Wastewater Injection Triggered Oklahoma's Earthquake Cascade

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Wastewater Injection Triggered Oklahoma's Earthquake Cascade
By Becky Oskin, Senior Writer | March 07, 2014 01:58pm ET

One of Oklahoma's biggest man-made earthquakes, caused by fracking-linked wastewater injection, triggered an earthquake cascade that led to the damaging magnitude-5.7 Prague quake that struck on Nov. 6, 2011, a new study confirms.

The findings suggest that even small man-made earthquakes, such as those of just a magnitude 1 or magnitude 2, can trigger damaging quakes, said study co-author Elizabeth Cochran, a seismologist with the U.S. Geological Survey.

"Even if wastewater injection only directly affects a low-hazard fault, those smaller events could trigger an event on a larger fault nearby," she told Live Science.


The Prague earthquake was the largest of thousands of quakes that rattled Oklahoma in late 2011. Three were magnitude-5 or stronger. The 2011 quakes struck along the Wilzetta fault, a fault zone near Prague. Earthquakes break faults like a boat plowing through thick ice — the fault zips open as the earthquake ruptures the fault, and then seals itself shut behind. Each of the three biggest quakes tore apart a different part of the Wilzetta fault, the researchers said. [Image Gallery: Deadly Earthquakes]

Triggered foreshock

The magnitude-5.7 earthquake near Prague was preceded by a 5.0 quake that hit a day earlier, on Nov. 5. This "foreshock" occurred near an active wastewater disposal well. The wastewater injection triggered the Nov. 5 earthquake, researchers concluded in a study published in March 2013 in the journal Geology. However, the Nov. 6 earthquake was farther from the wells.

"Just because two earthquakes occur close to each other in time and space doesn't necessarily mean they are related," said Cochran, who also co-authored the 2013 Geology study. "We wanted to look one step further and determine whether the stress change from the foreshock actually pushed the main shock rupture plane [the fault] to failure."

Earthquakes linked with fracking are rarely triggered by the actual oil-and-gas extraction. Rather, these quakes are caused by fluid disposal in deep wells. Fracking, short for hydraulic fracturing, involves injecting water, sand and chemicals into the Earth to crack open rock and remove oil and gas. The millions of gallons of waste fluids are usually pumped back into the Earth via deep "wastewater injection wells." The wastewater can lubricate or jack open fractures and faults, triggering earthquakes.

Fault primed

In the new study, the researchers modeled the stress added to the Wilzetta fault by the Nov. 5 earthquake (the foreshock). The findings suggest that the first earthquake primed the fault for another, larger earthquake, which, in this case, hit the next day. The study was published March 7 in the Journal of Geophysical Research.

"When you have an earthquake, the stress goes up in some places and down in other places," Cochran said. "We determined that the mainshock [the Nov. 6 Prague earthquake] occurred in an area that had an increase in stress."

The boom in fracking in the central United States has paralleled an uptick in seismicity, with moderate-size earthquakes increasing in Colorado, Texas, Oklahoma, Ohio and Arkansas. The number of quakes in the central United States has jumped 11-fold in the past 30 years, according to the March 2013 Geology study.

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Oklahoma Recognizes Role of Drilling in Earthquakes
By MICHAEL WINESAPRIL 21, 2015

Abandoning years of official skepticism, Oklahoma’s government on Tuesday embraced a scientific consensus that earthquakes rocking the state are largely caused by the underground disposal of billions of barrels of wastewater from oil and gas wells.

The state’s energy and environment cabinet introduced a website detailing the evidence behind that conclusion Tuesday, including links to expert studies of Oklahoma’s quakes. The site includes an interactive map that plots not only earthquake locations, but also the sites of more than 3,000 active wastewater-injection wells.

The website coincided with a statement by the state-run Oklahoma Geological Survey that it “considers it very likely” that wastewater wells are causing the majority of the state’s earthquakes.

The statement noted that the most intense seismic activity “is occurring over a large area, about 15 percent of the area of Oklahoma, that has experienced significant increase in wastewater disposal volumes over the last several years.”

The statement and the website’s acknowledgment amount to a turnabout for a state government that has long played down the connection between earthquakes and an oil and gas industry that is Oklahoma’s economic linchpin.

As recently as last fall, Gov. Mary Fallin, a Republican, indicated that suggestions of a relationship between oil and gas activity and seismicity were speculation, and that more study was needed.

In a news release issued Tuesday, Ms. Fallin called the Geological Survey’s endorsement of that relationship significant, and said the state was dealing with the problem.

“Oklahoma state agencies already are taking action to address this issue and protect homeowners,” she said in a statement.

Tuesday’s actions met a mixed response from the oil and gas industry and the governor’s critics. The Oklahoma Oil and Gas Association disputed the Geological Survey’s conclusions, saying in a statement that further study of the state’s quakes remained necessary.

“There may be a link between earthquakes and disposal wells,” the group’s president, Chad Warmington, said in the statement, “but we — industry, regulators, researchers, lawmakers or state residents — still don’t know enough about how wastewater injection impacts Oklahoma’s underground faults.”

Nor is there any evidence that halting wastewater injection would slow or stop the earthquakes, he said.

One of the most prominent advocates of stronger action on the earthquake issue, State Representative Cory Williams, a Democrat, said he had been pleasantly surprised by the change in what he called the state’s “head in the sand” approach to the quake problem.

But Mr. Williams, from earthquake-rattled Stillwater, criticized officials for failing to announce further steps to actually curtail the tremors.

Separately, he called on Tuesday for the state to halt wastewater disposal in a 16-county section of central and north-central Oklahoma that the Geological Survey has identified as posing the highest seismic risk.

“I want a moratorium and then an action plan,” he said. “The only way to protect the public is to say, ‘We’re done for now.’ ”

Oklahoma oil and gas regulators have taken steps to ensure that newly drilled disposal wells do not create seismic risks. But they say they have no authority to impose a moratorium, and only limited powers to address the existing wells that are behind the increase in tremors. Neither the governor nor the Legislature has pushed to increase their powers.

Ms. Fallin has also approved a directive from state regulators that Oklahoma insurance agents take courses in earthquake coverage. But few residents had coverage before the quakes began escalating in 2010, and policies have become increasingly restrictive as the pace of tremors has quickened. Some homeowners with significant damage have filed lawsuits seeking to recover repair costs from oil and gas operators.

In past decades, Oklahomans experienced only about one and a half earthquakes exceeding magnitude 3.0 in an average year. But since a boom in oil and gas exploration began in the mid-2000s, that number has mushroomed. The state recorded 585 quakes of 3.0 or greater last year, more than any state except Alaska, and is on course to register more than 900 such tremors this year.

Most of the quakes result in little more than cracked plaster and driveways, but residents in quake zones say the cumulative damage — to their property and to their nerves — is far greater.

Larger quakes have also occurred. A series of shocks in 2011 exceeding magnitude 5.0 caused millions of dollars in damage. Some seismologists have warned that the state is risking larger and more damaging quakes unless it acts to reduce the number of tremors.

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http://rt.com/usa/251905-fracking-study ... rthquakes/

Another slam-dunk for the anti-fracking lobby, as new evidence draws a more direct link between hydraulic fracturing and earthquakes in North Texas. The study is the first time researchers were able to move past ‘possible’ and into ‘most likely’ causes.

The Southern Methodist University (SMU) in Dallas conducted the work in partnership with USGS and the University of Texas. The study focused on a spate of earthquakes in the 2013-2014 period, near the city of Azle, and focused on creating a new model of induced seismicity – one involving comparisons in fluid pressure – unused in previous studies.

Even though the work, published in the journal Nature Communications, concerns itself with the last two years, the quakes are considered to be only the latest cluster in a series that started in 2008. Since then over 120 quakes hit North Texas. Prior to that year, scientists write, a felt earthquake had not been reported in the area in nearly 60 years.

SMU seismologists studied two intersecting faults and 3D-mapped the area to assess the degree to which fluid pressure played a part. They used the model to check for subsurface tensions caused by about 70 production and two wastewater injection wells in the area. These wells extract both, natural gas and significant volumes of salty water, known as brine. Their initial conclusions are that there is a connection.

"The model shows that a pressure differential develops along one of the faults as a combined result of high fluid injection rates to the west and high water removal rates to the east," Matthew Hornbach, associate professor of geophysics at SMU said. "When we ran the model over a 10-year period through a wide range of parameters, it predicted pressure changes significant enough to trigger earthquakes on faults that are already stressed."



The seismologists found that the stress levels caused by water fluctuations caused in Texas’ recent drought were tens of thousands of times smaller than the levels caused by fracking’s stress on the fault. This is called ‘induced seismicity’, i.e. it is man-made. That fact allows researchers to “rule out stress changes induced by local water table changes.

While some uncertainties remain, it is unlikely that natural increases to tectonic stresses led to these events,” Heather DeShon, another associate professor, said.

She explains that the more ancient faults in the region are susceptible to “surprisingly small changes,” which reactivated them, causing quakes.

This study is special because previously scientists were only able to investigate ‘possible’ links in the area, tying fracking with the disposal of natural gas production fluids. But the introduction into the study of variables from fluid pressure changes, caused by industry’s effects on water level fluctuations, allowed scientists for the first time to investigate whether fracking is ‘the most likely’ culprit.

Although a clearer link between fracking and earthquakes has been drawn with this latest study, SMU seismologists wish to point out that there are also thousands of fracking wells where no such link has been found. A growing body of evidence, however, continues to be in favor of the causal connection and necessitates further research.

“This report points to the need for even more study in connection with earthquakes in North Texas,” SMU’s Albritton Chair in Earth Sciences, Brian Stump, said. “Industry is an important source for key data, and the scope of the research needed to understand these earthquakes requires government support at multiple levels.”

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Oil companies can be sued by earthquake victim, Oklahoma court rules
Oklahoma has been hit by a dramatic spike in earthquakes in last 5 years
Thomson Reuters Posted: Jun 30, 2015 8:31 PM ET Last Updated: Jun 30, 2015 8:31 PM ET

Oklahoma experienced nearly 600 earthquakes last year, compared to just one or two annually prior to 2009.

An Oklahoma woman who was injured when an earthquake rocked her home in 2011 can sue oil companies for damages, the state's highest court ruled on Tuesday, opening the door to other potential lawsuits against the state's energy companies.

Oklahoma has experienced a dramatic spike in earthquakes in the last five years, and researchers have blamed the oil and gas industry's practice of injecting massive volumes of saltwater left over from drilling.

The state saw nearly 600 quakes of magnitude 3.0 or greater in 2014, compared to just one or two per year prior to 2009, according to the Oklahoma Geological Survey.

Oil production in Oklahoma has doubled in the last seven years, in part because drillers can dispose of vast amounts of saltwater found in oil and gas formations relatively cheaply by injecting it back into the ground.

That practice is separate from hydraulic fracturing or fracking, which has been linked to some smaller quakes but is not believed to be causing Oklahoma's tremors.

Oklahoma, home to major energy companies including Chesapeake Energy Corp., Devon Energy Corp., and Sandridge Energy Inc., has already tightened regulations on injection wells. The state is considering tougher rules, and lawsuits would further boost costs for energy companies.

Other potential suits

Falling rocks injured Sandra Ladra's legs when a 5.0 magnitude quake — the most intense in the state's history — toppled her chimney in 2011. She has sued two Oklahoma oil companies, New Dominion LLC and Spess Oil Company, which operate injection wells near her home in Prague, Okla.

A lower court ruled that the case had to go before the Oklahoma Corporation Commission, the regulator overseeing oil and gas, and dismissed Ladra's case in 2014.

On Tuesday, the Oklahoma Supreme Court reversed that decision, ruling that the commission's authority does not extend to the power to "afford a remedy" to those harmed by the violation of its regulations. The case will return to district court to decide whether Ladra should be granted any damages.

Ladra's lawyer, Arkansas-based Scott Poynter, told Reuters he can now move forward on several other potential suits from Oklahoma residents seeking compensation from energy companies for damages resulting from earthquakes.

Attorneys for New Dominion and Spess did not immediately respond to requests for comment.

Industry advocates on Tuesday downplayed the significance of the court's ruling, and cast doubt on whether Ladra and her attorneys could prove specific wells were responsible for the earthquake that caused her injuries.

Researchers say more work needs to be done to determine the exact mechanism of the link between underground injection and earthquakes, and whether location, volume, pressure, or other factors are the most significant.

Fracking under fire in Canada

Players in the Canadian oil and gas industry, especially those with fracking operations, are similarly coming under increasing scrutiny for both the connection to an increase in earthquakes and the alleged contamination of groundwater reserves.

Increased seismic activity throughout the natural-gas rich regions has been definitively linked to natural gas development, particularly to fracking. British Columbia's oil and gas commission recently tied 231 seismic events in the province's northeast to nearby fracking projects, for example.

Alberta fracking case to be heard by Supreme Court of Canada
That being said, no damage to infrastructure caused by fracking-related quakes has ever been recorded in Canada. Generally only earthquakes of at least magnitude 6.0 pose a significant structural threat to buildings. While B.C. and Alberta have recorded tremors of magnitude 4.4, no event of magnitude 6.0 or higher has ever been linked to fracking anywhere in the world.

As fracking projects continue in Canada, however, there will likely be legal challenges from residents and environmental groups who oppose the practice.

In April, the Supreme Court of Canada ruled it would hear the case of an Alberta woman who claims fracking operations have so badly contaminated her well that the water can be set on fire.

Jessica Ernst first took legal action against energy giant Encana in 2007 and later amended her claim to include Alberta Environment. A lower court ruled the provincial regulator was exempt from the suit, but Ernst and her legal team appealed the decision.

The Supreme Court will decide if Alberta Environment can be included in Ernst's suit.

Ernst says that fracking on her land northeast of Calgary has resulted in contamination of her well water and that her concerns were not properly investigated by the company and the province.

It's not clear when the top court will hear the case.