Well failure modelling uses pre-emptive risk assessment to address well integrity issues more effectively than risk assessing well barrier leaks and other integrity anomalies as they happen. Users of Well Failure Models (WFMs) benefit by spending less time doing risk assessments and achieve more consistent results; better understanding of well issues; more efficient well intervention planning and reduced well services costs; improved well reliability and thus reduced production losses and safer wells. By adopting a well failure model Maersk Oil Qatar rasies the bar with respect to HSE and management of their well integrity.Development of a WFM utilises a what-if risk assessment for specific well types, characterised by service, flow capability, well pressure, architecture and various environmental considerations. Well component leaks, failure modes and other integrity anomalies are analysed. Corrective actions, severity codes and repair grace periods are established for each issue for all well types.The Maersk Oil Qatar (MOQ) WFM has been in use since 2012. It considers failures and failure modes for all well barrier elements as well as preventative maintenance anomalies for the various well types in the Al-Shaheen field, offshore Qatar.The 2012 WFM has grace periods based on the subjective judgement of experienced drilling and production staff, agreed in facilitated workshops. In 2014 work was initiated to upgrade the WFM using quantitative risk assessment (QRA) techniques to calculate grace periods. This paper describes development and structure of the 2012 WFM. It also explains the QRA techniques used in the 2014 WFM upgrade and outlines the initial results obtained with both models. Currently MOQ are running the 2012 model and will soon begin to populate the 2014 QRA model with actual failure data in order to calibrate the model.Reductions in risk exposure and improvements in risk management are the most important objectives MOQ expect to realise from this approach. Further to this there potentially are substantial financial benefits for Maersk through efficiency gains, cost saving and increased production volumes, this underpins the company goal of being a top quartile performing operator with high focus on safety.