Safety of dynamic positioning operations on mobile offshore drilling units

Dynamic positioning of mobile offshore drilling units for drilling operation (termed as DP drilling operation) is analyzed in this paper. A safety modeling approach based on the barrier concept is developed. Safety of DP drilling operation is modeled in terms of three main barrier functions, i.e. barrier functions to prevent loss of position, to arrest vessel movement and to prevent loss of well integrity, respectively. Analyses of each barrier function are performed. The associated barrier elements are identified, their existing deficiencies are revealed based on operational experience on the Norwegian Continental Shelf (NCS), and recommendations to strengthen each barrier element are proposed. These recommendations could improve safety of DP drilling operation on the NCS. They are also valid to DP drilling operations worldwide.