Drilling of two relief wells, which are designed to permanently seal the well by mid-August, began as rigs returned to calmer waters 40 miles off the coast. BP also prepared to begin the so-called “static kill” procedure, an effort that involves dumping heavy mud into the newly capped well to force oil and gas back down into the reservoir.
The containment cap has integrity, Allen said, with pressure still rising. Late Saturday, pressure reached 6,891 pounds per square inch (psi) and by Sunday morning that number rose to 6,904 psi. When the cap was first installed a week earlier, the first reading was 6,700 psi.
Pressure readings of 7,500 psi or higher are considered a positive sign that the well bore has retained its integrity. A low pressure reading of 5,000 psi or below may suggest oil and gas are escaping through cracks in the well bore or the reservoir has been depleted of all its oil.
Increased pressure readings are a sign that conditions are ripe for static kill, since low pressure would suggest that some mud might escape during the operation. Allen said the entire procedure could take place between 24 and 48 hours depending on the pressure readings at the time of its launch.
The majority of the vessels working on the spill clean up and containment should be back in place Monday. Some 15 vessels and rigs, along with more than 2,000 personnel were evacuated due to the storm.
Even in its weakened state, the storm displaced residual oil not yet skimmed away and moved it toward the Mississippi Sound. Allen said Saturday that the Coast Guard was conducting aerial surveillance of the oil’s movement and would redeploy efforts to clean up tarballs left on beaches. The storm is not expected to affect the movement of oil located deeper below the surface.