To: 'Judy Woodruff (onlineda@newshour.org)'; 'voanews@VOANews.COM'
http://www.cbc.ca/world/story/2010/06/03/oil-rig-shears.html
The article states “Once the riser pipe is cut, BP hopes to cap it and start pumping some crude to a surface tanker, which would reduce but not end the spill. The next chance for stopping the flow won't come until two relief wells meant to plug the reservoir for good”.
The second article refers to a “top cap” and a “top hat”. My impression was that these devices had a value that could reduce the flow of oil.
The reduction in the flow of oil may it possible to re-inject mud and then cement to seal the well and stop the flow of oil (reduced flow such increase chance of the sealant working).
In other words containment and sealing could be used together if multiple systems are available to do both at the same time.