Risk-based Well P&A

Astrimar has an established track record supporting operator well P&A design decisions and ALARP justification to the regulator. Many wells to be decommissioned will have challenges requiring designs that deviate from those specified in OGUK or NORSOK guidelines or application of new plugging technologies. For these wells, a quantified or semi-quantified risk assessment is fundamental to demonstrating ALARP.

Astrimar’s well P&A risk assessment and assurance process follows industry guidelines, systematically and comparatively evaluating well barrier designs for their potential risk and associated uncertainty.  Astrimar's approach addresses:

  • Failure mode and effects (FMEA) for well bore and cross-flow barriers
  • Failure likelihoods using system reliability models (e.g. event tree analysis)
  • Risks and uncertainties associated with alternative barrier designs
  • Time dependence of reservoir recharge, cross-flow potential or other mechanisms (such as barrier degradation)
  • Quantification of leak potential using our bespoke STEM-flow analysis
  • Selecting the best P&A design option and demonstrating which design risks are ALARP
  • Demonstrating ability to meet regulatory requirements

All P&A design parameters can be modelled as statistical distributions to address uncertainty. These include, for example: the time for reservoir recharge or breakthrough; the likelihood of barrier failure; and associated environmental, financial and reputational risks.  

Additionally, if required, Astrimar’s STEM-flow software can support the analysis by quantifying estimated leak rates and times to breakthrough across a variety of well barriers and materials. Monte Carlo Simulation is an integral part of these analyses and enables the impact of input parameter uncertainty to be reflected in the outputs, a necessary requirement for higher risk wells.

Astrimar’s proven efficient and pragmatic approach provides value to operators by systematically evaluating risks associated with well P&A barrier design options enabling defendable comparison, and through a risk-based cost benefit analysis, assisting in determining and demonstrating the ALARP design.    

For more information please watch our overview video on our YouTube Channel.