BP Capping Stack for Well Blowout Containment
Since the Deepwater Horizon tragedy in 2010 the industry has taken long strides in well control and well blowout containment. British Petroleum, having been directly involved in the accident at the Macondo well, was forced to look into a solution that would permanently seal the gushing deepwater well. However, even before they could come up with a permanent solution, BP needed to cap the well over the damaged BOP (Blow-out Preventer). This eventually took BP a few months to accomplish, yet using a large amount of engineering ingenuity a capping stack was manufactured which got the job done. Since at the time there was no off-the-shelf solution to capture the spilling oil straight from the BOP, a great amount of oil spilled which seriously affected the environment on the ocean and along large stretches of coast bordering the GoM.
BP has continued developing its $50 million global deepwater well capping and tooling package. The capping package, is stored at a Houston warehouse, where the tools are maintained ready for deployment 24/7. The 5 1/8-in. capping stack is rated for up to 15,000 psi, 10,000-ft (3,048 meters) water depths and 100,000 bbl/day flow rate. The capping stack consists of two sections, the lower module is a horizontal subsea production tree with integrated pressure and temperature sensors, and the upper stack consists of a hydraulic connector and two gate valves. Due to logistics constraints the stack was designed as two separate sections the system, as it had to be air-transportable for rapid deployment to be possible. Altogether, the cap and tooling package weigh approximately 650 metric tons, requiring 60 lifts and 40 trailer loads. BP has selected the Antonov AN-124, a huge Russian transport aircraft, to transport the capping stack system as it is the only aircraft in the civilian market, which can haul such a massive load. Multiple Boeing 747s flights would be used to assist with the transport process in the case of an incident. The system includes tooling for the capping stack, and other support equipment that may be needed to contain a well blowout.
The equipment is continuously being developed, therefore new parts are sometimes added, while others are changed or upgraded. The toolkit includes more than 250 pieces of equipment, including a subsea dispersant package, a range of ROV tools with saws, torque tools and other debris removal tools, pipe grapples and pipe shears, and a subsea hydraulic power unit with a launch and recovery system that provides hydraulic power for the capping stack operations. A subsea hydraulic accumulator system is also included to provide emergency hydraulic power to the BOP stack. A range of cap adapters has been built to fit the different risers used on BP rigs around the world. The capping stack was designed for fitting on top of the BOP stack after removing the lower marine riser package (LMRP). Yet, if for some reason the LMRP cannot be removed, the capping stack must be capable of mating with the flex joint riser adapter, which is where the bottom riser joint hooks up to the LMRP. The system is definitely impressive, but there is still a significant problem in getting to a far off location quickly with so much equipment, and BP estimates that it would need at least 10 days to get the whole system to an accident location.