FINAL TASK 3.1 REPORT

Transcription

1 OCS Study MMS FINAL TASK 3.1 REPORT Alternative Oil Spill Occurrence Estimators and their Variability for the Alaskan OCS Fault Tree Method UPDATE OF GOM OCS STATISTICS TO 2006 MMS Contract Number CT By Bercha International Inc. Calgary, Alberta, Canada U.S. Department of the Interior Minerals Management Service Alaska Outer Continental Shelf Region

2 OCS Study MMS FINAL TASK 3.1 REPORT Alternative Oil Spill Occurrence Estimators and their Variability for the Alaskan OCS Fault Tree Method UPDATE OF GOM OCS STATISTICS TO 2006 Principal Investigator: Dr. Frank G. Bercha, P.Eng. Bercha International Inc Parkdale Boulevard N.W. Calgary, Alberta, T2N 3S9, Canada This study was funded by the U.S. Department of the Interior, Minerals Management Service (MMS), Alaska Outer Continental Shelf Region, Anchorage, under Contract No CT-39348, as part of the MMS Alaska Environmental Studies Program. DISCLAIMER The opinion, findings, conclusions, or recommendations expressed in this report or product are those of the authors and do not necessarily reflect the views of the U.S. Department of the Interior, nor does mention of products constitute endorsement or recommendations for use by the Federal Government.

3 i EXECUTIVE SUMMARY A. Introduction Historical data and their statistical analyses are used as a starting point for fault tree application to oil spill indicator quantification for the Alaskan OCS. In the initial fault tree analysis 1, data from the GOM OCS were analyzed for the period from 1972 to Subsequently, a more refined publication of the data characteristics by MMS 2 has made it possible to conduct a more thorough statistical analysis as well as an update of the data and its analysis to This report generally discusses and gives data summaries as well as detailed statistical results for the re-analysis of the data, including an update of the GOM OCS data for platform and pipeline spills, including an update to The work is covered by MMS contract number CT-39348, and it is the first update under Task 3, and accordingly, is considered to be Task 3.1. B. Pipeline Spills The pipeline spill statistics generated in this update are basic spill statistics. First, the number of spills by size occurring for each causal category is given. Next, spill causes by two principal spill size categories are given, and transformed to spill frequencies per kilometer-year by dividing the number of kilometer-years exposure. And finally, the spill frequency distribution for spills of different size categories, by pipe diameter is determined. Table 1 summarizes the spill occurrences by size for each of the principal causes. These causes are those that are reported in the MMS database 2. Both the exact spill size in barrels and the spill size distribution by each of the spill size categories are given in Table 1. Table 2 gives the pipeline hydrocarbon spill statistics by cause. These statistics are given as the probability of occurrence per kilometer-year of operating pipeline. Thus, for example, approximately spills per 100,000 km-yrs in the small and medium size category are likely to occur. Of these, it is expected that approximately 1.1 per 100,000 km-yrs can be attributed to pipe corrosion. Finally, Table 3 summarizes the pipeline hydrocarbon spill statistics by spill size and pipe diameter. 1 Bercha International Inc., Alternative Oil Spill Occurrence Estimators for the Beaufort and Chukchi Seas Fault Tree Method, Volume II, Appendix A Historical Data, OCS Study MMS , Final Report to US Department of the Interior, Minerals Management Service, Alaska Outer Continental Shelf Region, August MMS Website,

4 ii Table 1 Pipeline Hydrocarbon Spill Summary by Spill Size CAUSE CLASSIFICATION NUMBER OF SPILLS SPILL SIZE BBL NUMBER OF SPILLS S M L H SM LH CORROSION External Internal THIRD PARTY IMPACT Anchor Impact Jackup Rig or Spud Barge Trawl/Fishing Net OPERATION IMPACT Rig Anchoring Work Boat Anchoring MECHANICAL Connection Failure Material Failure NATURAL HAZARD Mud Slide Storm/ Hurricane UNKNOWN TOTALS

5 iii Table 2 Pipeline Hydrocarbon Spill Statistics by Cause Small and Medium Spills bbl Large and Huge Spills >=1000 bbl CAUSE CLASSIFICATION HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [km-years] FREQUENCY spill per 10^5km -year HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [km-years] FREQUENCY spill per 10^5km -year CORROSION External Internal THIRD PARTY IMPACT Anchor Impact Jackup Rig or Spud Barge Trawl/Fishing Net OPERATION IMPACT Rig Anchoring Work Boat Anchoring MECHANICAL Connection Failure Material Failure NATURAL HAZARD Mud Slide Storm/ Hurricane ARCTIC Ice Gouging Strudel Scour Upheaval Buckling Thaw Settlement Other Arctic UNKNOWN TOTALS

6 iv Table 3 Pipeline Hydrocarbon Spill Statistics by Spill Size and Pipe Diameter GOM OCS Pipeline Spills, Categorized Spill Statistics Number of Spills Exposure km-years Frequency spills per 10 5 kmyears By Pipe Diameter By Spill Size By Diameter, By Spill Size <=10" > 10" <= 10" , > 10" 20 85, Small <100 bbl , Medium bbl , Large bbl , Huge >=10000 bbl 3 273, Small <100 bbl 8 187, Medium bbl , Large bbl 7 187, Huge >=10000 bbl 1 187, Small <100 bbl 4 85, Medium bbl 9 85, Large bbl 5 85, Huge >=10000 bbl 2 85,

7 v C. Platform Spills The primary platform spill statistical information required is the spill frequency distribution by different causes and spill sizes, and the spill rate per well year. Table 4 summarizes the spill size distribution among the principal reported causes. As can be seen, the major cause attributable to almost 50% of the spills at 35 out of 74 spills is equipment failure. However, although hurricanes have only caused a relatively small number of spills, their total spill volumes are the largest, giving the largest spill volume total. The largest single spill, however, is the tank failure which caused a spill of nearly 10,000 barrels. The spill rate data, given per production well-year, is shown in Table 5, again, by causal distribution as well as two broad spill size categories of small and medium spills and large and huge spills. Here, it becomes immediately evident that the largest spill potential in terms of volume is attributable to hurricanes, which are responsible for roughly 43% of the large and huge spills. Table 4 Summary of GOM OCS Platform Hydrocarbon Spills by Size and Cause CAUSE CLASSIFICATION NUMBER OF SPILLS SPILL SIZE BBL NUMBER OF SPILLS S M L H SM LH EQUIPMENT FAILURE Process Equipment Transfer Hose Incorrect Operation HUMAN ERROR TANK FAILURE SHIP COLLISION WEATHER HURRICANE OTHER TOTALS

8 vi Table 5 GOM OCS Platform Hydrocarbon Spill Statistics ( ) Small and Medium Spills bbl Large and Huge Spills >=1000 bbl CAUSE CLASSIFICATION HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [well-years] FREQUENCY spill per 10^4wellyear HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [well-years] FREQUENCY spill per 10^4wellyear EQUIPMENT FAILURE Process Equipment Transfer Hose Incorrect Operation HUMAN ERROR TANK FAILURE SHIP COLLISION WEATHER HURRICANE OTHER TOTALS

9 vii ACKNOWLEDGEMENTS Grateful acknowledgement for funding and direction is made to MMS Alaska OCS Region. In particular, the following MMS personnel are acknowledged together with their roles: Dr. Dick Prentki, Contracting Officer s Representative Dr. James Craig, Resource Evaluation Section Caryn Smith, Oil-Spill-Risk-Analysis Coordinator Cheryl Anderson, MMS Spill Database Coordinator Debra Bridge, Contracting Officer Dr. Warren Horowitz, Oceanographer This work was carried out by Bercha International Inc. Key Bercha personnel on the project team were as follows: Dr. Frank G. Bercha, Project Manager and Principal Engineer Milan Cerovšek, Reliability Engineering Specialist Edmund A. Yasinko, Offshore Pipeline Specialist Wesley Abel, Offshore Engineering Specialist Susan Charlton, Editorial and Word Processing Manager

10 viii TABLE OF CONTENTS SECTION PAGE Executive Summary...i Acknowledgements...vii Table of Contents...viii List of Tables and Figures...ix Glossary of Terms and Acronyms...x 1 Introduction General Introduction Data Sources Outline of Report Pipeline Spills Introduction on GOM OCS Pipeline Spills Pipeline Exposure All Pipeline Spills Pipeline Hydrocarbon Spills Pipeline Spill Statistics Platform Spills Introduction to Platform Spills Platform Exposure All GOM OCS Platform Spills Platform Hydrocarbon Spills Platform Spill Statistics References...R.1

11 ix TABLE LIST OF TABLES AND FIGURES PAGE 2.1 GOM OCS Pipeline Exposure Data ( ) GOM OCS Pipeline All Spill Data Summary GOM OCS Pipeline Hydrocarbon Spill Data Summary Pipeline Hydrocarbon Spill Summary by Spill Size Pipeline Hydrocarbon Spill Statistics by Cause Pipeline Hydrocarbon Spill Statistics by Spill Size and Pipe Diameter Annual Number of Producing Wells in GOM OCS ( ) Summary of All GOM OCS Platform Spills ( ) Summary of GOM OCS Platform Hydrocarbon Spills ( ) Summary of GOM OCS Platform Hydrocarbon Spills by Size and Cause GOM OCS Platform Hydrocarbon Spill Statistics ( ) FIGURE PAGE 3.1 Annual Number of Producing Wells in GOM OCS ( ) Bar Chart Display...3.3

12 x Bbbl CDF Consequence GOM Hazard KBpd LOF MMbbl MMS Monte Carlo OCS QRA Risk RLS SINTEF Spill Frequency Spill Frequency per Barrel Produced Spill Index Spill Occurrence Spill Occurrence Indicator GLOSSARY OF TERMS AND ACRONYMS Billion Barrels Cumulative Distribution Function The direct effect of an accidental event. Gulf of Mexico A condition with a potential to create risks such as accidental leakage of natural gas from a pressurized vessel. Thousand Barrels per day Life of Field Million Barrels Minerals Management Service, Department of the Interior A numerical method for evaluating algebraic combinations of statistical distributions. Outer Continental Shelf Quantitative Risk Assessment A compound measure of the probability and magnitude of adverse effect. Release The Foundation of Scientific and Industrial Research at the Norwegian Institute of Technology The number of spills of a given spill size range per year. Usually expressed as spills per 1,000 years (and so indicated). The number of spills of a given spill size range per barrel produced. Usually expressed as spills per billion barrels produced (and so indicated). The product of spill frequency for a given spill size range and the mean spill size for that spill size range. Characterization of an oil spill as an annual frequency and associated spill size or spill size range. Any of the oil spill occurrence characteristics; namely, spill frequency, spill frequency per barrel produced, or spill index (defined above). Spill Sizes Small (S): bbl Medium (M): bbl Large (L): 1,000-9,999 bbl Huge (H): >=10,000 bbl Significant (SG): >=1,000 bbl

13 1.1 SECTION 1 INTRODUCTION 1.1 General Introduction Historical data and their statistical analyses are used as a starting point for fault tree application to oil spill indicator quantification for the Alaskan OCS. In the initial fault tree analysis [1] *, data from the GOM OCS were analyzed for the period from 1972 to Subsequently, a more refined publication of the data characteristics by MMS [2] has made it possible to conduct a more thorough statistical analysis as well as an update of the data and its analysis to This report generally discusses and gives data summaries as well as detailed statistical results for the re-analysis of the data, including an update of the GOM OCS data for platform and pipeline spills, including an update to The work is covered by MMS contract number CT-39348, and it is the first update under Task 3, and accordingly, is considered to be Task Data Sources The bulk of the data was obtained directly from the MMS website [2], and was generally collated and analyzed in a format similar to that of the earlier data analysis by Bercha International Inc. [1]. In addition to the data obtained directly from the MMS website, numerous clarifications and supplemental data was acquired through a meeting and a series of discussions between Bercha investigators and MMS staff, between October 1 and 31, Outline of Report Following this brief introduction, Section 2 deals with the pipeline spill data and its analysis, while Section 3 deals with the platform spill data and its analysis. * Numbers in square brackets refer to publications listed in References section of this report.

14 2.1 SECTION 2 PIPELINE SPILLS 2.1 Introduction on GOM OCS Pipeline Spills Subsea pipelines in the Gulf of Mexico (GOM) Offshore Continental Shelf (OCS) hold roughly 13 thousand kilometers in 2006, representing an exposure of nearly 300,000 kilometer-years between 1972 and Spill reporting for spills greater than 50 barrels has been carried out over this period. Although in the subsequent variability analysis to be reported elsewhere, continuous spill volume distributions will be utilized, spill size characterization is reported according to the following spill size categories: Small (S): Medium (M): Large (L): Huge (H): Significant (SG): bbl bbl 1,000-9,999 bbl >= 10,000 bbl >=1,000 bbl In the balance of this section, all reported spills in the Alaskan GOM OCS are summarized; those containing hydrocarbons (crude oil, diesel, condensate) are extracted from these, and analyzed both by causal distribution and frequency distribution. 2.2 Pipeline Exposure Table 2.1 summarizes the total length of GOM OCS subsea pipelines in operation between 1972 and In addition, it gives the total mile-years and kilometer-years and their distribution for pipelines of different nominal pipe size (NPS) representing an approximate outside diameter. In the notes below Table 2.1, a comparison is made between the exposure data used in the previous report [1] (showing 187,183 km) and the current report (totaling 184,600 km) between 1972 and The figures in the main part of Table 2.1, of course, include lengths operating up to and including All Pipeline Spills Table 2.2 gives a summary of all pipeline liquid spills. As can be seen, not all of these are hydrocarbons, as some include methanol, ethylene glycol, and other liquids although these other liquids are quite limited, and make only a small contribution. Nevertheless, all these spills have been shown in Table 2.2. It should be noted that minor updates on these spills were carried out through communications with MMS staff, October 19, 2007.

15 2.2 Table 2.1 GOM OCS Pipeline Exposure Data ( ) Miles of OCS OIL Pipeline Segments by Year and Size Year <=10" NPS >10" NPS Total 2" 3" 4" 5-6" 7-8" 9-10" 11-19" 20-36" TOTAL mile-yrs TOTAL km-yrs Note: For calculation used 1 mile = km and rounded to full number Current: <=10" >10" Total miles km Previous Report [1]: <10" >=10" Total km

16 2.3 # Year Table 2.2 GOM OCS Pipeline All Spill Data Summary Size bbl NPS Material Cause Water Depth (ft) Crude Oil Internal Corrosion Crude Oil Corrosion Crude Oil Anchor Crude Oil Anchor and Storm Crude Oil Hurricane Crude Oil Anchor and Corr Crude Oil Shrimp Trawl Crude Oil Mud Slide Crude Oil Anchor Crude Oil Anchor Crude Oil Pipeline Clamp Crude Oil Anchor Crude Oil Anchor Condensate Trawler Net Crude Oil Ext Corr and Metal fatigue Crude Oil Anchor Crude Oil Storm and mud slide Crude Oil Anchor Crude Oil Anchor Crude Oil Leak Crude Oil Anchor or construction Crude Oil Human, Anchor and Judgment Condensate Fish Net or Anchor tie-in Crude Oil Pipeline Valve Crude Oil Leak Crude Oil Hurricane Crude Oil Anchor Condensate Trawler Net Methanol Leak Crude Oil Anchor Condensate Anchor Crude Oil Hurricane Crude Oil External Damage Crude Oil External Damage - Anchor Ethylene Human Error Crude Glycol Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Methanol Hurricane Ivan Crude Oil Hurricane Katrina Crude Oil Hurricane Katrina Condensate Hurricane Katrina Condensate Hurricane Rita Crude Oil Hurricane Rita 180 * Crude Oil Hurricane Rita Crude Oil Hurricane Rita Crude Oil Hurricane Rita Crude Oil External Damage - Anchor 126 * Notes: All Data from MMS Web site(gom Region), October 1, 2007 * = updated by Cheryl Anderson October 19, 2007

17 Pipeline Hydrocarbon Spills Table 2.3 gives the same basic data, but only for hydrocarbon spills; that is, for crude oil and condensate spills from GOM OCS pipelines. The previous number of 53 spills, has now been reduced by 3 to 50 spills, showing a relatively insignificant contribution of the non-hydrocarbon spills. Table 2.3 is used as a basis of statistical analysis subsequently, and in the scenario simulations to be carried out in future studies. As can be seen, in addition to the year of occurrence, the reported spill size is given, the nominal pipeline size (NPS) in approximate inches, the spill material, and cause, as well as the water depth at which the spill occurs are all given. 2.5 Pipeline Spill Statistics The pipeline spill statistics generated in this update are basic spill statistics. First, the number of spills by size occurring for each causal category is given. Next, spill causes by two principal spill size categories are given, and transformed to spill frequencies per kilometer-year by dividing the number of kilometer-years exposure. And finally, the spill frequency distribution for spills of different size categories, by pipe diameter is determined. Table 2.4 summarizes the spill occurrences by size for each of the principal causes. These causes are those that are reported in the MMS database [2]. Both the exact spill size in barrels and the spill size distribution by each of the spill size categories are given in Table 2.4. Table 2.5 gives the pipeline hydrocarbon spill statistics by cause. These statistics are given as the probability of occurrence per kilometer-year of operating pipeline. Thus, for example, approximately spills per 100,000 km-yrs in the small and medium size category are likely to occur. Of these, it is expected that approximately 1.1 per 100,000 km-yrs can be attributed to pipe corrosion. Finally, Table 2.6 summarizes the pipeline hydrocarbon spill statistics by spill size and pipe diameter.

18 2.5 Table 2.3 GOM OCS Pipeline Hydrocarbon Spill Data Summary # Year Size bbl NPS Material Cause Water Depth (ft) Crude Oil Internal Corrosion Crude Oil Internal Corrosion Crude Oil Anchor Crude Oil Anchor and Storm Crude Oil Hurricane Crude Oil Anchor and Corr Crude Oil Shrimp Trawl Crude Oil Mud Slide Crude Oil Anchor Crude Oil Anchor Crude Oil Pipeline Clamp Crude Oil Anchor Crude Oil Anchor Condensate Trawler Net Crude Oil Ext Corr and Metal fatique Crude Oil Anchor Crude Oil Storm and mud slide Crude Oil Anchor Crude Oil Anchor Crude Oil Leak Crude Oil Anchor or construction Crude Oil Human, Anchor and Judgment Condensate Fish Net or Anchor tie-in Crude Oil Pipeline Valve Crude Oil Leak Crude Oil Hurricane Crude Oil Anchor Condensate Trawler Net Crude Oil Anchor Condensate Anchor Crude Oil Hurricane Crude Oil External Damage Crude Oil External Damage - Anchor Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Ivan Crude Oil Hurricane Katrina Crude Oil Hurricane Katrina Condensate Hurricane Katrina Condensate Hurricane Rita Crude Oil Hurricane Rita 180 * Crude Oil Hurricane Rita Crude Oil Hurricane Rita Crude Oil Hurricane Rita Crude Oil External Damage - Anchor 126 Notes: * All Data from MMS Web site(gom Region), October 1, 2007 * = updated by Cheryl Anderson October 19, 2007 <=10" 30 8 Small <100 bbl >10" Medium bbl <=10" 7 Large bbl 12 Small <100 bbl 1 Huge >=10000 bbl 23 Medium bbl 4 Small <100 bbl 12 Large bbl 9 Medium bbl >10" 3 Huge >=10000 bbl 5 Large bbl 2 Huge >=10000 bbl

19 2.6 Table 2.4 Pipeline Hydrocarbon Spill Summary by Spill Size CAUSE CLASSIFICATION NUMBER OF SPILLS SPILL SIZE BBL NUMBER OF SPILLS S M L H SM LH CORROSION External Internal THIRD PARTY IMPACT Anchor Impact Jackup Rig or Spud Barge Trawl/Fishing Net OPERATION IMPACT Rig Anchoring Work Boat Anchoring MECHANICAL Connection Failure Material Failure NATURAL HAZARD Mud Slide Storm/ Hurricane UNKNOWN TOTALS

20 2.7 Table 2.5 Pipeline Hydrocarbon Spill Statistics by Cause Small and Medium Spills bbl Large and Huge Spills >=1000 bbl CAUSE CLASSIFICATION HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [km-years] FREQUENCY spill per 10^5km -year HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [km-years] FREQUENCY spill per 10^5km -year CORROSION External Internal THIRD PARTY IMPACT Anchor Impact Jackup Rig or Spud Barge Trawl/Fishing Net OPERATION IMPACT Rig Anchoring Work Boat Anchoring MECHANICAL Connection Failure Material Failure NATURAL HAZARD Mud Slide Storm/ Hurricane ARCTIC Ice Gouging Strudel Scour Upheaval Buckling Thaw Settlement Other Arctic UNKNOWN TOTALS

21 2.8 Table 2.6 Pipeline Hydrocarbon Spill Statistics by Spill Size and Pipe Diameter GOM OCS Pipeline Spills, Categorized Spill Statistics Number of Spills Exposure km-years Frequency spills per 10 5 kmyears By Pipe Diameter By Spill Size By Diameter, By Spill Size <=10" > 10" <= 10" , > 10" 20 85, Small <100 bbl , Medium bbl , Large bbl , Huge >=10000 bbl 3 273, Small <100 bbl 8 187, Medium bbl , Large bbl 7 187, Huge >=10000 bbl 1 187, Small <100 bbl 4 85, Medium bbl 9 85, Large bbl 5 85, Huge >=10000 bbl 2 85,

22 3.1 SECTION 3 PLATFORM SPILLS 3.1 Introduction to Platform Spills Generally, platform spills in the GOM OCS have been reported to occur due to equipment failure, human error, tank failure, ship collisions, and weather, including hurricanes. In the period from 1973 to 2006, approximately 200 platform spills have been reported, with roughly 74 spills of hydrocarbon fluids. In the statistical analysis, the exposure factor utilized in the platform spill frequency computation is the number of active producing wells in any given time period. In the balance of this section, following a discussion of the exposure, all platform spills are summarized, followed by the platform hydrocarbon spill summaries, and the spill statistical analysis by both causal distribution and active well year. 3.2 Platform Exposure The exposure factor utilized for the platforms is the number of active producing wells in any given time period. The definition of the number of active producing wells is the number of OCS GOM wells producing oil and/or condensate which reported production greater than 0 barrels in each year (or the relevant time period). Table 3.1 summarizes the number of these active producing wells for each year between 1972 and The bar chart in Figure 3.1 simply illustrates these numbers of producing wells. A peak of roughly 7,000 producing wells in 1985, is followed by a gradual decline to the present number of approximately 4,800 producing wells in All GOM OCS Platform Spills All liquid spills reported from GOM OCS platforms between 1973 and 2006 are summarized in Table 3.2. As can be seen, numerous non-hydrocarbon spills such as zinc bromide, synthetic based muds, or methanol are included in this number of spills, which totals 190. As can be seen in the table, following the spill itemization number data given are the year of occurrence, the actual size in barrels, the material spilled, the reported cause, and the associated operation, as well as the water depth.

23 3.2 Table 3.1 Annual Number of Active Producing Wells in GOM OCS ( ) Year Wells Total

24 Figure 3.1 Annual Number of Active Producing Wells in GOM OCS ( ) Bar Chart Display

25 3.4 # Year Table 3.2 Summary of All GOM OCS Platform Spills ( ) Size bbl Material Cause Operation Water Depth ft Crude Oil Tank ruptured Production Crude Oil Rough Seas Production Diesel Human error Drilling and Motor Vessel Diesel Human error Drilling and Motor Vessel Crude Oil Liquid Level Control Production Crude Oil Hurricane Production Crude Oil Liquid Level Control Production Crude Oil Human error Production Crude Oil Hurricane Drilling, Compl., or Workover Diesel Collision Production and Motor Vessel Diesel Collision Drilling and Motor Vessel Diesel Eq failure and Human Err Drilling and Motor Vessel Diesel Eq failure and Human Err Drilling and Motor Vessel Crude Oil Eq failure LACT Production Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Weather related Motor Vessel Crude Oil Liquid Level Control Production Diesel Collision -Hurricane Drilling and Motor Vessel Diesel Human error Drilling Diesel Weather related Production and Motor Vessel Diesel Excessive wear Drilling Diesel Tank ruptured Motor Vessel Diesel Weather related Drilling and Motor Vessel Diesel Eq failure and Human Err Production Crude Oil Weather related Production Diesel Eq failure Transfer hose Drilling and Motor Vessel Crude Oil Eq failure, Human error Production Mineral Oil Tank ruptured Drilling Diesel Eq failure Transfer hose Drilling and Motor Vessel Crude Oil Not Indentified Completion or Workover Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Eq failure Transfer hose Drilling and Barge Crude Oil Eq failure Transfer hose Production Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Collision Drilling and Motor Vessel Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Eq failure Transfer hose Drilling and Motor Vessel Diesel Collision Drilling and Motor Vessel Diesel Collision Production and Motor Vessel Crude Oil Tank ruptured Production Diesel Human error Drilling and Motor Vessel Diesel Eq failure Pipe Elbow Drilling Diesel Eq failure, Human error Deactivation Crude Oil Eq failure Workover Diesel Eq failure Flow meter Drilling and Motor Vessel Mineral Oil Tank ruptured Drilling Condensate Weather related Production Diesel Eq failure Transfer hose Drilling and Motor Vessel Hydraulic Fluid Human error Construction Crude Oil Eq failure BOP Drilling Crude Oil Eq failure, Human error Production Diesel Human error Drilling Crude Oil Leak, Wellhead assembly Production Crude Oil Eq failure Liquid level Production 112

26 3.5 # Year Size bbl Table 3.2 ~ Continued ~ Material Cause Operation Water Depth ft Zinc Bromide Eq failure dump valve Drilling Crude Oil Eq failure, Human error Production Condensate Other, Inuff. Mud weight Drilling Zinc Bromide Eq failure Transfer hose Fuel Transfer and Motor Vesel Zinc Bromide Human error Completion or Workover Condensate Human error Drilling and Motor Vessel Condensate Eq failure Production Diesel Weather related Drilling and Motor Vessel Condensate Eq failure, Human error Production Diesel Weather related Drilling and Motor Vessel Zinc Bromide Eq failure Production Hydraulic Fluid Eq failure Construction Zinc Bromide Human error Completion Condensate Human error Production Zinc Bromide Human error Completion Diesel Weather related Production Ethylene Glycol Eq failure Production Paraffin Inhibitor Poor design Production Zinc Bromide Human error Completion Zinc Bromide Human error Completion Diesel Weather related Production and Motor Vessel Condensate Eq failure Workover Synthetic Based Mud Human error Drilling N/A Zinc Bromide Human error Workover and Motor Vessel Synthetic Based Mud Human error Drilling Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Eq failure Drilling Crude Oil Human error Drilling Synthetic Based Mud Human error Drilling Crude Oil Eq failure, Human error Production Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Human error Motor Vessel Zinc Bromide Eq failure Drilling Crude Oil Eq failure Production Zinc Bromide Human error Drilling Ethylene Glycol Eq failure Production Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Human error Workover Synthetic Based Mud Human error Drilling and Motor Vessel Synthetic Based Mud Human error Motor Vessel N/A Synthetic Based Mud Operetional Discharge Drilling Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Weather related Drilling Crude Oil Hurricane Production Diesel Hurricane Workover Diesel Hurricane Drilling Zinc Bromide Hurricane Rig Recovery Zinc Bromide Human error Completion Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Human error Drilling Synthetic Based Mud Human error Drilling Synthetic Based Mud Human error Drilling Diesel Human error Motor Vessel Diesel Human error Motor Vessel Synthetic Based Mud Weather related Drilling Synthetic Based Mud Eq failure, Human error Drilling Diesel Human error Motor Vessel N/A Synthetic Based Mud Human error Drilling Synthetic Based Mud Human error Drilling Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Eq failure Drilling 6040

27 # Year Size bbl 3.6 Table 3.2 ~ Continued ~ Material Cause Operation Water Depth ft Synthetic Based Mud Human error Exploration Ethylene Glycol Eq failure Production Synthetic Based Mud Human error Drilling Synthetic Based Mud Weather related Drilling Synthetic Based Mud Eq failure, Human error Drilling Methanol Eq failure Production Diesel Hurricane Ivan N/A Diesel Hurricane Ivan N/A Crude Oil Hurricane Ivan N/A Diesel Hurricane Ivan N/A Crude Oil Hurricane Ivan N/A Diesel Hurricane Ivan N/A Crude Oil Hurricane Ivan N/A Diesel Hurricane Ivan N/A Crude Oil Hurricane Ivan N/A Diesel Hurricane Ivan N/A Synthetic Based Mud Human error Drilling Hydrate Inhibitor Eq failure Drilling Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Eq failure, Human error Drilling Synthetic Based Mud Human error Drilling Synthetic Based Mud Human error Drilling Calcium Bromide Human error Completion Synthetic Based Mud Weather related Drilling Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Diesel Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Diesel Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Calcium Chloride Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Condensate Hurricane Katrina N/A Crude Oil Hurricane Katrina N/A Aviation Fuel Hurricane Rita N/A Crude Oil Hurricane Rita N/A Diesel Hurricane Rita N/A Condensate Hurricane Rita N/A Diesel Hurricane Rita N/A Condensate Hurricane Rita N/A Crude Oil Hurricane Rita N/A Condensate Hurricane Rita N/A Diesel Hurricane Rita N/A Crude Oil Hurricane Rita N/A Crude Oil Hurricane Rita N/A Diesel Hurricane Rita N/A Diesel Hurricane Rita N/A Crude Oil Hurricane Rita N/A 230

28 # Year Size bbl 3.7 Table 3.2 ~ Continued ~ Material Cause Operation Water Depth ft Synthetic Based Mud Eq failure, Human error Drilling Synthetic Based Mud Weather related Drilling Caustic Cleaner Eq failure Drilling Synthetic Based Mud Human error Drilling Condensate Hurricane Rita Production Calcium Bromide Human error Completion Synthetic Based Mud Human error Drilling Synthetic Based Mud Eq failure Drilling Synthetic Based Mud Human error Drilling Crude Oil Hurricane Rita Submerged Platform Crude Oil Hurricane Katrina Submerged Platform Crude Oil Hurricane Rita Submerged Platform 170

29 3.4 Platform Hydrocarbon Spills 3.8 Table 3.3 summarizes all of the platform hydrocarbon spills from among all spills associated with platforms between 1973 and It should be noted, that when the spills are attributable to an individual hurricane, such as Hurricane Katrina, spills in these hurricanes were counted as one single spill. However, the total spill volume was recorded and utilized as a basis for subsequent statistics. It can be seen from Table 3.3 that the total number of platform spills from 1973 to 2006 is 74, with sizes ranging between nearly 10,000 barrels and the threshold of reporting, 50 barrels. 3.5 Platform Spill Statistics The primary platform spill statistical information required is the spill frequency distribution by different causes and spill sizes, and the spill rate per well year. Table 3.4 summarizes the spill size distribution among the principal reported causes. As can be seen, the major cause attributable to almost 50% of the spills at 35 out of 74 spills is equipment failure. However, although hurricanes have only caused a relatively small number of spills, their total spill volumes are the largest, giving the largest spill volume total. The largest single spill, however, is the tank failure which caused a spill of nearly 10,000 barrels. The spill rate data, given per production well-year, is shown in Table 3.5, again, by causal distribution as well as two broad spill size categories of small and medium spills and large and huge spills. Here, it becomes immediately evident that the largest spill potential in terms of volume is attributable to hurricanes, which are responsible for roughly 43% of the large and huge spills.

30 3.9 Table 3.3 Summary of GOM OCS Platform Hydrocarbon Spills ( ) # Year Size bbl Cause Operation Tank ruptured Production Rough Seas Production Human error Drilling and Motor Vessel Human error Drilling and Motor Vessel Liquid Level Control Production Hurricane Production Liquid Level Control Production Human error Production Hurricane Drilling, Compl., or Workover Collision Production and Motor Vessel Collision Drilling and Motor Vessel Eq failure and Human Err Drilling and Motor Vessel Eq failure and Human Err Drilling and Motor Vessel Eq failure LACT Production Eq failure Transfer hose Drilling and Motor Vessel Weather related Motor Vessel Liquid Level Control Production Collision -Hurricane Drilling and Motor Vessel Human error Drilling Weather related Production and Motor Vessel Excessive wear Drilling Tank ruptured Motor Vessel Weather related Drilling and Motor Vessel Eq failure and Human Err Production Weather related Production Eq failure Transfer hose Drilling and Motor Vessel Eq failure, Human error Production Eq failure Transfer hose Drilling and Motor Vessel Not Identified Completion or Workover Eq failure Transfer hose Drilling and Motor Vessel Eq failure Transfer hose Drilling and Motor Vessel Eq failure Transfer hose Drilling and Motor Vessel Eq failure Transfer hose Drilling and Barge Eq failure Transfer hose Production Eq failure Transfer hose Drilling and Motor Vessel Collision Drilling and Motor Vessel Eq failure Transfer hose Drilling and Motor Vessel Eq failure Transfer hose Drilling and Motor Vessel Collision Drilling and Motor Vessel Collision Production and Motor Vessel Tank ruptured Production Human error Drilling and Motor Vessel Eq failure Pipe Elbow Drilling Eq failure, Human error Deactivation Eq failure Workover Eq failure Flow meter Drilling and Motor Vessel Weather related Production Eq failure Transfer hose Drilling and Motor Vessel Eq failure BOP Drilling

31 3.10 Table 3.3 ~ Continued ~ # Year Size bbl Cause Operation Eq failure, Human error Production Human error Drilling Leak, Wellhead assembly Production Eq failure Liquid level Production Eq failure, Human error Production Other, Inuff. Mud weight Drilling Human error Drilling and Motor Vessel Eq failure Production Weather related Drilling and Motor Vessel Eq failure, Human error Production Weather related Drilling and Motor Vessel Human error Production Weather related Production Weather related Production and Motor Vessel Eq failure Workover Human error Drilling Eq failure, Human error Production Eq failure Production Hurricane N/A Human error Motor Vessel Human error Motor Vessel Human error Motor Vessel Hurricane Ivan N/A Hurricane Katrina N/A Hurricane Rita N/A Only one spill (Crude Oil, Condensate, Diesel) counted per Hurricane 27 Small <100 bbl 40 Medium bbl 7 Large bbl 0 Huge >=10000 bbl

32 3.11 Table 3.4 Summary of GOM OCS Platform Hydrocarbon Spills by Size and Cause CAUSE CLASSIFICATION NUMBER OF SPILLS SPILL SIZE BBL NUMBER OF SPILLS S M L H SM LH EQUIPMENT FAILURE Process Equipment Transfer Hose Incorrect Operation HUMAN ERROR TANK FAILURE SHIP COLLISION WEATHER HURRICANE OTHER TOTALS

33 3.12 Table 3.5 GOM OCS Platform Hydrocarbon Spill Statistics ( ) Small and Medium Spills bbl Large and Huge Spills >=1000 bbl CAUSE CLASSIFICATION HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [well-years] FREQUENCY spill per 10^4wellyear HIST. DISTRIBUTION % NUMBER OF SPILLS EXPOSURE [well-years] FREQUENCY spill per 10^4wellyear EQUIPMENT FAILURE Process Equipment Transfer Hose Incorrect Operation HUMAN ERROR TANK FAILURE SHIP COLLISION WEATHER HURRICANE OTHER TOTALS

34 Alaskan OCS Oil Spill Estimators R.1 Final Task 3.1 Report P REFERENCES 1. Bercha International Inc., Alternative Oil Spill Occurrence Estimators for the Beaufort and Chukchi Seas Fault Tree Method, Volume II, Appendix A Historical Data, OCS Study MMS , Final Report to US Department of the Interior, Minerals Management Service, Alaska Outer Continental Shelf Region, August MMS Website,

35 The Department of the Interior Mission As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering sound use of our land and water resources; protecting our fish, wildlife, and biological diversity; preserving the environmental and cultural values of our national parks and historical places; and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to ensure that their development is in the best interests of all our people by encouraging stewardship and citizen participation in their care. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration. The Minerals Management Service Mission As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf (OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute those revenues. Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program administers the OCS competitive leasing program and oversees the safe and environmentally sound exploration and production of our Nation's offshore natural gas, oil and other mineral resources. The MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and accurate collection and disbursement of revenue from mineral leasing and production due to Indian tribes and allottees, States and the U.S. Treasury. The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for all Americans by lending MMS assistance and expertise to economic development and environmental protection.