Calculation of blowout and kill rates in the worst-case scenario of a potential blowout during well drilling forms part of the assessments of environmental risk and kill opportunities associated with a potential worst-case blowout event during drilling operations in hydrocarbon-bearing formations.

The evaluations in this study provide considerations on uncertainty associated with the development of blowouts and physical factors related to possible depletion in potentially flowing formations in the event of a blowout. The report assesses and summarises a number of historical incidents in this context, including the Montara and Macondo blowouts.

The report compiles knowledge concerning specific challenges linked to uncertainty about how reservoir pressure depletion may affect kill operations through one or more relief wells in the event of a potential blowout, with special reference to Section 86 of the Activities Regulations concerning well control.