Plug and abandonment (P&A) is a critical but often overlooked phase of the well life cycle, ensuring that wells are safely sealed once they reach the end of production. Poor abandonment can lead to sustained casing pressure, formation crossflow, aquifer contamination, and greenhouse‑gas leakage. During my recent internship, I contributed to designing P&A strategies for several wells. While I gained confidence in standard practices, I also recognized key opportunities for improvement.
This article outlines those observations and analyzes what can be done better to strengthen safety, reliability, and sustainability in P&A design.
Current Practice in P&A Design
Typical P&A workflows include well assessment, barrier placement, barrier verification, and wellhead removal with site restoration. Standards such as NORSOK D‑010 (Norway), UK OGA guidelines, and BSEE (US Gulf of Mexico) outline these steps. Yet persistent issues remain, particularly around interpreting geoscientific data for barrier placement, managing limited historical data, cost-safety trade-offs, material selection, and aligning with energy transition goals.
What Can Be Done Better?
Reducing Uncertainties in Determining Isolation Zones
Determining where to place barriers is one of the more uncertain aspects of P&A design. Geoscientists often rely on spontaneous potential (SP) and resistivity logs to identify aquifers and hydrocarbon-bearing zones. However, legacy wells may lack high-quality logs, and, in complex lithologies, SP and resistivity signatures can overlap, creating ambiguity. In addition, low-resolution older tools may miss thin or low-permeability zones that could still transmit fluids.
Improvements can be made in this process, including integration of multiple data sets, SP, resistivity, density, neutron, and core data while deploying advanced tools such as nuclear magnetic resonance and dielectric logging in high-risk wells. Machine learning models can reconstruct missing intervals, and multidisciplinary teamwork between geoscientists and engineers ensures uncertainties are explicitly factored into barrier design.
Improving Well Data Quality and Access
Incomplete or inconsistent legacy well records are a recurring problem in P&A design. During my internship, engineers often had to overcompensate for data gaps by adding extra barriers, which increased rig time and costs without proportionally reducing risk.
What can be done better is to develop centralized well-integrity databases that capture information across the well lifecycle. Artificial intelligence tools can reconstruct missing data from analogs, and global standards for well documentation should be mandated so future engineers are not burdened with the same gaps.
Balancing Cost and Long‑Term Integrity
P&A decisions are often made under economic pressure, with operators seeking to minimize cost and rig time. This can result in shorter plugs or fewer verification steps, which reduces upfront costs but increases the risk of future leakage and remediation.
What can be done better is to shift from compliance-based design to risk-based design. Life-cycle cost analysis should be standard practice, demonstrating how upfront investment avoids higher liabilities decades later. Regulators can also create incentives for companies that prioritize long-term integrity over immediate cost savings.
Aligning P&A With Energy Transition Goals
P&A is central to the energy transition. Poorly abandoned wells can leak methane, undermining climate goals. At the same time, secure wellbores are essential for carbon capture and storage (CCS) and may even be repurposed for geothermal energy. However, many current abandonment strategies overlook these broader implications.
What can be done better is to integrate sustainability key performance indicators, such as methane emission reduction, into P&A projects. Designs should be compatible with future CO2 injection and storage, and wells should be screened for geothermal potential before committing to permanent abandonment.
Lessons From Internship Experience
My time in P&A design highlighted the dedication of engineers and geoscientists to safe, compliant abandonment but also the limitations of current practices under uncertainty. Encouraging cross-disciplinary discussions and asking, “what can be done better?” often led to re-evaluating assumptions and exploring alternative tools or data approaches—a mindset the industry must continue to nurture.
P&A is not simply closing a well; it is a legacy decision with ramifications that may span centuries. While the industry has robust frameworks, there is room to improve in reducing geoscientific uncertainty in barrier placement, enhancing data completeness and accessibility, diversifying plugging materials, aligning cost decisions with long-term safety, and embedding sustainability and repurposing goals into designs.
For new professionals like me, P&A is not just a technical challenge; it is a stewardship opportunity to ensure that wells are left in a state that protects people, the environment, and industry trust well in the future.
For Further Reading
Reducing Risk by Inclusion of Robust Subsurface Analysis for P{ulgging and Abandonment Campaignsby A. Edwards, S. Green, and J. Heller.
Estimation of Plugging and Abandonment Costs Based on Different EU Regulations with Application to Geothermal Wells by O. Osundare, C. Teodoriu, G. Falcone, University of Oklahoma, et al.
Comparative Study of Plug and Abandonment Using Balanced Plug Cementing Method: Case Study of Well “NOV-01” Field “VITA” by K. Suhascaryo, G. Kaimena, A. Rachman.
