"Royal Dutch Shell said an oil sheen near two of its offshore Gulf of Mexico oil and natural gas platforms was dissipating Thursday, and it was 'very confident' its installations were not to blame."

"The Hague-based company said the 'orphan spill,' estimated to be about six barrels of oil, was breaking up. Shell said it would continue to monitor the sea floor with a pair of underwater robots.

'Shell's subsea surveillance today and tomorrow will continue to determine if there is a connection between natural seeps and this orphan sheen,' the company said.

News of the sheen, first reported to U.S. regulators on Wednesday, came nearly two years after BP Plc's deep sea Macondo well blew out on April 20, 2010, killing 11 workers and spewing more than 4 million barrels of oil into the Gulf of Mexico."

Kristen Hayes reports for Reuters April 12, 2012. [2]