Well Integrity within Norsk Hydro

1. Well Integrity within Norsk Hydro

2. Objective Develop a consistent procedure for management of annular leaks Risk based approach Routines for early detection and how to handle the leaks Procedure made in collaboration between NH, Exprosoft and K�re Kopren(PTG) � Wide range of methods are available and used. � Wide variety of hardware in a diverse producing basin. � Diverse operating practices over a wide range of well types and production histories. �No uniform operating practices established. � Approaches and action varies widely between operators. � Wide range of methods are available and used. � Wide variety of hardware in a diverse producing basin. � Diverse operating practices over a wide range of well types and production histories. �No uniform operating practices established. � Approaches and action varies widely between operators.

3. Principles Overview of well data and limitations shall follow the well throughout the lifetime All leaks shall trigger an internal deviation (synergi) � verification in B&B Well data shall be updated when a leak is detected Checkout of integrity of next casing Test program to identify leak above or below BSV, surface pressure after stabilizing of pressure, leak rate Update of well risk level, based on Wellmaster database Update of operational procedures

4. Status procedure for management of well annular leaks Procedure is finished Remains: Implementation Training of offshore personnel to detect leakages + diagnostic work A pilot course has been held in april. Standard course package will be developed based on the experience from the pilot course All personell involved in detection and diagnostic work offshore and onshore will be invited

5. Historical Norsk Hydro downhole annulus well integrity (WI) issues by field

6. Task Force : Well leaks - Root Cause Analysis

7. Ongoing work: Well Integrity Management System (WIMS) New database to be developed until 2007 JIP managed by Exprosoft with Hydro, Statoil and Total as participants. A development based on the procedure for management of well annular leaks Purpose: A uniform and structured approach for handling of well integrity during the lifetime of a well. All information available through one system A clear indication of the well barrier status at all times

8. Well Integrity Management System (WIMS) WellMaster software used as a basis � additional applications to be developed Important functionalities: Visualising the well barriers and well barrier elements (WBE) through use of barrier diagrams and barrier sketches Identify the functions and and requirements that the well and each WBE should fulfil Present the status/condition of each WBE (leak, erosion, etc.) Keep record of performed tests and results of tests Keep record of diagnosis results when deviations are identified Keep record of changes in well integrity and resulting corrective actions Overview of well risk status Structured / uniform approach to analyze and evaluate risk

9. Risk based procedure for management of well annular leaks

10. Rationale for risk based approach Reflect variations in actual well risk level Subsea, topside Gas, oil, water Etc. In principle no tubing and casing leaks accepted by the PSA �to be on the safe side� � leak(s) will affect the operational risk in a negative way However; Regulations and NORSOK D-010 open for risk assessment Departure normally granted by submission of supporting risk analysis results Must incorporate principle of �risk reduction� � risk should not be significantly higher as a result of the deviation

11. Procedure outline Procedure split in three main tasks (guidelines): 1. Detection and diagnosis 2. Evaluation 3. Implementation and follow-up Main results Extensive diagnosis part Risk assessment method Specific risk acceptance criteria Extensive use of quantitative risk analysis (fault tree analysis with WellMaster data as input) Specific risk reduction measures Documentation of process

12. Task 1; Detection and diagnosis Collection of basic well data (preparatory) Well schematic, P- tests/FIT/LOT, annulus capabilities (as well barrier), annular volumes, fluid densities, etc. When is it needed to assess if there is a leak? Establish Max operational A-annulus pressure (MOASP) = default bleed off alarm limit Establish pressure domain for initiation of diagnosis activities �External factors� diagnosis Abnormal pressure readings may not be attributed to downhole failure/degradation �Internal factors� diagnosis� The potential leak rate to the wellhead surroundings (if blowout through leak path) Amount of hydrocarbon influx to the annulus Leak location (depth and relative to well barriers) Leak failure cause (deterioration/escalation potential) Leak directions Flowcharts and spreadsheets developed to assist in the process Cause Erosion/Corrosion of material Excessive loads (fracture, burst or collapse) Failure of threads (poor make-up / damages) Failure of SCASSV or assembly Failure of packer element/seals Leak direction one-way two-way with no flow in annulus during well production/injection two-way with flow in annulus during well production/injection Flowcharts and spreadsheets developed to assist in the process Cause Erosion/Corrosion of material Excessive loads (fracture, burst or collapse) Failure of threads (poor make-up / damages) Failure of SCASSV or assembly Failure of packer element/seals Leak direction one-way two-way with no flow in annulus during well production/injection two-way with flow in annulus during well production/injection

13. Task 2; Risk assessment and response evaluation

14. Task 2; Well risk status code overview

15. RA step 1; Risk factor = Look at well barrier leak rate consequences Leak rate acceptance criteria based on leak sizes reflected in QRA�s on installation level API 14B leak rate criteria (SCSSV) Norsk Hydro risk matrix Different leak rate acceptance criteria for Non-natural flowing or Non-hydrocarbon flowing wells vs. Hydrocarbon flowing wells

16. RA step 2; Risk factor = Relative change in blowout probability � example Risk status codes based on calculated blowout probability and risk reduction potential assigned to Surface and subsea wells Conventional wells (applies to production and injection wells) and gas lift wells Informative calculations performed for multipurpose well, and gas lift well alternatives with combinations of deep set SCSSV, no SCASSV, annulus tail pipe SCSSV.

17. RA step 3; Risk factor = Look at well release risk (HC storage - single failure scenario) Hydrocarbon storage criteria relates to: For surface wells the quantity of hydrocarbons stored in the well annuli should not be greater than the typical mass of lift gas in the A-annulus above the SCASSV in a gas lift well OR alternatively the max recommended volume stored in other vessels on surface For subsea wells the release quantity criterion is based on distance to permanent surface installations (rising gas plume) and environmental acceptance criteria

18. RA step 4; Risk factor = Look at leakage cause (well functionality- degradation) Further escalation that cannot be controlled should not be accepted If further escalation/degradation of the well can be controlled by given risk reducing measures this can be accepted

19. RA step 5; Risk factor = Look at mechanical/ pressure loads (well functionality � loads/single failure scenario) Maximum Operational A-annulus Surface Pressure (MOASP) is the limiting wellhead pressure that the A-annulus is deemed safe to be operated under for an extended period of time (years), e.g., for well production. MOASP = Max known P-integrity of next outer functional annulus (from P-tests, LOT, FIT, recognised field formation fracture gradient data) Checklist for MTP vs. MOASP provided If A-annulus pressure can be controlled <= MOASP this can be accepted

20. RA step 6; Risk factor = Look at well kill/recoverability (well functionality � well kill /single failure scenario) If well kill procedures/preparations can be revised and be equally effective as the base case (well with no failure) this can be accepted

21. Response actions The resulting Well RSC determines a set of mandatory (M) and alternative (S) remedial actions/risk reducing measures to be implemented Remedial actions for each RSC based on Norsk Hydro and industry best practice The risk assessment (step 1 through 6)

22. Summary Applicable to the well types Norsk Hydro operates In compliance with regulations and standards for the upstream sector of the oil industry Guidelines and worksheets included for detection, diagnosis, and risk assessment and response to well barrier leaks Support tools and formulas for diagnosis included Modular system. Easy to update risk factor acceptance criteria, include additional risk factors, revise risk reduction measures, etc. Documentation of well �history� �Library� of relative well leak probabilities - The well leak probability for a wide variety of well types and leak locations are modelled for future reference

23. Questions?