Showing posts with label abandoned gulf oil wells. Show all posts
Showing posts with label abandoned gulf oil wells. Show all posts

Wednesday, April 20, 2011

Congress Fails To Pass A Single Oil Spill Law (2 articles)

Wednesday, April 20, 2011 by Huffington Post
by Marcus Baram

NEW YORK -- Soon after his son Gordon died in the Deepwater Horizon explosion last April, Keith Jones made eight trips to Washington D.C. to push for stronger safety measures in offshore oil drilling and to increase the compensation paid to victims of the tragic accident. He met with President Obama, who apologized for the families' "unimaginable grief" and cradled Gordon's baby boy Maxwell in his arms.

In the year since the worst environmental disaster in the nation's history, Congress hasn't adopted any major laws on oil and gas drilling -- despite introducing more than 150 bills to improve the safety and oversight of offshore drilling and holding more than 60 hearings to discuss the spill's causes and consequences with regulators, oil company officials, grieving relatives and Gulf-area fishermen. When Jones arrived on Capitol Hill, he says he was mobbed by Senators and Representatives eager to express their condolences and to promise that they would swiftly pass legislation to make sure such a tragedy never happens again.

He is still waiting.

In the year since the worst environmental disaster in the nation's history, Congress hasn't adopted any major laws on oil and gas drilling -- despite introducing more than 150 bills to improve the safety and oversight of offshore drilling and holding more than 60 hearings to discuss the spill's causes and consequences with regulators, oil company officials, grieving relatives and Gulf-area fishermen.

"Nothing has happened," said Jones, speaking by phone from his law office in Baton Rouge. "When oil was still gushing out of the Gulf, everybody wanted to do everything right, to do whatever they could to keep that from happening again. But that was then. Now, everybody is back to drilling more, making more money and not worrying about safety. That attitude is what cost the lives of 11 men and caused the biggest environmental disaster in our history," he said.
Jones traces the inaction to political gridlock and to the nation’s fading attention span. He claims that as soon as the gushing undersea well was capped and the nonstop TV coverage slowed to a trickle in July, he no longer commanded the same attention.

"I remember the day they capped that well -- those images had been up in the corner of every TV screen, all that oil gushing into the ocean -- I stopped seeing senators and congressmen and started seeing staffers."

In January, President Obama's oil spill commission released a slew of recommendations for changes that would seek to ensure safer drilling operations, provide better spill response, lift the existing liability cap on oil companies and secure funding for coastal restoration efforts in the Gulf. Yet though bipartisan leaders of the commission have personally lobbied members of Congress, no major legislation has been adopted. Lawmakers did accept the commission's recommendation for a budget increase for the federal agency with oversight of offshore drilling.
"I am disappointed," said oil spill commission co-chairman William Reilly, a former EPA administrator under President George H.W. Bush. He added that he is worried by House Natural Resources Committee chair Rep. Doc Hastings’ (R-Wash.) intention “to wait until all the investigations are resolved before developing his own legislation. One hopes that it will be responsive to the commission's recommendations," Reilly said.

A bill sponsored by Rep. Ed Markey (D-Mass.) that would enact many of the commission's recommendations has little chance of passing, given the Republican majority in the House.
Markey expressed his disappointment at the lack of a legislative response in a statement provided to The Huffington Post:

"One year after the BP spill began, the American people and the citizens of the Gulf shouldn't believe that another major spill couldn't occur, or that our response wouldn't be as sub-par as it was during last summer's spill. Many holes still exist in our offshore drilling safety regime, and another spill could happen again."

About 18 months after the Exxon Valdez oil spill in 1989 -- the largest spill in the nation's history at the time -- Congress passed the Oil Pollution Act, which required companies to detail their spill-prevention and spill-cleanup plans, notes Richard Charter, a senior policy adviser at Defenders of Wildlife, a conservation group.

"You're seeing Congress pretend that Deepwater never happened," he said. "You're seeing them say, 'Let's take similar risks in sensitive areas, in spite of what happened.’”

Just last week, the House Natural Resources Committee passed three bills to accelerate the offshore drilling permitting process and open up new areas to drilling off the coasts of California, Florida, Massachusetts and North Carolina. The bill's sponsor, Hastings, says his legislation increases safety oversight by writing a requirement for government permitting of offshore drilling projects into federal law.

The legislation, which would require federal regulators to act on offshore drilling permits within 30 days, alarmed environmentalists and members of the administration who expressed their concern that it rushes an important process.

Interior Secretary Ken Salazar blamed Republicans for having a "sense of amnesia" about last year's spill, adding, "much of the legislation that I have seen being bandied around, especially with the House Republicans, is almost as if the Deepwater Horizon Macondo well incident never happened."

The opposition to new legislation that requires stricter oversight largely stems from the anti-regulatory zeal of conservative lawmakers and from the influence of the oil industry, say congressional staffers from both parties.

In 2010, the oil and gas industry spent more than $146 million to lobby the federal government and donated $28 million to federal campaigns, according to the Center for Responsive Politics.
"The lobbying is relentless and continuous on the Hill," says John Amos, a former oil industry geologist who heads the SkyTruth environmental group. "And the public sector groups are no match for the well-oiled machine that the American Petroleum Institute is."

Shortly before he introduced his legislation, Hastings held a closed-door, invitation-only meeting with top energy lobbyists, Politico reported. A spokesperson for Hastings did not return several requests for comment.

And BP is back to making contributions to politicians -- largely to GOP leaders -- breaking a self-imposed moratorium on such donations in the wake of the oil spill. The oil giant gave $5,000 contributions to House Speaker John Boehner (R-Ohio), House Majority Whip Kevin McCarthy (R-Calif.), and House Energy and Commerce Committee Chairman Fred Upton (R-Mich.), among others.

Last week, Louisiana's senators, Mary Landrieu (D) and David Vitter (R), introduced legislation that calls for dedicating at least 80 percent of BP penalties paid under the Clean Water Act to Gulf states to restore the coastal ecosystem and its economies damaged by the spill.

Some lawmakers from both parties have argued that new legislation should await the results of several ongoing investigations into the accident by the National Academy of Engineering and the Chemical Safety Board. Though the same caution was preached in advance of the oil spill commission's findings in January, no new legislation has been proposed. Rep. John Fleming (R-La.) expressed his concern about the tendency in Washington for incidents to prompt new laws "and a whole new level of bureaucracy. ... There's no question we need to improve oversight, but I rather doubt that a new law is a good thing," he told the Shreveport Times. "That's sort of a knee-jerk reaction we have in Washington."

Offshore drilling watchdog SkyTruth's John Amos, whose satellite-imagery exposed the true extent of the spill, advocates legislation that requires stronger oversight of deepwater drilling but agreed it “may be appropriate to keep your powder dry while the Chemical Safety Board [probe] is still going on."

Some of the presidential oil spill commission's recommendations have been adopted by the Bureau of Ocean Energy Management Regulation and Enforcement, the regulatory agency that oversees offshore drilling. Led by former prosecutor Michael Bromwich, the successor agency to the scandal-prone Minerals Management Service has won praise for ramping up oversight, though critics claim that it still depends too much on industry-written standards and has not yet revamped its oil spill response plans. Since imposing new safety and environmental rules, the bureau has approved 46 new shallow-water wells and 10 permits for deepwater drilling projects that had been blocked by Obama's moratorium in the wake of the oil spill.

Among Jones's biggest frustrations was to witness first-hand the collapse of an uncontroversial bill to change an archaic law, the Death on the High Seas Act, that limits the damages that the families of the 11 victims of the Deepwater Horizon can recover. After passing the House, the bill was held up in the Senate due to lobbying by cruise lines and shipping companies until Sens. Patrick Leahy (D-Vt.) and Jay Rockefeller (D-Del.) adjusted it to only apply to the Deepwater victims. But one senator, Jim DeMint (R-S.C.) blocked the body from voting on it in December, just before the end of the congressional session.

Jones said that he tried to talk to the senator but "he didn't have time for me." One of DeMint's staffers told Jones that the senator objected because he did not believe that Congress should pass laws that have a retroactive effect, the staffer claimed.

"That's a lie," thundered Jones, explaining that DeMint voted in the House to pass legislation in 2000 that amended the liability for aviation accidents to make it retroactive by five years. And a week after blocking the bill to amend the Death on the High Seas Act, DeMint supported the legislation to help treat 9/11 first responders.

DeMint was also the only senator who prevented a vote by unanimous consent on a bill that would have given President Obama's oil spill commission subpoena power -- a spokesman later said that DeMint himself did not object to the provision but that he was acting on behalf of "members of the Republican conference." He eventually lifted the block and the measure passed. A similar measure had earlier passed the House by a vote of 420-1.
A spokesperson for DeMint declined several requests for comment.

Former Rep. Charlie Melancon (D-La.) who voted for the bill to amend the Death on the High Seas Act, says he was stunned that it didn't pass, especially since it appears that there was negligence.

"How do you tell these people that you and your children don't get a thing?” he asked. “In good conscience, it's difficult for me to understand."

+++++++++


3,200 Gulf Wells Unplugged, Unprotected
by Jeff Donn

More than 3,200 oil and gas wells classified as active lie abandoned beneath the Gulf of Mexico, with no cement plugging to help prevent leaks that could threaten the same waters fouled by last year's BP spill, The Associated Press has learned.

These wells likely pose an even greater environmental threat than the 27,000 wells in the Gulf that have been plugged and classified officially as "permanently abandoned" or "temporarily abandoned." Those sealed wells were first tallied and reported as a major leaking threat in an investigative report by the AP in July.


The unplugged wells haven't been used for at least five years, and there are no plans to restore production on them, according to the federal government. Operators have not been required to plug the wells because their leases have not expired.

As a result, there is little to prevent powerful leaks from pushing to the surface. Even depleted wells can repressurize from work on nearby wells or shifts in oil or gas layers beneath the surface, petroleum engineers say. But no one is watching to make sure that doesn't happen.
The addition of the unused but officially active wells, as documented in a list provided to the AP by federal officials under the U.S. Freedom of Information Act, means at least three-fifths of the 50,000 wells ever drilled in the Gulf have been left behind with no routine monitoring for leaks.

The 27,000 decommissioned wells were drilled mostly on federal leases that have now expired. Government rules for expired leases on the sea floor require operators to plug the wells or make plans to reuse them within a year. In its original report, the AP documented how oil and gas companies regularly flouted the rules regarding temporary abandonment, with some wells "temporarily abandoned" since the 1950s.

Rules for unexpired leases are different, and have allowed operators to simply walk away from idle wells. Some of the roughly 3,200 unsealed wells contained in the latest list were drilled 60 years ago, and most are more than 10 years old.

Federal regulators described idle wells on active leases as a "potential threat" to the environment in a September letter to operators announcing a new program, dubbed "Idle Iron," to plug them within three years. The letter said the program would cover more than 3,000 idle wells but didn't say what kind of wells would be included or whether the wells already contained at least some cement plugging.

The list of specific wells covered by the Idle Iron initiative was provided to the AP by the U.S. Bureau of Ocean Energy Management, Regulation and Enforcement, which regulates oil and gas leases on federal lands on the sea floor.

BOEMRE refused to provide the list when the AP first requested it in September. The agency said at the time that it first wanted to verify with gas and oil companies that the wells were correctly classified. The AP argued that the FOIA provides access to records as they exist at the time of the request, but the agency still refused to release the material.

In finally providing the list last month, BOEMRE said the wells had been "verified." But several weeks later, a representative of the agency, Eileen Angelico, contacted the AP and said it had mistakenly released the original unverified list.

It is that version — a listing of wells as they were classified in September without any challenges from the industry — that the AP has analyzed and used as a basis for this story. Angelico said the verified list wasn't yet ready, despite the earlier assurance that the released list had been checked by operators.

The list cites the American Petroleum Institute number of 3,253 oil or gas wells targeted by the initiative in September. Ninety-nine percent of them, or 3,212, were classified as completed wells. Most were drilled for regular production, but a few were exploratory.

Just 41 of the Idle Iron wells — 1 percent — were already classified in September as "temporarily abandoned."

When wells are drilled, they are lined with metal casing, which is then encased in cement to further shore up the borehole.

Whole segments of wells that are permanently abandoned are plugged with additional lengths of cement — known as plugs — to prevent any oil or gas from pushing its way to the top. Then, the top of the casing is sheared off, and a cap is placed over it.

When wells are temporarily abandoned, fewer cement plugs are placed, so it is easier to drill through the plugs and resume production, if desired.

The typical well in the Iron Idle program is finished only with a wellhead, which is the top of the metal lining, and perhaps a device called a tree, a faucet-like rig equipped with valves to open and shut the flow of hydrocarbons during production.

Federal regulators have acknowledged that even some plugged wells have leaked in the past. And, as the AP disclosed last summer, there is no routine monitoring of abandoned wells — plugged or unplugged.

The oil and gas industry generally views plugging on unexpired leases as an inconvenience and prefers the freedom to resume operations at any time on such wells.

When BP's Deepwater Horizon well blew in the Gulf last April 20, it was being temporarily abandoned to await later production. A poor cement plugging job has been identified as a chief cause of the deadly explosion and spill.

Engineers say the metal and cement lining inside abandoned wells, as well as the plugs, can break down over time and allow leaking. Petroleum or corrosive brine, which is even saltier than sea water, can leak from under the sea floor, harming aquatic life.

The most dramatic threat from the Idle Iron wells is a gusher akin to the BP spill, though probably on a smaller scale, specialists say.

Roger N. Anderson, an energy geophysicist at Columbia University, said he worries about a catastrophic failure of the cement lining in the unplugged wells. "The one thing we don't know very much about is how the cement will age. Highways only last so long, and the cement starts to degrade," he said.

Another danger is that many of the unused Idle Iron wells may be slowly leaking, hurting sea creatures that have adapted to the natural petroleum seepage from the sea floor, but not to higher amounts. "Elevated chronic leaks from thousands of sources spread widely across the Gulf can have much more impact than single spills," said Doug Rader, an ecologist for the Environmental Defense Fund.

A third danger is that hurricanes or other storms will wreck underwater structures and make them leak.

David Pettit, senior attorney for the Natural Resources Defense Council, said the lack of oversight of unused wells makes him nervous.

"I have no idea how badly they may be leaking," he said, adding that federal regulators should start with checking some of the oldest wells.

Under the Idle Iron program, operators can choose to seal the wells with a complete series of plugs and sheared-off well lining for permanent abandonment, or with fewer plugs for temporary abandonment.

As a third choice, they may apply limited plugs strategically around the oil or gas zones within the well — but must then seal the well more thoroughly within two more years.

It's not clear if companies would be required to fully seal the Idle Iron wells that are already listed as temporarily abandoned.

Under the new rules, future wells that drop out of production on active leases also must be sealed within three years.

Gene Beck, a petroleum engineer at Texas A&M University who used to work in the petroleum industry, said many companies won't like the Idle Iron program "because it's going to cost a lot of money." It is not clear how much, but companies will have to spend at least $3 billion to permanently plug wells on both active and expired federal leases, according to earlier BOEMRE estimates.

Apache Corp., which operates the most Idle Iron wells with 587 in its portfolio, foresees spending $317 million to plug and decommission its own assets in the Gulf just this year.
Drew Hunger, who manages Gulf decommissioning work for Apache, said he views the timetable of the Idle Iron program as reasonably ambitious, but he added that it also appears to allow for "the limitations on available contractor equipment and manpower."

He said industry complaints about the program revolve around the paperwork and the limited size of BOEMRE's staffing to process it.

Chevron U.S.A., the company with the second-highest number of wells in the program at 528, did not respond to a request for comment. BP has 24 such wells and also did not respond.
Federal officials have said little about how the new program will be enforced. Neither the BOEMRE nor the U.S. Environmental Protection Agency, which monitors sea pollution, responded to repeated requests for interviews about the program.

Tuesday, February 15, 2011

Gulf oil wells 10 miles from Deepwater Horizon site leaking since 2004

(I'll bet BP takes this story and runs with it. "See, it's not just our fault!"--jef)

++++++

By Ben Raines, Press-Register
Sunday, February 13, 2011

While the Deepwater Horizon well has been capped since July, another group of wells about 10 miles away has been leaking oil into the Gulf since 2004, according to federal records.

Citing litigation, federal officials refused last week to answer a series of questions about the ongoing leaks, including how many wells are involved, how much oil has escaped into the Gulf and whether any fines have been issued to Taylor Energy Co, LLC, the company that owns the wells.

Federal officials said a cleanup agreement between the government and Taylor Energy “is the subject of a pending lawsuit concerning the release of details about the decommissioning project.”

Taylor officials did not return calls seeking comment.

A Taylor Energy production platform near the mouth of the Mississippi River was toppled by a mudslide during Hurricane Ivan, according to federal reports. The platform was tied to 26 wells, though it is unclear how many are leaking. The company is reportedly in the process of drilling relief wells to staunch the flow.

The ongoing leaks gained national attention during the BP spill after the government released highly detailed satellite images of the Gulf’s surface. Skytruth, a watchdog group that uses satellite images to monitor environmental problems, first called attention to the ongoing spill.

In response to a Press-Register story about the leak, the Department of Interior and the U.S. Coast Guard suggested at the time that the leak volume was as small as 13 gallons a day.

But John Amos, president of Skytruth and a former oil industry engineer, reported the slick associated with the Taylor spill was 10 miles long June 18. Using a standard method of estimating how much oil is present in a sheen on water based on work by scientists at the University of Florida, Amos reported the slick contained a minimum of 3,157 gallons of oil.

“If the Coast Guard is right and the average leak rate was 14 gallons a day, it would take 225 days at that rate to accumulate 3,157 gallons of oil on the surface,” Amos said Friday. “That means no biodegradation, no waves, no current, no thunderstorms to break it up. It is simply not plausible that oil collected on that spot for 225 days.”

Since 2004, hundreds of incident reports on the Taylor spill have been filed with the National Response Center, the federal agency tasked with documenting oil spills. Those reports contain widely divergent estimates of the amount of oil present on the Gulf’s surface from day to day.

For instance, a report from 2004, shortly after the leak began, describes a sheen 4 miles long and a half-mile wide. Federal officials estimated that sheen contained about a quarter of a gallon of oil.

Meanwhile, a report from July of 2008 described a sheen of identical size, but here the federal estimate was 336 gallons of oil.

“We’re losing confidence in the NRC data, as to whether those official estimates are doing a good job of informing the public about what is happening offshore,” Amos said. “How much oil is coming out of Taylor’s wells, that’s a good question.”

Federal officials refused to answer the question last week.

Leak rates are important during ongoing oil spills, such as the Deepwater Horizon incident, as federal penalties are based on how much oil is spilled.

The Clean Water Act fine associated with the 3,157 gallons estimated by Skytruth on June 18 would be more than $80,000. Federal officials declined to address whether any fines have been levied against Taylor.

The Press-Register could not find any record of Taylor fines during an examination of criminal and civil penalties assessed in the Gulf oil field by the federal government between 2003 and 2010.

Wednesday, July 7, 2010

Gulf awash in 27,000 abandoned wells...

...and no one at all is checking to see if they are leaking
By The Associated Press | Wednesday, July 7th, 2010

More than 27,000 abandoned oil and gas wells lurk in the hard rock beneath the Gulf of Mexico, an environmental minefield that has been ignored for decades. No one — not industry, not government — is checking to see if they are leaking, an Associated Press investigation shows.

The oldest of these wells were abandoned in the late 1940s, raising the prospect that many deteriorating sealing jobs are already failing.

The AP investigation uncovered particular concern with 3,500 of the neglected wells — those characterized in federal government records as "temporarily abandoned."

Regulations for temporarily abandoned wells require oil companies to present plans to reuse or permanently plug such wells within a year, but the AP found that the rule is routinely circumvented, and that more than 1,000 wells have lingered in that unfinished condition for more than a decade. About three-quarters of temporarily abandoned wells have been left in that status for more than a year, and many since the 1950s and 1960s — eveb though sealing procedures for temporary abandonment are not as stringent as those for permanent closures.

As a forceful reminder of the potential harm, the well beneath BP's Deepwater Horizon rig was being sealed with cement for temporary abandonment when it blew April 20, leading to one of the worst environmental disasters in the nation's history. BP alone has abandoned about 600 wells in the Gulf, according to government data.

There's ample reason for worry about all permanently and temporarily abandoned wells — history shows that at least on land, they often leak. Wells are sealed underwater much as they are on land. And wells on land and in water face similar risk of failure. Plus, records reviewed by the AP show that some offshore wells have failed.

Experts say such wells can repressurize, much like a dormant volcano can awaken. And years of exposure to sea water and underground pressure can cause cementing and piping to corrode and weaken.

"You can have changing geological conditions where a well could be repressurized," said Andy Radford, a petroleum engineer for the American Petroleum Institute trade group.

Whether a well is permanently or temporarily abandoned, improperly applied or aging cement can crack or shrink, independent petroleum engineers say. "It ages, just like it does on buildings and highways," said Roger Anderson, a Columbia University petroleum geophysicist who has conducted research on commercial wells.

Despite the likelihood of leaks large and small, though, abandoned wells are typically not inspected by industry or government.

Oil company representatives insist that the seal on a correctly plugged offshore well will last virtually forever.

"It's in everybody's interest to do it right," said Bill Mintz, a spokesman for Apache Corp., which has at least 2,100 abandoned wells in the Gulf, according to government data.

Officials at the U.S. Interior Department, which oversees the agency that regulates federal leases in the Gulf and elsewhere, did not answer repeated questions regarding why there are no inspections of abandoned wells.

State officials estimate that tens of thousands are badly sealed, either because they predate strict regulation or because the operating companies violated rules. Texas alone has plugged more than 21,000 abandoned wells to control pollution, according to the state comptroller's office.

Offshore, but in state waters, California has resealed scores of its abandoned wells since the 1980s.

In deeper federal waters, though — despite the similarities in how such wells are constructed and how sealing procedures can fail — the official policy is out-of-sight, out-of-mind.

The U.S. Minerals Management Service — the regulatory agency recently renamed the Bureau of Ocean Energy Management, Regulation and Enforcement — relies on rules that have few real teeth. Once an oil company says it will permanently abandon a well, it has one year to complete the job. MMS mandates that work plans be submitted and a report filed afterward.

Unlike California regulators, MMS doesn't typically inspect the job, instead relying on the paperwork.

The fact there are so many wells that have been classified for decades as temporarily abandoned suggests that paperwork can be shuffled at MMS without any real change beneath the water.

With its weak system of enforcement, MMS imposed fines in a relative handful of cases: just $440,000 on seven companies from 2003-2007 for improper plug-and-abandonment work.

Companies permanently abandon wells when they are no longer useful. Afterward, no one looks methodically for leaks, which can't easily be detected from the surface anyway. And no one in government or industry goes underwater to inspect, either.

Government regulators and industry officials say abandoned offshore wells are presumed to be properly plugged and are expected to last indefinitely without leaking. Only when pressed do these officials acknowledge the possibility of leaks.

Despite warnings of leaks, government and industry officials have never bothered to assess the extent of the problem, according to an extensive AP review of records and regulations.

That means no one really knows how many abandoned wells are leaking — and how badly.

The AP documented an extensive history of warnings about environmental dangers related to abandoned wells:
_ The General Accountability Office, which investigates for Congress, warned as early as 1994 that leaks from offshore abandoned wells could cause an "environmental disaster," killing fish, shellfish, mammals and plants. In a lengthy report, GAO pressed for inspections of abandonment jobs, but nothing came of the recommendation.

_ A 2006 Environmental Protection Agency report took notice of the overall issue regarding wells on land: "Historically, well abandonment and plugging have generally not been properly planned, designed and executed." State officials say many leaks come from wells abandoned in recent decades, when rules supposedly dictated plugging procedures. And repairs are so routine that terms have been coined to describe the work: "replugging" or the "re-abandonment."

_ A GAO report in 1989 provided a foreboding prognosis about the health of the country's inland oil and gas wells. The watchdog agency quoted EPA data estimating that up to 17 percent of the nation's wells on land had been improperly plugged. If that percentage applies to offshore wells, there could be 4,600 badly plugged wells in the Gulf of Mexico alone.

_ According to a 2001 study commissioned by MMS, agency officials were "concerned that some abandoned oil wells in the Gulf may be leaking crude oil." But nothing came of that warning either.
The study targeted a well 20 miles off Louisiana that had been reported leaking five years after it was plugged and abandoned. The researchers tried unsuccessfully to use satellite radar images to locate the leak.

But John Amos, the geologist who wrote the study, told AP that MMS withheld critical information that could have helped verify if he had pinpointed the problem. "I kind of suspected that this was a project almost designed to fail," Amos said. He said the agency refused to tell him "how big and widespread a problem" they were dealing with in the Gulf.

Amos is now director of SkyTruth, a nonprofit group that uses satellite imagery to detect environmental problems. He still believes that technology could work on abandoned wells.

MMS, though, hasn't followed up on the work. And Interior Department spokeswoman Kendra Barkoff said agency inspectors would be present for permanent plugging jobs "only when something unusual is expected." She also said inspectors would check later "only if there's a noted leak." But she did not respond to requests for examples.

Companies may be tempted to skimp on sealing jobs, which are expensive and slow offshore. It would cost the industry at least $3 billion to permanently plug the 10,500 now-active wells and the 3,500 temporarily abandoned ones in the Gulf, according to an AP analysis of MMS data.

The AP analysis indicates that more than half of the 50,000 wells ever drilled on federal leases beneath the Gulf have now been abandoned. Some 23,500 are permanently sealed. Another 12,500 wells are plugged on one branch while being allowed to remain active in a different branch.

Government records do not indicate how many temporarily abandoned wells have been returned to service over the years. Federal rules require only an annual review of plans to reuse or permanently seal the 3,500 temporarily abandoned wells, but companies are using this provision to keep the wells in limbo indefinitely.

Petroleum engineers say abandoned offshore wells can fail from faulty work, age and drilling-induced or natural changes below the seabed. Maurice Dusseault, a geologist at the University of Waterloo in Ontario, Canada, says U.S. regulators "assume that once a well is sealed, they're safe — but that's not always the case."

Even fully depleted wells can flow again because of fluid or gas injections to stimulate nearby wells or from pressure exerted by underlying aquifers.

Permanently abandoned wells are corked with cement plugs typically 100-200 feet long. They are placed in targeted zones to block the flow of oil or gas. Heavy drilling fluid is added. Offshore, the piping is cut off 15 feet below the sea floor.

Wells are abandoned temporarily for a variety of reasons. The company may be re-evaluating a well's potential or developing a plan to overcome a drilling problem or damage from a storm. Some owners temporarily abandon wells to await a rise in oil prices.

Since companies may put a temporarily abandoned well back into service, such holes typically will be sealed with fewer plugs, less testing and a metal cap to stop corrosion from sea water.

In the Deepwater Horizon blowout, investigators believe the cement may have failed, perhaps never correctly setting deep within the well. Sometimes gas bubbles form as cement hardens, providing an unwanted path for oil or gas to burst through the well and reach the surface.

The other key part of an abandoned wells — the steel pipe liner known as casing — can also rust through over time.

MMS personnel do sometimes spot smaller oily patches on the Gulf during flyovers. Operators are also supposed to report any oil sheens they encounter. Typically, though, MMS learns of a leak only when someone spots it by chance.

In the end, the Coast Guard's Marine Safety Laboratory handles little more than 200 cases of oil pollution each year.

And manager Wayne Gronlund says it's often impossible to tell leaking wells from natural seeps, where untold thousands of barrels of oil and untold millions of cubic feet of gas escape annually through cracks that permeate the sea floor.