OKLAHOMA CITY (AP) The 37 wastewater disposal wells to be shut down in north-central Oklahoma, where a 5.6 magnitude earthquake struck this weekend, are just a fraction of the state's total number.

There are about 4,200 total wells across the state and about 700 in a 15,000-square-mile "Area of Interest" created by the commission to address earthquakes in the area that includes the epicenter of Saturday's temblor near Pawnee.

The earthquake tied a November 2011 quake as the strongest in recorded state history and was felt as far away as Nebraska, but no major damage was reported.

Not all of the state's wells operate simultaneously, Oklahoma Corporation Commission spokesman Matt Skinner said.

"We estimate that at any one time, there are about 3,200 active disposal wells," Skinner said.

An increase in magnitude 3.0 or greater earthquakes in Oklahoma has been linked to underground disposal of wastewater from oil and natural gas production, and since 2013, the commission has asked wastewater-well owners to reduce disposal volumes in parts of the state where the temblors have been most frequent. </s> When an earthquake struck Oklahoma on Saturday, one of the first steps state officials took was to shut down 37 of the state's 3,200 active disposal wells -- a move that drew national attention to the link between oil and gas drilling and earthquakes.

No one was seriously injured in the Oklahoma quake, and investigations and cleanup has begun. Here's what you need to know.

Disposal wells are used by oil and gas producers to get rid of wastewater from the drilling process. The wells push the wastewater deep underground, even deeper than where oil and gas are found.

The wastewater mostly consists of a substance called brine -- a mix of water and chemicals that comes to the surface with oil and gas when they are pumped from the Earth.

A small portion is also the water that's pumped underground in the modern hydraulic fracturing process, a drilling technique often referred to as fracking.

The EPA says there are about 40,000 disposal wells nationwide.

Did the disposal wells cause the earthquake?

That is the concern. Oklahoma didn't have much of a history of earthquakes. But a big one struck in November 2011, causing injuries and leveling houses, and officials said in 2014 that earthquakes in the state have increased 5,000%.

Scientists began looking into the role pumping liquid underground can play in seismic activity decades ago. And while much remains unknown, government scientists said in March that disposal wells have caused an increased risk for "induced" earthquakes in large areas of the country.

That includes the area where Saturday's earthquake occurred.

What's being done to stop it?

Oklahoma regulators have been monitoring the wells for years. In January, the state began forcing 27 disposal wells to reduce their activity. That's also when Oklahoma dedicated $1.4 million to fund "research and response" efforts.

Saturday's order that 37 wells shut down over the next 10 days marks the strongest action against disposal wells yet.

Why are disposal wells used?

The Oklahoma Oil & Gas Association said in April that producers would take "significant measures" to combat the earthquakes and promised to explore alternative disposal methods.

But OKOGA president Chad Warmington said "underground wastewater disposal is currently the safest and most cost-effective way to dispose of produced water."

Drillers also argue that recycling is more expensive, in part because they must pay to transport the wastewater to recycling facilities.

Some drillers do recycle. For example, about 90% of wastewater in Pennsylvania is recycled. In Texas, drought has spurred an increase in recycling.

But recycling has been slow to catch on in Oklahoma, and regulators have been criticized for not taking more aggressive action against disposal wells.

What happens next?

That's not clear. The state of Oklahoma has declared a state of emergency in the wake of Saturday's quake.

Halting or slowing the use of disposal wells won't necessarily resolve the seismic issues. Scientists studying the issue told PBS in March that even if Oklahoma shuttered all its disposal wells, the wastewater that has already been pumped can continue to cause problems.

And the ground is sensitive to sudden changes in disposal well pumping. In fact, Oklahoma regulators ordered the 37 wells offline over the course of 10 days for fear "that a large scale, sudden shutdown could cause an earthquake," according to authorities. </s> "I appreciate the quick response by the Department of Emergency Management and Department of Transportation to assess damage of the affected area and to ensure our state highway and turnpike bridges are safe. And I applaud the Oklahoma Corporation Commission, the state agency tasked with regulating the oil and gas industry, in taking swift action by ordering all Arbuckle disposal wells within a 725-square-mile area of today’s earthquake to shut down and working with the U.S. Environmental Protection Agency, which has sole jurisdiction over disposal wells in nearby Osage County. </s> Oklahoma officials on Saturday ordered oil and gas operators to shut down three dozen wastewater disposal wells following a 5.6-magnitude earthquake that tied a record as the strongest in state history.

The quake, centered near Pawnee, rattled the state just after 8 a.m. Eastern time Saturday, tying a record set in 2011 for the strongest such tremor in Oklahoma history, according to the National Weather Service.

Local officials reported moderate to severe damage and at least one nonlife-threatening injury.

“We are finding a lot of rural houses north, northwest of Pawnee that are seeing extensive damage,” Sheriff Mike Waters of Pawnee County said on Saturday.

Pawnee County Emergency Management posted photos on Facebook just before noon of a pile of rubble, noting that three buildings had moderate damage, while several others had minor damage. </s> Anchorage - A federal official says crews in Alaska are trying to shut down an oil well that is leaking explosive natural gas on the frozen North Slope.

The Environmental Protection Agency says a crack in a BP wellhead near Deadhorse sent up a mist of crude oil on Friday before it froze over and an initial leak stopped.

However, agency spokesperson Suzanne Skadowski says a second crack was discovered that's releasing flammable, explosive gas.

It's unclear how much has vented, but nearby workers have been evacuated and native Alaskan villages dozens of kilometres away have been notified.

The agency says the initial oil release may have affected an area of about one hectare and there were no reports of damage to wildlife.

Skadowski says the EPA, state and BP hope to shut down the well later on Saturday. </s> Five workers were missing after a fiery explosion on Monday at an oil and gas drilling site in eastern Oklahoma, officials said.



The fire had been fed by gas from a well being drilled for Red Mountain Energy by Patterson-UTI Energy Inc, preventing a full search of the scene throughout the day, but was later extinguished, the Pittsburg County Emergency Management Department (PCEMD) said in a statement.

Aerial video shows fires burning out of control 1:36



Houston-based Patterson-UTI said in a statement late on Monday the cause of the well explosion remained unclear. It said three of the five missing workers were its employees. Patterson-UTI declined to identify the workers, who were also

not identified by local authorities.



"Well control experts and emergency responders are on site and we will conduct a thorough investigation when the incident is fully contained," Patterson-UTI chief executive Andy Hendricks said in a statement. Houston-based Patterson-UTI said in a statement late on Monday the cause of the well explosion remained unclear. It said three of the five missing workers were its employees. Patterson-UTI declined to identify the workers, who were alsonot identified by local authorities."Well control experts and emergency responders are on site and we will conduct a thorough investigation when the incident is fully contained," Patterson-UTI chief executive Andy Hendricks said in a statement.

1 injured

PCEMD director Kevin Enloe said one of the 22 workers at the site when the explosion occurred was treated for injuries and 16 others were uninjured.



The blast occurred at around 9 a.m. CT near Quinton, Okla., about 235 km from Oklahoma City.

Kevin Enloe, director of Pittsburg County Emergency Management, speaks during a news conference to update details on a drilling rig explosion in Pittsburg County, Okla., on Thursday. (Mike Simons/Tulsa World/Associated Press)

The U.S. Occupational Safety and Health Administration, which investigates fatal workplace accidents, was closed on

Monday because of the federal government shutdown.



Boots & Coots, Halliburton's well control and prevention service, was called in to put out the fire. Staff from the

state's energy regulator, Oklahoma Corporation Commission, were also on the scene, officials said.

Series of accidents

The explosion is the latest in a series of accidents at oil and gas fields in the state. A gas explosion occurred at a

Trinity Resources well in the same area in February 2017, injuring a worker.



More recently, a 40-year-old Oklahoma man was killed in a backhoe accident this month at an oilfield near Ninnekah. A

worker was killed last month when equipment collapsed at a site near Preston, and a 36-year-old man was killed in November when a fitting failed during fracking at a well near Watonga, according to media reports.

Smoke billows from the site of the gas well fire near Quinton early Monday. (Kevin Harvison/McAlester News-Capital/Associated Press)

Accidents during oil and gas drilling claim about 100 lives a year in the United States, according to the U.S. Centers for

Disease Control (CDC). Using data from the Bureau of Labor Statistics, the CDC reported 1,189 workers were killed in the 11 years ended 2013, a period of intensive drilling.



Two-thirds of the fatalities involved transportation or contact with objects or equipment, the CDC found. More than 50

percent involved employees of oilfield service companies. </s> A federal official said crews in Alaska are trying to shut down an oil well that is leaking explosive natural gas on the frozen North Slope.

The Environmental Protection Agency said a crack in a BP wellhead near Deadhorse sent up mist of crude oil on Friday before it froze over and an initial leak stopped.

BP spokesman Brett Clanton said that “based on an overflight with infrared cameras, the release appears to be contained to the gravel pad surrounding the wellhead and has not reached the tundra.”

Clanton said BP is focused on safely securing the well.

However, agency spokeswoman Suzanne Skadowski said a second crack was discovered that’s releasing flammable, explosive gas.

It’s unclear how much has vented, but nearby workers have been evacuated and native Alaskan villages dozens of miles away have been notified.

No injuries have been reported.

There were no reports of damage to wildlife.

The agency said the initial oil release may have affected an area of about one-and-a-half acres.

Skadowski said the EPA, state and BP hoped to shut down the well on Saturday. </s> OKLAHOMA CITY (AP) — A record-tying earthquake in the edge of Oklahoma’s key energy-producing areas rattled the Midwest from Illinois to the southwest part of Texas on Saturday, and likely will bring fresh attention to the practice of disposing oil and gas field wastewater deep underground.

The United States Geological Survey said a 5.6 magnitude earthquake happened at 7:02 a.m. Saturday in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region.

An increase in magnitude 3.0 or greater earthquakes in Oklahoma has been linked to underground disposal of wastewater from oil and natural gas production.

The Oklahoma Corporation Commission, which since 2013 has asked wastewater-well owners to reduce disposal volumes in parts of the state, is requiring 37 wells in a 514 square mile area around the epicenter of the earthquake to shut down within seven to 10 days because of previous connections between the injection of wastewater and earthquakes.

“All of our actions have been based on the link that researchers have drawn between the Arbuckle disposal well operations and earthquakes in Oklahoma,” spokesman Matt Skinner said Saturday. “We’re trying to do this as quickly as possible, but we have to follow the recommendations of the seismologists, who tell us everything going off at once can cause an (earthquake).”

Skinner said the commission’s “area of interest” includes another 211 square miles in Osage County, but doesn’t know how many wells may be involved because the area is under the jurisdiction of the Environmental Protection Agency, and that the commission is working with that agency.

“EPA decides on the wells in Osage County. We don’t know anything about Osage County, legally we’re not even allowed to ask,” Skinner said.

People in Kansas City and St. Louis, Missouri; Chicago; Gilbert, Arizona; Fayetteville and Little Rock, Arkansas; Des Moines, Iowa; Memphis, Tennessee; and Big Lake in southwest Texas, all reported feeling the earthquake. Dallas TV station WFAA tweeted that the quake shook their studios, too.

Pawnee County Emergency Management Director Mark Randell said no buildings collapsed in the town of 2,200 about nine miles southeast of the epicenter. “We’ve got buildings cracked,” Randell said. “Most of it’s brick and mortar, old buildings from the early 1900s.”

Randell also said a man suffered a minor head injury when part of a fireplace fell on him as he protected a child. The man was treated and released.

Oklahoma Gov. Mary Fallin has declared a state of emergency for the county, allowing state agencies to make emergency purchases related to disaster relief and preparedness. The declaration is also the first step toward seeking federal aid should it be necessary

The damage is not as severe as the 2011 quake near Prague, Oklahoma, about 60 miles south of Pawnee, despite being the same magnitude and approximately the same depth. Saturday’s was 3.7 miles deep, compared to 3.1 miles in 2011. Both are shallow quakes, during which shaking is more intense, like setting off “a bomb directly under a city,” USGS seismologist Susan Hough has said.

However, hard bedrock beneath the surface in north-central Oklahoma is likely the reason for less damage, Oklahoma Geological Survey geophysicist Jefferson Chang said, adding that the subsurface around Prague is softer.

“It’s pretty much comparable to the Prague event,” Chang said. “But in harder rock, it won’t shake as much.”

Pawnee furniture store owner Lee Wills told The Associated Press that he first thought it was a thunderstorm.

“Then it just … Everything went crazy after that. It just started shaking,” said Wills, who lives about 2½ miles outside of town. “It rocked my house like a rubber band. Threw stuff off cabinets and out of cabinets, broke glasses.”

Sandstone bricks from the side of the historic Pawnee County Bank litter the sidewalk after an early morning earthquake in Pawnee, Oka., on Saturday, Sept. 3, 2016. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. (Paul Hellstern/The Oklahoman via AP) Sandstone bricks from the side of the historic Pawnee County Bank litter the sidewalk after an early morning earthquake in Pawnee, Oka., on Saturday, Sept. 3, 2016. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. (Paul Hellstern/The Oklahoman via AP) Sandstone bricks from the side of the historic Pawnee County Bank litter the sidewalk after an early morning earthquake in Pawnee, Oka., on Saturday, Sept. 3, 2016. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. (Paul Hellstern/The Oklahoman via AP) Sandstone bricks from the side of the historic Pawnee County Bank litter the sidewalk after an early morning earthquake in Pawnee, Oka., on Saturday, Sept. 3, 2016. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. (Paul Hellstern/The Oklahoman via AP) Kyndra Richards cleans up at “White’s Foodliner” after an early morning earthquake in Pawnee, Oka., on Saturday. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region. Kyndra Richards cleans up at “White’s Foodliner” after an early morning earthquake in Pawnee, Oka., on Saturday. The United States Geological Survey said a 5.6 magnitude earthquake happened Saturday morning in north-central Oklahoma, on the fringe of an area where regulators had stepped in to limit wastewater disposal. That temblor matches a November 2011 quake in the same region.

Associated Press writers Kelly P. Kissel in Little Rock, Arkansas, Erica Hunzinger in Chicago and Ben Thomas in Washington, D.C., contributed to this report. </s> A federal official says crews in Alaska are trying to shut down an oil well that is leaking explosive natural gas on the frozen North Slope. The Environmental Protection Agency says a crack in a BP wellhead near Deadhorse sent up mist of crude oil Friday before it froze over and an initial leak stopped.

Start the conversation, or Read more at KWWL-TV Waterloo.
State officials order closure of three dozen wastewater disposal wells by oil and gas operators.