Professional Engineers Of North Carolina

FALL 2014

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8 the Professional Engineer Fall 2014 F E AT U R E S T O R Y What is fracking? Typical fracking fl uids How fracking works Why it's controversial Hydraulic fracturing, or fracking, is a method of forcing natural gas or oil from rock layers deep below the earth's surface. A pressurized mixture of sand, water and chemicals is injected into a horizontally drilled well. The mix cracks the shale and fi lls the cracks with sandy grit, allowing natural gas to fl ow up the well. The recovered water is stored in lined pits or taken to a treatment plant. Much of the water used in fracking is collected from the well and processed, but some experts have raised concerns that potentially carinogenic chemicals can escape into drinking water. Groundwater Bedrock Drilling rig Holding tanks Bedrock Shale Scientist worry that concrete well casings can crack and leak chemicals. Environmentalists fear that cracks created by frack- ing can spread to existing cracks in the rock layer and become pathways to ground water. Nearby water wells face a slight risk of contamination. 1 1 2 2 3 3 Water and sand 99.51% Acid .123% Friction reducer .088% Surfactant .085% KCI .06% Gelling agent .06% Scale inhibitor .06% pH adjusting agent .011% Iron Control .011% Corrosion inhibitor .002% Biocide .001% Breaker .01% Crosslinker .007%

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