Introducing a new Recommended Practice for Fit for Purpose Well Abandonment

Globally, operators and regulators are pushing to ensure wells are abandoned successfully and securely. DNV GL is introducing a new, risk-based Recommended Practice (RP) for performing and qualifying well abandonments, entitled DNVGL-RP-E103 "Risk-based abandonment of offshore wells." The RP lays out a process to assess and control subsurface pressures and prevent the free flow of pore fluids between formations and to the seafloor. The ultimate objective of the RP is to protect the environment and ensure safety standards are upheld. Most of the current regulations use prescriptive requirements for well abandonment design and the necessary plugging operations. As an alternative to the established ‘one-size-fits-all’ approaches, the DNV GL RP analyzes the abandonment requirements for each well and field using a quantitative method that takes account of sub-surface uncertainties. This approach is founded on best industry risk management techniques. Using these techniques, well-specific acceptance criteria for the environment and safety are established, setting the abandonment requirements for each well. Up until now, offshore wells have been plugged generically and not according to well-specific requirements. Results from case studies have identified solutions ensuring long lasting integrity, robust well abandonment designs and tremendous cost savings potential by using fit for purpose abandonment methodology. Environmental protection and safety considerations are maintained when using the DNV GL RP, while saving operators considerable rig time and overall cost. Differing flow potentials in the reservoir and overburden formations have been studied quantitatively, leading to the development of the DNVGL-RP-E103. The fit for purpose method uses environmental mapping, quantitative risk calculations and well seepage models to evaluate each well and evaluate the suitability of the final abandonment design. By combining disciplinary expertise, the RP sets a new standard for well plug and abandonment (P&A).