Britannica Sources used in this answer

How did the capping stack help stop the Deepwater Horizon oil leak?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Fireboats battle a blaze on the Deepwater Horizon drilling rig in the Gulf of Mexico, April 2010. — Deepwater Horizon oil spill Fireboat response crews attempt to extinguish the blaze aboard the Deepwater Horizon oil rig in the Gulf of Mexico, April 21, 2010.

The capping stack was a critical component in the effort to stop the Deepwater Horizon oil leak. Installed by July 12, 2010, it served as a more permanent seal than the previous Lower Marine Riser Package (LMRP) cap.1

The capping stack helped stop the leak in two primary ways:

Stabilization: It provided a stabilizing influence on the well, which allowed BP to conduct a "static kill" procedure on August 3. During this operation, drilling mud was pumped into the well through the blowout preventer (BOP) at much lower pressures than the failed "top kill" attempt, as the stack helped contain the flow.1
Facilitating the Final Seal: By stabilizing the well, the capping stack cleared the way for a "bottom kill." This final, successful maneuver involved pumping cement through a relief well that intersected the original well, ultimately sealing it completely on September 19, 2010.1