In May 2011, a new well capping device was successfully tested on the Venus 1 wellhead in a water depth of more than 2,000 meters on Angola’s Block 31. This is integral to the regional well capping plan, which is able to be deployed offshore Angola, should it ever be required.
The project, the first for any oil company working in Angola, is the culmination of five months work by BP Angola, supported by key contractors, Subsea 7, Oceaneering, FMC and Cameron. The Angola subsea operations team developed the concept for the capping device, and co-ordinated the multi-disciplinary effort needed to produce the plan. Cameron and FMC fabricated and assembled the capping device at the Sonils base in Luanda.
How it works
The capping device is a modified subsea assembly of valves, spools, and fittings used to control flow. The plan provides for the capping device to be landed out onto the top of a blowout preventer from which the top part, known as the lower marine riser package, has been removed.
A support vessel deploys a remotely operated vehicle (ROV) to execute the locking of the well cap connector to the wellhead and to carry out the post-closure monitoring of the operation using its on-board umbilical system to control the well cap subsea control module.
When the capping device has been carefully seated onto the wellhead and locked in place, the support vessel and ROV close the well bore caps and then activate the umbilical system to power-up the well cap. The process can be reversed, recovering the device to the surface.
Complete capping plan developed
Over the five-month period leading to the successful tests, a complete Angola regional capping plan has been developed, consisting of:
- plans and procedures
- seabed survey
- subsea injection of dispersant
- debris clearance and site preparation
- well capping operations
- post well shut-in surveillance
The capping plan is just one aspect of the wider BP response following the Deepwater Horizon accident. The top priority is to prevent accidents and to enhance planning for a spill, should one occur, including the planning of contingent relief wells and upgraded oil spill response and crisis management plans.