The source of an oil sheen in the Gulf of Mexico near BP’s Deepwater Horizon rig wreckage remains a mystery after a study by the company and the Coast Guard was inconclusive.
Officials stated on Tuesday that the sheen is persistent and located near the Deepwater Horizon rig, but that inspections by both sides have confirmed the company’s Macondo well isn’t leaking, reports The Huffington Post.
The Macondo well famously blew out in April 2010, spawning America’s worst offshore oil spill. BP and the US Coast Guard also inspected the relief wells that were drilled to help stop the initial gusher. The relief wells were also found to be secure.
While the oil sheen may not be caused by the Deepwater Horizon rig wreck, investigators did collect samples of a white, cloudy substance that appeared to be originating from several areas of the rig’s wreckage, which lies overturned on the sea floor.
The substance is not believed to be oil, but lab analysis is planned to find out what the substance is. The Seattle Times notes that Coast Guard Captain Duke Walker stated of the inspection:
“No apparent source of the surface sheen has been discovered by this effort. Next steps are being considered as we await the lab results of the surface and subsurface samples and more detailed analysis of the video shot during the mission.”
BP and the Coast Guard used robot submarines to inspect the rig, portions of the riser that used to connect the rig to the sea floor, and the 86-ton steel cap that was lowered over the leaking drill pipe in the aftermath of the spill.
A sheen was initially spotted near the site of the Gulf oil spill in September. Workers capped and plugged the steel container that was suspected to be the source of the sheen. Another sheen was reported in the same spot on November 2, however, meaning that the source was not plugged.
BP stated that the Macondo well and the Deepwater Horizon rig wreckage have been surveyed four times since the well was permanently sealed in September of 2010.