Oil Spill Risk Management E-Book

David E. Dietrich

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 283

Veröffentlichungsjahr: 2014

Beschreibung

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.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Dedication

Preface

Organization of the Book

Reference

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

Chapter 1: The 2010 Deep Water Horizon and 2002 Supertanker Prestige Accidents

1.1 Introduction

1.2 The Oil Spills Described

1.3 How Much Material Remains in the Gulf?

1.4 The Role of Ocean Models to Explain what Happened

References

Chapter 2: Gulf of Mexico Circulation

2.1 General Characteristics

2.2 Exchanges at Lateral and Surface Boundaries

2.3 Loop Current Eddies

2.4 Blocking by the Pycnocline

2.5 Fate of the Deepwater Horizon Well Blowout Material

2.6 Summary

References

Chapter 3: Geophysical Fluid Dynamics and Modeling Challenges

3.1 Modeling the Circulation and Mixing of the Gulf Waters

3.2 External Boundaries

3.3 Addressing the Water Column Contamination and Fluxes

3.4 Effects of Bottom Dynamics on Accumulated Hydrocarbons

3.5 Churning by Extreme Weather Events

3.6 Summary

References

Chapter 4: Flow and Oil Transport Model Choices, Setup and Testing

4.1 The DieCAST Ocean Circulation Model

4.2 Korotenko Oil Transport Module KOTM

4.3 Gulf Modeling Approach

4.4 Model Vertical Eddy Viscosity and Diffusivity

4.5 Surface Wind Driving and Open Boundary Conditions

4.6 Comments on Modeling Equatorial Dynamics and the Gulf of Mexico

4.7 Modeling Multi-Century Gulf Currents

References

Chapter 5: Modeling the 2010 DWH Oil Spill

5.1 Introduction: the BP/Deepwater Horizon Accident

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

5.3 Oil Spill Model for Gulf of Mexico (GOSM)

5.4 Results and Discussion

5.5 Summary

References

Part 2: Special Topics in Oil Spill Modeling

Chapter 6: DieCAST Model Origin and Development

6.1 Introduction

6.2 Recent Model Attributes

6.3 Challenges in Modeling the Gulf of Mexico Circulation

6.4 Complications of Modeling near-Equatorial Circulation

6.5 Non Hydrostatic Effects

6.6 Sponge Layers in the Global Model

6.7 Inflow Considerations

References

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

7.1 COMS history

7.2 Background and motivations

7.3 COMS elliptic solver history

7.4 Evolution of DieCAST

7.5 Outlook

References

Chapter 8: DieCAST Model Equations1

8.1 Model Equations

8.2 Model Layer Depths

References

Chapter 9: Some Basic Physical, Mathematical and Modeling Concepts

9.1 Buoyancy, Density and the Hydrostatic Approximation

9.2 Pycnocline Slope: Geopotential Surface as a Natural Vertical Coordinate

9.3 Rotation and Coriolis Terms

9.4 Pycnocline and the Florida Strait Sill Depth

9.5 Surface and Bottom Mixed Layers

References

Chapter 10: Modeling Challenges, Validations and Animations

10.1 Incompressibility, Geostrophy, Data Assimilation and Initialization Issues

10.2 Thermocline Maintenance, Ventilation and Extreme Events

10.3. Nesting, Grid Coupling and Open Boundary Conditions

10.4. Validation of Simulated Major Current Patterns in the Gulf

10.5 Note on Data Assimilation

10.6 Gulf Circulation Animations

10.7 Animation 116

10.8 Animation 218

10.9 Animation 319

References

Chapter 11: A Five-Century Gulf Simulation using DieCAST

11.1 Motivation

11.2 Basic Flow Patterns

11.3 Some Results Observed during the 5th Century

11.4 Internal Waves

11.5 Island/Headland Wake Effects in the Yucatan Channel

11.6 Deeply Suspended and Bottom Deposited Material

References

Chapter 12: Extreme Events and Oil Rig Stability

12.1 Introduction

12.2 An Unusual Northern Gulf Eddy Event

12.3 Detailed Discussion of Run A

12.4 Some Comments

12.5 Other Extreme Events Found during the 500-year simulation

References

Chapter 13: Initialization and Data Assimilation; MAM Procedure

13.1 Introduction

13.2 Preliminary Comment

13.3 MAM Procedure

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

References

Chapter 14: On the Simulation of Density Currents by z-level Models

14.1 Motivation

14.2 Introduction

14.3 Analysis

14.4 Summary and Conclusion

14.5 Acknowledgements

References

Appendix I: Notes on Modeling Hurricanes with DieCAST

A1.1 Introduction

A1.2 Model Setup

A1.3 Results and Discussion

A1.4 Final Remarks

A1.5 Summary

A1.6 Acknowledgements

References

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

A2.1 Abstract

A2.2 Introduction

A2.3 Model Setup

A2.4 Results

A2.5 Concluding Remarks

References

Index

Oil Spill Risk Management

Gulf of Mexico satellite sea surface temperature (SST) images (upper left: May 28, 20101,2; lower left: April 20, 1984) and sample DieCAST ocean circulation model SST plots (upper right: day 180; lower right: day 1220 (from Dietrich et al., 1997, see Ch 10).

The similarity between observations and model results published many years before is remarkable. The same DieCAST model was coupled to the authors’ oil spill dispersal model to hind-cast the oil spread from the 2010 Deepwater Horizon blowout (see cover picture and described in detail in Ch. 5).

1http://eddy.colorado.edu/ccar/data_viewer/index

2http://podaac.jpl.nasa.gov/dataset/JPL-L4UHfnd-GLOB-MUR

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Library of Congress Cataloging-in-Publication Data:

ISBN 978-1-118-29038-5

This book is dedicated to Dr. Verne E. Dietrich, the father of the first author. Dr. Dietrich Sr. was a mathematician who understood the nature of science, and who emphasized that it is as important to understand the reasoning behind science as it is to know science. His favorite hymn, “In the Garden” relates closely to the inspirational poem “Footprints”, which explains any successes that I [David E. Dietrich] have had in science.

Preface

The Deepwater Horizon oil spill accident (variously referred to as the BP oil spill/disaster or the Macondo blowout) commenced on April 20th, 2010 on the BP-operated Macondo Prospect drilling platform. The ensuing fire aboard the drilling platform claimed eleven lives. Following the explosion and sinking of the floating oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on July 15th, 2010. The total discharge has been estimated at 4.9 million barrels (780,000 m3), and the event was considered by some authorities to be the largest accidental marine oil spill in the history of the petroleum industry.1

Gulf fisheries, tourism, nearshore and wetlands environments were also severely damaged by the blowout [1]. Much of the released material was less dense than the Gulf surface waters, so its buoyancy caused it to rise to the surface and accumulate in a spreading surface patch. Some of the surface material was quickly blown ashore by winds. Some floating residues were entrained into Gulf of Mexico mesoscale eddies and into the Loop Current that are dominant features of the central and eastern Gulf. The combined action of winds and underlying Gulf currents apparently kept the surface material from escaping from the Gulf through the Florida Strait.2 A small amount of subsurface suspended denser material may have escaped undetected, either eastward through the Florida Strait or southward through the Yucatan Strait between Cuba and Mexico.

In this book, we attempt to address several important questions:

i. During the period of the Deepwater Horizon gusher, how did the major ocean circulation features transport and disperse oil fractions, both at the surface and at depth?

ii. Based on the oceanography of the Gulf, where might deeply-suspended and coated bottom sediments be concentrated and where might they remain concentrated over many years?

iii. How much remaining oil residue, if any, might be possibly churned up by future extreme weather events and subsequently made available to be blown ashore?

Organization of the Book

In Chapter 1 we compare the 2010 DWH event to the 2002 Prestige supertanker event; the ship broke up near the northwest corner of Spain and sank to about 3,500 m depth. This is of interest as both events leaked huge amounts of oil material near an open coast. In Spain and Portugal it gravely damaged fisheries and deposited tar-balls on beaches, damaging sensitive ecosystems and negatively impacting tourism. We also raise the question of how much of the DWH spilled oil remains in deep waters of the Gulf and the role of ocean models in explaining what happened.

In Chapter 2 we describe the dominant physical properties of the Gulf and its circulation patterns with a focus on those that affected the transport and fate of the DWH well blowout material. We describe exchanges of water and material at the lateral and surface boundaries, the spectacular Loop Current eddies, properties of the water column pycnocline and close with a brief discussion of the possible fate of the well blowout material.

In Chapter 3 we introduce basic concepts of geophysical fluid dynamics and how the motion and mixing of the Gulf’s waters influenced the transport and fate of spilled materials near surface, in the water column and near the bottom.

In Chapter 4 we discuss the coupling of the DieCAST ocean model to the Korotenko Oil Transport Module to create the Gulf of Mexico Oil Spill Model (GOSM) and the modeling approach to investigate the spreading, diffusion, transformation and evaporation of the spilled materials. The numerical approach is described along with the complexities of modeling near-equatorial circulation dynamics. We discuss major Gulf flow features that affect the fate of material leaked during the DWH event, plus the challenges inherent in running very long (multi-century) simulations.

In Chapter 5 we present the results obtained using the coupled GOSM to predict the transport pathways and fate of the various oil fractions released during the DWH accident.

Advanced Topics: Finally, in a series of appendices, we present a variety of advanced modeling topics for the expert modeler, with a focus on applications to the Gulf of Mexico.

It is hoped that our studies will provide useful information about how natural oceanographic and atmospheric processes can be successfully modeled using modern numerical methods in order to shed light on how these processes effect the transport and dispersion of hydrocarbons accidently released into the sea.

David Dietrich, Lakeland, Florida Malcolm Bowman, Stony Brook, New York Konstantin Korotenko, Moscow, Russian Federation M. Hamish Bowman, Dunedin, New Zealand

Reference

1. Safina, C. A Sea in Flames: The Deepwater Horizon Oil Blowout. 2011. Crown Publishing Group, 352 pp.

1http://en.wikipedia.org/wiki/Deepwater_Horizon_oil_spill

2http://en.wikipedia.org/wiki/Deepwater_Horizon_oil_spill

Part I

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

Chapter 1

The 2010 Deep Water Horizon and 2002 Supertanker Prestige Accidents

1.1 Introduction

The Gulf of Mexico is a marginal sea forming the southern coast of the United States, bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The Gulf has a surface area of ~ 1.6 million km2 with almost half of the basin being shallow continental shelf waters. However, in the Sigsbee Deep, an irregular trough more than 550 km long, the maximum depth is almost 4,400 m deep. The dominant circulation feature is the Loop Current, which flows into the Gulf from the Caribbean Sea through the Yucatan Channel between Mexico’s Yucatan Peninsula and Cuba. The Loop Current subsequently feeds the Gulf Stream as it flows through the Florida Strait that lies between Florida, Cuba and the Bahamas.