Is it necessary to install a downhole safety valve in a subsea ... - NTNU

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Is it necessary to install a downhole safety valve in a subsea oil/gas well? Contents Preface.........................................................................................................................................I Summary and conclusions......................................................................................................... II List of Acronyms and Abbreviations ........................................................................................ V Contents...................................................................................................................................VII List of figures ...........................................................................................................................IX List of tables .............................................................................................................................IX 1 Introduction ........................................................................................................................ 1 1.1 Objectives................................................................................................................... 1 1.2 Limitations .................................................................................................................2 1.3 Report structure.......................................................................................................... 3 2 Rules and regulations .........................................................................................................4 2.1 Norway....................................................................................................................... 4 2.2 United Kingdom......................................................................................................... 4 2.3 United States of America ........................................................................................... 5 2.4 Standard organizations ............................................................................................... 5 2.5 Regulatory challenges ................................................................................................ 5 3 Use of acceptance criteria .................................................................................................. 7 3.1 The ALARP principle ................................................................................................ 8 3.2 Safety integrity level (SIL)......................................................................................... 9 4 Overall risk assessment .................................................................................................... 11 4.1 Consequences........................................................................................................... 11 4.1.1 Economic.......................................................................................................... 12 4.1.2 Blowouts........................................................................................................... 12 4.2 Installation related risk............................................................................................. 14 4.3 Production related risk ............................................................................................. 14 4.4 Workover related risk............................................................................................... 15 5 Risk reducing effect of a DHSV ...................................................................................... 17 5.1 Case example............................................................................................................ 17 5.1.1 Production tree ................................................................................................. 17 5.1.2 Production well ................................................................................................ 18 5.2 Barrier analysis......................................................................................................... 21 5.2.1 Case example.................................................................................................... 21 5.3 Fault Tree Analysis .................................................................................................. 25 5.3.1 Case example.................................................................................................... 25 5.4 Unavailability calculations....................................................................................... 26 5.4.1 The Mean Fractional Dead Time calculation model........................................ 26 5.4.2 Calculations done in CARA............................................................................. 28 5.4.3 Calculations done by hand ............................................................................... 28 5.4.4 CARA calculation results................................................................................. 29 5.4.5 Hand calculation results ................................................................................... 30 5.5 Risk reducing findings in the Case example ............................................................ 33 5.5.1 Comments to the risk reducing findings .......................................................... 35 6 Well intervention.............................................................................................................. 36 6.1 Intervention types..................................................................................................... 36 6.1.1 Light intervention............................................................................................. 36 6.1.2 Heavy intervention (workover) ........................................................................ 36 6.1.3 Workover equipment........................................................................................ 36 Diploma thesis, NTNU 2002 VII
Is it necessary to install a downhole safety valve in a subsea oil/gas well? 6.1.4 Well intervention example ............................................................................... 38 6.2 HAZOP (Hazard and Operability Analysis) ............................................................ 42 6.2.1 Background ...................................................................................................... 42 6.2.2 HAZOP methodology ...................................................................................... 43 6.2.3 HAZOP of the BOP handling procedure.......................................................... 45 6.2.4 The BOP handling procedure........................................................................... 45 6.2.5 The HAZOP analysis ....................................................................................... 47 6.2.6 Result of the HAZOP analysis ......................................................................... 52 7 Conclusions and recommendations for further work ....................................................... 53 7.1 Conclusions .............................................................................................................. 53 7.2 Recommendations for further work ......................................................................... 55 8 References ........................................................................................................................ 56 9 Appendices....................................................................................................................... 58 Diploma thesis, NTNU 2002 VIII
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APPENDIX A A1 Subsea production sys
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A1.3 Well completion A1.3.1 Tubing
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A1.5.2 Guidelineless system Several
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Appendix B In this appendix a figur
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Appendix C Fault trees constructed
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Production Wing valve ITL WV Produc
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Component: Production Packer Failur
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Reliability data dossier Component:
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Component: Production wing valve Fa
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Component: Crossover line Failure r
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Appendix F The guide-words used in
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Is it necessary to install a downhole safety valve in a subsea ... - NTNU

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