They are able to pump mud slower and at lower pressure because a new cap atop the well has stemmed the flow of oil.

Costing £120,000 over three years, the project involves pumping mud from the bottom of the lake.

Investigators believe that the influx began about 8:50 p.m. Preparing to plug the well, the drilling crew was pumping mud from it, reducing the weight bearing down on the hydrocarbons.

During operations to kill the leak by pumping heavy mud down the relief well, a fire broke out from the H1 well on the well head platform.

Then the drill crew pumped mud in on top of it to seal in the blast.

The brute-force mechanics of drilling still involves pumping high-pressure mud down the hole to spin the grinding faces of the drill bit.

Allen says the Q4000 has been retrofited to pump mud rather than collect oil.

The bottom kill process is delayed during an evaluation to see if pumping mud into the well's annulus would break the cement seal on the top.

However, Lapindo Brantas initially tried to staunch the flow by pumping mud and concrete into the mouth of the volcano.

(However, most relief wells are used to pump heavy mud and cement deep into the wild well.)