap. 1). This movie was recorded at M2 contains the introduction of the second author to rock stress as a key parameter to Solid Earth Sciences (Chap. 2). This movie was recorded at GFZ. Movie M3.1 shows a laboratory uniaxial compression test and the result of a laboratory triaxial compression test. The licence to use 27 seconds of ZDF Enterprises GmbH material is grateful acknowledged. M3.2 shows laboratory equipment used to perform triaxial testing. Both Chap. 3 movies were recorded at GFZ Sect. 3.2 facilities using an MTS (Mechanical Test Systems GmbH) 815 loading frame. Special thanks go to Prof. Dr. Georg Dresen, our colleagues Dipl.-Ing. Andreas Reinicke, Dr. Sergei Stanchits and our former colleague Dr. Christian Wagner. Movie M4 captures a discussion of both authors about the Stress Terminology shown in diagram 4.1 (Chap. 4). In movie M5.1 an introduction to the high-pressure-high-temperature Paterson Laboratory at GFZ Sect. 3.2 facility is given. In movie M5.2 our colleague Dr. Erik Rybacki is interviewed about the stress depth variation in terms of extrapolating laboratory creep data to nature. Both Chap. 5 movies were recorded at GFZ Sect. 3.2 facilities. Special thanks go to Prof. Dr. Georg Dresen and our colleagues Dipl.-Ing. Michael

11 Acknowledgements xiii Naumann and Dr. Erik Rybacki. The two movies M6.1 Overcoring Borre Probe and M6.2 Overcoring Data Analysis were recorded at Vattenfall Power Consultant AB, Lulea, Sweden (Chap. 6). We are grateful to MSc Civil Eng. Ulf Lindfors, Dr. Daniel Ask and Mrs. Sofi Berg. The movie M7.0 Interview with Prof. Bezalel C. Haimson (Chap. 7) was recorded at GFZ Potsdam during the World Stress Map Conference in October Movie M7.1 is split into Conventional Hydraulic Fracturing and the latest development of the Quadruple Packer system at Vattenfall Power Consultant AB, Lulea, Sweden. Movies M7.2 Sleeve Fracturing and M7.3 Hydraulic Test on Pre-existing Fractures (HTPF) all are recorded at Vattenfall Power Consultant AB, Lulea, Sweden. We are grateful to Dr. Daniel Ask for the final interview in movie M7.4 related to Chap. 7 topics. Movie M8 Anelastic Strain Recovery was recorded at DCM GmbH Walluf, Germany (Chap. 8). We are grateful to geologist Dr. Klaus E. Wolter. The KTB drill core 202A1c used for demonstration purpose in this movie was kindly provided by Ulrich Harms and Thomas Wöhrl both located at ICDP, GFZ. Movie M9.1 Interview with Prof. Mark D. Zoback (Chap. 9) was recorded at GFZ in January We apologize for digital zooming and low resolution pictures, but the student will find all important information in the spoken words. Finally, Movie M9.2 Interview with Dr. Jonny Sjöberg (Chap. 9) was recorded at Vattenfall Power Consultant AB, Lulea, Sweden. The World Stress Map (WSM) release 2008 data set was kindly provided by Dr. Oliver Heidbach. He also contributed to Fig by sending WSM data released 2005 and smoothed stress orientations from Heidbach et al. (2007) publication via electronic mail. We gratefully acknowledge the permission of the Heidelberg Academy of Sciences and Humanities to store and distribute the World Stress Map data set on the accompanying DVD. We also thank the WSM Editors for their agreement to do so, namely O. Heidbach, M. Tingay, J. Reinecker, A. Barth, D. Kurfeß, B. Müller, K. Fuchs and F. Wenzel. The initial help of Prof. emeritus Karl Fuchs in getting this permission is appreciated. We thank Martin H. Trauth who encouraged the first author to contact Springer about the book manuscript for the very first time at European Geosciences Union 2006 meeting on a flight from Berlin to Vienna. Discussing the book project with Martin at the University of Potsdam was very helpful in design, advertising and short course related queries. Our final thank goes to the publisher Springer SBM NL. We acknowledge the excellent support by Petra D. van Steenbergen (Senior Publishing Editor) and Hermine Vloemans (Publishing Assistant Geosciences) while working together on the book manuscript.

12 Permissions to Reproduce Figures We would like to thank the following publishers, organizations and individuals for permission to reproduce previously published material: American Geophysical Union (Figs. 1.3b, 3.7a, 3.8b, 4.3a, 4.6, 5.8a, 5.12a, 7.10, 7.13, 9.1b, 9.6c, 9.7b, 9.13, , 10.3, 10.9, 11.2, 11.3, 11.5, 11.7a, b, 11.9a, ); American Institute of Physics (Fig. 3.9); American Society of Mechanical Engineers (Fig. 8.2b); Arctic Institute, Copenhagen (Fig. 1.7); ASM International (Fig. 8.10); Prof. Dr. H. Berckhemer (Fig. 1.3a); Blackwell Publishing Ltd. (Figs. 4.9d, 6.7); Cambridge University Press (Figs. 5.8b, 5.9, Tables 3.3, 5.2); CSIRO Publishing and Australian Society of Exploration Geophysicists (Fig. 4.3b); Elsevier (Figs. 3.3, 3.5a, b, 3.6b, 4.5, 4.9c, 4.11, 5.4, 5.7, 5.10, 7.11b, d, f, 8.14, 8.16, 9.7a, 10.7, 11.4); E. Schweizerbart sche Verlagsbuchhandlung (Fig. 7.6a); Geological Society of America (Fig. 4.4c, Table 4.2); GFZ German Research Centre for Geosciences, Sect. 3.2 (Table 3.3); GFZ German Research Centre for Geosciences, ICDP (Fig. 9.2); Dr. O. Heidbach, GFZ German Research Centre for Geosciences (Cover, DVD World Stress Map database and software CASMI for the World Stress Map database); Japan Agency for Marine- Earth Science and Technology (Fig. 1.8); John Wiley & Sons Ltd (Fig. 11.9b); Dr. B. Müller (Figs. 10.2, 10.4); Nature Publishing Group (Figs. 9.1c, 11.9c); Niedersächsisches Landesamt für Bodenforschung, Hannover (Fig. 9.1a); CRC Press Balkema (Taylor and Francis Group) (Figs. 3.2a, b, 8.13); Posiva Oy, Finland (Figs ); Princeton University Press (Fig. 8.4); Prof. Dr.-Ing. A. Peiter (Figs. 6.4, 6.5, 6.9, 6.10); Rudarsko-Geolosko-Naftni Zbornik, Kroatia (Fig. 7.11a, c, e); Prof. Dr. F. Rummel (Fig. 9.4); Society of Petroleum Engineers (Fig. 8.17); Springer (Figs. 3.6a, 5.12c, 6.6, 6.8, 7.14, , 8.11, 9.5c, 9.7a, c, 10.la, b, 10.10, Tables 3.la, b, 3.2, 4.2, 5.1); SINTEF, Norway (Fig. 7.7); Swedish Nuclear Fuel and Waste Management Company (Fig ); Taylor & Francis Group (Figs. 8.15, 11.1); The American Association for the Advancement of Science (Fig. 9.14); Wissenschaftliche Verlagsgesellschaft mbh, Stuttgart (Fig. 11.8). xv

13 Contents 1 Introduction Stresses in a Body Importance of Rock Stress History of Interest in Rock Stress Part I Definition and Terminology Stress Definition Stress Tensor Principal Stresses Mohr Circle of Stress Visualizing Stress Rock Fracture Criteria Phenomenological Theories Mechanistic Failure Theories Fracture Mechanics Crack Initiation Crack Propagation Crack Interaction and Coalescence Nonlinear Fracture Mechanics Rock Stress Terminology Gravity Stress Tectonic Stress Residual Stress Structural Stress Anisotropy Heterogeneity Crustal Stress Models Lithostatic Stress Biaxial State of Stress xvii

14 xviii Contents 5.3 Tectonic Stress Field Effective Stress Laboratory Stress Profiles Part II Measuring Stress Physics of Stress Measurements Mechanical Methods Strain Gauges and Overcoring Diffraction Methods Optical Methods Ultrasonic Wave Speed Micromagnetic Method Measuring Crustal Stress: Borehole Methods Classification of Measurement Techniques Hydraulic Fracturing Theoretical Basis of Hydrofracs Practice of Hydrofracturing Borehole Breakouts Theory of Breakouts Application of Breakout Analysis Measuring Crustal Stress: Core-Based Methods Anelastic Strain Recovery Rheological Basis Relaxation Apparatus Kaiser Effect Triaxial Kaiser Stress Approach Uniaxial Kaiser Stress Approach Core Damage and Kaiser Stress Microphysical Models Part III Interpreting Stress Data Local Stress Data Continental Deep Drilling Site KTB, Germany Nuclear Waste Site Olkiluoto, Finland San Andreas Fault Observatory at Depth, USA Generic Stress Data Magnitude Depth Profiles Orientation Maps and Smoothing Stress State-Scale Relations Best-Estimate Stress Model

15 Contents xix Data Extraction and Perturbation Stress-Measurement Methods Integrated Stress and Modelling Final Rock Stress Model Global Stress European Stress World Stress Map Plate Tectonic Interpretation Epilogue References Stress Movies Content on DVD-ROM Index DVD-ROM included inside back cover