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 operations. The major reasons for such accidents are the lack of understanding of how such events unfold or how the early warning signs of a potential major accident could be integrated into a risk assessment and management framework. A well blowout is among the most undesired and feared accidents during drilling operations. The dynamic nature of a blowout accident is a result of rapidly changing physical parameters and time-dependent failures of safety barriers. To better predict and prevent such accident, one needs real time risk assessment of a well control system. This paper briefly recapitulates the application of dynamic risk assessment to well control systems using early warnings usually known as accident precursors. Drilling operation and well control systems are modeled using Bow-tie (BT) approach. The BT model represents a potential accident scenario and associated consequences. Further, a real time predictive model for the failure probabilities of key elements of well control systems is developed and subsequently used in conducting the risk assessment of drilling operations. The present work provides both a real time assessment of well control systems and a basis to make timely safety critical decisions. The risk assessment methodology is demonstrated for a well blowout accident. This case study highlights the applicability and advantages of the proposed method in drilling operations