By Andrew Mah
At 11:27 a.m. on Tuesday, January 12, 2016, a low rumble was felt by some residents of Fox Creek, Alberta. The town, a centre for natural gas production in the Duvernay formation, is located about 260 kilometres northwest of Edmonton. Roy Dell, the chief administrative officer for the town, was in a meeting at the time.
“Personally, I didn’t feel the event,” he says, “But others did. The mayor described it as the kind of shake you get when a truck drives by.” Seismic monitoring connected this seismic event, which had a local magnitude of 4.5 ML according to Natural Resources Canada, to a hydraulic fracturing operation just west of Fox Creek.
There were no injuries or property damage caused by the event, and in compliance with Alberta Energy Regulator (AER) regulations, the hydraulic fracturing operation was immediately shut down.
Dell notes that the event, the third in the area to measure greater than 4.0 ML over the past two years, has raised some concerns regarding induced seismicity among the 2,000 residents of the northern Alberta community. It has also generated media attention, bringing fresh scrutiny to the practice of hydraulic fracturing.
REACHING OUT TO THE COMMUNITY
“While rare, any time there’s a seismic event felt at the surface that’s related to hydraulic fracturing, that’s something industry takes very seriously,” says Chris Montgomery, CAPP’s manager of exploration and production communications and engagement.
A necessary step, and a key part of Montgomery’s job, is to reach out to local community members: to share knowledge and listen to concerns. He’s visited the town of Fox Creek several times over the past few years, including soon after the January event. He’s met with town council, residents and the town’s business support network.
During these meetings, he presents the latest scientific and fact-based information on issues related to hydraulic fracturing, including induced seismicity. Montgomery notes that the responses have generally been positive, and that knowledge of the issues has grown with time.
“We’re able to let residents know there’s a great deal of research and collaboration going on right now among regulators, industry and experts in seismology into the phenomenon of induced seismicity. At the same time, we can reassure them that hydraulic fracturing is a technology that’s been safely used in the Western Canadian Sedimentary Basin for almost 60 years without any reported instances of injury or property damage,” Montgomery says.
Dell agrees that responsive engagement by industry is helpful: “It’s very important. We are an oil and natural gas town, and people understand the risks associated with development—it’s the livelihood of the town. However, if there are incidents, I believe the townspeople should be notified quickly.”
SEISMICITY AND HYDRAULIC FRACTURING
It is now generally accepted that hydraulic fracturing in certain areas can trigger induced seismicity. Hydraulic fracturing is, after all, the literal fracturing of layers of rock two kilometres or deeper below the earth’s surface. (For a visual perspective, the height of Calgary’s tallest building, The Bow, is 236 metres—that's one tenth the depth at which hydraulic fracturing occurs). The energy released through this process generates small tremors within rock layers very near the hydraulic fracturing, called microseismic events. Due to the great depth and small magnitude of these events (from <-3 ML to -1 ML), they are imperceptible at the surface. These events can only be detected by very sensitive seismic recording devices.
Once in a while, higher magnitude events of 3.0 ML and above can occur. At above 4.0 ML, seismic events begin to be felt at the surface, but typically cause no damage. These events are called anomalous (or irregular) induced seismicity because higher magnitude events are unusual in association with hydraulic fracturing. It’s believed they occur when the hydraulic fracturing area coincides or connects with a naturally occurring, pre-existing buried geological fault line (a break in the rock layer), causing that fault to shift or slip.
Recent larger seismic events that have been linked to hydraulic fracturing in the Western Canadian Sedimentary Basin (WCSB) include three events in the Fox Creek region of the Duvernay, and one near Fort St. John in the Montney Formation in British Columbia.
CAUSES OF ANOMALOUS INDUCED SEISMICITY
David D’Amico is manager of geoscience— North American subsurface development at Repsol Oil & Gas Canada Inc. The 4.5 ML January 2016 event near Fox Creek has been associated with a Repsol hydraulic fracturing operation.
“In situations like these, the safety of the public and our workers is always our number one concern,” says D’Amico. “As soon as we detected the event, we immediately ceased operations and reported the incident to the AER as required. We then began reaching out to area stakeholders, including community leaders in Fox Creek.”
D’Amico notes that while hydraulic fracturing is a proven technology, a number of factors may be at play in relation to these recent larger seismic events.
One factor is advances in hydraulic fracturing technology which allow for the pumping of water at higher rates and greater pressure using multiple stages. This creates more energy underground that can potentially trigger a seismic event.
A second factor is the overall increase during the past few years of the number of wells completed with hydraulic fracturing. “While the risk of induced seismicity might remain very small for any given individual well, or within a certain area, the larger number of hydraulic fracturing operations spread over a larger regional footprint means you have a greater statistical probability to expose that risk,” explains D’Amico.
A third factor is the unique features of the local geology, such as the existence of critically-stressed, pre-existing faults. The clustering of events near Fox Creek and a few other areas suggests this might be an important variable.
“There are some places, even within other parts of the same Duvernay play, where there is no seismicity strong enough for us to measure even with our sensitive induced seismicity monitoring,” says D’Amico.
D’Amico further cautions that while the occurrence of several high-profile seismic events might give the impression that there’s been a jump in induced seismicity, “it’s still a very rare occurrence.” Indeed, a recent publication [Atkinson et al, 2016] identified only 39 hydraulically fractured wells (0.03 per cent) correlated with >3.0 ML seismicity out of a total of 12,289 hydraulically fractured wells from 1985- 2015 in the WCSB.
MITIGATING SEISMICITY: REGULATIONS
Regulators in British Columbia (B.C. Oil and Gas Commission) and Alberta (the AER) have introduced the requirement for continuous seismic monitoring during hydraulic fracturing operations in areas where seismicity is an issue. As well, both regulators have instituted a risk-based protocol requiring the reporting of all seismic events of 2.0 ML or greater, and an immediate suspension of operations if a 4.0 ML or greater event is detected.
“These regulations are in place to reduce the risk of seismicity associated with hydraulic fracturing operations,” notes Ryan Bartlett, senior advisor of public affairs at the AER. “The requirements ensure the safe, orderly, and environmentally responsible development of energy resources while minimizing the risks to the public and environment.” Bartlett adds that the AER posts information about any event 4.0 ML or greater to its Compliance Dashboard available on their website.
The BC OGC has published two studies, one investigating seismicity in the Montney and the other in the Horn River Basin. The AER is currently working with industry and experts in seismology to better understand the factors causing the reported events in the Fox Creek area.
“We began a formal study in September 2015,” notes Bartlett. He adds that the study is led by a team of experts from the AER’s Alberta Geological Survey (AGS) branch. The team consulted with energy operators in the region, as well as seismology experts at Natural Resources Canada, the University of Alberta, University of Calgary, Western University and the BC OGC. An interim report is due out in May, with a final report arriving in November.
“This should be a pretty significant study,” Bartlett notes. “The results will give us a better understanding both of the geological conditions present in the subsurface, and how hydraulic fracturing in the area contributes to induced seismicity.”
“The goal is to use this knowledge to further refine our regulations to ensure public safety and environmental protection.”
MITIGATING SEISMICITY: INDUSTRY LEADING RESEARCH
While regulators are quickly adapting to the issue of induced seismicity, industry is looking to lead the way in understanding the underlying science and what operational factors contribute to events. This has led to an unprecedented level of collaboration among the different companies operating in the WCSB.
“As an industry, we’ve been working together with academia and regulators to come up with a framework of operating guidelines and procedures,” says Leanne Laverick, external relations advisor at Shell. Shell has operations in the Duvernay and is one of 12 companies participating on CAPP’s Induced Seismicity Task Group, which has a mandate to “engage in deep sharing of industry best practices in mitigation and management of induced seismicity risk from hydraulic fracturing.”
The key for D’Amico, who sits on both CAPP’s Induced Seismicity Task Group, and an operators group specific to the Fox Creek region, is industry’s willingness to share data with regulators, academics and each other—a level of sharing D’Amico calls “unprecedented in my career.”
“Each operator has seismic monitoring arrays to monitor their own operations. By sharing this data, we can all get a more accurate representation of the location, depth and magnitude of seismic events throughout the region, as well as hydraulic fracturing operational factors like flow rate and fluid pressure occurring just prior to and during these events,” says D’Amico. “This allows for a much more sophisticated and regionalized data analysis.”
This data analysis includes work being done in cooperation between industry and academic researchers like David Eaton, a professor in the Department of Geoscience at the University of Calgary.
“Industry’s been very supportive of working with us to gain a deeper scientific understanding of the mechanisms underlying induced seismic events,” says Eaton. Professor Eaton is also the NSERC/ Chevron Industrial Research Chair in Microseismic Dynamics, and leads a team investigating regional differences in the geological response to fluid injection within North America.
“This research could help companies and regulators quantify the hazard potential for induced seismicity based on a site-specific geological model,” he says.
Eaton’s team is also studying the mapping of basement faults—a type of fault believed to be linked to induced seismic events. These faults do not always show up well in standard 3-D seismic images used by industry.
“We’re thinking outside the box to develop some new techniques to delineate and map these fault systems,” notes Eaton.
The goal for industry is to apply these kinds of new knowledge and tools in the field.
“It may be that we’ll be able to identify precursor patterns that predict an imminent larger event,” notes D’Amico. “With an enhanced understanding of the science and geology of induced seismicity, companies may also be able to optimize controllable factors like hydraulic flow rates and injection volume, wellbore placement and flowblack procedures, all with the aim of reducing the chance of triggering larger seismic events.”
The companies on the CAPP Induced Seismicity Task Group have taken a first step towards practical application of shared knowledge, collaborating on a shared practices document that enables each operator to gain insight on how others are currently handling the issue and what kind of successes they’ve had. Soon, they will translate findings from the AER study and other research into stronger mitigation measures incorporated directly into industry operational guidelines.
“As research and our understanding progresses, industry’s goal is to be able to shift from reacting to these events to predicting, minimizing and ultimately preventing felt-level seismicity from occurring,” says Laverick.
“Canada is recognized as a leader in developing natural gas from shale resources. Among our companies, regulators and researchers, we have the right expertise and leadership to also lead the way in terms of understanding the relationship between hydraulic fracturing and induced seismicity,” adds Laverick, “Ultimately, we believe that hydraulic fracturing can continue to be done safely within the framework of science-based regulations and the use of shared industry best practices.”
When Montgomery visits communities that are near industry operations throughout B.C. and Alberta, he has found that residents have two main categories of concerns. One is environmental safety—in particular, concerns about induced seismicity and water usage.
“They want to know that we take these issues seriously and that we’re taking steps to minimize risk,” says Montgomery.
The second concern is economic.
“People want to know that industry will still be around and what we’re doing to protect jobs,” says Montgomery. “It’s a good opportunity for us to talk about the need for competitiveness and the importance of building an LNG industry to get natural gas to new markets overseas.” ’ “People in these towns and communities are generally supportive and have a great willingness to engage on these issues,” he adds.
Roy Dell, meanwhile, is hopeful that the regulator and industry can find solutions to prevent these kinds of issues in the future. He would rather have the focus on Fox Creek be about something else.
Regarding the widespread media coverage of the January 2016 event, Dell says, “Are we proud of it? No, definitely not.” Dell would rather emphasize the positive aspects of living in a robust, growing and economically strong oil and gas community.
“We’d like to attract more direct industry investments and have more families come here to live,” he says, noting the town has recently upgraded its water infrastructure, purchased land for development and is building a multiuse facility with a swimming pool, field house and arena. “Fox Creek is a great place to live and work. We should write about that,” he says.
For industry and regulators, the belief is that by becoming leaders in researching, understanding and mitigating induced seismicity, we can get to the point where induced seismic events are no longer an issue for the newspaper headlines.