well abandonment

Well Plug & Abandonment

We plan safe and efficient plug and abandonment of subsea and platform wells that have reached the end of their working lives using a holistic structural analysis approach and risk-based engineering assessments.

Re-entering ageing subsea wells for plug and abandonment requires an understanding of the remaining structural capacity of the wellhead and conductor. Incomplete asset data, time-dependent degradation such as corrosion and subsidence and changes in design approach from installation to present day make this challenging. The latter is particularly important when the operation of modern, high specification vessels and well control equipment on obsolete wellhead designs is proposed.

Our structural analysis experts apply a thorough understanding of the safety philosophy on which industry design codes are based, and a pragmatic approach to risk, to abandonment assessments. They select an analytical approach that minimises the conservatism of the assessment within appropriate limits. This will allow you to identify and mitigate potential concerns early to ensure plug and abandonment operations are conducted as smoothly as possible.

Our engineers have a proven track record in planning plug and abandonment operations in the Gulf of Mexico, North Sea, Irish Sea and offshore Australia. We can also work with other companies in our Group, who offer complementary capabilities in casing cutting and retrieval tools, marine procedure management, lifting and retrieval services, and facilitation of multi-operator abandonment programmes.

Key Services

Subsea & Platform Well Abandonment

  • Strength, fatigue and stability analysis of riser, wellhead and conductor systems
  • Tensioning requirements of the conductor and casing during plugging and abandonment
  • Vertical well loading assessment
  • Identification of maximum tubing pull loads
  • Engineering criticality assessment
  • Corroded and displaced well integrity assessment
  • Original well build simulation for in situ loads
  • Definition of allowable pressures for abandonment operations
  • Vessel drift-off limits and watch circle assessment
  • Jack-up rig modelling
  • Jack-up barge cantilever assessment
  • Component analysis of crossover tools and existing connectors
  • Design of conductor strengthening systems

Planning & Supervision Services

  • Data gathering and review of historic records
  • Cost comparisons and concept selection
  • Vessel selection and feasibility studies

Project Experience

  • Centrica Energy – F3-8 well plug and abandonment from a jack-up
  • Interact – HRL Morecambe Bay abandonment riser analysis
  • Shell – Draugen well plug and abandonment wellhead system fatigue analysis
  • Chevron – Alder suspended well plug and abandonment fatigue analysis
  • BG – Everest subsea exploration well plug and abandonment fatigue analysis
  • TAQA – Cormorant UMC 13-5/8” wellhead system plug and abandonment fatigue analysis
  • BP – Na Kika F3 well plug and abandonment analysis with Ensco DS3 rig
  • BP – Thunder Horse 777-5 well plug and abandonment analysis with West Capricorn
  • BP – MC217-1 well plug and abandonment analysis with West Vela
  • Shell – Macaroni and Europa plug and abandonment analysis with Q4000
  • Shell – Popeye upper abandonment analysis with Atwood Condor