BP: The Cap's On, Tests Under Way

After securing a new, tight-fitting cap on top of the leaking well in the Gulf of Mexico, BP prepared today to begin tests to see if it will hold and stop fresh oil for the first time in nearly three months. The tests could last anywhere between six to 48 hours, according to National Incident Commander Thad Allen.

The cap will be tested by closing off three separate valves that fit together snugly, choking off the oil from entering the Gulf. BP expects no oil will be released into the ocean during the tests, but remained cautious, again warning that the cap was untested at these depths and conditions. The oil giant will be watching pressure readings, looking for high pressure, because it would mean the leak has been contained inside the wellhead machinery. But if readings are lower than expected, that could mean there is another leak elsewhere in the well. (More British Petroleum stories.)