117 - Recommended Guidelines Well Integrity Rev4, 06.06. 11

7/28/2019 117 - Recommended Guidelines Well Integrity Rev4, 06.06. 11

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Norwegian Oil and Gas Association recommended guidelines for Well Integrity

No.: 117 Established: 01.10.08 Revision no: 4 Date revised: 06.06.2011 Page: 2__________________________________________________________________________

Preface

This guideline is supported by Norwegian Oil and Gas Association's Resource Group DrillingDrilling Managers Forum (DMF) and recommended by Well Integrity Forum (WIF) and byNorwegian Oil and Gas' Committee for Operations. Further it has been approved by

Norwegian Oil and Gas general director.

The work group has been composed of the following members:

Tommy Skjerven, BP;yvind Lunde, ConocoPhillips;

Morten Perander, Eni Norge;Bruce Williams, ExxonMobil;Rod Farquhar, Marathon;

Jean-Claude Sinet, Nexen Inc.;Jan Sby, Norske Shell;

Hilde Brandanger Haga, Statoil;rjan Finnseth, Talisman

Stle Johnsen, Total.

Responsible manager in Norwegian Oil and Gas is Manager Drilling who can be contacted at

the Norwegian Oil and Gas switchboard + 47 51 84 65 00.

The guidelines express a joint solution developed between the operating companies including

support from the Petroleum Safety Authority (PSA).

These Norwegian Oil and Gas guidelines have been prepared with the broad-basedparticipation of interested parties in the Norwegian petroleum industry, and they are owned bythe Norwegian petroleum industry, represented by Norwegian Oil and Gas. Norwegian Oil

and Gas is responsible for administrat ion of these guidelines.

Norwegian Oil and Gas AssociationVassbotnen 1, SandnesP.O. Box 8065

4068 Stavanger, Norway

Tel.: + 47 51 84 65 00Fax: + 47 51 84 65 01Web site: www.norskoljeoggass.noE-mail: [email protected]

NOTE: Revision 4 dated 06.06.2011 is issued to add Chapter 6
http://www.norskoljeoggass.no/http://www.norskoljeoggass.no/http://www.norskoljeoggass.no/


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Index

CHAPTER 1............................................................................................................................... 7

WELL INTEGRITY TRAINING .............................................................................................. 71. Introduction ........................................................................................................................ 72. Abbreviations ..................................................................................................................... 73. Background ........................................................................................................................ 74. Training Guidelines ............................................................................................................ 8

Appendix A ........................................................................................................................ 9Well Integrity Fundamentals Trainingrecommended subjects....................................... 9

CHAPTER 2............................................................................................................................. 11WELL HANDOVER DOCUMENTATION ........................................................................... 11

1. Introduction ................................................................................................................... 112. Background ................................................................................................................... 113. Discussion ..................................................................................................................... 11a. Well Construction Data .................................................................................................... 12

b. Well Diagrams.................................................................................................................. 12C. Handover Certificate........................................................................................................ 12d. Operating Input ................................................................................................................ 13

CHAPTER 3............................................................................................................................. 14WELL BARRIER SCHEMATICS FOR THE OPERATIONAL PHASE .............................. 14

1. Introduction ................................................................................................................... 142. Background ................................................................................................................... 143. Guidelines of minimum data ......................................................................................... 144. Discussion on minimum data ........................................................................................ 15

4.1 The formation strength should be indicated for formation within the barrier

envelopes .......................................................................................................................... 15

CHAPTER 4............................................................................................................................. 19WELL INTEGRITY WELL CATEGORIZATION ................................................................ 19

1. Objective ....................................................................................................................... 192. Abbreviations & Definitions ......................................................................................... 20

Abbreviations ................................................................................................................... 20Definition of terms ........................................................................................................... 20

3. Background ................................................................................................................... 214. Philosophy ..................................................................................................................... 225. Use of Categorization System ....................................................................................... 23


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Categorization approach................................................................................................... 23Information required for categorization ........................................................................... 24

6. Category Descriptions ................................................................................................... 25

Overview of Category Principles ..................................................................................... 25Green Category ................................................................................................................ 26Yellow Category .............................................................................................................. 29Orange Category .............................................................................................................. 31Red Category .................................................................................................................... 33

7. Attachment A - Well categorization description comparison table .............................. 348. Attachment B - Well with casing cement not fulfilling Norsok D-010 acceptancecriteria................................................................................................................................... 36

CHAPTER 5............................................................................................................................. 40WELL INTEGRITY MANAGEMENT SYSTEM.................................................................. 40

1. Objective ....................................................................................................................... 402. Abbreviations ................................................................................................................ 413. Background ................................................................................................................... 424. Elements in a Well Integrity Management System ....................................................... 435.

Discussion of each main element .................................................................................. 45

5.1 Organisation ........................................................................................................... 455.2 Design .................................................................................................................... 455.2.1 Technical standards ............................................................................................ 465.2.2 Barriers ............................................................................................................... 465.2.3 Equipment requirements .................................................................................... 465.2.4 Safety systems .................................................................................................... 465.2.5 ALARP principle................................................................................................ 475.3

Operational Procedures .......................................................................................... 47

5.3.1 Operate within the design load limits................................................................. 475.3.2 Monitoring, verification and maintenance program ........................................... 485.3.3 Well control and emergency preparedness......................................................... 485.3.4 Transfer of information ...................................................................................... 485.4 Data system ............................................................................................................ 485.5 Analysis.................................................................................................................. 49

6. Appendix Asummary of the regulations relevant for a WIM system ....................... 50Chapter 6 .................................................................................................................................. 54Sustained Casing Pressure........................................................................................................ 54


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1. Objective ....................................................................................................................... 542.

Abbreviations & Definitions ......................................................................................... 55

2.1 Abbreviations ............................................................................................................. 552.2 Definition of terms ..................................................................................................... 55

3. Sustained Casing Pressure Definition ........................................................................... 564. Sustained Casing Pressure Management....................................................................... 57

4.1 Monitoring & Detection ............................................................................................. 574.2 Evaluation................................................................................................................... 604.2.1 Evaluation of source, mechanism and locat ion ....................................................... 604.2.2 Leak rate evaluation ................................................................................................ 634.2.3 Annulus pressure evaluat ion ................................................................................... 634.2.4 Hydrocarbon gas volume and mass evaluation ....................................................... 644.2.5 Escalation potential evaluat ion................................................................................ 644.3 Acceptance Criteria Determination ............................................................................ 654.3.1 Leak rate criteria...................................................................................................... 654.3.2 Annulus pressure cr iteria......................................................................................... 664.3.2.1 Failure Modes....................................................................................................... 674.3.2.2 Fluid Densities...................................................................................................... 684.3.2.3 Degradation of Tubulars....................................................................................... 684.3.2.4 Safety Factors ....................................................................................................... 684.3.2.5 Maximum Operational Pressure (MOP) .............................................................. 684.3.2.6 Hydrocarbon gas mass ......................................................................................... 694.3.2.7 Degradation o f tubulars ........................................................................................ 694.3.3 Hydrocarbon gas mass criter ia ................................................................................ 704.3.4 Escalation potential criteria ..................................................................................... 714.4 Mitigating Measures................................................................................................... 714.4.1 Technical ................................................................................................................. 714.4.2 Operational .............................................................................................................. 72

5. Sustained Casing Pressure Prevention & Elimination .................................................... 755.1 Well Design and Operational Considerations ............................................................ 755.2 Pumping Operations ................................................................................................... 775.3 Workover & Interventions ......................................................................................... 79


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CHAPTER 1

WELL INTEGRITY TRAINING

1. Introduction

The Well Integrity Forum (WIF) was established in 2007 and one of the main issues that wasinitially brought up for review was well-integrity training. WIF members acknowledge a need

for well-integrity training of key personnel working with well integrity offshore and onshore.

This was also one of the key findings in an earlier PSA well-integrity survey.

A survey of operators well-integrity-training practices, experiences, opinions and ideas wascarried out and used as a basis for developing a well-integrity-training guideline. This chapter

describes WIF members recommendations for well-integrity training and is intended tofunction as a guideline to the oil industry.

2. Abbreviations

ASV is Annulus Safety ValveHSE is Health, Safety and Environment

OIM is Offshore Installation ManagerPSA is Petroleum Safety Authority

SCSSV is Surface Controlled Subsurface Safety ValveWBS is Well Barrier SchematicWIF is Well Integrity Forum

3. Background

A survey was completed by WIF members and this formed the basis for discussion and

development of the guidance in section 4. The feedback focused on learning, present practice,opinions and ideas.The survey included the following questions:

Main objective for a well integrity course?

What should be covered in the well integrity training? Should the course include any exercises?

Timing and schedule, how many days and if applicable, when?


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Who to participate and mixture of skills in one group? Handouts and/or documentation?

Computer based vs. class room based or other methods?

Training a part of competency management system?

4. Training Guidelines

What to cover in a well integrity course and timing of training

The recommended training is listed below in a preferred sequence and with estimated numberof training days for each element. Note that this recommendation applies to all personnel with

assigned responsibilities for well maintenance, operations, servicing, design and construction.

1. Well Integrity Fundamentals (see Appendix A)Typically 1 to 2 days

2. Norsok D-010 terminology and principles Typically 1 day

3. Company specific training (test procedures, well design and internal requirements)

Typically 1day

Who should participate?

Personnel directly responsible and or involved in Well Integrity should have therecommended training. Examples of who may be required to have this training are as follows:

1. Production operation personnel offshore (including OIM, production supervisors,control room operators, technicians and senior technicians);

2. Production operation personnel onshore (incl. Ops sup, production engineers,production technologies, HSE personnel);

3. Drilling/completion/intervention engineers (including drilling supervisor and drillingsuperintendent);

4. Rig contractors like drillers and tool pushers; and,

5. Service-company engineers and operators with delegated responsibilities in wellintegrity.

Each company should evaluate on as per needs basis who in their workforce is required toattend the recommended training.


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It is recommended that management responsible for Well Integrity should be trained.

Type of training Class room based versus computer based

Class room training is preferred for company specific training. Both class room based and

computer based training is good for training in Norsok D-010 and well integrityfundamentals.

Particularly for the computer based training method, it is recommended that the traininginclude exercises, case solving and questions and be completed with a test. Additionally for

class room training it is recommended to include group work exercises.

Appendix A

Well Integrity Fundamentals Training recommended subjects.

1. Roles and Responsibilities for Well Integrity

Who monitors / who do they report to / who fixes? Who manages the Well IntegritySystem?

2. Basic Wellbore Physics

Discuss formations / pressures / overbalance / underbalance / temperature increaseswhen wells flow etc. Illustrat ions should be available to describe what is happening.

3. Basic Well Construction with Emphasis on Barriers

Describe minimum barrier requirements. Provide a typical Well Schematic. Discusstubing burst / collapse etc. Discuss SCSSVs / ASVs / Xmas trees / tubing. Schematics,

incl. WBS and cutaways should be provided.

4. Basic Well Control Requirements

Discuss and describe simple hydrostatics for well control.Discuss and describe Well Emergency Shutdown functionality.

5. Well Integrity Hazards

Use case studies. Discuss hydrates / sand / corrosion - erosion / Well Intervention Opsetc. Well start up/shut down.

1. Annulus Monitoring and importance of reporting / trending.2. Discuss operating and design limits (pressure, temperature, flowrates etc).

Describe and provide typical Annulus Monitoring Spreadsheet.3. Discuss annulus leak rate and other acceptance criteria. Discuss risk resulting from

annulus leaks.

6. Annulus Bleed-Down


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Discuss what should be reported and the reasons for bleed-down during production.Discuss sources of tubing to annulus communications - eg; pipe / cement etc.

7. Wellhead Maintenance Activities

Discuss importance of regular and adequate well maintenance.SCSSSV Testing - discuss frequency / acceptance criteria / functionality / controlline integrity /repeat tests

Xmas Tree Valve Testing - discuss functionality / acceptance criteria

Void Monitoring - discuss implications for hydrocarbons in voids / repair methodsMonitoring equipment, accuracy and maintenance

8. Handover of WellsNeed to ensure accurate and timely reporting.

Discuss information required and who gets it. Provide an example WellHandover Documentation.

9. DocumentationDiscuss need for keeping good well integrity records.

Discuss and describe need for non-conformance system for operating wells not inaccordance with the 'Standard'. Provide an example.


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CHAPTER 2

WELL HANDOVER DOCUMENTATION

1. Introduction

The Well Integrity Forum (WIF) was established in 2007 and one of the main issues that wasinitially identified for its review was well handover documentation. NORSOK D-010 has one

section (section 8.7.1) where the content of a well handover documentation package isoutlined. Availability of, knowledge about and content of the well handover document werealso main elements that were highlighted by the PSA in their well integrity survey as an area

for improvement.This chapter describes WIF members recommendations for well handover documentation

and is intended to function only as a guideline for the Norwegian oil and gas industry.

2. Background

A survey completed by WIF members formed the basis for discussion and development of theguidance given in section 3. The body content of the handover documentation varied very

little amongst the members, but the information was located and organized in different places.

3. Discussion

The survey showed that the majority of information already included in the company specificwell handover documents was common amongst the companies. All companies also hadexceeded the NORSOK standard by including well barrier schematics. In the sections below

the recommended guidelines for minimum content per focal area are listed. The format forhow the documentation is structured has not been looked at, and is left to the discretion ofeach operator to organize the information.


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a. Well Construction Data

The handover should contain the following well construction information:

Wellhead data with schematic

Xmas tree data with schematic

Casing program (depths, sizes)

Casing and tubing data, including test pressures

Cement data

Fluid status, tubing and all annuli

Wellhead pressure tests

Tree pressure tests

Completion component tests

Perforating details

Equipment details such as identification or serial numbers

b. Well DiagramsThe handover documentation should include the following two well schematics:

Well barrier schematic with well barrier elements listed

Completion schematic

c. Handover Certificate

The handover documentation should also include a handover certificate. The certificateshould include actual status at handover on the following:

Valve status


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Pressure status

Fluid status

d. Operating InputOperating limitations for the well should also be included in the well handover documentation

package. As a minimum the following information should be included:

Tubing and annulus operating limit

Test and acceptance criteria for all barrier elements (could be referenced to valid internal

company documents)

Deviations which are identified and valid for the well


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CHAPTER 3

WELL BARRIER SCHEMATICS FOR THE OPERATIONAL

PHASE

1. Introduction

One of the Petroleum Safety Authority's (PSA) findings from the spring-2006 well-integrityaudit was the requirement for the creation of well barrier schematics (WBS) for the

operational-phase of each individual well on the Norwegian Continental Shelf (NCS). Eachoperating-company worked to fulfil this requirement, independently of other operators. As awhole the industry used the WBS's presented and well-barrier elements (WBE) defined in the

NORSOK D-010 standard as a basis in developing their own WBS format. At the industry-organized, well-integrity workshop held in March 2007, the need for common, minimum

guidelines for the subject WBS's was identified to help standardize this tool within theindustry. The same workshop resulted in calls for establishing a well-integrity forum (WIF)to promote open and frequent discussion of well-integrity related issues amongst the NCS

operators. One of the WIF's tasks was to further investigate the use of WBS amongst theoperating companies and propose a minimum level of detail which should be included in each

well specific WBS.

This document summarizes the WIF's guideline of minimum data to be presented on WBS's

of all NCS wells in the operational phase. These guidelines may re-state and/or add to existingrequirements specified in the governmental regulations and NORSOK D-010 standard. The

attached example WBS has been included for the purpose of illustrating the recommendedguidelines

2. Background

The task to establish a common WBS has been discussed and refined in WIF. The agreedguidelines of minimum data are listed below.

3. Guidelines of minimum data

The following minimum data have been agreed upon and act as a guideline:1. The formation strength should be indicated for formation within the barrier envelopes.2. Reservoir(s) should be shown on the drawing.3. Each barrier element in both barrier envelopes should be presented in a table alongwith its initial integrity-verification test results.


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4. Depths should be shown relatively correct according to each barrier element on thedrawing.

5. All casing and cement, including the surface casing, should be on the drawing andlabelled with its size.

6. There should be separate fields for the following well information: Installation, wellname, well type, well status, rev. no and date, Prepared by, Verified/Approved by.

7. Include a Note field for important well integrity information.

4. Discussion on minimum data

4.1 The formation strength should be indicated for formation within the

barrier envelopes

In all well designs, formation will be within the barrier envelopes and may therefore beexposed to reservoir and well pressures. It is important that it is understood which formations

are inside the barrier envelopes and ensured that they are not exposed to pressures exceedingtheir strength. Exceeding the formation strength may result in leaks on the outside of cas ingsand cement, outside the barrier envelopes. This is important for all well types; however,

special attention should be given to injector wells.

The strength of the formations which is within the barrier envelopes should therefore beindicated on the barrier drawing and should be considered when determining operationallimits for the well. The formation strength can typically be based on physical measurements

performed during drilling of the well, e.g. Formation Integrity Tests (FIT), Leak Off Tests

(LOT) or Extended Leak Off Tests (XLOT). The indicated formation strength can also bebased on tests done on core samples, results from downhole logs or correlations based on

historical field data. The type of value used to indicate formation strength can differ inmeaning and uncertainty (e.g. a FIT value has another meaning than a LOT value, a valuederived from a downhole log has a higher uncertainty than a value based on tests on core

samples), and it should therefore always be stated what the indicated formation strength isbased on.

The formation provides containment of reservoir fluids together with the well barrier elementswhich constitute the barrier envelopes, but the properties of formation is not tested, designed,monitored or known in the same manner as for a well barrier element, which have defined

acceptance criteria. There is currently no common understanding of what well barrier elementacceptance criteria should be used for formation to ensure that formation in a meaningful and

adequate way can be treated and defined as well barrier element in the same manner as e.g.casing or production packers.

Reservoir(s) should be shown on the drawing.

The reservoir(s) should be shown on the drawing to be able to verify proper barriers. This willalso ensure that any zone isolation requirements are fulfilled.


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Each barrier element in both barrier envelopes should be presented in atable along with its initial integrity-verification test results

By presenting each barrier element in the table, there will be no doubt regarding whichelements are a part of the barrier envelope. In addition, this exercise will help the engineer to

ensure the actual elements are qualified according to requirements and the ability to verify theintegrity of each element.

It is intended that the actual test results that verified the integrity is presented. For examplepressure test and CBL are methods used. The actual results should be presented.- e.g. pressuretest to 320 bar, FIT to 1,79 sg EMW, 100% bond at 3000 mMD.

When the well is completed, it is important to keep data and status of the well barriers. Bystating the actual integrity-verification method and test results for each element on the well

barrier schematic, the status of the well is known and documented. This information is alsoimportant for the operational phase and later interventions and/or workovers.

Depths to be shown relatively correct according to each barrier element onthe drawing

It is important that the drawing show the barrier elements at the correct depths relative to eachother, and do not show e.g. that the production packer is set in cemented casing if the actual

layout is otherwise.Likewise it is important to show the relative positioning of the reservoir(s) and the positioning

of the cap rock relative to the cement and production packer.The relative positioning of the barrier elements is important in relation to integrity,robustness, and the ability to detect any leakages after initial installation and testing.

For the same reason, it is also advised to show all packers, PBRs and similar equipment onthe drawing.

The drawing should be well specific and show/illustrate the actual layout of the well.

All casing and cement, including the surface casing, should be on thedrawing and labelled with its size

For the same reason as above (4.4), it is important to show all casing sizes and the cement

behind. This will give important information of the robustness of the well, and not lead to anymisinterpretation of the design.

There should be separate fields for the following well information:

Installation,well name, well type, well status, rev. no and date, Preparedby,Verified/Approved by

It is important that the well specific barrier schematic contain information about the validity

of the drawing. Therefore installation name and/or field name should be clearly stated, and thename of the well.


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To be able to understand the well barriers the "well type", if the well is an oil producer, waterinjector, gas injector etc, should also be stated.

The status of the well, e.g. if the well is operational, shut in, temporary plugged for nipplingetc should also be defined. This is important such that the validity phase of the well barrier

schematic is clearly defined.Document and quality control is needed. Revision number, date, information about who has

prepared, and who has verified or approved the schematic is therefore also needed.

Include a Note field for important well integrity information

Special well conditions that have changed the barrier envelope over time and other important

well integrity information should be highlighted. This ensures any weaknesses are madeaware of, and also shows the actual situation.

References to where the integrity dispensations are located (e.g. number) should be made,with a short explaining text.

The WBS should be updated when well conditions such as e.g. detected tubing/cas ing leaks,have changed the barrier envelope.Other important well integrity information that has not changed the barrier but still should be

highlighted in the note field could e.g be leaks outside the barrier envelope.

Attachment 1: Example of a well specific barrier schematic.

Note that data have to be filled out where xx is stated for a real well.


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Logo

WELL BARRIER SCHEMATIC

Well informationInstallation: xxxxx

Well no.: xx/xx-xx

Well type: e.g.Oil producer

Well status: e.g. Operational

Revision no. / Date: x xx.xx.xxxx

Prepared: xxxxx

Verified/Approved: xxxxx

Well barrierelements

Verification of barrierelements

PRIMARY7 liner cement xx bar with xx sg fluid

Method: prognosed / measuredTOC: xx mMDMethod: volume control / logse.g. CBL xx bonding at xx mMD

7 liner xx bar with xx sg fluid

7 liner hanger packer xx bar with xx sg fluid

9 5/8 casing betweenliner hanger packerand production packer

xx bar with xx sg fluid

Production packer xx bar with xx sg fluid

Production tubing xx bar with xx sg fluid

SCSSV Inflow test to xx bar

SECONDARY9 5/8 casing cement FIT to xx sg EMW.

Method: prognosed / measuredTOC: xx mMD above prod.packer/ csg.shoe.Method: volume control / logse.g. CBL xx bonding at xx mMD

9 5/8 casing xx bar with xx sg fluid

9 5/8 casing hangerwith seal assembly


Wellhead / annulusaccess valve


Tubing hanger withseals


X-mas tree valves xx bar with xx sg fluid

Reference /

Disp. no.well integrity issues

Comments / Notes:

N/A

X-mas

tree

PWV

PUMV

PLMV

KV

PSV

18 5/8" csg

13 3/8" csg

SCSSV

9 5/8" csg

7" liner

FG = xx s.g.

FIT = xx s.g.

FG = xx s.g.


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CHAPTER 4

WELL INTEGRITY WELL CATEGORIZATION

1. Objective

In response to heightened industry and regulatory interest, WIF developed a system ofclassifying a well based on its integrity status. Operators can benefit from this categorization

system as a method of ranking well integrity within its operations, whereas the PSA will beable to use it to summarize well integrity across the entire NCS. A common categorization

system will also promote a level of consistency amongst the various operators whenevaluating the integrity of their wells. This guideline presents the resultant categories,summarizes the basis of each one and goes further in that it provides examples in an effort to

promote a common understanding of each category for the end user. The system is intendedfor categorisation of all wells types which are in operation, shut in, suspended or temporarily

abandoned. Wells which are under construction or permanently plugged and abandoned arenot covered by this guideline. Defining acceptance criteria is outside the scope of thisguideline, and is left to the discretion of the individual operators.


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2. Abbreviations & Definitions

Abbreviations

ASCSSV Annulus Surface Controlled Sub-Surface Safety Valve - see also ASVASCV Annulus Safety Surface Controlled Valve

ASV Annulus Safety Valve - see also ASCSSVDHIV Downhole Injection Valve - see also WIVDHSV Downhole Safety Valve

DMF Drilling Manager Forum

ESD Emergency ShutdownGLV Gas Lift ValveKPI Key Performance Indicator

NCS Norwegian Continental Shelf

Norsok Norsk Sokkels KonkurranseposisjonNorwegian Oil

and Gas Norwegian Oil and Gas AssociationPSA Petroleum Safety AuthorityRNNP Risikoniv i norsk petrolumsvirksomhet (Risk level in Norwegian petroleum

activity) - see also RNNSRNNS Risikoniv p norsk sokkel (Risk level on Norwegian Shelf) - see also RNNP

SCSSV Surface Controlled Sub-Surface Safety ValveTRSCSSV Tubing Retrievable Surface Controlled Sub-Surface Safety ValveWBE Well Barrier Element

WIF Well Integrity ForumWIV Water Injection Valve - see also DHIV

WRSCSSV Wireline Retrievable Surface Controlled Sub-Surface Safety Valve

Definition of terms

Leak to surface - Uncontrolled leak of fluids either to air, sea or seabed


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3. Background

Since the inaugural attempt to incorporate a NCS well-integrity summary in the 2006 RNNS

report, the PSA has expressed interest for the Norwegian oil industry to develop a KPI systemwhich would benefit operators and authorities alike. This effort was one of the initial tasks

adopted by the WIF upon being established in the summer of 2007 under the auspices ofDMF/Norwegian Oil and Gas. Work began with an overall review of the current practices ofWIF-member companies in ranking the integrity of their wells. Systems varied from operator

to operator in terms of stage of development and level of complexity. Some, having adoptedcorporate programs which had been pushed out globally, suggested another system would

have limited benefit; however, most had developed or were developing local programs andbelieved that a common categorization process would be useful. It was decided that WIF

should work on a Norwegian oil-industry recommendation that would focus on wells in theproduction phase. Furthermore; it should be kept simple and a matrix of 3-4 "traffic lights"would lend itself to this simplicity. With feedback from DMF and PSA, WIF was able to

propose the 4-category, traffic-light system based on double-barrier principles. A pilotproject was run in 2008 during which various operators applied the categorization to a sampleof their wells. Based on encouraging pilot results, WIF proposed the system for use in the

PSA's 2008 RNNP report. The WIF guideline for the well-integrity categorization waspurposely held off until 2009 in order to be optimized with experiences from the previous

year's RNNP and the 2009 Well Integrity Norwegian Oil and Gas workshop.


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4. Philosophy

Double BarriersThe well-integrity categorization is based on compliance to the barrier policy outlined in the

regulations and the Norsok D-010 Standard. Chapter 4 of the standard states There shall betwo well barriers available during all well activities and operations, including suspended or

abandoned wells, where a pressure differential exists that may cause uncontrolled outflowfrom the borehole/well to the external environment. It should be noted that Norsok onlyrequires one barrier against cross flow in the wellbore between formations.

Risk

The barrier policy was established as a means of reducing the hazard of an uncontrolledrelease from a well. As such the categorization has an association with risk; however, it is notabsolute. The categorization system does not replace risk assessments. For instance, two wells

with only one remaining barrier can pose different levels of risk if one is a high-rate gas wellon a manned platform whereas the second is a subsea water injector. The operator should

consider a further in-depth risk assessment process for wells that are ranked high.

Traffic Lights

The four-category system utilizes a green/yellow/orange/red traffic-light, colour-coded systemfor visualization purposes which is similar to many operator and regulatory ranking

systems. Green and yellow are acceptable according to standards and in compliance with the

two-barrier principle, with yellow only serving to highlight some well-integrityanomalies. Orange and red spotlight non-compliant wells with well-integrity problems which

usually will be further diagnosed, evaluated and risk assessed for appropriate follow-upaction. Red is used to highlight wells which in addition to failure of one barrier have

considerable degradation or failure of the second barrier.

Current State

The categorization should reflect the current condition and status of the well. Ranking of awell could change if it is put on gas lift, secured with a plug, shut- in, repaired, etc. The PSA's

RNNP report usually requires the state of an operator's wells as of a specific date near the endof the year; however, the well condition could change anytime throughout the

year. Operating companies should strive to keep their categorization up-to-date.


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5. Use of Categorization System

Categorization approach

Well categorization can be approached in multiple ways and will depend on the complexity ofthe wells to be categorized.

It is recommended to base the categorization on the overall category principles as defined inSection 7.1. Examples and further descriptions of specific conditions and status of individual

WBEs within the different categories are elaborated on in Sections 7.2 to 7.5. However, notethat the examples stated in these sections are not complete and definitive. They are included

for guidance only, and the categorization of individual wells should always be checkedagainst the overall category principles.

Previous surveys indicate that the majority of wells on the NCS fall into the Green category.Section 7 takes this into consideration and is built up to minimize the time required for

categorization by an inexperienced user. When categorizing a well, one could first evaluatethe well against the criteria described in Section 7.2 Green Category. If it is discovered thatthe well does not fulfil the criteria described in this section, and therefore can not be

categorized as Green, the user can proceed to the next section, and so forth.

The guideline is based on describing how specific conditions and state of individual WBEs

should be translated into a categorization for the well. When categorizing a well, it isimportant to remember that this is a categorization of the entire well; therefore, all the specific

conditions and individual WBEs should be evaluated together. For example, if a well has aTRSCSSV with leak rate outside acceptance criteria, qualifying for the Orange category, the

well shall be categorized as Orange even if all other WBEs are in perfect condition and noother abnormalities or non-conformances related to the well exist.

Attachment A is a tabular overview of the content in Section 7 that can be used as a quickreference to evaluate if minor and specific changes in well condition result in changes to well

categorization. It also provides a one-page summary where progression of various concerns

from category to category can be observed.


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Information required for categorization

The information required to perform an adequate categorization of a given well will vary withits age, complexity and presence of abnormalities or non-conformances.

In general, the information required to evaluate and categorize a well can include, but is not

limited to:

Information about well type and well service

Well Barrier Schematic

Well construction details, including measured and/or predicted formation strength

Design pressures, test pressures and pressure limits

Operational limits

Flowing and shut in pressures & temperaturesFluid type in tubing and annuli

Annulus pressure and pressure trends

Findings from well interventions and preventive maintenance tests

Known deviations, abnormalities or non-conformances

In cases where abnormalities or non-conformances are discovered in a well, furtherinformation will usually be required. Depending on the severity and complexity of the

abnormality/non-conformance further assessment may be required to properly categorize thewell.

The additional information which may be required to categorize a well with anabnormality/non-conformance can include, but is not limited to:

Leak rate

Location of leak/degradation

Leak direction

Cause(s) of leak and associated potential for escalation

Degradation mechanism, and the rate and impact

Volume/mass of influx to annuli and fluid type

Available mitigating measures and control measures

Status of remaining barrier elements and potential elements which can take over WBE

function

Well control limitations caused by an abnormality/non-conformance

Changes to load scenarios caused by an abnormality/non-conformance, andconsequence of these changes


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6. Category Descriptions

Overview of Category Principles

The principles and colour designations for the different categories are as follows:

Category Principle

RedOne barrier failure and the other isdegraded/not verified, or leak to surface

OrangeOne barrier failure and the other is intact, or a

single failure may lead to leak to surface

Yellow One barrier degraded, the other is intact

Green Healthy well - no or minor issue

Table 0-1: Overview of category principles

In the following sections the categories will be described in more detail; and different

conditions which usually would fall into the different categories will be addressed.


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Green Category

The principle for the Green Category is:

Healthy Well-no or minor integrity issue

A well categorized as Green should be regarded to have an associated risk which is identicalor comparable to the risk associated with an identical new well with a design in compliancewith all regulations. It does not necessarily mean that the well has a history without failures or

leaks, or that the WBEs fulfil all acceptance criteria described in the latest revision of NorsokD-010, but the well is in full compliance with the double barrier requirement.

It should also be noted that even if the well has a history without any leaks or failures and theWBEs fulfil all acceptance criteria described in Norsok D-010 the well should not be

categorized as Green if conditions exist which constitute a considerable threat to both barriersand risk of dual failures is present.

Typically a well categorized as Green will not require any immediate repairs or mitigatingmeasures (in addition to the ones that may already be performed and implemented).

For a well to fall within the Green category the condition of typical well barrier elementswould usually fulfil criteria described below:

WBE ConditionDHSV or deep set plug Leak rate within acceptance criteria

Christmas tree ESD valves and annulus valves Leak rate within acceptance criteria

Tubing hanger and internal wellhead seals Leak tight

Completion and casing string Leak tight

Production packer Leak tightTable 0-2: Condition for typical well barrier elements for wells to fall within Green category

A well with sustained casing pressure can fall within the Green category: if there are noleaks through both established primary and secondary barriers; no hydrocarbons in the annuli

(unless intentionally placed there); annuli pressures are below the defined pressure limits;and, the leak rate into the annuli is within acceptance criteria.


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Other considerations:

Well on gas lift with failed ASV or no ASV

A well on gas lift with a failed ASV or no ASV can fall within the Green category ifappropriate mitigating measures are present (e.g. periodically testing of GLV andinstallation of ASCV).

Well with failed SCSSVA well with a failed SCSSV can fall within the Green category if an appropriate

subsurface controlled DHSV (e.g. WIV, DHIV) or plug is installed and has taken overthe WBE function previously fulfilled by the SCSSV.

Well with leaking completion string and/or casing

A well with leaking completion string and/or casing functioning as WBE can fallwithin the Green category if all leaks have been eliminated in an appropriate manner

(leak tight), e.g. by straddle or patch, or if an ASV is available above the completionstring leak(s) to take over WBE function previously held by the production packer

Well with leaking casingA well with leaking casing functioning as WBE can fall within the Green category if

another well barrier envelope fulfilling criteria in table 7.2 (Green Category) canreplace the leaking casing.

Well with failed Christmas tree valve

A well with failed Christmas tree valve(s) can fall within the Green category if theChristmas tree system still fulfils WBE function, design, construction and selection

described in Norsok D-010.

Well with failed annulus valve

A well with a failed annulus valve functioning as WBE can fall within the Greencategory if another valve is available to take over WBE function.

Well with leaking production packer element

A well with a leaking production packer element can fall within the Green category ifthe leak has been sealed of in an appropriate manner (leak tight), e.g. by cement or

similar.

Well with completion string leak above DHSV

A well with a completion string leak above the DHSV can fall within the Greencategory if the tubing above the DHSV is not a part of the barrier envelope and the

leak is not effecting or leading to degradation of any WBE. Additional mitigatingmeasures may also be required (e.g. increased test frequency).

Well with leaking tubing hanger neck seal

A well with a leaking tubing hanger neck seal can fall within the Green category if theleak rate is within acceptance criteria and the void exposed to pressure due to the leak

is capable of taking over WBE function.

Well with leaking tubing hanger seal

A well with a leaking tubing hanger seal can fall within the Green category if the leakrate is within acceptance criteria and the void exposed to pressure due to the leak iscapable of taking over WBE function.


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Well with casing cement not fulfilling Norsok D-010 acceptance criteriaA well not cemented according to the latest version of Norsok D-010 can fall within

the Green category if the cement still could be qualified as WBE or the cement isreplaced with another qualified WBE. See figure I in Attachment B.

Well with casing head leak

A well with internal leaks in casing head can fall within the Green category if the leakis not through a barrier.

Well with control line leakA well with leaking control line(s) can fall within the Green category if 2 barrier

envelopes are still intact (e.g. control line leak(s) are located between primary andsecondary barrier envelope).

Well with risk of dual barrier failures

A well where there is considerable risk of dual barrier failures (typically DHSV andChristmas tree valves) due to phenomena such as scale, erosion, corrosion, asphaltene,

wax or similar should not be placed within the Green category.


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Yellow Category

The principle for the Yellow Category is:

One barrier degraded, the other is intact

A well categorized as Yellow should be regarded to have an incremental associated riskwhich is not negligible compared to the risk associated with an identical new well withdesign in compliance with all regulations. Although a well categorized as Yellow has an

increased risk, its condition is within regulations.

It should also be noted that even if the well has a history without any leaks or failures and the

WBEs fulfil all acceptance criteria described in Norsok D-010 the well may fall within theYellow category if conditions exist which constitutes a threat to both barriers and risk of dual

failures is present.

For a well to fall within the Yellow category the condition of typical well barrier elements

would usually fulfil criteria described below:

WBE Condition

DHSV or deep set plug Leak rate within acceptance criteria

Christmas tree ESD valves and annulus valves Leak rate within acceptance criteria

Tubing hanger and internal wellhead seals Leak rate within acceptance criteria

Completion and casing string Leak rate within acceptance criteria

Production packer Leak rate within acceptance criteria

Table 0-3: Condition for typical well barrier elements for wells to fall within Yellow category

Note that the condition of DHSV and/or Christmas tree ESD valves and annulus valves as

described in Table 7-3 above will not on its own result in a well falling within the Yellowcategory (See 0 Green Category).

A well with sustained casing pressure can fall within the Yellow category: if there are noleaks through both established primary and secondary barriers; if annuli pressures are

maintained below the defined pressure limits in a controlled manner; and, the leak rate intothe annuli are within acceptance criteria - but hydrocarbons are present in the annuli (not

intentionally placed there).


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Well with failed completion string and/or casing

A well with failed completion string and/or casing functioning as WBE can fall withinthe Yellow category if all leaks have been reduced or minimized from unacceptable toacceptable leak rate in an appropriate manner (leak rate within acceptance criteria),

e.g. by straddle or patch.

Well with leaking casing

A well with failed casing functioning as WBE can fall within the Yellow category ifanother well barrier envelope fulfilling criteria in table 7.3 (Yellow Category) canreplace the leaking casing.

Well with failed Christmas tree valveA well with failed Christmas tree valve(s) can fall within the Yellow category if

compensating measures let other valve(s) take over the WBE function.Well with leaking production packer element

A well with a failed production packer element can fall within the Yellow category ifthe leak has been sealed off in an appropriate manner (leak rate within acceptance

criteria), e.g. by cement or similar.

Well with completion string leak above DHSV

A well with a tubing leak above the DHSV can be categorized as Yellow if the tubingabove the DHSV is not a part of the barrier envelope but the leak is effecting orleading to degradation of any WBE.


the Yellow category if sufficient strength or impermeability does not exist in theformation which would be exposed to well pressure should a barrier failure occur

below the production packer (i.e. potential for crossflow, but not breaching to surface)

as long as the cement is still qualified as WBE. See figure II in Attachment B.

Well with control line leak

A well with leaking control line(s) should be categorized as Yellow if leak(s) arethrough established barrier (e.g. control line leak(s) are located inside primary barrier

envelope).

Well with risk of dual barrier failures

A well where there is considerable risk of dual barrier failures (typically DHSV andChristmas tree valves) due to phenomena such as scale, erosion, corrosion, asphaltene,wax or similar should be placed within the Yellow category.


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Orange Category

The principle for the Orange Category is:

One barrier failure and the other is intact, or a single failure may lead to leak to surface

A well categorized as Orange should be regarded to have an associated risk which is higherthan the risk associated with an identical new well with design in compliance with allregulations.

Typically a well categorized as Orange will be outside the regulations. Repairs and/or

mitigations will be required before the well can be put into normal operation, but the well will

still have an intact barrier and there will usually not be an immediate and urgent need foraction.

If the condition of one typical well barrier element is as described below, the well will usuallyfall within the Orange category:

WBE Condition

DHSV or deep set plug Leak rate outside acceptance criteria

Christmas tree ESD valves and annulus valves Leak rate outside acceptance criteria

Tubing hanger and internal wellhead seals Leak rate outside acceptance criteria

Completion and casing string Leak rate outside acceptance criteria

Production packer Leak rate outside acceptance criteriaTable 0-4: Condition for typical well barrier elements for wells to fall within Orange category

Note that a well can fall within the Orange category even if more than one WBE has thecondition as mentioned in Table 7-4 above if all these WBEs are in the same barrier envelope

(e.g. typically the DHSV and completion string will be in the primary barrier envelope).

On the other side, a well should not be placed in the Orange category if at least one WBE in abarrier envelope has a condition as described in this section (7.4 Orange Category) and atleast one WBE in the other barrier envelope has a condition as described in the previous

section (7.3 Yellow category) or this section, e.g. leak outside acceptance criteria incompletion string and leak within acceptance criteria in casing string. For such cases see 7.5

Red Category.

A well with sustained casing pressure will fall within the Orange category if the leak rate

into the annuli is outside acceptance criteria. If annuli pressures are above defined pressurelimits and the leak rate into the annuli is outside acceptance criteria see 7.5 Red Category.


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Crossflow

A well with confirmed uncontrolled crossflow will fall within the Orange category ifthere is no potential for breaching to surface.

Well with failed primary barrier and leaking Christmas tree valve

A well with failed primary barrier and leaking Christmas tree valve(s) functioning asWBE can fall within the Orange category if the Christmas tree system still fulfils

WBE function, design, construction and selection described in Norsok D-010.

Well with one failed barrier and leaking casing in the other barrier

A well with one failed barrier and leaking casing functioning as WBE in the otherbarrier can fall within the Orange category if another well barrier envelope fulfillingcriteria in table 7.2 (Green Category) can replace the leaking casing.


the Orange category if sufficient strength or impermeability does not exist in theformation which would be exposed to well pressure should a barrier failure occur

below production packer, and there is a potential for breaching to surface, as long asthe cement is still qualified as WBE. See figure III in Attachment B.


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Red Category

The principle for the Red Category is:

One barrier failure and the other degraded/not verified, or leak to surface

A well categorized as Red should be regarded to have an associated risk which isconsiderably higher than the risk associated with an identical new well with design incompliance with all regulations.

Typically a well categorized as Red will be outside the regulations. Repairs and/or mitigations

will be required before the well can be put into normal operation and there will usually be an

immediate and urgent need for action.

A well should fall within the Red category if at least one WBE in a barrier envelope has failedand at least one WBE in the other barrier envelope has also failed or is regarded as degradedor not verified (e.g. exposed to pressure outside verified design limit or evidence of

corrosion).

For a well to fall within the Red category the condition of at least one typical WBE in abarrier envelope will usually be as mentioned in table 7-4 (Orange), and at the same time atleast one typical WBE in the other barrier envelope will usually be as mentioned in table 7-3

(Yellow) or table 7-4 (Orange). This could for example be leak outside acceptance criteria in

completion string and additional leak within acceptance criteria in casing string. Anotherexample is a leak outside acceptance criteria in DHSV and additional leak outside acceptancecriteria in Christmas tree ESD valve.

A well with sustained casing pressure will fall within the Red category if annuli pressuresare above the defined pressure limits and the leak rate into the annuli is outside acceptance

criteria.


CrossflowA well with confirmed uncontrolled crossflow will fall within the Red category if

there is potential for breaching to surface.

Well with casing cement not fulfilling Norsok D-010 acceptance criteria

A well not cemented according to the latest version of Norsok D-010 can fall withinthe Red category if sufficient strength or impermeability does not exist in the

formation which would be exposed to well pressure should a barrier failure occurbelow production packer, and there is a potential for breaching to surface and thecement is not qualified as WBE. See figure IV in Attachment B.

Leak to surfaceA well with recordable and reportable uncontrolled leak to surface should fall within

the Red category.


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7. Attachment A - Well categorization descriptioncomparison table


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8. Attachment B - Well with casing cement not fulfillingNorsok D-010 acceptance criteria

Green Category

A well not cemented according to the latest version of Norsok D-010 can fall within theGreen category if the cement still could be qualified as WBE or the cement is replaced with

another qualified WBE.

Figure I: Green Category Example

Cap Rock

Reservoir

E.g. verified

impermeable formationwith sufficient strength

sealing to csg


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Yellow CategoryA well not cemented according to the latest version of Norsok D-010 can fall within

the Yellow category if sufficient strength or permeability does not exist in theformation which would be exposed to well pressure should a barrier failure occur

below the production packer (i.e. potential for crossflow, but not breaching to surface)

as long as the cement is still qualified as WBE.

Figure II: Yellow Category Example - Potential leak paths indicated

Cap Rock

Reservoir

Fm with insufficient

strength or

permeable formation

Impermeable fm

with strength


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Orange Category

A well not cemented according to the latest version of Norsok D-010 can fall withinthe Orange category if sufficient strength or impermeability does not exist in theformation which would be exposed to well pressure should a barrier failure occur

below production packer, and there is a potential for breaching to surface, as long asthe cement is still qualified as WBE.

Figure III: Orange Category Example - Potential leak paths indicated

Cap Rock

Reservoir


strength or

permeable formation


strength or

permeable formation


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Red Category

A well not cemented according to the latest version of Norsok D-010 can fall withinthe Red category if sufficient strength or impermeability does not exist in theformation which would be exposed to well pressure should a barrier failure occur

below production packer, and there is a potential for breaching to surface and thecement is not qualified as WBE.

Figure IV: Red Category Example - Potential leak paths indicated

Cap Rock

Reservoir


strength or

permeable formation


strength or

permeable formation


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CHAPTER 5

WELL INTEGRITY MANAGEMENT SYSTEM

1. Objective

Each operator on the NCS shall have a system to manage the integrity of its wells. Suchsystems will comprise of dedicated personnel, assets and processes provided by the operator

to monitor and assess its well integrity. Whereas the Norwegian regulations refer tomanagement systems in general, the specifics are left to the discretion of each operator. This

guideline provides some minimum criteria for WIM systems as interpreted by the WIF basedon a review of the Norwegian regulations (as of 01-01-2009), and as such is intended tosupplement the regulations. It is understood that a proper WIM system should take into

account the entire life cycle of a well; however, the focus in this guideline is mainly on theoperational phase.

Each operator should refer to the details in the relevant regulations and standards to ensuretheir well integrity management system is in compliance.


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2. Abbreviations

ALARP As Low As Reasonably PracticableAPI American Petroleum InstituteDHSV Downhole Safety Valve

DFU Defined situations of hazard and accidentESD Emergency Shut Down

HMV Hydraulic Master ValveHSE Health, Safety and EnvironmentISO International Organization for Standardization

NCS Norwegian Continental ShelfNORSOK Norsk Sokkels Konkurranseposisjon

PM Preventive MaintenancePSA Petroleum Safety AuthoritiesSIMOPS Simultaneous Operations

WIF Well Integrity ForumWIM Well Integrity Management


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3. Background

In the 2006 well-integrity-survey, phase-1-summary report, the PSA recommended: .thatthe operating companies review their in-house management systems for compliance with therequirements in the regulations for barriers and how this is distributed and actively used

internally in order to reduce the chances for any incidents. This was the basis for one of theinitial items on the WIF task list upon being organized in 2007 which was to investigate the

need for a Norwegian, oil-industry guideline covering the management of well integrity.

As has been common practice with the WIF on previous projects, a review was conducted of

the WIF-member-companies efforts towards managing the integrity of their wells. Then areview of the various regulations (Framework, Management, Information Duty, Facilities and

Activities) and Norsok D-010 standard (chapters 4 and 8) was completed and all aspectsapplicable to well integrity were summarized. Based on this review, the items have beengrouped into the following categories: Organization, Design, Operational Procedures, Data

and Analysis. These categories form the basis of the guideline.


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4. Elements in a Well Integrity Management System

A well-integrity-management system should be the complete system necessary to managewell integrity at all times through the life cycle of the well. The system could be grouped into5 main elements: Organisation, Design, Operational Procedures, Data System, and Analysis.

The relation of these elements is illustrated below:


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Even though the regulations have some well-integrity-specific requirements, most of the

integrity-management regulations are general in nature. A bullet summary of the maincontent from these general and specific regulations relevant for a well-integrity-management

system is therefore provided in the table in appendix A. The bullet summary groups attributesof the 5 main elements in a well-integrity- management system against the relevant regulation

where the references were found. Each element is further described and discussed in section5.

WellIntegrity

Management

System

Organisation

Design

Operational

Procedures

Data system

Analysis


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5. Discussion of each main element

This section discusses the main elements of a well-integrity-management system. Despite therequirement that a well-integrity-management system should cover the entire life cycle of thewell, this section will focus on application of the elements in the operational phase. It is up to

each operator to tailor the contents of their management-system elements to reflect theiroperations.

5.1 Organisation

The licensees are responsible to see that the operator complies with the regulations. Theoperator shall establish, follow up and further develop a management system in order to

ensure compliance with well-integrity requirements. The operator should also see to it that allinvolved parties and contractors carrying out the activities, have their own managementsystem in place to ensure well integrity.

Company management should provide competent resources to support the provisions of its

well-integrity- management system. It should assign and document responsibilities for theindividual(s) to execute the provisions of this Well Integrity Management System guideline asit applies to its operations. Such individual(s) should develop and document the companys

well-integrity strategy and objectives and clearly define roles and responsibilities for allprofessional, supervisory, operational and maintenance staff involved in well-integrity

activities. Furthermore, the individual(s) should manage the delivery of the well integrity

program throughout the complete well life cycle.

An emergency-preparedness organization and plan should be able to handle defined situationsof hazard and accidents, including those related to well integrity. Competency of resources

shall be ascertained through training and drills.

5.2 Design

Well design is a process with the objective of establishing, verifying and documenting theselected technical solution that fulfils the purpose of the well, complies with requirements andhas an acceptable risk against failure throughout the life cycle of the well. A well-design

process shall be carried out for:

Construction of a new well

Alteration, changes or modification to existing wells

Changes in the well-design basis or premises


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5.2.1 Technical standards

The foundation of well integrity requires a design to withstand loads and anticipateddeterioration to which the well is exposed to during its entire life cycle. This needs to be

based on a design philosophy which addresses applicable technical standards.

Technical standards that are applicable can be of several different origins

Recognised industry standards (API, ISO, etc.)

National standards (NORSOK etc.)

Company specific standards

Supplier specific standards

5.2.2 Barriers

Well barriers shall be designed to prevent unintentional influx, crossflow to shallowformation layers and outflow to the external environment, and so that they do not obstruct

ordinary well activities. Failure of one barrier shall not lead to a blowout..

The well barriers shall be designed so that their performance can be verified. Hence the

conditions of the barriers shall be known at all times when such monitoring is possible.

There shall be sufficient independence between the barriers. If common elements exist, a riskanalysis shall be performed and risk reducing/mitigation measures applied to reduce the riskALARP.

.

5.2.3 Equipment requirements

Equipment which is a part of the well barriers must ensure well integrity. It shall be designed,manufactured and installed to withstand all loads it may be exposed to and maintain itsfunction throughout the life cycle of the well.

Materials should be selected to withstand the loads and environment they may be exposed to.

5.2.4 Safety systems

Wells shall have independent, fail-safe, safety systems (i.e. PSD & ESD) which are able toprevent situations of hazard and accident from developing and to limit the consequences of

accidents.

Emergency shutdown valves shall be installed which are capable of stopping streams of

hydrocarbons and chemicals to and from the facility, and which isolate the fire areas on thefacility.


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5.2.5 ALARP principle

When well design and equipment are selected, the ALARP principle should be adhered to.This should be applied to the technical solution with all the below phases of a well in mind:

Construction

Production operation

Maintenance and repair

Plug and abandonment

5.3 Operational Procedures

Petroleum activities shall be carried out in a safe and prudent manner. A description of thewell-integrity- management system and barrier philosophy shall be described early on in the

development. The party responsible shall establish criteria for when procedures are to beused as a means to prevent faults and situations of hazard and accident. Therefore activity

programs and procedures should be in place to prevent faults and help deliver safe operations.

5.3.1 Operate within the design load limits

The production/injection philosophy and operating parameters shall at all times remain withinthe boundaries of the well and completion design. Operational limits could be temperature,

pressure, flow rate, and compositional limitations. These operational limitations should

consider the effects of, but not limited to: material corrosion (e.g. from CO 2, H2S, O2); sandproduction; scale deposition; and, hydrate formation.

Criteria for shut-down of the activities or operations shall be determined. Actions andlimitations necessary in the event of overriding, disconnection or impairment of safety

systems shall be established beforehand. If at any time the functionality or established valuesmay be exceeded, a well-design verification shall be undertaken.

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