August 8, 2011
USTAR’s alternative energy gets cracking to stimulate geothermal power production
(From innovationutah.com) — A long-time oilfield technology may help geothermal energy take a larger role in our nation’s energy production, according to University of Utah USTAR researcher John McLennan, associate professor of chemical engineering.
With his peers at the Energy & Geoscience Institute, McLennan is looking at ways to deploy hydraulic fracturing to enhance or stimulate geothermal energy production.
Hydraulic fracturing involves pumping substantial volumes of fluid (usually water) at high pressure down a well into rock layers thousands of feet below the surface. The fluid creates and forces open networks of cracks in the rock layers, much like the spider-web patterns in broken windshields. The fractures allow hydrocarbons to more readily move up the wellhead and into an energy grid.
Hydraulic fracturing has been used in the oil and gas industry since the 1940s. An estimated 90 percent of natural gas wells in the United States use the technique to increase production.
Geothermal energy production may likewise benefit from fracturing, McLennan says. Most geothermal power plants today exploit naturally occurring sources of hot water, such as geologic formations that support hot springs. Developers tap underground reservoirs of hot water for electric generation or direct uses.
The trouble, McLennan says, is that most of these naturally occurring geologic environments are geographically sparse and far from centers of population where electrical use is highest.
“Enhanced hydraulic fracturing may open up other geologic formations to geothermal. If you drill deep enough — possibly 5,000 to 10,000 feet or more — you’re going to find a wide range of rocks all over the country that are 240C or hotter.”
By inducing cracks in target formations, an artificially stimulated reservoir can be produced. Water injected into these cracks in the hot rocks can then be produced and used for electric generation or direct use. Thus, these resources could be tapped over a broad geographic area. More…Posted by: psilberman