(CNN) -- BP has completed work on a relief well that will allow the oil giant to permanently seal the well at the heart of the Gulf oil disaster, the government's commander in charge of overseeing response to the spill said.
"Through a combination of sensors embedded in the drilling equipment and sophisticated instrumentation ... BP engineers and the federal science team have concluded that the Development Driller III relief well has intersected the Macondo well," said Thad Allen, the appointed national incident commander, in a statement released late Thursday.
The relief well was started about 100 feet from the original well and intersects with it about 18,000 feet under the surface of the Gulf.
BP can now proceed with a "bottom kill" -- a process in which heavy mud and cement are pumped into the bottom part of the original well via the relief well to permanently seal it.
Oil gushed from the ruptured well after the Deepwater Horizon rig exploded April 20, leaving 11 workers dead.
The government estimates some 4.9 million barrels (206 million gallons) of oil gushed into the Gulf, 800,000 barrels (33.6 million gallons) of which was captured by surface ships. A cement plug was installed at the top of the well on July 15.