Well Decommissioning

The transition to a net zero-carbon-emitting economy will require multiple uses of the subsurface. Wastes from nuclear power generation, which is often cited as a low-carbon provider of base-load electricity, will need underground disposal. Carbon capture and storage will require underground injection of CO2, and underground hydrogen storage will require the cyclical injection and retrieval of hydrogen. Wells will need to be drilled as part of these projects, while legacy wells might also be present. It is necessary to ensure that wells perform as required during any operations and do not leak or adversely disturb natural groundwater movement thereafter.

Quintessa’s Well Decommissioning consulting services help to achieve cost-effective decommissioning and help the long-term integrity of well seals to be evaluated.

Deciding on the appropriate selection of barrier materials, and their placement and verification are key questions that need to be addressed in designing solutions for safe and cost-effective well decommissioning. Drawing upon our extensive experience in numerical modelling of long-term behaviour of cement and concrete, geochemical modelling of metals/metalloids, clay properties, and coupled modelling of thermo-hydraulic-mechanical-chemical (THMC) processes, Quintessa can advise on the long-term behaviour of barrier materials and their compatibility with a range of geological environments. Combined with our expertise in systematic and structured decision-making, statistical modelling, and risk assessment and performance assessment approaches, Quintessa can provide well operators and technology developers with qualitative and quantitative assessments which will result in optimised well decommissioning designs enabling demonstration of ALARP (As Low As Reasonably Possible) and achieving cost savings.

For more than a decade, Quintessa has been providing support to an International Atomic Energy Agency (IAEA) initiative to develop and implement a safe and secure borehole disposal route for disused sealed radioactive sources. More recently, Quintessa has been supporting the Offshore Energies UK (OEUK) in developing Well Decommissioning for CO2 Storage Guideline.

Quintessa has recently issued a Well Decommissioning White Paper highlighting the importance of well decommissioning in the transition to a net zero carbon-emitting economy. Quintessa has been also developing a well decommissioning workflow consisting of the:

  • Well Decommissioning Features, Events and Processes (FEPs) database;
  • Decision Trees to support an informed decision on developing an assessment tool for risk-based approach to well decommissioning, which takes into account the information available and all uncertainties in a specific well system; and
  • development of the assessment tools of different levels of complexity, appropriate to the specific well type and geological conditions.