Risk Register and Risk Ranking of Non-Integral Wells
- Saleh Abdul Samad (ZADCO) | Obadah Saleem Al Sawadi (Zakum Development Co.) | Muhammad Afzal (Zakum Development Co.) | Naeem Khan (Zakum Development Co.)
- Document ID
- Society of Petroleum Engineers
- Abu Dhabi International Petroleum Exhibition and Conference, 1-4 November, Abu Dhabi, UAE
- Publication Date
- Document Type
- Conference Paper
- 2010. Society of Petroleum Engineers
- 3 Production and Well Operations, 3.1.6 Gas Lift, 4.3.4 Scale, 1.14.4 Cement and Bond Evaluation, 5.2 Reservoir Fluid Dynamics, 4.2.3 Materials and Corrosion, 4.4.2 SCADA, 1.14 Casing and Cementing, 1.14.1 Casing Design, 1.7.5 Well Control, 4.5.7 Controls and Umbilicals, 7.2.1 Risk, Uncertainty and Risk Assessment
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Non-Integral Wells are common in every aged field and managing their integrity is becoming a challenging issue, particularly in large fields and for complex dual completions such as the case in ZADCO operated fields. As part of the Well Integrity Management System (WIMS), integrity concerns are identified, investigated and subsequently mitigation measures are recommended to restore the well integrity, all in a systematic approach. Well barrier integrity is given the highest priority; therefore a comprehensive Risk Register and Risk Ranking process is implemented by ZADCO Well Integrity Team.
The Risk Register process utilizes every related data and integrity investigation results to evaluate the integrity of the well primary & secondary barriers for every flow path. An individual integrity assessment is performed on the different containment sections in a well such as wellhead, inner and outer annuli and zonal isolation. Based on the severity, consequences and likelihood of a barrier failure the individual containment is given a risk rank according to ADNOC/ZADCO risk matrix. The overall risk ranking of a well reflects the highest risk rank of any of its containments. To complete the risk register, existing safeguards are addressed
and appropriate short and long term mitigation actions are recommended to keep the risk at ALARP.
Key Words: Well Integrity Management System, Well Barriers, Wellhead Equipment, Sub-surface Equipment, Risk Management, Risk Matrix.
ZADCO owns a huge inventory of around ~500 wells, mostly completed with dual string to produce from or inject into two different reservoirs. In order to provide standard guidelines to ensure that technical integrity of all these wells is maintained throughout their life cycle, a comprehensive Well Integrity Management System (WIMS) has been developed and put in place. The WIMS recognizes following three types of wells based on their integrity status but irrespective of their service status (i.e. producer, water injector, gas injector, gas lift, observer etc.)
1. Integral Well
2. Abnormal Well
3. Non-Integral Well
Integral Well: A wells that operates within design envelope and its integrity is assured.
Abnormal Well: A well that has no safety issue (i.e. two barriers are intact) but it may have potential threats to integrity and/or operating conditions, e.g. scale prone, corrosion potential, thermal annulus pressure, injection gas breakthrough, poor cement integrity / zonal isolation etc.
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