Discusses the relationship between pumping speed and inlet pressure of an oil-sealed mechanical pump and the reason why its pumping efficiency drops down.

Following the explosion and fire on the rig, the blow-out preventer on the sea bed should have automatically sealed the well, but it failed, resulting in the massive oil spill.

As previous analyses of the accident, including BP's own, have shown, the flawed cementing that let oil into the bottom of the supposedly sealed well was not the only issue.