Well Diagnostics: The “Health Check” That De‑Risks Decommissioning

Well diagnostics act as a structured “health check,” uncovering well integrity, pressure, and access risks ahead of physical Decommissioning. This proactive stance ensures decommissioning is executed correctly the first time and is central to Promethean Energy’s delivery of safe, efficient, and cost-conscious outcomes across late-life assets. Discover how it’s been applied in our recent projects via News & Media .

Why Diagnostics First?

Successful Decommissioning begins with clarity. Diagnostics equip asset owners with a data-driven snapshot of each well’s condition before any heavy intervention. With this clarity, planning decisions – like choosing rigless versus rig-assisted execution or fine-tuning barrier design and sequence – are made confidently, reducing offshore uncertainties and sharpening scope.

Promethean believes in proper planning and preparation by conducting thorough reviews of all historical well files, BSEE records, well logs, and other data before any offshore testing. We leverage the latest well diagnostic tools and technologies – such as advanced multi-string logging instruments and fiber-optic sensing – to ensure each well can be accessed and analyzed effectively, de‑risking the project and determining a fit-for-purpose abandonment plan that feeds into a “Minimum Viable Barrier Program.” By leaving certain details a bit high-level, we invite readers to reach out and learn more about our unique approach.

The above is packaged into an expert diagnostic service deployed before the “Define” and “Execute” stages of a decommissioning, so that plug-and-abandonment technologies can be selected with foreknowledge of actual downhole conditions and specific regulatory or risk requirements. In practice, this diagnostics-first approach – supported by hard data, formal workflows, and specialized skill sets – addresses all facets of well retirement: well integrity, geological considerations, regulatory compliance, operational complexity, and safety risk. All these insights feed into the “Minimum Viable Barrier Program,” our tailored roadmap for abandonment.

What Diagnostics Deliver

Well diagnostics transform uncertainty into actionable insight, forming a sturdy foundation for compliant and optimized decommissioning. Key deliverables of a diagnostics program include:

• Pressure Integrity Monitoring: Analyze annular pressure trends to identify sustained casing pressure (SCP) early. Performing pressure communication checks can detect cross-flow pathways between wellbore annuli, and verifying tubing integrity ensures existing isolation systems are reliable. (Notably, SCP is a common issue – studies estimate 25–35% of wells globally suffer annular pressure build-up, often due to cement or barrier failures – so early diagnostics are crucial to mitigate this risk.)
• Access, Injectivity & Tool Reach Verification: Use deep gauge runs to confirm wellbore clearance for intervention tools and to pinpoint any obstructions or scale build-up. If restrictions are found, minor remedial work can be planned in advance. Conduct injectivity testing by pumping fluids into target zones to gauge formation acceptance, which guides cement squeeze or plugging strategies with precision. Ensuring tools can reach intended depths and fluids can be placed as designed eliminates guesswork before executing the job.
• Engineering Data for FEED-Level Design: Diagnostics feed comprehensive Front-End Engineering Design (FEED) data for abandonment. Real well condition data helps define optimal plug types and placement depths, verify which casing strings or annuli require remedial sealing, and set test protocols and contingency plans. For example, detecting poor cement bonding behind casing or fluid migration paths will inform whether section milling or additional barriers are needed in the plan. By grounding the abandonment design in verified conditions, the project team can develop and refine the Engineering Studies and procedures with much higher confidence.
• Comprehensive Documentation: Every diagnostic finding is compiled into a complete, auditable record – including pressure charts, logging tool results, and well schematics. This thorough documentation supports regulatory compliance and gives stakeholders transparent insight into the well’s condition. Regulators like BSEE expect operators to demonstrate well integrity before abandonment; a diagnostics report provides the evidence to secure approvals and ensures all parties are aligned on the well’s status. All diagnostic elements ultimately feed into the Minimum Viable Barrier Program, meaning the final abandonment plan is driven by actual risk and geological realities rather than assumptions.

By front-loading these deliverables, the abandonment program is custom-fit to the well. In essence, well diagnostics deliver clarity by converting unknowns into reliable, actionable data that shape every step of the plan.

Why Diagnostics Make All the Difference

Without diagnostics, Decommissioning plans often encounter unexpected complications – hidden corrosion, unanticipated pressure build-ups, blocked tubing, or unknown cement conditions – which can lead to rework, delays, and cost overruns. By preemptively addressing uncertainties, Promethean can:

• Define a precise, minimized scope of work: Armed with diagnostics, we only do what’s necessary to secure the well. For instance, if only one annulus shows pressure communication, interventions can be targeted to that area alone. This precision shrinks the project scope and eliminates extraneous steps, directly reducing cost and time.
• Maximize safe rigless execution opportunities: Rig mobilization is one of the most expensive aspects of offshore work. If diagnostics confirm that certain abandonment operations (like setting some plugs or performing circulation) can be done via lightweight, rigless methods (wireline, snubbing, or vessel-based units), we integrate those methods to avoid a full drilling rig. Increasing the portion of work that is done rigless has a huge impact on cost savings and safety exposure offshore.
• Ground engineering designs in verified conditions: Rather than relying on decades-old well files or best guesses about downhole conditions, our designs are based on measured data. This means fewer “contingency” operations and more confidence in each barrier. The team can engineer fit-for-purpose solutions (like choosing a specific plug type or setting depth) knowing the well’s actual geometry and condition, which improves the long-term integrity of the abandonment.
• Ensure early regulatory and stakeholder alignment: When we present a diagnostics-driven plan to regulators and partners, it instills confidence that all decisions are evidence-based. Early diagnostics allow issues to be flagged and discussed with regulators (such as BSEE in the Gulf of Mexico) well before execution, ensuring the planned approach meets all regulatory requirements with no surprises. Stakeholders – from joint venture partners to local authorities – gain assurance that the decommissioning will be done right the first time. In fact, industry case studies have shown that performing diagnostics and well prep with small crews ahead of the main campaign greatly improves planning, permitting, and cost estimation, leading to smoother execution.

In summary, a diagnostics-first model means fewer surprises and a more streamlined project. It transforms decommissioning from a reactive process into a proactive one.

Industry Context & Best Practices

Promethean’s diagnostics-first model is grounded in broader industry trends and standards:

• Multiple barrier verification: Well integrity guidelines (e.g., NORSOK and API standards) demand multiple independent barrier layers for isolation at each phase of well abandonment. Diagnostics provide the necessary information to verify each well barrier element and identify any weaknesses, enabling us to design and validate barriers that truly meet the “two independent barriers” rule before pulling the tree or wellhead. This data-driven verification upholds industry best practices for safety.
• Growing decommissioning activity: Offshore decommissioning is a fast-growing sector worldwide, with tens of thousands of aging wells due for P&A in the coming decades. Meticulous engineering, planning, and regulatory execution across multiple stages are required to manage this workload efficiently. A diagnostics-first approach directly addresses this need by front-loading information gathering. It’s an approach increasingly adopted in mature basins – for example, the UK’s North Sea reports emphasize upfront well diagnostics and prep work to drive down P&A costs as activity scales up.
• Advanced tools and real-time monitoring: The use of cutting-edge logging tools, real-time monitoring, and predictive analytics is becoming central to maintaining well integrity throughout the lifecycle, including abandonment. Technologies like through-barrier acoustic “spectral” logging and multi-string electromagnetic scanning can pinpoint leaks or corrosion behind casing that traditional tools miss. Fiber-optic sensing (distributed temperature and acoustic sensing) can provide continuous monitoring of well conditions, revealing dynamic changes like gas percolation or seal failures in real time. Promethean leverages these advanced diagnostics to gather a comprehensive well profile that earlier generations of operators simply didn’t have when planning abandonments.
• Diagnostics plus verification = best practice: Industry bodies recognize that doing detailed diagnostics before designing the P&A program, and then performing targeted verification during and after the P&A, is a best practice for risk reduction. By investigating the well thoroughly upfront and then confirming that each plug or seal achieved its objective (for example, via pressure tests or post-abandonment logs), operators significantly reduce long-term leakage risks. Promethean’s workflow embraces this full lifecycle view – diagnostics inform the plan, and subsequent verification validates the execution – ensuring a compliant and secure abandonment in line with leading industry methodologies.

Real-World Implementation: Promethean in Action

A clear example of our diagnostics-first philosophy is demonstrated in Promethean’s recent orphan wells project in the Gulf of Mexico. Before starting any plugging operations, our team began with preliminary platform surveys (including drone-assisted inspections for visual intelligence) to ensure site safety and readiness. This groundwork fed directly into a structured program of well diagnostics testing – forming the backbone of our risk management approach. Multi-string logs were run in each orphan well to check for hidden integrity issues, and pressure monitoring devices were installed to observe any sustained pressures over time. The result was a detailed condition baseline for every well. Using these insights, we developed a Minimum Viable Barrier Program tailored to the actual state of each orphan well and selected the appropriate abandonment methods (many rigless) well in advance.

The project demonstrates how diagnostics support informed, safe, and budget-aligned execution. In fact, all nine orphaned wells were plugged safely and ahead of schedule and under budget. By identifying issues early (such as one well with sustained casing pressure that required a specific remedial cement squeeze), we avoided surprises during execution. We completed the campaign with zero safety incidents. This success is a direct reflection of Our Strategy in action – leveraging data, technology, and expertise to turn complex Operatorship of Late Life Assets liabilities into orderly, efficient projects. It also showcases how a diagnostics-led plan can satisfy regulators: the Bureau of Safety and Environmental Enforcement (BSEE) closely oversaw the orphan wells project, and our comprehensive diagnostics documentation helped secure approvals for each step. The Gulf of Mexico project is now a replicable model guiding similar projects, and Promethean is scaling this approach as we tackle more of the ~14,000 remaining unplugged Gulf wells.

Bringing It All Together

Emphasizing diagnostics early ensures that:

• Well diagnostics deliver clarity by converting unknowns into reliable, actionable data, eliminating doubt about well conditions.
• The Minimum Viable Barrier Program embodies this clarity in a practical, fit-for-purpose decommissioning roadmap, with every plug and procedure grounded in real well information.
• This approach parallels industry best practices and meets regulatory expectations, anchoring projects in safety, sound engineering, and efficient execution from the outset.

Curious to learn more about how Promethean Energy’s structured diagnostics can convert uncertainty into a streamlined, safe abandonment plan for your assets? Contact Us to explore our Well Diagnostics approach further – we’re here to ensure your late-life wells are retired right, the first time.