Hydrofracking Chemicals Revealed
by Richard A. Engberg
Hydraulic Fracturing (hydrofracking) is not a household term but recently has become more well known with the release over a year ago of the film documentary, “Gasland.” The movie dealt with concerns caused by hydrofracking of natural gas wells in the Marcellus Shale in Pennsylvania and in other locations in the U. S.. It asserted that hydrofracking caused the Marcellus to be charged with methane gas posing contamination risks to the water supply.
What is hydrofracking? Quite simply, it is a technique used to increase or create fractures in source rocks to increase the rate of recovery of natural gas and, in some cases, oil. The practice is to introduce a slurry of chemicals, sand and water into a well that is drilled into a formation containing natural gas. The action of the slurry is to create fractures to increase the release of natural gas and bring it to the surface. Typically, some but not all of the slurry is recovered with the natural gas. This technique has been around for a long time. It was first used commercially in the U. S. in 1949 by Halliburton.
Sierra Crane-Murdoch, in the February 21, 2011 issue of High Country News, reported the “chemical cocktail” used in hydrofracking by Encana Corporation in gas wells it drills in Wyoming. According to Crane-Murdoch, lists of the chemicals used in hydrofracking weren’t available until September 2010 when Wyoming adopted a rule requiring companies to disclose them.
The Encana “cocktail” contains 28 organic and inorganic chemicals. For each well, drillers mix nearly 12,000 gallons of the “cocktail” with more than a million gallons of water and “a heavy dose of sand”, and inject it underground. According to Crane-Murdoch, 30 to 70 percent of the solution re-emerges along with high volumes of wastewater and is routed to evaporation pits.
The ten most used chemicals in percent of volume, all but one organic, comprise 91 percent of the “cocktail”. They are:
Distillates (petroleum), hydrotreated light
Vinylidene chloride/methylacrylate copolymer
1,2,3 – Propanetriol
Sodium tetraborate decahydrate
There are known potential health effects associated with each of these chemicals. The effects are dependent upon the degree and route of exposure. Most have skin and sensory organ effects, several have respiratory, gastrointestinal or liver effects or cardiovascular and blood effects, and some have brain and nervous system effects. Four may potentially affect the immune system, four may potentially affect the kidneys, three may affect the reproductive system, three are endocrine disruptors, two are mutagens, and one is a carcinogen. Again, I stress that these effects are related to the degree and route of exposure.
“Dilution is the solution to pollution” is a well known and overused expression. Does dilution of the “cocktail” with the large amounts of water render these chemicals relatively harmless? Are there possible synergistic effects with this mixture? Does the “cocktail” release other constituents of concern from the formations into which it is ejected? I leave it to the reader to draw his/her conclusions about this reasonably common but not well known process and whether there are associated health risks to humans and biota.
Richard A. 'Dick' Engberg is Technical Director of the AWRA. The views expressed here are his alone.
Want to see more of what is in a fracking cocktail? View this. And read Emily Green's fracking update.