Annual report 2011 SINTEF Offshore Blowout Database Final_tcm109-486730.pdf

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Blowout and Well Release Characteristics and Frequencies, 2011

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Per Holand, ExproSoft CLIENT(S)

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Espen Fyhn Nilsen, Statoil

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\\Bombay\es201016\BLOWOUT\Tekst 2011\Annual report 2011 SINTEF Offshore Blowout Database Final.docx

Per Holand

Lars Bodsberg

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2011-12-29

Lars Bodsberg, Research Director

ABSTRACT

This report is based on the 2011 Version of the SINTEF Offshore Blowout Database. The report gives an overview of offshore blowout and well release characteristics and frequencies. Blowout data from the US Gulf of Mexico Outer Continental Shelf, the Norwegian waters, and the UK waters from the period 1980-01-01 until 2009-12-31 have been focused on.

KEYWORDS

ENGLISH

NORWEGIAN

GROUP 1

Marine Technology

Marin Teknikk

GROUP 2

Offshore

Offshore

SELECTED BY AUTHOR

Risk Blowout

Risiko Utblåsning Frekvenser

Frequencies

Blowout and Well Release Characteristics and Frequencies, 2011 version

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PREFACE This report is based on the SINTEF Offshore Blowout Database, version 2011. The intention of the report is to give an overview of blowout/well release characteristics and frequencies, and not to analyse and evaluate the different blowout types. The format of the report is similar to the report that was issued last year. Three new tables concerning drilling rig type vs. water depth have been added. Table 2.8, page 19 (concerning incident occurrences), and Table 6.7 and Table 6.8 on page 68 and 69 (concerning exposure data). A new Phase of operation has been defined. The new phase is “other”. This phase was defined because a couple of incidents have been observed were abandoned wells having developed leaks after many years. A new Installation type has been defined. The new installation type is “other”. This installation type was defined because one incident occurred during well intervention with a service vessel. Appendix 1 to this report lists criteria used for the database fields in general. Some key updates from 2010 version Software Some minor bug fixes have been carried out. Exposure data The exposure data has been updated also to include the 2009 exposure data. New Blowouts Eight new blowouts/well releases have been added to the database (ID612 – ID619). They were observed for the following countries and years: Table 0.1 New blowouts/well releases 2010 version Blowout ID Country 612 US/GOM OCS 613 US/GOM OCS 614 UK 615 US/GOM NOT OCS 616 US/GOM NOT OCS 617 AZERBAIJAN 618 NETHERLANDS 619 BRAZIL

Main Category Well release Blowout (surface flow) Well release Blowout (surface flow) Well release Blowout (surface flow) Well release Blowout (surface flow)

Phase Production Workover Completion Production Workover Production Workover Expl.drlg

Well depth Deep Deep Deep Deep Deep Deep Deep Deep

Date 07.10.2010 16.01.2011 23.12.2009 27.07.2010 01.12.2010 17.09.2008 01.04.2010 08.12.2011

Edited Blowouts Twelve blowouts/well releases have been significantly edited. Table 0.2 shows where and when these blowouts/well releases occurred.

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Blowout and Well Release Characteristics and Frequencies, 2011 version

Table 0.2 Edited blowouts and well releases Blowout ID Country 378 US GoM OCS 495 UK 497 UK 498 UK 499 UK 500 UK 530 UK 595 UK 596 UK 597 UK 598 UK 610 US GoM OCS

Main Category Diverted Well Release Blowout (surface flow) Well release Well release Well release Well release Blowout (surface flow) Well release Well release Well release Well release Well release

Deleted Blowouts, 2011 No blowouts have been deleted in 2011

Phase Dev.drlg Expl.drlg Workover Workover Completion Unknown drlg Wireline Dev.drlg Production Workover Workover Other

Well depth Shallow Shallow Deep Deep Deep Deep Deep Deep Deep Deep Deep Deep

Date 10.05.1990 12.11.1992 11.05.1995 09.06.1997 14.08.1997 28.10.1998 01.05.2000 17.11.2007 04.06.2007 15.07.2007 13.12.2007 20.11.2007

Blowout and Well Release Characteristics and Frequencies, 2011 version

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LIST OF CONTENTS PREFACE

..................................................................................................................................................... 3

1. ABOUT THE DATABASE ................................................................................................................................ 7 1.1 PARTICIPANTS ...................................................................................................................................................7 1.2 DATABASE STRUCTURE .......................................................................................................................................7 1.3 IMPORTANT DEFINITIONS ....................................................................................................................................9 1.4 CATEGORY AND SUB-CATEGORY .........................................................................................................................10 1.5 PHASE OF OPERATION.......................................................................................................................................11 1.6 NORTH SEA STANDARDS ...................................................................................................................................11 2. OVERVIEW OF BLOWOUTS/WELL RELEASES INCLUDED IN THE DATABASE ................................................ 13 2.1 INTRODUCTION ...............................................................................................................................................13 2.2 DATA QUALITY................................................................................................................................................13 2.3 OVERVIEW OF COUNTRIES REPRESENTED IN THE DATABASE .....................................................................................14 2.4 DURING WHAT OPERATIONAL PHASES DO BLOWOUTS/WELL RELEASES OCCUR? .........................................................16 2.5 NO. OF BLOWOUTS/WELL RELEASES PER YEAR ......................................................................................................17 2.6 WATER DEPTH VS. BLOWOUTS/WELL RELEASES.....................................................................................................18 2.7 INSTALLATION TYPE VS. WATER DEPTH FOR DRILLING INCIDENTS ...............................................................................18 3. BLOWOUTS VS. WELL RELEASES ................................................................................................................ 21 4. OVERALL BLOWOUT/WELL RELEASE EXPERIENCE ...................................................................................... 23 4.1 BLOWOUT/WELL RELEASE VS. FLOW MEDIUM .....................................................................................................23 4.2 BLOWOUT/WELL RELEASE VS. FLOW-RATES .........................................................................................................24 4.3 SEVERITY .......................................................................................................................................................24 4.4 IGNITION OF BLOWOUTS/WELL RELEASES ............................................................................................................24 4.5 BLOWOUT/WELL RELEASE DURATION .................................................................................................................26 4.6 BLOWOUT/WELL RELEASE FLOW-PATHS AND RELEASE POINTS ................................................................................27 4.7 BLOWOUT/WELL RELEASE CAUSES .....................................................................................................................31 4.8 OPERATIONS AND ACTIVITIES WHEN BLOWOUT/WELL RELEASE OCCURS....................................................................35 4.9 EXPLORATION WILDCATS VS. EXPLORATION APPRAISAL BLOWOUTS/WELL RELEASES ....................................................39 4.10 BLOWOUTS FROM AUSTRALIA, CANADA EAST COAST, THE NETHERLANDS, AND US/CALIFORNIA OCS ..........................39 5. “NORMAL” DRILLING AND PRODUCTION EXPOSURE DATA ....................................................................... 41 5.1 DRILLING EXPOSURE DATA ................................................................................................................................41 5.1.1 US GoM OCS .......................................................................................................................................41 5.1.2 United Kingdom ..................................................................................................................................43 5.1.3 Norway ...............................................................................................................................................43 5.1.4 The Netherlands .................................................................................................................................46 5.1.5 Canadian East Coast ...........................................................................................................................47 5.1.6 US Pacific OCS .....................................................................................................................................49 5.1.7 Australia .............................................................................................................................................50 5.1.8 Denmark .............................................................................................................................................52 5.1.9 Compiled Drilling Exposure Data ........................................................................................................52 5.2 PRODUCTION EXPOSURE DATA...........................................................................................................................54 5.2.1 US GoM OCS .......................................................................................................................................54 5.2.2 United Kingdom ..................................................................................................................................55 5.2.3 Norway ...............................................................................................................................................56 5.2.4 US Pacific OCS .....................................................................................................................................57 5.2.5 Compiled Production Exposure Data ..................................................................................................58 6. VARIOUS EXPOSURE DATA ........................................................................................................................ 61 6.1 WELL DEPTH RELATED EXPOSURE DATA ..............................................................................................................61 6.1.1 US GoM OCS Wells ..............................................................................................................................61 6.1.2 Norwegian Wells ................................................................................................................................62 6.2 WATER DEPTH RELATED DRILLING EXPOSURE DATA ...............................................................................................64

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6.3 DRILLING INSTALLATION TYPE VS. WELL TYPE AND WATER DEPTH ............................................................................. 68 6.4 SHUT-IN WELLHEAD PRESSURE RELATED EXPOSURE DATA ...................................................................................... 69 6.4.1 US GoM OCS Drilling Wells ................................................................................................................ 69 6.4.2 Norwegian Drilling Wells ................................................................................................................... 71 6.4.3 US GoM OCS Wells in Production ....................................................................................................... 72 6.5 PRODUCTION RATES AND GAS OIL RATIO DATA, US GOM OCS.............................................................................. 73 6.5.1 Production Rates ................................................................................................................................ 73 6.5.2 Gas Oil Ratio ...................................................................................................................................... 75 6.6 WORKOVER FREQUENCY EXPOSURE DATA ........................................................................................................... 76 6.7 WIRELINE FREQUENCY EXPOSURE DATA .............................................................................................................. 77 6.8 COILED TUBING AND SNUBBING EXPOSURE DATA ................................................................................................. 78 7. OVERALL BLOWOUT/WELL RELEASE FREQUENCIES ................................................................................... 81 REFERENCES .................................................................................................................................................. 85 APPENDIX 1 BLOWOUT DATABASE STRUCTURE AND CODING ........................................................................ I A1. OVERALL DATABASE STRUCTURE .......................................................................................................................... II A2. DESCRIPTION OF DATABASE FIELDS AND ASSOCIATED CODES .................................................................................... IV FIELD 3 CATEGORY ......................................................................................................................................... IV FIELD 4 SUB CATEGORY....................................................................................................................................V FIELD 5 COUNTRY .......................................................................................................................................... VI FIELD 10 INSTALLATION TYPE ............................................................................................................................. VI FIELD 12 WELL STATUS ..................................................................................................................................... VI FIELD 18 MTSIP (MAKS THEORETIC SHUTIN WH PRESSURE) ................................................................................. VI FIELD 24 ROCK TYPE ...................................................................................................................................... VIII FIELD 25 FORMATION AGE .............................................................................................................................. VIII FIELD 27 PHASE............................................................................................................................................. VIII FIELD 28 OPERATION ....................................................................................................................................... IX FIELD 29 ACTIVITY ........................................................................................................................................... XI FIELD 30 EXTERNAL CAUSE ............................................................................................................................... XII FIELD 31 LOSS OF BARRIER 1 ............................................................................................................................ XII FIELD 32 LOSS OF BARRIER 2 ........................................................................................................................... XIV FIELD 34 NORTH SEA STANDARDS .................................................................................................................... XIV FIELD 35 FLOWPATH ....................................................................................................................................... XV FIELD 36 RELEASE POINT.................................................................................................................................. XV FIELD 37 FLOW MEDIUM ................................................................................................................................ XVI FIELD 41 IGNITION TYPE.................................................................................................................................. XVI FIELD 42 CONSEQUENCE CLASS ....................................................................................................................... XVII FIELD 44 POLLUTION ..................................................................................................................................... XVII FIELD 48 CONTROL METHOD .......................................................................................................................... XVII FIELD 50 DATA QUALITY ................................................................................................................................ XVII

Blowout and Well Release Characteristics and Frequencies, 2011 version

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1. About the Database 1.1 Participants The SINTEF Offshore Blowout Database was initiated in 1984. There are two new participants in 2011, URS Energy and Construction, Inc and Maersk Drilling. One participant, Mide Technology Corporation, has left the project. By December 2 2011 the following companies were sponsoring the database: 1. Statoil 2. BP Norge 3. Safetec Nordic A/S 4. Total E&P Norge AS 5. Scandpower AS 6. Shell Research Limited 7. DNV 8. Lilleaker Consulting a.s. 9. Eni Norge AS 10. ConocoPhillips Norge 11. BHP Billiton 12. Torus Insurance Marketing Limited 13. Husky Energy 14. AconaWellpro AS 15. Proactima 16. URS Energy and Construction, Inc 17. Maersk Drilling 1.2 Database Structure The SINTEF Offshore Blowout Database includes blowout/well release descriptions, drilling and production exposure data for certain areas in the world. Blowout/ well release descriptions The database contains 51 different fields describing each blowout/well release. The various fields are grouped in six different groups. They are: 1. 2. 3. 4. 5. 6.

Category and location Well description Present operation Blowout causes Blowout Characteristics Other

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Blowout and Well Release Characteristics and Frequencies, 2011 version

Category and location Includes information related to the incident category (blowout vs. well leak), offshore installation such as location, operator, installation name and type, and water depth. Well description Includes well and casing depths, last casing size, mud weight, bottom hole- and shut in pressure, GOR, formation age and rock type. Present operation Includes the phase (exploration drilling, development drilling, workover etc.), the operation presently carried out (for example casing running) and the present activity (for example cementing) Blowout causes Include external cause (stating if an external cause contributed to the incident), loss of the primary barrier, loss of the secondary barrier (describing how primary and secondary barrier were lost) and human error. It should be noted that the field regarding human error in general holds low quality information. Human errors are frequently masked. A field named North Sea standards highlights if the development of the blowout could have been avoided if North Sea type equipment had been used (for instance in other parts of the world a blind shear ram is not required in surface BOP stacks) Blowout characteristics Twelve fields are included comprising flow-path, flow medium, flow-rate (low quality), release point, ignition type, time to ignition, lost production (low quality), duration, fatalities, consequence class, material loss and pollution Other In the Other screen five fields is included, they are: control method, remarks (includes a description of the incident, data quality (includes an evaluation of the source data quality), last revision date and references. Exposure data The various areas represented with exposure data area shown in Table 1.1. Table 1.1 Overview of exposure data included in the database Country US GoM OCS Norway United Kingdom The Netherlands Canada East Coast Australia US Pacific Denmark

Drilling exposure data Yes Yes Yes Yes Yes Yes Yes Yes

Production exposure data Yes Yes Yes No No No Yes No

Search possibilities and reporting facilities Almost any type of search may be performed to select specific blowout /well release event types. Search criteria may be established by selecting predefined codes, specific numeric values, specific free text, or any combinations of these. The predefined codes are spelled out to ease understanding.

Blowout and Well Release Characteristics and Frequencies, 2011 version

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The database program counts and presents the events satisfying the search criteria. The selected data may be viewed, printed or copied to separate Excel files for further analyses. The exposure data and the blowout data are not linked. Blowout frequencies can therefore not directly be established. 1.3 Important Definitions The following main definitions have been utilised when categorising the blowouts/well releases in categories and sub-categories. Blowout definition NPD came up with a blowout definition in their proposal for the new regulations. (“Aktivitetsforskriften, eksternt høringsutkast av 3.7.2000, høringsfrist 3.11.2000”). Med utblåsing som nevnt i denne paragrafen første ledd, menes formasjonsfluid som strømmer ut av brønnen eller mellom formasjonslagene etter at alle definerte tekniske brønnbarrierer eller operasjon av disse har sviktet. Translated to English the definition will be: A blowout is an incident where formation fluid flows out of the well or between formation layers after all the predefined technical well barriers or the activation of the same have failed. The definition has however not become a part of the Petroleum Safety Authority Norway regulation, but remains the database blowout definition. Well release definition: The reported incident is a well release if oil or gas flowed from the well from some point were flow was not intended and the flow was stopped by use of the barrier system that was available on the well at the time the incident started. Shallow gas definition: Any gas zone penetrated before the BOP has been installed. Any zone penetrated after the BOP is installed is not shallow gas (typical Norwegian definition of shallow gas). All shallow gas incidents in the database have at the extent possible been categorised according to the typical Norwegian definition of shallow gas. This definition is not relevant for all US GoM incidents because:    

US GoM OCS reservoirs vary highly in depth. Some reservoirs were as shallow as 200 meters. For some incidents they had sat a full BOP stack, but had no intention to use it because it would likely cause a blowout outside the casing and a possible crater. For some incidents they had drilled very deep without running an extra casing string and the BOP. And for some incident they had used a combination of a BOP and a diverter.

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Blowout and Well Release Characteristics and Frequencies, 2011 version

Further, for many of the incidents the description of the incident in the sources is insufficient, and some assumptions have to be made. A general comment is that it is not easy to categorise all the incidents in shallow and deep incidents because of the above. It should further be noted that it is in many cases difficult to determine if a shallow gas incident shall be regarded as a blowout or not. In February 2007 a report was published, named “Shallow Gas Project, Shallow gas events 1984 – 2006 in the Norwegian Sector”, by AGR – Triangle. The report was prepared for the Petroleum Safety Authority Norway. This report describes 44 shallow gas events. These 44 events have been reviewed, and some blowouts were added to the database, and many incidents were disregarded. Typically incidents that were reported with a strong seafloor flow, or the diverter was used, were regarded as blowouts. Incidents only referring to gas bubbles were disregarded. This report is enclosed the West Vanguard Blowout (Blowout ID 278) in the database.

1.4 Category and Sub-category The categories and subcategories utilised when classifying the incidents in the SINTEF Offshore Blowout Database are shown in Table 1.2. Table 1.2 Main

Blowout and well release

Main categories and subcategories for the incidents in the SINTEF Offshore Blowout database Category Blowout (surface flow)

Blowout (underground flow)

Sub category 1. Totally uncontrolled flow, from a deep zone 2. Totally uncontrolled flow, from a shallow zone 3. Shallow gas “controlled” subsea release only 4. Underground flow only 5. Underground flow mainly, limited surface flow

Well release

6. 7.

Diverted well release Unknown

8.

Limited surface flow before the secondary barrier was activated Tubing blown out of well, then the secondary barrier is activated

Shallow gas controlled flow (diverted) Unknown

Comments/Example Totally uncontrolled incidents with surface/subsea flow. Typical the diverter system fails Typical incident is that riserless drilling is performed when the well starts to flow. The rig is pulled away The limited surface flow will be incidents were a minor flow has appeared, but typical the BOP has been activated to shut the surface flow Typical incident will be that flow is through the drillpipe and the shear ram is activated Typical incident occurring during completion or workover. Shear ram is used to close the well after the tubing has been blown out of the well. All incidents were the diverter system functioned as intended. Unknown may be selected for both the category and the subcategory

The list of sub-categories, shown in Table 1.2, may be extended if found appropriate. One option will be to split the sub category for Well release further down to highlight incidents with an ignition potential.

Blowout and Well Release Characteristics and Frequencies, 2011 version

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1.5 Phase of operation Each of the blowout/well releases in the database is categorised in the phase of operation they occurred. Table 1.3 shows the pre-set codes used for phase of operation. Table 1.3

Phase of operation

Description Completion Dev.drlg Expl.drlg Production Unknown drlg Unknown Wireline Workover

Remarks Activities associated to well completion activities Development drilling Exploration drilling, includes wildcats and appraisal wells Production, injection, closed in wells When it is not known whether it is dev.drlg or expl.drlg Unknown Wireline operations in connection with a production/injection well, not wireline operations carried out as a part of well drilling, well completion or well workover Workover activities, not including wireline operations. Snubbing and coiled tubing operations

1.6 North Sea Standards The intention with the field North Sea Standards is to identify blowout/well release incidents that likely would have been prevented in North Sea operations because the procedures or equipment utilised when the incident occurred are different from North Sea equipment or procedures. Table 1.4 presents the coding used for this field. Table 1.4

North Sea standards Description

Yes No, no shear ram No, BOP not North Sea standard No, two barrier principle not followed Sometimes not relevant, BOP removed to install casing seal Unknown Not evaluated

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Blowout and Well Release Characteristics and Frequencies, 2011 version

Blowout and Well Release Characteristics and Frequencies, 2011 version

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2. Overview of Blowouts/Well releases Included in the Database 2.1 Introduction The SINTEF Offshore Blowout Database does per December 2010 include information about 584 offshore blowouts/well releases that have occurred world-wide since 1955. The number of blowouts/well releases related to the different periods is presented in Table 2.1 Table 2.1

Number of blowouts/well releases related to the different periods Period 1950-ties

No. of blowouts/well releases 9

1960-ties

54

1970-ties

114

1980-ties

177

1990-ties

119

2000 – 2009-12-31

112

2010 and 2011 Total

7 592

Blowouts/well releases that have occurred in the period 1980-01-01 - 2009-12-31 in US GoM OCS, UK, and Norway are focused on. Blowouts/well releases that have occurred after 200912-31 are not included in this report at all. Blowouts/well releases from before 1980 and the rest of the world are only briefly included. 2.2 Data Quality SINTEF's intention is to collect data from all occurring blowouts. However, it is a fact that many blowouts/well releases occurring in this period have never been recorded in the database. This because, public sources, which are the main source of information for blowouts/well releases occurring outside US GoM OCS, and UK, and Norway, do frequently not describe blowouts/well releases with small consequences. Therefore, several blowouts/well releases are believed to be missing from the database. It is SINTEF's belief that from 1980-01-01 most blowouts occurring in the US Gulf of Mexico (GoM) Outer Continental Shelf (OCS), the UK, and Norway have been included in the database. The quality of data related to blowouts occurring after 1970-01-01 is significantly better than the data from before 1970. However, for many blowouts the quality still is low because proper descriptions of the incidents are lacking. Blowout information is frequently hidden from the public.

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Blowout and Well Release Characteristics and Frequencies, 2011 version

For each of the blowout/well release records in the database the quality of the source material is given. Table 2.2 shows an overview of the data quality for the blowouts/well releases that have occurred in the period 1980-01-01 – 2009-12-31. Table 2.2

Quality of blowout/well release data source material

Quality of blowout/well All blowouts except US GoM OCS, UK, Only US GoM OCS, UK, and Norwegian release data source and Norwegian blowouts in the period blowouts in the period 1980-01-01 – material 1980-01-01 – 2009-12-31 2009-12-31 Very good 9 65 Good 11 55 Fair 20 61 Low 36 54 Very low 79 18 Total 155 253

2.3 Overview of Countries Represented in the Database In Table 2.3 shows an overview of the number of blowouts and well releases for the countries represented in the database.

Blowout and Well Release Characteristics and Frequencies, 2011 version

Table 2.3

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Overview of countries represented in the database

COUNTRY ANGOLA AUSTRALIA AZERBAIJAN BRAZIL BRUNEI BURMA CABINDA CANADA EAST CANADA NORTH CHINA CONGO DENMARK DUBAI EGYPT EQUATORIAL GUINEA ETHIOPIA GABON GERMANY INDIA INDONESIA IRAN ITALY LIBYA MALAYSIA MEXICO NETHERLANDS NIGERIA NORWAY PAPUA NEW GUINEA PERU PHILLIPPINES QATAR SAUDI ARABIA SOUTH KOREA SPAIN TAIWAN THAILAND TRINIDAD UK UNKNOWN US US/ALASKA State US/CALIFORNIA OCS US/CALIFORNIA state US/GOM NOT OCS US/GOM OCS USSR VENEZUELA VIETNAM YUGOSLAV Total

50ties

60ties

70ties 3

80ties 1 1

2 1

1 1 1 2

90ties 1

1Jan 00 31 Dec 09 1 3

3 1 1 2 2 2 2 1 3

1 2 2 1

later than 31 Dec 09

1

1

1

1 1

3

1 1 1

1 1

4 4 1 1 2

3

3 3

1

3 11 7 1 2 6 1 2 13 1

5 2 1 1

5 1

2

2

1 15

1 4

1

2 1 2 1

3

1 1

1

4

3 1

1 8

2 2 1 11

2 15

1

1 3

10 52

9 58

1

2 6

1 1 1

1

5 30

17 58 2 1

3 2 7 77 6 3

2 3

1 1

9

1 54

114

177

119

112

7

Total 1 7 5 6 4 1 2 2 2 4 3 1 3 7 1 1 1 1 8 22 14 3 1 3 12 2 10 35 2 2 1 2 5 1 1 2 2 7 39 1 2 5 5 2 52 284 8 5 1 1 592

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2.4 During what Operational Phases do Blowouts/Well Releases Occur? In Table 2.4 and Table 2.5 no. of blowouts/well releases have been related to the operational phases. Table 2.4

No. of blowouts/well releases experienced during different operational phases (including all blowouts/well releases until 2009-12-31)

PERIOD

Dev. drlg

Before 1980

43 24,3 % 95 23,3 % 138 23,6 %

1980 to 2009-12-31 Total

Table 2.5

Expl. drlg 75 42,4 % 141 34,6 % 216 36,9 %

Completion

1 0,6 % 9 2,2 % 10 1,7 %

Workover

12 6,8 % 26 6,4 % 38 6,5 %

Production

18 10,2 % 64 15,7 % 82 14,0 %

20 11,3 % 45 11,0 % 65 11,1 %

Wireline

Unknown/ other 3 5 1,7 % 2,8 % 9 19 2,2 % 4,7 % 12 24 2,1 % 4,1 %

Total

177 408 585

Area specific overview of no. of blowouts/well releases experienced during different operational phases (including all blowouts/well releases 01-01-1980 2009-12-31)

AREA

US GoM OCS

Dev. drlg 54

Expl. Unk. Comp- WorkProduction drlg ** drlg letion over External No ext. cause* cause* 53 13 39 8 11

28,9 % 28,3 %

UK, and Norwegian waters Rest of the world Total

9

33

7,0 %

1

13,6 % 50,0 % 1,5 %

32

55

8

20,6 % 35,5 % 5,2 %

95

141

9

23,3 % 34,6 % 2,2 %

* **

Unk. drlg

20,9 %

4,3 %

7

9

1

10,6 %

13,6 %

1,5 %

6

16

3,9 %

10,3 %

26 6,4 %

64 15,7 %

Wire- Unline known/ other 5 4

5,9 % 2,7 %

2

187 66

12

11

15

7,1 %

9,7 % 100,0 %

21

24

5,9 % 2,2 %

9

65

0,0 % 100,0 %

7,7 % 5,1 %

Total excl. ext. cause* 179

2,1 % 100,0 %

4

3,0 % 6,1 %

Total

19

155 408

143 387

4,7 % 100,0 %

External causes are typical; storm, military activity, ship collision, fire and earthquake. One of the Expl. drilling blowouts in the "rest of the world” was caused by volcanic activities

When reading and Table 2.5, it is important to note that the most thorough data is from the US GoM OCS, UK, and Norway. In the US GoM OCS they have experienced a relatively high no. of blowouts/well releases during development drilling compared to exploration drilling. This is explained by the fact that in US GoM OCS they are drilling relatively more development wells than exploration wells, compared to UK and Norway. Further, the relatively high no. of well workover blowouts/well releases in US GoM OCS area does indicate that the number of workovers in that area is high. It should, further, be noted that external causes were involved in approximately 50% of the production blowouts. External causes are discussed in Section 4.7, on page 31.

Blowout and Well Release Characteristics and Frequencies, 2011 version

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2.5 No. of Blowouts/Well releases per Year Table 2.6 shows a year-to-year overview of no. of blowouts/well releases for US GoM OCS, UK, and Norway in the period 1980-01-01 - 2009-12-31. Table 2.6 Year

1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Total

*

Dev. Drlg

Year to year overview of no. of blowouts/well releases for US GoM OCS, UK, and Norway in the period 1980-01-01 – 2009-12-31

UnComp- WorkProduction Wire- UnTotal known letion over No ext. External line known/ drilling other cause* cause* 2 1 2 1 9 2 5 2 11 5 1 4 1 11 7 2 3 1 1 14 1 6 1 8 2 2 6 2 12 1 1 2 1 2 1 1 2 1 8 1 3 1 1 6 4 5 2 3 2 1 17 3 3 2 3 1 12 4 1 3 1 1 10 2 2 1 1 3 9 2 2 2 6 1 1 1 1 4 1 1 2 4 1 2 2 1 6 3 1 5 2 2 13 3 1 1 1 2 1 9 3 2 5 3 2 3 1 1 1 11 3 1 1 2 4 2 13 2 1 1 1 1 1 7 2 1 1 1 1 1 7 2 1 3 6 2 1 1 4 3 1 4 1 1 5 2 1 10 1 2 3 1 1 8 2 2 1 1 1 7 33 51 2 13 9 63 1 20 48 9 4 253 External causes are typical; storm, military activity, ship collision, fire and earthquake. Appraisal 1

Expl. Drlg WildUncat known 2 2

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Blowout and Well Release Characteristics and Frequencies, 2011 version

2.6 Water depth vs. Blowouts/Well releases Table 2.7 shows the water depth vs. blowouts/well releases for US GoM OCS, UK, and Norway in the period 1980-01-01 - 2009-12-31. Table 2.7

Water depth vs. blowouts/well releases for US GoM OCS, UK, and Norway in the period 1980-01-01 – 2009-12-31

Water depth grouped (m) Phase

MainCategory

Deep or Shallow $ 0.5 M Material loss > $ 3 M

Pollution

Table A 21 shows the classification for oil/condensate pollution to the sea. Table A 21 Pollution ID Description 0 NO 1 LARGE 2 MEDIUM 3 SMALL 4 UNKNOWN

In case the amount of oil/condensate pollution has been determined it is commented under remarks Field 48

Control Method

Control method includes information related to the method used to stop the blowout. Table A 22 shows the possible key words. Table A 22 Control method ID Description 0 BOP 1 BRIDGED 2 CAPPED 3 CEMENTED 4 DEPLETED 5 INSTALLED 6 MUD 7 RELIEF WELL 8 UNKNOWN 9 CEASED

Field 50

Remarks

Equipment, e.g. VALVE Killed with mud

Data Quality

The Data quality field gives an indication of the reference data quality. Table A 23 shows the alternatives.

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Blowout and Well Release Characteristics and Frequencies, 2011 version, Appendix 1

Table A 23 Data Quality ID Description Remarks/criteria 3 VERY GOOD is used if the data record is based on the authorities or the companies investigation report 1 GOOD Is used if the incident is well documented through technical articles or other sources 0 FAIR If the source list an overall description of the incident 2 LOW If the quality of the source information is low, but some crucial facts are described 4 VERY LOW When the source material is very scarce