This paper presents a quantitative risk analysis for well integrity issues associated with ultra deep water well intervention in the Gulf of Guinea (GoG). The basis for the work is the history of well barrier breach, loss of well integrity during completion and or re-completion in the GoG and oil spill. The reliabilities of the subsea completion components and accessories will also be investigated. The study will draw on available industry data base on well integrity failures, barrier breaches and well integrity problems encountered in the course of field development and workover.
A hypothetical ultra-deep water well will be used as the model for problem definition and boundary conditions establishment. The estimated Quantitative Risk Assessment (QRA) of well integrity events will be compared against available real data for verification and correlation check. For the purpose of this work a rig based well intervention will be considered.