WASHINGTON — Scientists have detected oil or natural gas seeping from the seafloor near BP's unstable Deepwater Horizon oil well and have also found "undetermined anomalies" near the wellhead that scientists fear might also be leaking oil — possible signs that the well may have suffered damage that will complicate technicians' abilities to shut off the flow permanently.
No details were given on the size or exact location of the seep, or what it was made of — crude oil, methane, natural gases or hydrocarbons. But the prospect is ominous. If oil is entering from areas distant from the well bore, it suggests that areas of the seafloor and substrata are allowing oil to escape.
If this scenario is accurate, the well cap will likely be reopened to prevent the existing environmental disaster from becoming even worse and even harder to fix. Once the valves are open, oil would gush once again into the ocean, cutting the pressure on the well system for the first time in three days.
It is possible, too, that monitors have sensed naturally occurring seeps, which are a common phenomenon in the Gulf.
Retired Coast Guard Adm. Thad Allen, the Obama administration's point man on the Gulf of Mexico oil catastrophe, revealed the findings Sunday in a letter to BP managing director Bob Dudley.
Allen demanded that the oil giant step up monitoring efforts and report any additional seafloor leaks to the government within four hours of their discovery.
Allen also raised the possibility that he would order an end to what BP and government officials call the well integrity test — the closing of valves in the well's most recent containment cap that has kept oil from flowing into the Gulf since Thursday. Allen demanded that BP provide a plan for allowing oil to resume flowing from the well and into ships waiting to capture it on the surface.
"I direct you to provide me a written procedure for opening the choke valve as quickly as possible without damaging the well should hydrocarbon seepage near the well head be confirmed," Allen said.
Allen's letter, which was distributed to reporters at 8:40 p.m. EDT, was the first indication of problems with the test. During a conference call with reporters 12 hours earlier, BP's cheif operating officer Doug Suttles said the "extensive monitoring" of the site had given officials no reason for concern.
"All of that data continues to show encouraging signs," Suttles said. "We're not seeing any problems at this point or any issues with the shut in."
Suttles said BP wants to keep the well sealed until the relief well is completed. "We're hopeful that if the encouraging signs continue we'll be able to continue the integrity tests all the way to the point that we get the well killed," he said. "Right now there is no target set to open the well back up to flow."
Just when the seepage mentioned in Allen's later letter was discovered wasn't clear. The letter, however, left no doubt that government officials were alarmed by the discovery — and perhaps startled by BP's plans to keep the well sealed.
"Given the current observations from the test, including the detected seep a distance from the well and undetermined anomalies at the well head, monitoring of the seabed is of paramount importance during the test period," Allen wrote.
He added, "Now that source control" — an apparent reference to the sealing of the containment cap — "has evolved into a period beyond the expected 48-hour interval of the well integrity test, I am requiring that you provide me a written update within 24 hours of your intentions going forward."
The ability of BP to seal off the well for the past few days and seemingly prevent any oil from leaking into the Gulf had been hailed as the first bright spot in the three-month ordeal that began April 20 when a giant gas bubble surged up the well's drill pipe, engulfing the Deepwater Horizon drilling rig in a cloud of methane gas that exploded into flames. Eleven people were killed in the initial explosion. The rig burned for more than 36 hours, before sinking into the Gulf, taking a mile of pipe down with it.
Since then, attention has been focused largely on the tens of thousands of barrels of crude that had been spewing daily from the broken pipes atop the well's failed blowout preventer, a gusher that ended on Thursday with the installation of a new containment cap.
Oil seeping from the well into the rocks and up through the seafloor, however, would pose a new problem because it would be difficult to locate the many paths it might be taking to the surface. BP currently hopes to seal the well permanently by intercepting it with a relief well. Heavy drilling mud would then be pumped into the Deepwater Horizon well, filling the well bore and drill pipe and stopping the oil from flowing by its sheer weight. A leak from the well bore through rock and to the seafloor, however, might defy such efforts.
Scientists have been concerned that such leaks could be one reason pressure in the new containment cap has not reached the levels they had expected. A pressure reading of over 7,500 psi, or pounds per square inch, would indicate the well casing is intact. A lower reading could suggest a leak. On Sunday, pressure had reached 6,775 psi, BP said. Officials have said the low pressures might be caused either by a leak in the well or depletion of the oil reservoir during the past three months.
The relief well is still 100 vertical feet from the point where engineers hope to intersect the Deepwater Horizon well. Drilling that distance will take until the week of July 27, Suttles said Sunday.
(Miami Herald reporter Jaweed Kaleem contributed to this report.)