BP is gearing up to begin sealing the broken Maconda well in the Gulf of Mexico either tonight or tomorrow, more than three months after an explosion sparked the biggest environmental disaster in American history.Mud will be injected into the well to overpower the pressure from huge oil and gas reserves beneath the sea, allowing engineers to plug the well.The process, known as "static kill" in the industry, is a precursor to the final solution of a relief well, which BP has almost completed and is expected to have up and running by the middle of the month.A temporary seal has been in place for two weeks now. About 60,000 barrels of oil a day has been spilling out since the well blew up on 20 April killing 11 workers on the Deepwater Horizon platform.It also led to a pre-tax loss of $17bn in the second quarter and the departure of under-fire chief executive Tony Hayward.National Incident Commander Thad Allen told reporters Sunday that the latest attempt to seal the well would depend on results of ongoing tests.He also warned that the static kill "is not the end-all, be-all," suggesting there is much work to be done before the disaster is over.