The operation “static kill” finally began on Tuesday, which got delayed by a week due to Tropical Storm Bonnie, and again on Monday when a leak was discovered in the cap that had been sealing the well since July 15. BP said after eight hours of pumping mud into the well, the mud is controlling pressure inside the well.

BP said in a statement on Wednesday, “The well is now being monitored, per the agreed procedure, to ensure it remains static. Further pumping of mud may or may not be required depending on results observed during monitoring.” Initially, the Oil giant BP tested the operation by pumping refined oil into the well to check well pressures and determine that they could inject liquids into the reservoir.

About 4.9 million barrels of crude oil spilled into the Gulf of Mexico since it began as the Deepwater Horizon rig, 80km off the Louisiana coast, exploded on April 20, killing 11 people. BP, who was responsible for the operations of the Deepwater Horizon offshore rig, made cost provisions amounting to $32.2 billion associated with the Gulf of Mexico oil spill.