IOGP has published Well Control Incident Definitions a classification system for Well Control Incidents (WCIs).
A WCI occurs when there is a failure or degradation of the defined well barrier envelope(s) that are designed and managed to keep fluids in the well or the reservoir. This classification system was established to allow IOGP Member Companies to notify each other, and the wider community, of the lessons learned from well control incidents and near misses. The sharing of these lessons helps to promote learning, avoid the repetition of similar errors, and enable safer operations.
Well Control Incident Definitions is available to download from the IOGP Publications Library.