Model code of safe practice Part 17 Volume 2

Transcription

1 Model code of safe practice Part 17 Volume 2 Well control during the drilling and testing of high pressure, high temperature offshore wells 2nd edition

2 ENERGY INSTITUTE MODEL CODE OF SAFE PRACTICE IN THE PETROLEUM INDUSTRY PART 17: VOLUME 2 WELL CONTROL DURING THE DRILLING AND TESTING OF HIGH PRESSURE, HIGH TEMPERATURE OFFSHORE WELLS

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4 ENERGY INSTITUTE MODEL CODE OF SAFE PRACTICE IN THE PETROLEUM INDUSTRY PART 17: VOLUME 2 WELL CONTROL DURING THE DRILLING AND TESTING OF HIGH PRESSURE, HIGH TEMPERATURE OFFSHORE WELLS 2nd edition April 2008 Published by ENERGY INSTITUTE, LONDON The Energy Institute is a professional membership body incorporated by Royal Charter 2003 Registered charity number

5 The Energy Institute (EI) is the leading chartered professional membership body supporting individuals and organisations across the energy industry. With a combined membership of over individuals and 300 companies in 100 countries, it provides an independent focal point for the energy community and a powerful voice to engage business and industry, government, academia and the public internationally. As a Royal Charter organisation, the EI offers professional recognition and sustains personal career development through the accreditation and delivery of training courses, conferences and publications and networking opportunities. It also runs a highly valued technical work programme, comprising original independent research and investigations, and the provision of IP technical publications to provide the international industry with information and guidance on key current and future issues. The EI promotes the safe, environmentally responsible and efficient supply and use of energy in all its forms and applications. In fulfilling this purpose the EI addresses the depth and breadth of energy and the energy system, from upstream and downstream hydrocarbons and other primary fuels and renewables, to power generation, transmission and distribution to sustainable development, demand side management and energy efficiency. Offering learning and networking opportunities to support career development, the EI provides a home to all those working in energy, and a scientific and technical reservoir of knowledge for industry. This publication has been produced as a result of work carried out within the Technical Team of the Energy Institute (EI), funded by the EI s Technical Partners. The EI s Technical Work Programme provides industry with cost-effective, value-adding knowledge on key current and future issues affecting those operating in the energy sector, both in the UK and internationally. For further information, please visit The Energy Institute gratefully acknowledges the financial contributions towards the scientific and technical programme from the following companies: BG Group BHP Billiton Limited BP Exploration Operating Co Ltd BP Oil UK Ltd Chevron ConocoPhillips Ltd ENI E.ON UK ExxonMobil International Ltd Kuwait Petroleum International Ltd Maersk Oil North Sea UK Limited Murco Petroleum Ltd Nexen Saudi Aramco Shell UK Oil Products Limited Shell U.K. Exploration and Production Ltd Statoil (U.K.) Limited Talisman Energy (UK) Ltd Total E&P UK plc Total UK Limited Copyright 2008 by the Energy Institute, London: The Energy Institute is a professional membership body incorporated by Royal Charter Registered charity number , England All rights reserved No part of this book may be reproduced by any means, or transmitted or translated into a machine language without the written permission of the publisher. The information contained in this publication is provided as guidance only and while every reasonable care has been taken to ensure the accuracy of its contents, the Energy Institute cannot accept any responsibility for any action taken, or not taken, on the basis of this information. The Energy Institute shall not be liable to any person for any loss or damage which may arise from the use of any of the information contained in any of its publications. The above disclaimer is not intended to restrict or exclude liability for death or personal injury caused by own negligence. ISBN Published by the Energy Institute Further copies can be obtained from Portland Customer Services, Commerce Way, Whitehall Industrial Estate, Colchester CO2 8HP, UK. Tel: +44 (0) sales@portland-services.com Electronic access to EI and IP publications is available via our website, Documents can be purchased online as downloadable pdfs or on an annual subscription for single users and companies. For more information, contact the EI Publications Team. e: pubs@energyinst.org.uk

6 CONTENTS Acknowledgements...xi Page Foreword... xiii 1 HPHT wells safety management HPHT definitions Health Safety and Environment (HS&E) HS&E ALARP Hazard identification HAZID HAZOP Failure modes and effects analysis (FMEA) Risk estimation Identification of potential risk reduction Risk evaluation Demonstration of ALARP Review Management Managing the engineering process Well proposal Basis of design Joint operations manual (JOM) End of well report (EOWR) Managing risk Clear reporting lines Risk ranking Monitoring risks Risk register Capturing learnings and lessons Change management Management of change (MOC) Assessing the impact of change Approval of change Communicating change Identifying new risks Mitigating risks... 7 v

7 Contents cont... Page 1.4 Quality assurance and quality control Failures Document control and statement of requirement (SOR) Life of well issues Dispensations Training References and related web sites Well planning High pressure wells Code of Practice Hazards associated with loss of well control Well control equipment rating Reservoir data Maximum predicted temperatures Formation temperatures Seabed and surface temperatures Production testing temperatures Minimum predicted temperatures Maximum predicted pressure Drilling Production testing Hydrogen sulphide design standards Corrosion design standards (including CO 2 ) Casing/tubing design Deep intermediate casing string Production casing Quality assurance Elastomer design Well control programme Field policies and procedures Well control policies Primary control Secondary control Fluid influx detection Fluid influx detection 'fingerprinting' Heavy lifting operations Managed pressure drilling Drilling procedures Drilling data analysis Drilling limitation Formation pressure integrity tests Communications and responsibilities Blowout preventer drills Drill string back pressure valve Mud mixing and transferring Weighting material supplies Temperature monitoring Flow checks Coring Slow circulating rates Measurement while drilling (MWD) equipment, downhole motors Tripping procedures vi

8 Contents cont... Page Preparation prior to the trip Procedures during the trip Running pipe in the hole Swabbing Stripping Shut-in procedures While tripping While drilling While out of hole Well kill procedures Slow circulating rates Kick volume Mud gas separator monitoring Choke operations Preferred choke line outlet Temperature monitoring Maximum allowable annular surface pressure (MAASP) Mustering of crews Move-off procedures Well kill methods Responsibilities and administration Communications Operator supervision Level of supervision Duties of individual personnel Offshore installation manager (OIM) Personnel reporting to the OIM Level of rig supervision provided by operator Operator s day drilling supervisor Operator s night drilling supervisor Operator s drilling engineer Wellsite geologist Completion/well test engineer Senior toolpusher Toolpusher Drillers Recommended crew for emergency well control situation Equipment standards, inspection and testing Blowout preventer standards Surface BOP Subsea BOP Choke and kill manifold Surface gas handling system Mud gas separator (MGS) MGS instrumentation MGS by-pass By-pass overboard lines Hydrate inhibitor injection system Temperature monitoring equipment Choke and kill line remotely operated valves Kill system vii

9 Contents cont... Page 5.7 Drill string circulating capability Pit level indicator Choke and kill lines Flexible lines Steel lines Hydrogen sulphide design standards Factors affecting failure Selection of steels for use in H 2 S environments Drill pipe, tubing, etc Drill collars BOPs Wellheads and valves for H 2 S Welding of materials Inspection of components Testing and inspection (pressure control equipment) Pressure test frequency Function test frequency Equipment to be tested Pressure test fluids Pressure test values Mud gas separator Flexible choke and kill lines Gas detectors Sensors and monitors Casing wear Inspection of major well control components Flexible lines System description Flexible lines End-fittings Design and mechanical considerations Storage, handling, transportation and installation Storage Handling and transportation Installation In-service inspection, survey, test and repair Inspection manual Periodical inspection Frequency of periodical inspections and tests External inspection Internal inspection In-service tests Major surveys Repair Well testing and stimulation flexible lines Well testing flexible lines Well stimulation flexible lines Emergencies and safety Contingency policies and plan Contingency policies Contingency plan Relief well contingency plan viii

10 Contents cont... Page 7.2 Hydrogen sulphide Drilling considerations Emergency procedures Emergency disconnect practices during well kill operations Conditions that may require disconnect Procedures for emergency disconnect (time permitting) Procedures for emergency disconnect (no warning) Suspension of operations due to weather Weather services General procedures Permit to work system Well testing Design considerations Tubing Packers Downhole test tools Subsea equipment Surface equipment Wireline operations Emergency shutdown (ESD) system Operational procedure considerations Monitoring and control of testing operations Well preparation Running the test string Flow periods Well shut-in Well kill procedure Safety Safety meetings Pressure testing on the surface Wireline operations Perforating Actions prior to and during testing Hydrogen sulphide (H 2 S) Contingencies Temperature monitoring Subsea test tree disconnect procedures Hydrates Tubing leaks Role of the verification scheme Training Survival, firefighting and emergency safety Drilling and production operations Well control course Drilling personnel safety awareness meetings Hydrogen sulphide training Drills Permit-to-work system training ix

11 Contents cont... Page ANNEX A RECOMMENDED PRACTICES, SPECIFICATIONS, STANDARDS ETC., RELEVANT TO THIS CODE ANNEX B WORST CASE SCENARIO FOR THE DRILLING OF HIGH PRESSURE WELLS B.1 Definition B.2 Objectives for the computer model B.3 Background B.4 Modelling data and assumptions B.5 Predicting maximum anticipated wellhead temperature while drilling B.6 Predicting peak surface temperature during annular flow ANNEX C WELL CONTROL DECISION CHARTS ANNEX D WELL TESTING EQUIPMENT REQUIREMENTS AND PLANNING D.1Testing equipment general requirements D.2 Selection of downhole components for well test string D.3Tubing leak contingency plan ANNEX E FLEXIBLE CHOKE AND KILL LINE GUIDANCE E.1 General E.2 Operational requirements and design considerations E.3 Materials of construction E.4 Tests ANNEX F GLOSSARY OF TERMS AND ABBREVIATIONS USED IN THIS CODE F.1 Glossary of terms F.2 Abbreviations Figures Figure 1 The risk assessment process... 2 Figure 2 Criticality awareness framework... 4 Figure C.1 Kill procedure determination decision chart Figure C.2Pore pressure analysis decision chart Figure C.3Lost returns while tripping in Decision chart Figure C.4 Lost returns while drilling Decision chart Tables Table 1 Example of risk matrix and consequences that may be considered... 6 x

12 ACKNOWLEDGEMENTS The revision and updating of this publication was undertaken by consultants from Think-Well (Scotland) Limited under the direction of a Steering Group formed from expert representatives from the operating and service companies serving the North Sea industry. The consultants and Steering Group members met on several occasions to permit discussion and agreement on the direction and format of the revised code as it was being developed. The group also provided written comment and feedback on the various draft versions produced outwith the meetings. The Steering Group comprised the following members: Bruce McEwan (Chairman) Donald Dobson Norman Day Peter Greaves Luc Fambon John Watters Steve Mellor Steve Hand/Adrian Blake Keith Hart (Secretary) Shell UK Exploration & Production HSE OSD BP Exploration Operating Company BG Group Total E & P UK GDF Britain Limited Rowan Drilling & IADC Liaison Transocean Drilling Energy Institute The Energy Institute wishes to acknowledge the expertise and work provided for the development of this publication by the following consultants: Eric Low Steve Walters Think-Well (Scotland) Think-Well (Scotland) Acknowledgement is also attributed to other personnel who provided valuable assistance early in the project to the Steering Group: Bill White John Edmundson BP Exploration Operating Company Ltd Maersk Oil North Sea UK Limited Affiliations refer to the time of participation. xi

13 MCoSP PART 17: VOLUME 2 WELL CONTROL DURING THE DRILLING AND TESTING OF HIGH PRESSURE, HIGH TEMPERATURE OFFSHORE WELLS xii

14 FOREWORD Volume 2 of Model Code of Safe Practice Part 17 has been developed as a guide for those concerned with well control during the drilling and testing of high pressure and high temperature (HPHT) offshore wells. It provides guidance on those well control activities associated with HPHT wells which have an impact on safety offshore, and therefore require detailed care and attention. This 2nd edition replaces the original version published in The revision was commissioned in response to the requirements of the UK industry for the Model Code to include updated changes to equipment and procedures that supersede those referenced in the original publication. The Model Code now includes an Introduction that sets out the additional corporate and legislative demands on company systems and their personnel for improved safety performance through additional emphasis on risk evaluation and mitigation and application of as low as reasonably practicable (ALARP) principles. The revision exercise has also provided an opportunity to incorporate where appropriate, the valuable operational experience gained in the UK Continental Shelf (UKCS) over recent years. Guidance provided in this Model Code should be considered as a starting point for the operators and drilling contractors in developing the programme and associated operational plans and procedures for drilling and testing a HPHT well. While this Model Code provides good industry practice, this is only a starting point: each operator and drilling contractor should review and apply the guidance provided in this Model Code according to its own policies and experience for the particular area of operation. The Model Code has been developed in a UKCS context of HPHT well drilling and testing; however, its guidance is universally applicable provided it is read, interpreted and applied in conjunction with relevant national and local statutory legislation and publications (codes of practice, design standards, specifications, recommended practices, guidance, etc.). Where the requirements differ, the more stringent should be adopted. In addition, readers should take account of developments in legislation and publications which have been issued since this Model Code was published. For the purpose of this publication, definitions of pertinent terms and abbreviations which are in common usage in the oil and gas industry are given in Annex F: these apply irrespective of any other meaning they have in other connections. Although the adoption of this publication should help to promote safe well control practice, the Energy Institute and the technical representatives listed in the Acknowledgements cannot accept responsibility in any way for injury to personnel or damage to equipment, installations or property which may arise from the use of any of the information contained in this Model Code. The Model Code forms Volume 2 of Part 17 of the Model Code of Safe Practice. It will be complemented by two further volumes which are under technical development with publication expected in 2008/9: Volume 1 HPHT well planning (provisional title) and Volume 3 HPHT well completions and interventions (provisional title). xiii

15 MCoSP PART 17: VOLUME 2 WELL CONTROL DURING THE DRILLING AND TESTING OF HIGH PRESSURE, HIGH TEMPERATURE OFFSHORE WELLS xiv

16 1 HPHT WELLS SAFETY MANAGEMENT INTRODUCTION This code is intended to provide guidance for those planning and managing operations relating to 'high pressure high temperature' (HPHT) well construction. It is intended to assist in identification and assessment of risk and risk mitigation that may be required, and to help demonstrate that the ALARP principle has been achieved. It is a principle of Health and Safety Legislation in the UK that risks of personal injury are reduced to 'as low as reasonably practicable' (ALARP). Therefore, it is imperative that risks involved in HPHT well operations are clearly communicated to everyone involved, including management, service providers, designers, and safety and environmental advisors. It is also imperative to comply with all relevant international, national, and regional laws, statutory instruments and regulations. Therefore liaison with legislative, fiscal, and regulatory stakeholders is paramount and should be given high priority from day one. Attention to detail is needed throughout when planning, designing, drilling, testing, and operating HPHT wells. Both company and contractor policies should be reviewed for their suitability for operating within an HPHT environment. Also important is that appreciation of the lead times that are often required for the selection and procurement of a suitable drilling facility, associated safety critical equipment, people, products, and services can prove demanding and can greatly extend the time needed for planning. This publication is intended to provide advice and help communicate HPHT risks to management and others, emphasising the company s duty of care. 1.1 HPHT DEFINITIONS HT: high temperature and HP: high pressure High temperature in this context can be defined as when the undisturbed bottom hole temperature at prospective reservoir depth (or total depth) is greater than 300 F (149 C). High pressure can be defined as either when the maximum anticipated pore pressure of any porous formation to be drilled through exceeds a hydrostatic gradient of 0,8 psi/ft (representing an EMW of 1,85 SG or 15,4 ppg) or, needing deployment of pressure control equipment with a rated working pressure in excess of psi (690 bar, 69 MPa). Note that areas of high pressure (abnormal pressure) need not necessarily be accompanied by high temperatures and vice versa. 1.2 HEALTH SAFETY AND ENVIRONMENT (HS&E) HS&E When planning an HPHT well, HS&E should be considered the primary value driver. Therefore, HS&E considerations should have high priority/weighting and be factored into the planning of the following work 1

17 MCoSP PART 17: VOLUME 2 WELL CONTROL DURING THE DRILLING AND TESTING OF HIGH PRESSURE, HIGH TEMPERATURE OFFSHORE WELLS flows: project objectives; well objectives; recommended codes of practice/best practices and guidelines; rig selection and audit; management of simultaneous operations (SIMOPS); management of combined operations; safety management system (SMS) interfaces; well type (people exposure); HPHT procedures; classification v. certification; drill the well on paper (DWOP); complete well on paper (CWOP), and test well on paper (TWOP) ALARP It is a principle of UK Health and Safety Law that risks to persons are reduced to 'as low as is reasonably practicable'. This is commonly referred to by the acronym ALARP. A demonstration of ALARP should cover the HPHT project and associated components, systems and HSEMS (health, safety and environment management system). All phases of the development should be assessed and managed such that the residual risks can be demonstrated as being ALARP. The means of demonstrating ALARP is via a risk assessment process the main purpose of which is to identify and rank the risks so that they can be adequately managed. The main stages of the risk assessment process are shown in the following Figure 1. Each stage of the risk assessment can be seen as an opportunity to identify potential risk reduction options Hazard identification Hazard identification needs to be comprehensive whatever approach to risk assessment is used. Typical methods of hazard identification that can be used are hazard identification (HAZID), hazard and operability (HAZOP) and failure modes effects analysis (FME(C)A) HAZID HAZID is a high level systematic assessment of a system using guidewords to help identify potential hazards HAZOP HAZOP is a well-established method, which takes a full description of a process system and questions every part of it to discover what deviations from the intention of the design can occur and what the causes and consequences of these deviations may be. This is done systematically by applying suitable guidewords (the methodology is detailed in 1.6 Ref. A) and is an Hazard Identification Risk estimation and ranking of risks Risk evaluation and implementation of risk reduction to achieve ALARP Identification of possible additional risk reduction Review Figure 1: The risk assessment process 2