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29th July 2015
PART TWO......

Many scientific uncertainties

Scientists are now concerned that industry's potential to trigger unplanned seismic events has increased significantly with hydraulic fracturing and water well injection, because critically stressed faults can exist nearly anywhere. 

In addition, teams of scientists studying the issue in western Canada admit that they are dealing with much uncertainty because the shaking hazards caused by industry-triggered tremors can be greater than those from natural earthquakes. 

University of Western Ontario seismic hazard expert Gail Atkinson, the leader of a research effort called the Canadian Induced Seismicity Collaboration, explained that researchers "cannot predict the likelihood or magnitude of such events from specific planned operations because we do not have enough data on the complex natural rock systems, nor do we have validated predictive models." 

Nor do scientists know if industry-triggered events can change fluid and gas flows in the earth the same way that natural earthquakes can. 

Earth scientists, for example, have long observed that the energy released from natural earthquakes can force dramatic changes in groundwater flow, levels and quality. At the same time, the shaking motion caused by earthquakes can also release a variety of gases through newly formed faults and fractures in the ground. 

According to one industry textbook on the subject of gas migration, seismic activity can form "vertical and subvertical faults and fractures above petroleum reservoirs." As a result, the increased upward migration of radon, hydrogen sulphide, methane and carbon dioxide in seismically active areas "can become a major environmental hazard."

Despite research in Australia showing high levels of methane, radon and CO2 escaping from fracked landscapes into the atmosphere, no such monitoring is taking place in either Alberta or B.C. 

Once quiet, now seismically active

Although recent B.C. research sheds little insight on the impacts on groundwater and gas migration, it does show that the injection of highly pressurized fluids from hydraulic fracturing or wastewater disposal at depths of two kilometres can change pressure and trigger fault activity sometimes months after the blasting of fluids underground. 

The research began in 2012 after hundreds of mini-quakes were recorded in the Horn River basin. To get a handle on the growing problem, federal and provincial researchers have since installed eight more seismograph stations in northern B.C. to capture the ground shaking. 

A June 2015 study published in The Leading Edge reported that hydraulic fracturing had now turned a quiet seismic area into a highly active one. The paper concluded that "the level of local seismicity in the shale gas production area clearly has increased, both in number of events and in magnitude, as the scale of hydraulic fracturing operations expanded from late 2006 through 2011."

John Cassidy, a Natural Resource Canada seismologist and one of the paper's researchers, explained that the Horn River basin experienced some small natural tremors prior to hydraulic fracturing, but none in the shale gas zone. 

However, the introduction of fracking, which can pump down 25 million gallons of water into one horizontal well in the Horn River basin, changed local seismic patterns. 

The study also found that a higher volume of injected fluid (more than a million gallons a month) was a necessary "but not sufficient condition to induce larger earthquakes." 

In other words, large blasts of fluid into the ground only caused earthquakes in some places and at some times, perhaps due to pre-existing faults or background stress in the ground. 

"There is something else involved there and what it is - that's our focus. There appears to be a time delay in some cases, and we don't know exactly what's controlling that," Cassidy said. 

How frequent and how large the earthquakes can get is also part of the ongoing research. 

Meanwhile, the shaking has not stopped in the most active drilling area, the Montney Shale basin, a large swath of land stretching from northeast B.C. to northwest Alberta. Since the start of 2015, Natural Resources Canada recorded more than 79 earthquakes: seven exceeded magnitude 2.0. The BC Oil and Gas Commission estimates that the injection of wastewater produced from shale gas wells triggered at least 16 of the quakes. 

The B.C. research mirrors to a degree what's happening in Oklahoma, where the shale gas industry has made the state more seismically active than California. 

Last June, a Science paper concluded that injection wells shooting the most wastewater into the ground more than 300,000 barrels a month were more likely to be linked to earthquakes throughout Oklahoma. 

In particular, researchers linked four of Oklahoma's most prolific wastewater wells, which injected a total of three million barrels of salt water a month into the ground at depths between two and five kilometres, to a swarm of 2,547 small earthquakes near Jones, Oklahoma.

In contrast, high-volume hydraulic fracturing has caused the majority of B.C.'s industry-triggered quakes. 

Groundwater monitoring inadequate: scientists

To date, the BC Oil and Gas Commission says "there have been no cases of aquifer contamination resulting from induced seismicity." 

But hydrogeologists argue that the province's seven groundwater observation wells for an immense geography punctured by 8,000 high-volume, fractured horizontal wells is inadequate to the task at hand. (The Ministry of Environment collects samples from the wells periodically and tests for certain chemicals.)

"It is ridiculous for the B.C. government to refer to the seven shallow wells in that area or any other area as a 'groundwater observation network,'" said John Cherry, one of the nation's top groundwater researchers. 

Groundwater systems are so complex that proper monitoring requires scores of stations with many wells at different depths depending on the local geology, Cherry said. 

Gilles Wendling, a 55-year hydrogeologist with extensive experience in northern B.C., described groundwater resources in the region as an irreplaceable treasure. The province would need a multimillion-dollar groundwater monitoring network, he said, to demonstrate that neither hydraulic fracturing nor related earthquake activity have contaminated aquifers with hydrocarbons. 

"It's not being required, so why would industry do it?" Wendling asked. 

Moreover, industry-caused quakes pose a definite risk to groundwater, he said. "There is a chance industry-made earthquakes can create pathways for fluids, gas or liquids to move underground. They will move from the area where pressure is highest to the lowest... The migration will be upwards."

Neither industry nor citizens appreciate the importance and complexity of groundwater movement, he said. "The general public sees the subsurface as an inert place where there is no life, and if it's fractured, so what? The fact that there is a moving system of fluids 2,000 metres under our feet -- they can't visualize that."

Texas researchers have reported groundwater contamination with hydrocarbons overlying the Barnett Shale region.*

Risk to dams?

The importance of extensive earthquake monitoring in shale gas regions was recently underscored by Gail Atkinson and other researchers in a recent paper for Seismological Research Letters. 

Atkinson's team looked at three significant earthquakes set off by oil and gas industry: two magnitude 4.0 events near Fort St. John triggered by hydraulic fracturing, and one 3.5 event near Rocky Mountain House possibly set off by wastewater disposal or gas extraction.

The seismic hazard expert concluded "that moderate-induced events may be damaging to nearby infrastructure, because the shallow focal depth may result in localized strong ground motions to which some infrastructure may be vulnerable; this is a particular concern in low-to-moderate seismicity regions, because seismic design measures for structures in these regions may be minimal." 

As a consequence, the earthquakes have caught the attention of BC Hydro, which operates and maintains 79 dams at 41 sites across British Columbia.

Steven Rigby, chief of dam safety for BC Hydro, said in an email that the utility has been in discussion with the BC Oil and Gas Commission for a while on this issue. "Nothing official as yet, but certainly we'll be notified in advance of any new proposed licensing activity anywhere near our facilities, or any planned activity on existing licenses, so as to ensure the necessary discussions take place prior to any work." 

The U.S. Army Corps of Engineers has expressed a number of concerns with hydraulic fracturing. The agency says industry-triggered earthquakes could crack a dam, and that the transmission of frack fluids through natural faults could erode a dam's embankment.

Industry-made fractures in rock cannot always be controlled and tend to find the path of least resistance. Since 2010, hydraulic fractures have "communicated" with neighbouring well sites and drilling pads in northern B.C. more than 107 times.

*Due to a posting error, two paragraphs of this story were left out on first publication. They have since been re-added. [Tyee]

Andrew Nikiforuk is an award-winning journalist who has been writing about the energy industry for two decades and is a contributing editor to The Tyee