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Operational Geomechanics

A Rock-Based Science for Environmental, Energy, and Engineering Applications (EET 14)

image of Operational Geomechanics
  • By Mohammed S. Ameen
  • Format: EPUB
  • Publication Year: 2018
  • Language: English
  • Ebook ISBN: 9789462824508

“OPERATIONAL GEOMECHANICS” is a new concept coined by the author. It encompasses all aspects of rock stress and rock failure in the lithosphere, both artificially induced and naturally occurring. It applies to a full range of depths from surface/near surface to extremely challenging depths and environments.

Thus, it presents the principal tools and tests relevant to the full array of geomechanical applications for assessing and accessing the Earth’s energy, mineral and water resources, as well as for environmental probing, conservation, natural hazards, and waste disposal. As such the book is a challenge to the traditional approach of compartmentalising geomechanics into discrete topics and instead presents a wholistic geomechanical workflow involving:

1. The characterization of the mechanical and stress properties of the rock mass targeted in environmental, engineering and energy operations of human activities and natural hazards such as earthquakes.
2. The timely prediction of instability risks to both infrastructure and drill holes associated with the above
activities.
3. Recommending, designing and conducting preventative precautions for the identifiable instability risks, and remedial steps to mitigate and/or stop subsequent instability damage.

The ultimate objectives of OPERATIONAL GEOMECHANICS are saving time, costs and lives, and in that context, the book discusses the building blocks of the topic in terms of: definitions of geomechanical/rock mechanical parameters; tools; analysis; and interpretations utilized particularly in operations involving drilling/boring operations relevant to all the above engineering, energy and environmental applications. In the final part of the book the
author gives examples of key drilling-related applications.

The book is enriched by the author’s industrial experience which spans more than three decades and will be a suitable text book for undergraduate and graduate students and a practical guide to professionals and managers alike working on projects for which operational geomechanics plays a vital role.

Table of Contents

Preface

Acknowledgements

1  Force, stress & strain

1.1.  Force
1.2.  Stress
1.2.1  Stress Heterogeneity
1.2.2  Stress Anisotropy
1.2.3  Kinematic impact of stress on rock
1.3.  Strain (Deformation)
1.3.1  Types of strain

2  Rock fractures, their statistical, geometric, and kinematic categories
2.1.  Rock fractures
2.2.  Fracture mechanics
2.3.  Modes of crack surface displacement in the process one
2.3.1  Mode-I (opening mode)
2.3.2  Mode-II (sliding mode)
2.3.3  Mode-III (tearing mode)
2.3.4  Mode-IV (Anticrack or Pressure Dissolution Mode)
2.4.  Kinematics (opening) mode of fractures
2.4.1  Joints
2.4.2  Faults
2.4.3  Stylolites
2.5.  Causative stress regimes and resultant suite of fractures
2.6.  Scale of fractures
2.7.  Fracture clustering
2.8.  Fractures associated with major host structures

3  Borehole-scale tools: Borehole images
3.1.  Definitions of borehole imaging, and borehole images
3.2.  Borehole imaging categories according to tool conveyance
3.2.1  Wireline or conventional
3.2.2  Unconventional conveyance
3.3.  Image logging categories according to their acquisition time relative to borehole drilling
3.3.1  Post drilling Image logs
3.3.2  Image logging while drilling (LWD image logging)
3.4.  Image logs categories according to the measured property type
3.4.1  Optical (Optical Televiewer or OTV Imaging)
3.4.2  Electrical (resistivity) tools
3.4.3  Ultrasonic (Acoustic) tools
3.4.4  Density and Gamma tools
3.5.  Borehole image types according to the logging environment
3.6 Image logs’ categories according to their quality
3.6.1  Reasons for image logs impairments
3.6.2  Quality control on image logging
3.6.3  Classification of image logs’ quality
3.7.  Image logs processing
3.7.1  Resistivity image logs processing
3.7.2  Ultrasonic (acoustic) image logs processing
3.7.3  LWD resistivity image logs processing
3.7.4  Other LWD resistivity image logs processing
3.8.  Image logs delivery format

4  Borehole-scale tools: Borehole rock samples
4.1.  Full-diameter core
4.1.1  Definition of core and coring
4.1.2  Coring categories
4.1.3  Coring system
4.1.4  Types of coring systems
4.1.5  Core categories
4.1.6  Key aspects of core handling, packaging, transportation, testing and archival
4.2.  Sidewall cores
4.2.1  Sidewall core types
4.3.  Drill cuttings

5  Rock mechanical characterization
5.1.  Rock mechanics
5.2.  Historical background
5.3.  Applications of rock mechanics
5.4.  Methods of laboratory-based rock mechanical testing
5.4.1  Non-destructive (dynamic) rock mechanical tests
5.4.2  Destructive (static) rock mechanical tests
5.5.  Laboratory-acquired mechanical properties of rocks
5.5.1  Uniaxial compressive testing
5.5.2  Triaxial compressive testing
5.6.  Mechanical properties of rocks
5.6.1  Tensile strength
5.6.2  Compressive strength
5.6.3  Triaxial compressive strength
5.6.4  Elastic moduli
5.6.5  Shear strength, cohesion and internal friction
5.6.6  Swelling indices or parameters
5.6.7  Plasticity indices
5.6.8  Fracture toughness
5.6.9  Effective stress coefficient and biot’s coefficients
5.6.10 Upscaling of laboratory measured static elastic moduli
5.6.11 Dynamic elastic moduli measurements
5.6.12 Elastic anisotropy assessment of rocks
5.6.13 Core sampling for laboratory tests of anisotropy
5.6.14 Anisotropy core testing
5.6.15 Interpretation of anisotropy
5.6.16 Dynamic rock mechanical assessment from down-hole geophysics
5.6.17 Sonic (acoustic) downhole logging
5.6.18 Evolution of borehole sonic tools
5.6.19 Vertical resolution and lateral resolution (depth of investigation) of sonic logs
5.6.20 Categories of acoustic logging tools
5.6.21 Sonic logs interpretation
5.7.  Upscaling of laboratory measured static elastic moduli
5.7.1  Sample size
5.7.2  Rock fabric
5.7.3  Rock texture
5.7.4  Confining pressure
5.7.5  Pore fluid effect
5.7.6  Influence of water content on the strength of rock
5.7.7  Effects of intermediate stress
5.7.8  Loading or strain rate impact
5.7.9  Effect of temperature

6  Assessment of in situ stress magnitude
6.1.  In situ stresses
6.2.  In situ stresses (definition)
6.2.1  Gravitational stresses (overburden pressure or geostatic pressure)
6.2.2  Tectonic stresses
6.2.3  Remnant and residual stresses
6.2.4  In situ stresses characterization
6.2.5  Estimation of in situ stress magnitude
6.3.  The vertical in situ stress σv
6.4.  The horizontal in situ stresses
6.5.  Estimation of formation stresses using borehole sonic data

7  Assessment of in situ stress orientation
7.1.  Estimation of in situ stress orientation from borehole data
7.1.1  The caliper logs
7.1.2  Resistivity and acoustic (ultrasound) borehole image logs
7.1.3  Coring-induced fractures
7.1.4  Sonic logs
7.2.  Estimation of in situ stress orientation from field scale data
7.2.1  Shear-wave splitting
7.2.2  Earthquake focal mechanisms
7.2.3  Neotectonic structures

8  Operational geomechanics: application areas and sources of borehole instability risks
8.1.  Definition
8.2.  Application areas of operational geomechanics
8.3.  Borehole instability causes
8.3.1  Fluid sensitive rocks
8.3.2  Fissile siliciclastic and carbonate mudstones
8.3.3  Naturally fractured or faulted formations
8.3.4  Pressure se“ensitive and critically-stressed formations
8.3.5  Unconsolidated or poorly consolidated rocks
8.3.6  Heavy oil deposits
8.3.7  Mobile salt formation
8.4.  Borehole instability symptoms
8.4.1  Stuck pipe
8.4.2  Loss of circulation
8.4.3  Sand production

Appendix

References

Websites

Index

About the Author

A Word of Appreciation from EAGE

References

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