Let’s talk about earthquakes and fracking. To be clear, I’m going to try to address this from a scientific approach, to explain potential environmental concerns (and not just say that fracking is causing earthquakes). I recently attended a lecture presented by Cliff Frohlich, an Associate Director and Senior Research Scientist for Jackson School of Geosciences at the University of Texas, Austin. Dr. Frolich gave an engaging lecture on his research related to seismic activity and hydraulic fracturing. Most of the information I’ll bring up came from that lecture.
But to back up a bit, let’s define some important subjects so we’re all on the same page. “Hydraulic Fracturing” (fracking) is the process of injecting a fluid into a non-permeable bedrock formation to fracture the bedrock, allowing the flow of hydrocarbons (1). The technology has been in use since the 1940’s, but its popularity has increased over the last decade. Water is typically used, and may contain salts, acids or other additives to improve the fracturing of bedrock based on its chemical composition. Another important industrial practice to address is injection wells. These wells inject waste water produced during hydrocarbon extraction (2). This may be excess waste water from the fracking injection, or water that contains salts or other contaminants that were present in the hydrocarbon deposit. Injection wells are commonly used with fracking wells, as it is very difficult to process the excess contaminated water. Given the pressurized nature of fracking operations, it is possible that fracking may cause seismic activity! But, it’s important that we figure out which process, if any, is actually responsible for additional seismic activity. Seismic activity is relevant from an environmental perspective, as it has a direct impact on human quality of life, and can disrupt ecosystems.
Dr. Frohlich brought up the Barnett Shale formation near Dallas-Fort Worth, Texas. In his research, he found that 10 small earthquakes were experienced within 1 km^2 of an injection well in 2008. This concentration of seismic activity was determined to be the result of the injection well, which meant that fracking related activities were responsible(3). However, it is important to note that these quakes were caused by injection, rather that the act of fracking. Another case that Dr. Frohlich discussed was North Dakota. Fracking practices increased in North Dakota, as they did in Texas, but no noticeable increase in seismic activity. He drew the conclusion that the geological make up of North Dakota is arranged in such a way that shifting pressures will not cause major seismic activity.
Here in Alberta, fracking operations have been tied to a recent increase in seismic activities near Fox Creek. Research has found that both fracking and injection wells have caused seismic activity in the region. The geology in the area is affected both by the injection of fracking fluids and waste aqueous solutions. In response to the increases in seismic activity, the Alberta Energy Regulator (AER) created Subsurface Order No. 2(4). All well licensees on the Duvernay Shale performing fracking and related operations have to follow Subsurface Order No. 2. The Duvernay Shale is a formation in Alberta which is currently being explored and developed through fracking, and is deeper than most of the traditional formations being explored in the area(5). Subsurface Order No. 2 requires operators of fracking or related operations to have a monitoring and response procedure in place for induced seismicity within 5 km of operations. Seismic events between 2.0 and 4.0 on the Richter scale detected during fracking or other injection events must be reported immediately to the AER and a site specific “induced seismicity plan”(4) must be enacted. This is put in place to reduce the likelihood of escalating seismic activity in Alberta. In the case of induced seismicity exceeding 4.0, it must immediately be reported, and fracking or injection operations on the site will be suspended, pending approval from the AER.
Reviewing these three case studies brings about the conclusion that the geologic make up of an area and the formations being worked with will determine the degree of seismic activity caused by fracking. Since the geologic formations being interacted with are extremely deep underground, it is difficult to predict how they will react to the increases in pressure and available fluids caused by fracking and deep well injection. More research is required before any complete consensus can be made, but as fracking becomes more common, its environmental impacts will become more apparent; the impacts it has on seismic activity may not be apparent in all areas, but fracking and injection has the potential to cause significant seismic activity and subsequent issues.