While horizontal drilling allows gas companies to extract natural gas from several vertical fractures of the Marcellus shale, there is still a lot of gas trapped within the pores of the shale. A process known as hydraulic fracturing, or fracking, allows even greater quantities of natural gas to be removed from the Marcellus shale. During this process, millions of gallons of water containing sand and chemicals are pumped into the well at an extremely high pressure. This causes artificial fractures to form in the shale, and the sand holds the fractures open, allowing natural gas to flow into the well.
A well drilled next to the Beaver Run Reservoir.
Hydraulic fracturing seems like an excellent process. With some water, sand, and a few chemicals, drilling companies are able to extract a lot more gas; natural gas that can be used to heat our homes and generate electricity. The problem is that each well will require three to nine million gallons of water to fracture the shale, and many wells will require the fracking process numerous times. Trucking in that enormous quantity of water would be extremely expensive. It would be much easier to pump the water from a nearby stream or river directly into the well.
Pennsylvania, the heart of the Marcellus shale play, has over 85,000 miles of waterways. So why not use water from the streams and rivers of Pennsylvania to secure the energy we so desperately need? The problem is that removing millions of gallons from a stream would disrupt the stream’s ecosystem.
After a well is fractured, only 45 percent of the water is recovered. This water cannot be returned to the water cycle because the chemicals used during the fracking process, such as hydrochloric acid and biocides, are deadly to all organisms in a stream. In addition this flowback water often contains heavy metals and oils and may even be radioactive. The water must be treated before it is returned to the water cycle, but most wastewater treatment plants are not equipped to handle this level of contamination.
Many drilling companies have begun reusing their flowback water, but companies are still exploring new methods of disposal. I will address some of these methods as well as more environmental impacts of hydraulic fracturing and drilling in upcoming posts.