One aspect of geology that has been making the news lately is the practice of hydraulic fracturing. Usually the news about fracking is not very flattering as it seems to
shoulder the blame for any sort of groundwater contamination, earthquakes and plagues of locust that should strike. Most reports that concern fracking, properly called hydraulic fracturing, don't adequately explain what it is and why it could be causing all of these problems. However, that is about to end since you can just read the following handy post to learn what the frickin fack is up with fracking.
Why are we fracking?
The first question that we should ask, before discussing what fracking is, is why are are we using hydraulic fracturing and what are its benefits. It's an undeniable fact that the world is highly dependent on fossil fuels for energy, particularly natural gas and oil. However, our thirst for fossil fuels has led to the depletion of most of the easily accessible reserves around the world. This means that oil and gas companies, in their quest to meet demand, are developing new technologies and exploring new regions that were previously overlooked. One new source of natural gas is in shale. Most oil and natural gas is produced in shales due to their high organic content and subsequent heating during lithification (turn to rock). This heating produces oil and natural gas that slowly migrates from the shale into other rocks where it is trapped in what, until recently, were conventional reserves. Oil and gas recovery in the past focused on looking for places where oil and gas was trapped. However, the depletion of these reserves has forced us to look elsewhere, such as in the source rocks like shale, primarily for natural gas and coalbed methane. In theory this sounds great, similar to the old adage: why get an apple from the basket when you can get one from the tree, but in practice things are a little more difficult. The reason for this is that shale is made of very, very fine mineral grains. The natural gas that we would like to recover is trapped in the tiny pore spaces between these grains making it almost impossible to extract. In order to overcome this, the oil and gas industry has been forced to develop new technologies to enhance recovery. One of the most successful, but controversial, is fracking.
What is Hydraulic Fracturing (Fracking)??
The simplest answer to "what is fracking" is that it is a process in which fluids (more on that later) are injected into a borehole to increase pressure. This results in the rock at the bottom of the borehole fracturing. This allows us to recover resources that are hard to get more efficiently.
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| EPA Hydraulic Fracturing Study Plan, November 2011 |
A good analogy is to think of a common scenario you likely tried as a kid. Imagine you have a juice box and instead of sucking on the straw (which represents the borehole) you blow into it instead. Most often this increase in pressure results in juice spraying out to top of the straw. However, one day you blow particularly hard, so hard that the sides of your juice box spit open and you experience catastrophic juice spillage on your favourite pants (not that this actually happened to me or anything...) However, the point is that this increase in pressure inside your juice box resulted in the sides splitting. Fracking works on the exact same principle.
What gets injected?
Unfortunately, only the oil companies know the exact answer to this question. However, we do know that the mixture is mainly water with numerous chemical additives.
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| EPA Hydraulic Fracturing Study Plan, November 2011 |
Obviously there is a laundry list of chemicals that may be incorporated. It is worth noting that it would certainly not be beneficial to ingest any of these substances or to find them in groundwater. Furthermore, this is by no means a full list. The above chart is merely and example of some the chemicals you might expect to find in a fracking fluid. The fracking fluid that is used for each well is tailored specifically for that rock formation being targeted in order to maximize recovery.
What are the environmental effects?
One of the most controversial issues with fracking is the potential for environmental harm that may result from the practice. Some of these include surficial spills of the fracking fluid at the well site, contaminating groundwater either through subsurface migration of the fluid, infiltration from a spill, leaking around a bad well casing, or even earthquakes from the injection of the fluids. Furthermore, fracking requires large amounts of water and also produces large amounts of waste water. The problem created by getting this much clean water and then disposing of the resulting waste water also has potential for large environmental impacts on water sources such as local groundwater reserves in terms of both depleting and contaminating them.
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| EPA Hydraulic Fracturing Study Plan, November 2011 |
As of now, the impact of fracking is still being studied and moratoriums on drilling and fracking exist in many states and provinces in the U.S. and Canada. To date there have been numerous studies on the environmental impact of fracking and it is essential that these studies be performed in order to truly gauge the impact fracking could have at a particular site.
That is all for now. I realize that I have not addressed some of the more complex issues surrounding fracking. My intention was not to omit any piece of information, but to provide a basic primer about what fracking is and the issues surrounding it. For more detailed information or information about a particular site I encourage you to do more research. Thanks for reading.
Matt
References:
US Environmental Protection Agency:
http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/index.cfm
US Environmental Protection Agency Hydraulic Fracturing Study Plan
http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/upload/hf_study_plan_110211_final_508.pdf
Chesapeake Energy - Hydraulic Fracturing Facts
http://www.hydraulicfracturing.com/Process/Pages/information.aspx
