A much-needed, precise and practical treatment of a key topic in the energy industry and beyond, Applied Concepts in Fractured Reservoirs is an invaluable reference for those in both industry and academia

Authored by renowned experts in the field, this book covers the understanding, evaluation, and effects of fractures in reservoirs. It offers a comprehensive yet practical discussion and description of natural fractures, their origins, characteristics, and effects on hydrocarbon reservoirs. It starts by introducing the reader to basic definitions and classifications of fractures and fractured reservoirs. It then provides an outline for fractured-reservoir characterization and analysis, and goes on to introduce the way fractures impact operational activities.

Well organized and clearly illustrated throughout, Applied Concepts in Fractured Reservoirs starts with a section on understanding natural fractures. It looks at the different types, their dimensions, and the mechanics of fracturing rock in extension and shear. The next section provides information on measuring and analyzing fractures in reservoirs. It covers: logging core for fractures; taking, measuring, and analyzing fracture data; new core vs. archived core; CT scans; comparing fracture data from outcrops, core, and logs; and more. The last part examines the effects of natural fractures on reservoirs, including: the permeability behavior of individual fractures and fracture systems; fracture volumetrics; effects of fractures on drilling and coring; and the interaction between natural and hydraulic fractures.

* Teaches readers to understand and evaluate fractures

* Compiles and synthesizes various concepts and descriptions scattered in literature and synthesizes them with unpublished oil-field observations and data, along with the authors' own experience

* Bridges some of the gaps between reservoir engineers and geologists

* Provides an invaluable reference for geologists and engineers who need to understand naturally fractured reservoirs in order to efficiently extract hydrocarbons

* Illustrated in full color throughout

* Companion volume to the Atlas of Natural and Induced Fractures in Core

John C. Lorenz and Scott P. Cooper, are Senior Geologists at FractureStudies LLC, in Edgewood, NM.

Inhalt

Foreword xi

Preface xiii

Acknowledgements xv

Introduction xvii

Part 1 Understanding Natural Fractures: Fracture Types, Dimensions, and Origin 1

1.1 Introduction 1

1.2 Nomenclature and Fracture-Classification Systems 1

1.2.1 Introduction 1

1.2.2 Other Classification Systems 3

1.2.3 Classifications for Fractures in Outcrops and Cores 4

1.2.4 Expulsion Fractures and Natural Hydraulic Fractures 5

1.2.5 Other Fracture Terminology 5

1.2.6 Sets, Systems, Domains, and Systematic Fractures 7

1.3 Fracture Characteristics and Dimensions 8

1.3.1 Introduction 8

1.3.2 Fracture Distribution Patterns 8

1.3.3 Fractography 10

1.3.4 Fracture Dip Angles 13

1.3.5 Fracture Distributions 13

1.3.6 Fracture Heights and Terminations 16

1.3.7 Fracture Lengths 18

1.3.8 Fracture Widths, Apertures, and Mineralization 19

1.3.9 Fracture Spacing 22

1.3.10 Fracture Strike 27

1.3.10.1 Fracture Orientations Relative to the In Situ Stresses 28

1.3.11 Discussion 28

1.4 The Mechanics of Fracturing Rock in Extension and Shear 29

1.4.1 Introduction 29

1.4.2 Origins of Geologic Stress Systems 31

1.4.2.1 Stresses in a Tectonically Quiescent Basin 31

1.4.2.2 Other Potential Sources of Horizontally Isotropic Stress 32

1.4.2.3 Stresses in a Tectonically Active Basin 32

1.4.3 Rock Susceptibility to Fracture: Basic Concepts 35

1.4.3.1 Introduction 35

1.4.3.2 Intrinsic Controls on Fracture Susceptibility 38

1.4.3.3 Extrinsic Controls on Fracture Susceptibility 39

1.4.3.4 How Rock Breaks: Grain-Scale Cracking, Yield, and Failure 41

1.4.3.5 Extrapolation to the Subsurface 43

1.4.4 Interplay Between Developing Fractures and the In Situ Stresses 44

1.4.5 The Importance of Pore Pressure 45

1.4.5.1 Introduction 45

1.4.5.2 The Relationship between Pore Pressure and Stress 45

1.4.5.3 Biot's Coefficient 47

1.4.5.4 Mohr Diagrams and Pore Pressure 47

1.4.5.5 Pore Pressure Makes Rock Weak and Brittle 47

1.4.5.6 Sources of Pore Pressure 50

1.4.5.7 Alternate Theories 51

1.4.6 Summary 52

1.5 Other Fracture Types 53

1.5.1 Introduction 53

1.5.2 Deformation-Band Shear Fractures, Compaction Bands, and Dilation Bands 53

1.5.2.1 General Characteristics 53

1.5.2.2 Dimensions and Distributions 53

1.5.2.3 Origin 54

1.5.3 Faults and Fractures 55

1.5.4 Microfractures 56

1.5.5 Stylolites and Associated Extension Fractures 59

1.5.6 Bed-Parallel Shear Fractures 59

1.5.7 Beef-Filled Fractures 62

1.5.8 Ptygmatically Folded Fractures 63

1.5.9 Alteration of Fracture Systems by Dissolution 64

Appendix 1.A The Relationship Between Pore Pressure and the In Situ Effective Stresses 66

Introduction 66

Vertical Stress 67

Horizontal Stress 67

Effective Vertical Stress 67

Effective Horizontal Stress 68

Stress Differential 68

Part 2 Measuring and Analyzing Fractures in Reservoirs 71

2.1 Introduction 71

2.1.1 Reasons to Take Core 72

2.1.2 Analyses 73

2.1.3 Fracture Data Sources 73

2.1.4 Quantitative vs. Semi-Quantitative Data 73

2.1.5 Timing of a Fracture Study 73

2.1.6 Need for Experience 74

2.1.7 Other Data Sources 74

2.2 Planning a Core Program for Fracture Analysis 74

2.2.1 Introduction 74

2.2.2 Core Diameter and Length 74

2.2.3 Substituting Sidewall Core Samples 74

2.2.4 Orienting a Core 74

2.2.5 Drilling Parameters 75

2.2.6 Trip Time for Core Recovery 75

2.2.7 Collecting Data on Site 75

2.2.8 Running an Image Log 76