Changes in technology and regulatory regimes now require operators to follow stricter Plug and Abandonment (P&A) programs which ensure well integrity after abandonment. The permanent well barriers installed as part of the P&A program must extend across the full cross-section of the well such that no fluid or flow is possible through the wellbore. This requires establishing barriers in all annuli, which can be time-consuming and costly.
Re-entering wells for plug and abandonment requires an understanding of the remaining capacity of the well barrier elements: Incomplete well information, well barrier elements degradation and changes in design approach from installation to present day make this challenging.
AIE works closely with operators and regulatory bodies to provide customised P&A strategies that allow our clients to cost effectively meet engineering challenges and regulatory requirements. Our P&A strategy involves a detailed study from FEED through to project execution and operation. AIE’s P&A experts apply a thorough understanding of the well integrity standards on which P&A design practice is based, and a pragmatic approach to well abandonment risk assessments. We select an approach that minimises the conservatism of the assessment within appropriate limits. This will ensure plug and abandonment operations are conducted as economically as possible.
Our well abandonment approach involves setting goals, determining actions to achieve the goals, and managing the required resources to execute the plug and abandonment (P&A) operations. The details of an operational P&A procedure may differ significantly from well to well, depending on the type of well and the actual well conditions. A general sequence of a typical P&A operation adopted for permanent well plug and abandonment activities is summarised below:
- Phase 1: Reservoir abandonment
- Phase 2: Intermediate abandonment
- Phase 3: Wellhead and conductor removal
The benefit of dividing the operational P&A sequence into different phases highlights opportunities for performing simpler parts of the P&A operation by rigless methods, instead of more traditional and costly rig-based methods.
- Phase 1 – Reservoir Abandonment
At this point, no barrier has been set against the reservoir so full well control is required. It is defined as the phase when primary and secondary permanent barriers are set to isolate all reservoir producing zones.
- Phase 2 – Establish Barriers
Intermediate well abandonment will isolate the intermediate permeable zones with a flow potential, isolating them from each other and avoiding communication within the wellbore. This phase consists of pulling the upper completion (i.e. production tubing above production packer) to evaluate the annular barriers. If the sealing capacity of the annular barrier is inadequate, remediation methods must be conducted. An open hole-to-surface barrier is then set in place to completely isolate the well. The phase will be completed when no further permanent barriers are required.
- Phase 3 – Wellhead Removal and Surface Plugging
The third phase of the P&A operation consists of cutting and removing the casing strings and retrieving the wellhead. A surface plug is set in its place.
THE WELL INTEGRITY EXPERTS
AIE is currently supporting clients with a comprehensive service solution in relation to Well P&A activities. From engineering a robust P&A strategy, liaising with Regulatory bodies to offering a complete project management and delivery service solution. AIE is able to cover all client requirements under one umbrella.
AIE’s proprietary software Veracity Wells is engaged to support P&A programs and facilitates well integrity assessments. Veracity wells delivers effective well integrity management throughout the life cycle of a well whilst ensuring compliance to international standards (e.g. NORSOK D-10 & ISO/TS 16530-2).
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