Capping Stack deploys from on board the Transocean Discoverer Inspiration on the MC 252 location 11 July 2010

Oil company BP is considering a so-called "static kill" to seal off its damaged Macondo well in the Gulf of Mexico, even as plans go forward to complete a relief well nearby. The plan would have to be approved by U.S. government officials who are working closely with BP engineers at the site.

The static kill would consist of an operation to pump mud into the damaged well through the cap that was successfully placed over it last week. The mud would overcome the flow of oil and gradually reduce the pressure so that the well could be sealed from above.

In a conference call with reporters, BP Senior Vice President Kent Wells explained.

"On the static kill we will actually start pumping at very low rates and just marginal pressure above what it is currently at," said Wells. "After we get some mud in the hole, assuming everything goes according to plan, the pressure at the well head actually starts to go down, so you very quickly start to see benefits."

The advantage of the static kill is that it would push the flow of oil back down into the reservoir below the ocean floor and then seal it with cement. The procedure would effectively choke off the lines and openings of the old blowout preventer that failed to shut off the flow of oil after the explosion on the drilling rig in April. The static kill is similar to the unsuccessful top kill that BP tried in May. Company engineers think that a reduction in oil flow pressure now favors this approach.

Kent Wells says BP is continuing with its plan to intersect with the underground well shaft by next week and that one of two relief wells being drilled is now within a few meters of that intersection 4,200 meters below the seabed.  Mud and cement would also be used in this procedure to seel the well below the seabed.  Wells said the tandem approach of the static kill and relief well should permanently seal the well by the middle of August, assuming U.S. officials approve the plan. But, he said, company engineers are moving very slowly with what he called an abundance of caution so as not to have any unintended consequences.

Wells said BP is continuing to test the pressure of the well daily and is using seismic tests to make sure there are no leaks from the seabed.

"We are looking to see if we see any signs of oil and gas leaking out and, to this point, of all the lines we have run and all the analysis we have done, we have yet to see any anomalies that would indicate we have oil or gas leaking out of the Macondo well, i.e. that we do not have integrity of the well," he said.

Over the weekend, scientists monitoring the seabed near the damaged well found seepage in an area around three kilometers away, but the U.S. government's point man on the disaster, former Coast Guard Admiral Thad Allen, says the leaks are not consequential and probably are associated with another abandoned well in the same area. There are also natural seepages of oil from the Gulf seabed that are totally unrelated to oil and gas exploration and production activity.

Even if all goes according to plan and the well is permanently sealed off sometime next month, clean-up operations will continue for some time to come. Skimmers are being used on ships at the site of the oil slick in an attempt to clean oil off the water surface, while crews in some coastal areas of Louisiana, Mississippi and Alabama are trying to clean befouled beaches and marshes. The ecological damage from the spill could take years to overcome and environmental experts say some sensitive areas may never completely recover.