In the unlikely event of a subsea well control incident, the Capping Stack is a temporary solution in order to stop an uncontrolled release of hydrocarbons to the environment while a relief well drilling operation with well kill is considered to be a permanent solution.

SWIS membership provides access to the four capping stack systems, which have been designed by the leading industry experts to provide the means to safely soft shut in the majority of anticipated worst-case flow rates.

Members are entitled to mobilise two of the four capping stacks in the event of an incident which ensures redundancy in the service for other members.

OSRL is the custodian of the equipment, storing and maintaining the capping stack systems in four international locations. 15 kpsi capping stacks are located in Brazil and Norway, and 10 kpsi capping stacks are located in Singapore and South Africa.

The units can be configured for a variety of subsea interface requirements, and can be transported by land, sea or air. Maximum depth of 12,500ft/ 3800 m and include chemical injection points for direct dispersant injection to mitigate the formation of hydrates. It is suitable for both exploration and production wells, and can safely contain, choke and cap up to 100,000 bpd flow in a controlled manner.