This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Thursday, April 21, 2011

"Gas Well Spews Polluted Water" --What is "fracking?"

Well drilling in Leroy Township, PA.
Drillers are Chesapeake Energy.
Photo by C.J. Marshall published in
The Daily Review.com
The New York Times today is reporting on a blowout of a natural gas well in rural northern Pennsylvania. The well is in Bradford County, PA. Seven families have been evacuated after the accident, which took place late night last Tuesday. An undetermined amount of fluid containing chemicals from the fracking process has been released into the environment, and officials are monitoring nearby Towanda Creek, which is stocked with trout.

What is fracking? Some will know already because it was the subject of the hit movie "Gasland" last year. It is a controversial process that pits the needs for gas resources against the needs for a clean environment, in this case, particularly, the needs for clean water. "Fracking" is a popular term used for "fracturing" of rocks for the purpose of improving the recovery of oil and gas from subsurface reservoir rocks. It is not a new technique, having been around since the late 1940's when Haliburton introduced it. A version of it was explored extensively in the 1980's and 1990's as a way to circulate fluids in warm areas of the crust to bring geothermal heat to the surface. "Fracking" occurs naturally in the earth when fluids, such as magma, create pressure in the rocks to create dikes and sills, though the term is not used by geologists in this context.

During fracking, fluid is pumped into a well bore at a pressure that cause the rocks hosting the well to fracture.  In order to keep the fractures open after the injection of the fracturing fluid, a substance referred to as the "proppant" is added to the fracture fluid. This is often sand that has been chosen to have a shape and size that will have high permeability.

Fracking is in the news a lot now because of the urgent need for the US to produce its own coal and gas, and a rich reservoir of gas-containing rocks is the Marcellus Formation, a shale that extends through much of the Appalachian Basin in Pennsylvania and New York State. There is an excellent resource here if you are interested in details from the state of New York.

The controversial part of fracking is related to the nature of the fluids injected. Fluids range from water to gels, foams, and sometimes, even gases such as air, nitrogen, or carbon dioxide. Additives are numerous, as evidenced by this list of those allowed in New York State.  (I took this list from the Wiki article on fracking, and it is an extensive article for further materials.)

CAS Number↓Chemical Constituent↓
2634-33-51,2 Benzisothiazolin-2-one / 1,2-benzisothiazolin-3-one
95-63-61,2,4 trimethylbenzene
10222-01-22,2 Dibromo-3-nitrilopropionamide, a biocide
15214-89-82-Acrylamido-2-methylpropane sulphonic acid sodium salt polymer
46830-22-22-acryloyloxyethyl(benzyl)dimethylammonium chloride
111-76-22-Butoxy ethanol
1113-55-92-Dibromo-3-Nitriloprionamide (2-Monobromo-3-nitriilopropionamide)
104-76-72-Ethyl Hexanol
67-63-02-Propanol / Isopropyl Alcohol / Isopropanol / Propan-2-ol
26062-79-32-Propen-1-aminium, N,N-dimethyl-N-2-propenyl-chloride, homopolymer
9003-03-62-propenoic acid, homopolymer, ammonium salt
25987-30-82-Propenoic acid, polymer with 2 p-propenamide, sodium salt / Copolymer of acrylamide and sodium acrylate
71050-62-92-Propenoic acid, polymer with sodium phosphinate (1:1)
66019-18-92-propenoic acid, telomer with sodium hydrogen sulfite
107-19-72-Propyn-1-ol / Propargyl alcohol
51229-78-83,5,7-Triaza-1-azoniatricyclo[,7]decane, 1-(3-chloro-2-propenyl)-chloride,
127087-87-04-Nonylphenol Polyethylene Glycol Ether Branched / Nonylphenol ethoxylated / Oxyalkylated Phenol
64-19-7Acetic acid
68442-62-6Acetic acid, hydroxy-, reaction products with triethanolamine
108-24-7Acetic Anhydride
The concerns with fracking include risk of contamination of ground water with these chemicals, migration of the chemicals and the gas produced to the surface in uncontrolled ways, handling of waste, air quality due to released gases, as well as the usual concerns about natural gas production, such as the practice of flaring. The legal and regulatory challenges are complex, summarized in the Wiki article referred to above.

1 comment:

jack said...

So what happens to the geological stability when large areas of rock are fractured during this process? Are we seeing the result in Arkansas, an unstable substructure that could lead to micro quakes?