Assessing Well Integrity Risk: A Qualitative Model
- Jerald C. Dethlefs (ConocoPhillips) | Bettina Chastain (Arktis LLC)
- Document ID
- Society of Petroleum Engineers
- SPE/ICoTA Coiled Tubing & Well Intervention Conference and Exhibition, 5-6 April, The Woodlands, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2011. Society of Petroleum Engineers
- 4.2.3 Materials and Corrosion, 7.2.1 Risk, Uncertainty and Risk Assessment, 5.6.4 Drillstem/Well Testing, 4.4.2 SCADA, 3 Production and Well Operations, 2.2.2 Perforating, 7.1.5 Portfolio Analysis, Management and Optimization
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For successful delivery of Well Integrity, there needs to be an understanding of the risks that can cause undesirable events such as safety hazards or loss of containment. Performing a risk assessment on a well, or type of well, will help determine and rank the potential risks and provide information that allows limited resources to be applied in the most effective manner. The main objectives of performing a risk assessment include:
• Follow a formal process to assess risk consistently and to enable comparison between well barrier failure mode scenarios;
• Qualitatively assess well barrier failure risk for every segment of a well;
• Document suggestions that are offered by the risk assessment team for mitigating well barrier failure risk; and
• Provide a report of the methodology, failure mode scenarios, risk ranking, and potential mitigation actions for use as a reference tool for managing well integrity on a routine basis.
The Well Integrity Risk Assessment Model follows a common qualitative risk assessment process; a team-based, structured brainstorming format, utilizing the What-If Methodology, to identify potential hazards associated with well barrier failure modes. In addition, the model has the following attributes:
• Incorporates a unique method to segment well barriers into discrete sections, successively "failing?? each section for evaluation. The list of analyzed well barrier failure modes, along with their risk ranking, becomes the risk register for the well or type of well.
• Is adaptable for assessing well barrier failure modes on a single well, or a group of wells, having the same general design parameters. An entire well portfolio can be assessed quickly by analyzing types of wells rather than individual wells.
• Can be used to assess well barrier failure risk for any type of well.
• The model can easily be modified to conform to any company's risk model.
The Well Integrity Risk Assessment Model has been proven to:
• Successfully assess well barrier failure risk for thousands of wells;
• Focus specifically on well barrier failure modes, and as a result is an effective tool that should be incorporated into a "Best in Class?? Well Integrity Program;
• Be utilized as a management tool to provide guidance for how limited resources can be used effectively to continuously deliver well integrity.
One definition of Well Integrity (WI) is "the application of technical, operational, and organizational solutions to reduce the risk of an uncontrolled release and/or unintended movement of well fluids throughout the life-cycle of a well?? (NORSOK Standard D-010, Rev 3, August 2004). Using this definition, for successful delivery of WI there must be an understanding of potential problems or situations of elevated risk that may cause an uncontrolled release from, or unintended fluid movement in, a well. Performing a risk assessment (RA) on a well, or type of well, will increase the understanding of the potential negative impacts, or consequences, that may result from specific problems a well may have or may develop. The asset operator can use this information to reduce risk from well operations and minimize potential WI problems. This may include updating or modifying processes, procedures and practices used during the construction and operation of the wells.
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