CNN reports :
An oil sheen about four miles long has appeared in the Gulf of Mexico near the site of the worst oil spill in U.S. history, a Coast Guard spokesman said Thursday.
It was not immediately clear where the oil is coming from, said Petty Officer 3rd Class Ryan Tippets. [Although previous oil has been matched as a "dead ringer" to the BP well .]
Coast Guardsmen went to the location after seeing the oil on a satellite image, Tippets said. The response team collected samples and sent them to the Coast Guard Marine Safety Lab in Connecticut for testing.
The sheen is near the spot where, on April 20, 2010, BP’s Deepwater Horizon drilling rig exploded over the Macondo well, killing 11 workers and spewing oil that spread across a huge portion of the Gulf.
(And see this .)
As we’ve noted for years , BP’s Macondo oil well is still leaking … and will leak for years.
For example, we noted  in March:
In June of 2010, BP officials admitted to damage beneath the seafloor  under BP’s Gulf Macondo well.
Numerous scientists have speculated that the blowout and subsequent clumsy attempts by BP to plug the well could have created new seeps, and made pre-existing natural seeps bigger .
Washington’s Blog interviewed  one of the world’s leading experts on oil leaks in 2010, Robert Bea. Dr. Bea noted that we may never be able to fully stop BP’s oil leak:
Few people in the world know more about oil drilling disasters than Dr. Robert Bea.
Bea teaches engineering at the University of California Berkeley, and has 55 years of experience in engineering and management of design, construction, maintenance, operation, and decommissioning of engineered systems including offshore platforms, pipelines and floating facilities. Bea has worked for many years in governmental and quasi-governmental roles, and has been a high-level governmental adviser  concerning disasters. He worked for 16 years as a top mechanical engineer and manager for Shell Oil, and has worked with Bechtel and the Army Corps of Engineers. One of the world’s top experts in offshore drilling problems , Bea is a member  of the Deepwater Horizon Study Group , and has been interviewed by news media around the world concerning the BP oil disaster.
WB: Is it possible that this fractured, subsea salt geology will make it difficult to permanently kill the oil leak using relief wells?
Bea: Yes, it could. The Santa Barbara channel seeps are still leaking, decades after the oil well was supposedly capped. This well could keep leaking for years.
Scripps mapped out seafloor seeps in the area of the well prior to the blowout. Some of the natural seeps penetrate 10,000 to 15,000 feet beneath the seafloor. The oil will follow lines of weakness in the geology. The leak can travel several horizontal miles from the location of the leak.
[In other words, the geology beneath the seafloor is so fractured, with soft and unstable salt formations, that we may never be able to fully kill the well even with relief wells. Instead, the loss of containment of the oil reservoir caused by the drilling accident could cause oil to leak out through seeps for years to come. See this  and this  for further background].
WB: I have heard that BP is underestimating  the size of the oil reservoir (and see this ). Is it possible that the reservoir is bigger than BP is estimating, and so – if not completely killed – the leak could therefore go on for longer than most assume?
Bea: That’s plausible.
WB: The chief electronics technician on the Deepwater Horizon said that the Macondo well was originally drilled in another location, but that “going faster caused the bottom of the well to split open, swallowing tools”, and that BP abandoned that well. You’ve spoken to that technician and looked into the incident, and concluded that “they damn near blew up the rig.” [See this  and this ].
Do you know where that abandoned well location is, and do you know if that well is still leaking?
Bea: The abandoned well is very close to the current well location. BP had to file reports showing the location of the abandoned well and the new well [with the Minerals Management Service], so the location of the abandoned well is known.
We don’t know if the abandoned well is leaking.
WB: Matthew Simmons talked  about a second leaking well. There are rumors on the Internet that the original well is still leaking. Do you have any information that can either disprove or confirm that allegation?
Bea: There are two uncorroborated reports. One is that there is a leak 400 feet West of the present well’s surface location. There is another report that there is a leak several miles to the West.
[Bea does not know whether either report is true at this time, because BP is not sharing information with the government, let alone the public.]