Dynamic Risk Assessment of Well Control System

The recent offshore drilling accident such as Deepwater Horizon drilling rig explosion, in April 2010; Vermillion 380 oil rig explosion in September 2010, and Chevron Nigeria limited oil rig explosion in January 2012 have raised serious concerns about the safety of drilling operation. The major reasons for such accidents are the lack of understanding how event unfolds and the integration of early warning sign to a potential major accident. Well blowout is among the most undesired and feared accidents during drilling operations. The dynamic nature of blowout accident is a result of rapidly changing physical parameters and time-dependent failure of barriers. To better predict or possibly prevent such accident one need real time risk assessment of well control system. The present work aim at modeling well control system and risk assessment using early warnings often termed as accident precursors. Drilling operation and well control system are modeled using Bow-tie (BT) approach. The BT model represents potential accident scenario and associated consequences. Further, real time predictive model for the failure probabilities of key elements of well control system are developed and used in conducting the risk assessment of the drilling operations.  The present work provides the real time assessment of drilling risk assessment and a basis to make timely safety critical decisions. The risk assessment methodology is demonstrated on the Macondo well blowout accident. This case study highlights applicability and advantages of the proposed method in drilling operations.