The company said “small, intermittent bubbles” emanated from the cement at the base of the wellhead, and that these are consistent with bubbles of nitrogen seen last year as a byproduct of the nitrogen-foamed cement used prior to the blowout.
“BP and the US Coast Guard have conducted multiple surveys of the area in recent days and found no evidence of oil sheens in the Macondo vicinity,” the company said.
A report by the Press-Register in Mobile, Ala., has incited a flurry of investigatory activity around the well, which blew out on April 20, 2010, in what became the worst oil spill in U.S. history.
The Coast Guard used a plane and a cutter to search for the oil Thursday. The Coast Guard is working with BP, the National Oceanic and Atmospheric Administration (NOAA) and the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE).
“We are planning to conduct a routine ROV inspection of the Macondo wellhead tonight to further confirm that there is no release,” BP said.
The company is eager to put to rest persistent rumors among bloggers and activists that the well, which was choked with a mile of cement last August and declared dead in September, is leaking.
“We’re committed to working with U.S. Coast Guard and BOEMRE to get to the bottom of this mystery,” BP spokesman Scott Dean said.
BOEMRE would not provide details of the investigation.
“We are aware of the reports and are currently coordinating with BP, USCG and NOAA to investigate the sightings,” a BOEMRE spokesman said.
The Press-Register published its story Thursday, based on a trip to the site two days earlier. The paper stated that “hundreds of small, circular patches of oily sheen dotted the surface within a mile of the wellhead,” and it published pictures of oil in the water. Most of the oil was in an area about 50 yards wide and a quarter-mile long.
The most likely source of any oil is a natural seep, said Coast Guard Capt. Jonathan Burton, commanding officer of the Marine Safety Unit in Morgan City, La. Another possibility is that it was “a burp of oil” from the collapsed riser pipe, which crumpled to the floor of the gulf when the immolated Deepwater Horizon sank two days after the blowout.
“Those are pretty damning pictures. Those are oil drops, no question about it,” said Ian MacDonald, a Florida State University professor of oceanography and an expert on the gulf’s natural oil seeps.
“Hopefully, it’s nothing serious. But like if you had a heart attack and get chest pains, you better have a look at what’s going on,” he said.