New BP cap set for slow tests

With a tight new cap freshly installed on its leaking well in the Gulf of Mexico, BP planned gradual tests starting Tuesday to see if the device can stop oil from pouring into the sea for the first time in nearly three months.

The cap would be just a temporary solution, but it offers the best hope yet for cutting off the crude that has fouled the Gulf since the Deepwater Horizon rig leased by BP exploded April 20, killing 11 workers.

Engineers will slowly shut down three valves that let oil flow through the 75-ton capping device to see if it can withstand the pressure of the erupting crude and to watch if leaks spring up elsewhere in the well.

National Incident Commander Thad Allen said the process of closing the valves, one by one, would start later Tuesday.

If pressure inside the cap stays in a target range for roughly six hours after the valves are closed, there will be more confidence the cap can contain the oil, Allen told a news briefing at BP's United States headquarters in Houston.

Allen and BP officials repeatedly cautioned there are no guarantees about the delicate work a mile (1,500 metres) below the sea. Allen urged Gulf Coast residents watching the possible fix evolve to be patient.

The tests could last anywhere from six to 48 hours, Allen and BP said.

Kent Wells, a senior vice-president at the oil giant, declined to talk about BP's next steps until the test results are in hand.

"It's not simple stuff. What we don't want to do is speculate around it," Wells said in a BP news briefing.

Bp cautious

The cap will be tested by closing off three separate valves that fit together snugly, choking off the oil from entering the Gulf. BP expects no oil will be released into the ocean during the tests, but remained cautious about the success of the system.

Pipes can be hooked to the cap to funnel oil to collection ships if BP decides the cap can't take the pressure of the gusher, or if low pressure readings indicate oil is leaking from elsewhere in the well.

Even if the cap works, the blown-out well must still be plugged. A permanent fix will have to wait until one of two relief wells being drilled reaches the broken well, which will then be plugged up with drilling mud and cement. That may not happen until mid-August.

Even if the flow of oil is choked off while BP works on a permanent fix, the spill has already damaged everything from beach tourism to the fishing industry.

Tony Wood, director of the National Spill Control School at Texas A&M-Corpus Christi said the sloppiest of the oil - mousse-like brown stuff that has not yet broken down - will keep washing ashore for several months, with the volume slowly decreasing over time.

He added that hardened tar balls could keep hitting beaches and marshes each time a major storm rolls through for a year or more. Those tar balls are likely trapped for now in the surf zone, gathering behind sand bars just like sea shells.

"It will still be getting on people's feet on the beaches probably a year or two from now," Wood said.

Tar-ball threat

Meanwhile, in Texas, Coast Guard Chief Warrant Officer Lionel Bryant said Tuesday that tar balls found on a Galveston beach last week are from the blown-out BP well off Louisiana.

As of Tuesday, the 84th day of the disaster, between 90 million gallons (340 million litres) and 179 million gallons (677 million litres) of oil have spewed into the Gulf of Mexico.

Tar balls found on July 5 at another beach, east of Bolivar Peninsula, were the first confirmation that crude from the massive BP oil spill had reached Texas shores. Officials say they may have been brought by ships that worked in the spill area.

Last week, new laboratory results had officials backing off claims that many of the tar balls on Texas shores were from the Gulf spill. The confusion was attributed to contradictory test results from two labs.

- AP