Does Gas Fracking Cause Earthquakes?
It’s only a dozen years ago that "slick-water fracks" were introduced. This form of fracking uses huge amounts of water mixed with sand and dozens of toxic chemicals like benzene, all of which is injected under extreme pressure to shatter the underground rock reservoir and release gas trapped in the rock pores. Contamination of fresh water, and potential damage to aquifers are already major concerns, but now communities need to think about the possibility that the practice can trigger earthquakes.
The US federal Environmental Protection Agency (EPA) has just begun a comprehensive two-year study into the risks associated with hydraulic fracturing (called "fracking") in the oil and gas industry, which argues that it's been safely fracking for some sixty years.
But it's only a dozen years ago that "slick-water fracks" were introduced. This form of fracking uses huge amounts of water mixed with sand and dozens of toxic chemicals like benzene, all of which is injected under extreme pressure to shatter the underground rock reservoir and release gas trapped in the rock pores. Not only does the practice utilize millions of gallons of freshwater per frack (taken from lakes, rivers, or municipal water supplies), the toxic chemicals mixed in the water to make it "slick" endanger groundwater aquifers and threaten to pollute nearby water-wells [see "Frack Attack," March-April 2010, Watershed Sentinel].
Horizontal drilling and multi-stage fracking (which extend fractures across several kilometres) were introduced around 2004 and are now used across North America. As conventional natural gas dwindles, the industry is drilling for "unconventional" sources like shale gas, which depend on these new production methods. The toxic flowback wastewater from fracking (as much as 3 million gallons per well) is usually re-injected into deep disposal wells.
On January 21, several leading US investment companies (including Trillium Asset Management) announced they have filed shareholder resolutions with nine major oil and gas companies, pressing them to disclose their plans for managing "the water pollution, litigation and regulatory risks increasingly associated with ever-expanding natural gas hydraulic fracturing operations." The investment firms' press release notes: "Concerns about water contamination incidents are growing as operations expand, creating reputational and litigation liabilities for companies."
While much of the concern about fracking relates to its impact on potable water supplies, other impacts include air pollution, wastewater disposal, industrialization of farm land, increased carbon dioxide emissions, and destruction of wildlife habitat from multi-pad fracking sites that can be as large as five square acres.
But there's another impact that is less well known.
Official written comments submitted to the EPA by the environmental group Natural Resources Defense Council asked that the EPA also "look at the potential for fracking to cause earthquakes." In 2009, the Wall Street Journal (June 12) called earthquakes "the natural gas industry's big fracking problem."
Texas' Barnett Shale
In north-central Texas, the Barnett Shale field has some 14,000 natural gas wells and at least 200 wastewater disposal injection wells. In recent years, a series of small, but measurable and felt earthquakes have hit Cleburne, Irving and the Dallas/Fort Worth area. The Fort Worth Business Press (June 10, 2009) stated: "It's clear the incidence of earthquakes has increased as Barnett Shale production increased during the past two decades."
Slick-water fracks were first introduced in the Barnett Shale field. Subsequently, the number of wells drilled in the area went from a yearly average of 73 in the late 1990s to 2,500 in 2007.
Dallas News (Nov. 1, 2008) interviewed John Ferguson, a geosciences professor at the University of Texas at Dallas, and reported: "Nobody knows exactly what causes a particular quake, Dr. Ferguson said. But it's possible that the recent increased drilling and extraction of natural gas from the Barnett Shale had an effect. The extraction process affects the fluid pressure deep inside the earth, which is the sort of thing that could nudge a nearby fault, he said. It's happened elsewhere."
But a spokesman for major shale gas producer Devon Energy Corp. countered that drilling has never been connected to any significant earthquake. "To draw a correlation between earthquakes and oil and gas production, that just hasn't happened."
Nonetheless, the Wall Street Journal (June 12, 2009) reported that, in Cleburne, Texas, where thousands of natural gas wells have been drilled and fracked, "More earthquakes [at least 100] have been detected in the area since October  than in the previous 30 years combined." The WSJ report continued: "Oil and gas production has been suspected of causing earthquakes in the past, including in Texas, particularly when it involves injecting fluids into the ground."
In August 2009, researchers from Southern Methodist University in Dallas said the preliminary results of their study show a "possible correlation" between disposal injection wells and small earthquakes in the Dallas/Fort Worth area.
Arkansas Earthquake "Swarms"
Since October 2010, the town of Guy, Arkansas has experienced hundreds of small, but felt, earthquakes, sometimes coming at a rate of three or four per minute. Seismic researchers at the Arkansas Geological Survey (AGS) have been investigating this earthquake "swarm," the largest of which was a "moderate" size 4.0 magnitude quake on October 11 and more recently, a 4.3 magnitude on February 18, 2011.
In the past six years, nearly 3,700 natural gas wells have been drilled and fracked in the Arkansas Fayetteville Shale field, most of them in a four-county area of which the town of Guy is almost dead-centre. There are at least six disposal wells within a 500-square-mile zone around Guy. Some of the disposal wells have reportedly been injected with more than 10.5 million gallons of fracking wastewater each month in recent years.
On October 15, Scott Ausbrooks, AGS geohazards supervisor, said, "What we believe is happening is when the old [fracking flowback] water is put into the deeper [disposal] wells, it reduces the friction in the fault [fault-line]. This doesn't cause a quake, it just speeds up the process. The quake will happen somewhere down the line anyway, but this process may be making them happen sooner."
The local press reports "a shocking surge" in quake activity. The number of earthquakes recorded in Arkansas for 2010 - more than 600 - nearly equals all of Arkansas' quakes for the past 100 years.
In late October, the website for Arkansans for Gas Drilling Accountability stated: "We now have a total of over one hundred earthquakes for October and we still have days to go. Just think. Fracking and injection wells cause earthquakes...earthquakes can damage cement casings...cement casings are the front line defence to protect our water from toxic fracking fluids."
In November, 200 local residents packed the school cafeteria in Guy, demanding that drilling be stopped. According to CNN (December 13, 2010), the state government has now issued a moratorium on further injection wells and new drilling in the area. But during the first two weeks of January 2011, Guy experienced another six quakes.
On February 17, Scott Ausbrooks of the AGS told AOL News that the earthquakes "are getting stronger" and that he can see a "direct correlation" with disposal wells.
In New York state, thousands of gas wells are being planned, including in urban areas.
"They're already drilling all over Buffalo," researcher/activist Pat Carson told me in a recent phone interview. "There's been a steady increase in local quakes in western New York since drilling began in this area. The industry "plans on fracking right along Lake Erie, where there's a huge fault line." If they trigger that, she said, it could be catastrophic for the whole region.
New York lawyer/activist Rachel Treichler is working to oppose fracking wastewater disposal wells planned for the upstate Finger Lakes region. "We have had two earthquakes in upstate New York that are associated with disposal wells," she told me. "No community is a proper site for a deep injection well disposing of toxic fluids." There are too many reports of contamination and earthquakes from these types of wells, she says.
On February 8, 2011, Buffalo City Council banned fracking and waste water disposal within city limits and is warning all Great Lakes cities to do the same.
Central Oklahoma has been hit with a series of at least six earthquakes since October 2010, including a 5.1 magnitude quake on October 13 - the second strongest in the state's history. Oklahoma has been the site of extensive natural gas drilling and fracking in the Arkona Natural Gas Basin. The local press states that 2009 and 2010 "have been peak years for earthquakes" in Oklahoma. When asked if that could be connected to the drilling, Andrew Holland, a seismologist for the Oklahoma Geological Survey, said, "At this point, we don't see any indication that that's the case. But I'm examining it as a real possibility. The jury is still out, I'd say."
West Virginia, part of the Marcellus Shale field, has experienced at least eight small earthquakes in the Braxton County area since April 2010. Martin Chapman, director of Virginia Tech Seismic Observatory, told the Associated Press (AP) (September 2) that earthquakes are rare in the area. "Something's going on there," he said, "and I have a strong suspicion that it's something associated with [gas] drilling." According to the AP report, "Some geologists suspect high pressure and wastewater have lubricated old fault-lines, allowing them to slip and trigger small earthquakes."
Marshall University geology professor Ronald Martino told AP that it's "quite possible" the quakes are linked to the high-pressure injection of fluids. "Geologists have known of a possible link between fluid injection and small quakes for a half-century, he said, and the potential impact on fault lines under Braxton County should be explored further."
In May 2009, Calgary geologist Jack Century, president of J.R. Century Petroleum Consultants Ltd., gave a speech to communities in the Grande Prairie, Alberta area addressing the issue (among others) of "human-induced seismicity." He was hosted by the Peace River Environmental Society.
Century, who has been in the industry for decades, said that "many induced earthquakes" have resulted from oil and gas industry activity. "Mostly, it's the injecting of water, but also it's just production of oil and gas in big fields that happen to be overlying faults [fault-lines] in the earth." He said the "unloading of massive amounts of fluids changes the pressure where these faults are and causes them to move." He added, "Once local seismicity starts, it can't be turned off."
Dr. David Oppenheimer, a seismologist with the US Geological Survey, told Power Magazine (July 2009) that fracking could certainly generate seismic activity "because that is how the [hydraulic] fractures are made." The journal's August 2009 issue reported that Dr. Christian Klose, a geophysical hazards research scientist at Columbia University said that, "the quake risk is intensified by hydrofracturing."
Dr. Klose also considers carbon capture and storage (CCS) a possible cause of induced seismicity. In the Nov-Dec. 2009 Watershed Sentinel, Stephen Leahy reported that according to Dr. Klose, the CCS demonstration site at Norway's Sleipner gas field in the North Sea may have triggered a magnitude 4.0 earthquake in the area. In mid-December 2010, Stanford geophysicst Mark Zoback also warned that CCS could trigger small to moderate earthquakes through the injection of massive amounts of carbon dioxide into the subsurface. "When we start perturbing the system by changing fluid pressure, we have the potential for activating faults," he told the press. "While the seismic waves from such earthquakes might not directly threaten the public, small earthquakes at depth could threaten the integrity of CO2 repositories expected to store C02 for periods of hundreds to thousands of years."
Jack Century told his audience that, in March 2007, he attended a Calgary meeting of the Geological Survey of Canada, with 25 GSC geologists in attendance. One of the "main issues" discussed was "the risk of earthquakes induced by the mining and removal of billions of tonnes of overburden from tar sands bitumen." Century presented a paper there called "Tar Sands: Key Geologic Risks." As he recalled for his 2009 audience, "Nine months after warning that human-induced earthquakes could result from aggressive tar sands development, a magnitude 3.8 earthquake occurred near Fort McMurray." Century was unavailable for an interview by press-time.
Peace River Arch
In his 2009 speech, Jack Century referred to "the seismically active Peace River Arch" - a major geologic structure which extends from High Prairie, Alberta to Fort St. John, BC - and said there is "serious earthquake risk" there. In April 2001, an earthquake measuring 5.3 on the Richter scale hit northeastern BC and northwestern Alberta, centred 40 kilometres northeast of Dawson Creek, where Blair Lekstrom was mayor at the time. It was the largest earthquake in the area in 50 years. Dawson Creek (located in the Montney Shale field) is 72 kilometres southeast of Fort St. John. The W.A.C. Bennett dam, built in the l960s and located in the area, was unharmed.
In June 2010, Lekstrom (MLA for Peace River South) resigned from his cabinet position as BC Minister of Energy, Mines and Petroleum Resources, citing policy disagreement over the harmonized sales tax. But as Charlie Smith noted in the Georgia Straight (June 11), "Lekstrom's resignation comes shortly after the BC government declared that it was going to seek regulatory approval for the Site C dam on the Peace River," to be located about seven kilometres southwest of Fort St. John. "In addition," wrote Smith, "the BC government has sat on the sidelines as oil-and-gas companies have ramped up the controversial practice of hydraulic fracturing to extract natural gas in northeastern BC."
Local citizens in the Peace are predicting that the frenzy of drilling in the area will likely remove as much as 135 billion litres of freshwater per year from the watershed for the purposes of fracking. According to Andrew Nikiforuk (The Tyee, October 15, 2010), in northeastern BC, "the shale gas industry now has permits to daily withdraw up to 274,956 cubic metres or 60,481,864 imperial gallons from 540 creeks, rivers and lakes as well as aquifers."
In his October 2010 report called "24/7 Less Peace in the Peace," Will Koop of BC Tap Water Alliance (www.bctwa.org) reveals that at Talisman Energy's Lynx Creek site, "The BC Oil and Gas Commission has authorized a revised withdrawal limit here of 5,000 cubic metres (1,100,000 imperial gallons, or 5 million litres) per day. That's almost enough water for 2 frack jobs."
Koop's November 9th report on EnCana's natural gas Cabin Lake project in the Horn River Basin near Fort Nelson ("EnCana's Cabin Not So Homey") states that the company is averaging 28 fracks per well. Earlier last year in the Horn River Basin, EnCana and Apache conducted 274 consecutive fracks over a 100-day period - a global record.
Standard industry practice in the area is to dispose of the massive volumes of toxic fracking flowback water by re-injecting it into deep disposal wells. Talisman's senior vice-president Jim Fraser told the Daily Oil Bulletin (July 19, 2010), "As far as what we're going to do with the water when we get it back, fortunately in BC and Alberta there's numerous opportunities for commercial disposal which are sub surface underground injection. So that's our plan going forward in the Montney [Shale field]. I think it's a very good way to dispose of water."
But in the US, these deep disposal wells are being linked to quakes.
Jack Century told his audience that since 1984, dozens of induced earthquakes have occurred east of Fort St. John, measuring up to a 4.3 magnitude, "and they are still ongoing." But "industry denies it all," he said. "They say the earthquake was going to happen anyway."
Century said that in 1995 he presented a paper, called "Oil and Natural Gas Induced Seismicity," to the American Association of Petroleum Geologists and then to the Canadian Society of Petroleum Geologists, but the industry showed little interest in the topic.
That attitude may be changing, however.
The Canadian Society of Exploration Geophysicists website listed a course being offered in November 2010 by two geophysicists from Schlumberger - one of the top hydraulic fracturing companies in the world. The (partial) course description: "The increasing interest in shales as reservoir rocks, and the use of horizontal wells and active fracture treatments, has led to a rapid growth in the application of microseismic monitoring projects to better understand what these interventions [i.e. horizontal drilling and fracking] are actually doing in the subsurface...The course will cover some basic earthquake monitoring ideas and the methods used to locate and quantify them, and then extend this to the monitoring of microseismic events caused by hydraulic fracturing activity, or reservoir movement through depletion, injection or other externally imposed activities."
Meanwhile, the reputation of shale gas - as a "clean" fossil fuel that could last for a hundred years or more - is rapidly deteriorating. On January 25, 2011, ProPublica's Abrahm Lustgarten reported that new research by the EPA shows that greenhouse gas emissions from hydraulic fracturing for shale gas "are almost 9,000 times higher than it had previously calculated" because of the methane emissions associated with the full life-cycle of gas production. [See "Methane: Integrity versus Integrity Management," Watershed Sentinel, September-October 2010.]
And the Toronto Star's energy reporter Tyler Hamilton (July 26, 2010) has called most industry estimates of natural gas supply "a gross exaggeration." He wrote: "Some petroleum geologists say the ‘probable' supply [in North America] is less than 20 years, and that shale gas represents maybe seven years of that supply."
In other words, the drilling and fracking endanger the groundwater, deplete rivers and lakes, and threaten earthquakes all for a quick payoff to industry, after which the local taxpayers are left with the consequences.
In February 2010, while discussing Schlumberger's proposed merger with Houston-based drilling specialist Smith International, Schlumberger CEO Andrew Gould said that shale gas production is characterized by "brute force and ignorance." That seems a fair appraisal of the entire shale gas "revolution."
Joyce Nelson is a freelance writer/researcher and author of five books.