Oil Spill Risk Management: Modeling Gulf of Mexico Circulation and Oil Dispersal

ISBN-13: 9781118290385 / Angielski / Twarda / 2014 / 240 str.

David Dietrich

Opis

This book is designed to help scientifically astute non-specialists understand basic geophysical and computational fluid dynamics concepts relating to oil spill simulations, and related modeling issues and challenges. A valuable asset to the engineer or manager working off-shore in the oil and gas industry, the authors, a team of renowned geologists and engineers, offer practical applications to mitigate any offshore spill risks, using research never before published.

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Preface xiii

Part 1: Applied Oil Spill Modeling (with applications to the Deepwater Horizon oil spill) 1

1 The 2010 Deep Water Horizon and 2002 Supertanker Prestige Accidents 3

1.1 Introduction 3

1.2 The Oil Spills Described 5

1.3 How Much Material Remains in the Gulf? 6

1.4 The Role of Ocean Models to Explain what Happened 7

References 8

2 Gulf of Mexico Circulation 9

2.1 General Characteristics 9

2.2 Exchanges at Lateral and Surface Boundaries 11

2.3 Loop Current Eddies 12

2.4 Blocking by the Pycnocline 13

2.5 Fate of the Deepwater Horizon Well Blowout Material 14

2.6 Summary 15

References 16

3 Geophysical Fluid Dynamics and Modeling Challenges 17

3.1 Modeling the Circulation and Mixing of the Gulf Waters 17

3.2 External Boundaries 18

3.3 Addressing the Water Column Contamination and Fluxes 18

3.4 Eff ects of Bottom Dynamics on Accumulated Hydrocarbons 20

3.5 Churning by Extreme Weather Events 20

3.6 Summary 21

References 22

4 Flow and Oil Transport Model Choices, Setup and Testing 23

4.1 The DieCAST Ocean Circulation Model 23

4.2 Korotenko Oil Transport Module KOTM 24

4.3 Gulf Modeling Approach 25

4.4 Model Vertical Eddy Viscosity and Diff usivity 25

4.5 Surface Wind Driving and Open Boundary Conditions 26

4.6 Comments on Modeling Equatorial Dynamics and the Gulf of Mexico 26

4.7 Modeling Multi–Century Gulf Currents 27

References 29

5 Modeling the 2010 DWH Oil Spill 31

5.1 Introduction: the BP/Deepwater Horizon Accident 31

5.2 Deepwater Blowouts: Processes Affecting the Transport and Fate of Oil throughout the Water Column 32

5.3 Oil Spill Model for Gulf of Mexico (GOSM) 57

5.4 Results and Discussion 68

5.5 Summary 82

References 86

Part 2: Special Topics in Oil Spill Modeling 95

6 DieCAST Model Origin and Development 97

6.1 Introduction 97

6.2 Recent Model Attributes 98

6.3 Challenges in Modeling the Gulf of Mexico Circulation 99

6.4 Complications of Modeling near–Equatorial Circulation 99

6.5 Non Hydrostatic Effects 101

6.6 Sponge Layers in the Global Model 101

6.7 Inflow Considerations 101

References 102

7 Brief History of the Community Ocean Modeling System (COMS) 105

7.1 COMS history 105

7.2 Background and motivations 106

7.3 COMS elliptic solver history 107

7.4 Evolution of DieCAST 108

7.5 Outlook 108

References 110

8 DieCAST Model Equations 113

8.1 Model Equations 113

8.2 Model Layer Depths 115

References 116

9 Some Basic Physical, Mathematical and Modeling Concepts 117

9.1 Buoyancy, Density and the Hydrostatic Approximation 117

9.2 Pycnocline Slope: Geopotential Surface as a Natural Vertical Coordinate 119

9.3 Rotation and Coriolis Terms 120

9.4 Pycnocline and the Florida Strait Sill Depth 121

9.5 Surface and Bottom Mixed Layers 121

References 122

10 Modeling Challenges, Validations and Animations 125

10.1 Incompressibility, Geostrophy, Data Assimilation and Initialization Issues 125

10.2 Thermocline Maintenance, Ventilation and Extreme Events 127

10.3 Nesting, Grid Coupling and Open Boundary Conditions 127

10.4 Validation of Simulated Major Current Patterns in the Gulf 127

10.5 Note on Data Assimilation 133

10.6 Gulf Circulation Animations 134

10.7 Animation 1 134

10.8 Animation 2 135

10.9 Animation 3 136

References 136

11 A Five–Century Gulf Simulation using DieCAST 139

11.1 Motivation 139

11.2 Basic Flow Patterns 140

11.3 Some Results Observed during the 5th Century 142

11.4 Internal Waves 143

11.5 Island /Headland Wake Eff ects in the Yucatan Channel 143

11.6 Deeply Suspended and Bottom Deposited Material 144

References 145

12 Extreme Events and Oil Rig Stability 147

12.1 Introduction 147

12.2 An Unusual Northern Gulf Eddy Event 148

12.3 Detailed Discussion of Run A 148

12.4 Some Comments 151

12.5 Other Extreme Events Found during the 500–year simulation 152

References 153

13 Initialization and Data Assimilation; MAM Procedure 155

13.1 Introduction 155

13.2 Preliminary Comment 156

13.3 MAM Procedure 156

13.4 Refinements, Variations, Generalizations and Specializations of the MAM Approach 158

References 160

14 On the Simulation of Density Currents by z–level Models 161

14.1 Motivation 161

14.2 Introduction 162

14.3 Analysis 164

14.4 Summary and Conclusion 167

14.5 Acknowledgements 168

References 168

Appendix I: Notes on Modeling Hurricanes with DieCAST 171

A1.1 Introduction 171

A1.2 Model Setup 172

A1.3 Results and Discussion 174

A1.4 Final Remarks 178

A1.5 Summary 179

A1.6 Acknowledgements 179

References 179

Appendix II: A Model Study of Ventilation of the Mississippi Bight by Baroclinic Eddies: Local Instability and Remote Loop Current Effects 181

A2.1 Abstract 181

A2.2 Introduction 182

A2.3 Model Setup 183

A2.4 Results 184

A2.5 Concluding Remarks 208

References 213

Index 215