The controversial practice of "hydraulic fracturing"--using high-pressure water, chemicals and sand to pry open pockets of trapped natural gas buried deep underground--may be less threatening than critics have warned, according to researchers from the University of Texas at Austin.

In a report released today at the AAAS Annual Meeting, the scientists say that contamination of household drinking water and other problems blamed on "fracking" may in fact result from near-surface issues--gas leaks from old wells, cracks in casing pipe, and poor drilling structures. 

"There is work to be done, but a lot of these [problems] are common with oil and gas wells" that do not involve deep-rock fracturing, said Charles G. Groat, principal investigator for the Energy Institute. Another concern frequently associated with fracking is the incidence of small earthquakes (micro-seisms) occurring near drill sites. While that warrants more study, Groat said such small quakes are also associated with conventional drilling operations.

[UPDATE 07-24-12: ScienceInsider reports: "Fracking Report Criticized for Apparent Conflict of Interest"]

In a special symposium at the 2012 AAAS Annual Meeting, Groat and a University of Texas colleague, Danny Reible, agreed that problems can arise when drilling operators extract too much groundwater if they are working in areas, such as parts of Texas, where severe droughts are creating water shortages. But the drilling companies are learning to reduce the amounts of water needed, in part by treating water for re-use in drilling.

[See the full report and related materials by the Energy Institute at the University of Texas at Austin, and a video of Groat discussing the report.]

As for widespread publicity about home drinking water that becomes flammable after contamination with natural gas, the Texas experts said the source is probably from shallower ground, perhaps from old wells, or from leaky gas pipes. They found no evidence that it stems directly from "fracking."

"Most of these questions are common for oil and gas operations," Reible added, and that means existing local and state regulations must be enforced better, in terms of water runoff, the worsening of droughts and ground surface disruption caused by drilling operations.

These worries have arisen recently because gas exploration and production operations have expanded dramatically as new technology has allowed well drillers to bore their holes horizontally in deeply buried formations that contain a lot of gas. These rocks have been "off limits" because they are so dense that the gas cannot flow easily unless they are broken open. By drilling horizontal channels, and cracking them open by forcing fluids in at extreme pressure, and propping them open with sand, an enormous supply of gas has rather suddenly become available. In some areas, such as western Pennsylvania and upstate New York, gas prospecting and well drilling have blossomed.

In fact, so much gas is coming onto the market that the economics of energy are changing. The price of gas for residential use is declining in some parts of the United States, and energy experts think natural gas will soon significantly reduce the amounts of coal used for generating electricity. They also say the same promise is being seen abroad where "tight" formations containing huge amounts of gas are known to exist, and are now being explored.

The study was conducted by the Energy Institute at the University of Texas-Austin. The research project discussed at the symposium was not supported by energy industry companies, Groat added. Instead, the money came from the university's own funds.