A safer way to get gas?
In a major energy security speech in March, President Barack Obama had some nice things to say about a new technique for extracting domestic natural gas deposits: "Recent innovations have given us the opportunity to tap large reserves– perhaps a century's worth of reserves, a hundred years worth of reserves– in the shale under our feet."
The innovation that has unlocked those vast new reserves of natural gas is a process known as hydrofracking
– or fracking for short– in which horizontal drilling is combined with blasts of pressurized water and sand. But for Obama, along with other more strident critics, the natural gas unlocked by fracking may come at too great a cost.
The biggest, most headline-grabbing fear is that fracking chemicals will contaminate drinking water. Environmental scientists at Duke University recently published a study titled "Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing," in the Proceedings of the National Academy of Sciences
. The study found that natural gas concentrations in water wells within 3,000 feet of gas wells were higher than in wells that were further from gas wells. Interestingly, the researchers included water wells near Dimock, Pennsylvania where it is well known that improperly constructed natural gas well casings had resulted in the fugitive gas contaminating local water wells.
Sounds like bad news. But when you read the fine print, the Duke researchers admit that "based on our data, we found no evidence for contamination of the shallow wells near active drilling sites from deep brines and/or fracturing fluids."
Despite its misleading title, the study did not find that the fracking technique contributed at all to the natural gas found the nearby water wells. In fact, the gas-rich shale lies several thousand feet below strata of impermeable rock from shallow surface drinking water aquifers. Instead, bad well casings that also occur with conventional gas wells appear to be the culprits. States already set standards for constructing proper well casings and impose penalties when companies fail to comply.
Another major fear about hydrofracking is that chemical-laden wastewater spills will contaminate surface waters. Fracking uses mostly water and sand to blast open cracks in the shale deposits thousands of feet below the surface to release the trapped natural gas. Drilling companies add small amounts of chemicals to prevent corrosion, reduce friction, and kill fouling bacteria.
In April, the Democratic members of the Energy and Commerce Committee in the House of Representatives released a report listing the chemical contents of the 2,500 hydraulic fracturing products used by the 14 leading oil and gas service companies. Some of the chemicals such as diesel (used in 51 products), naphthalene (44 products), formaldehyde (12 products), benzene (3 products), and lead (1 product) are deemed hazardous and carcinogenic.
In addition, some of the water and chemicals used in fracking flow back out of the gas wells containing dissolved salts and other minerals from the shale. This wastewater can often be reused, but some is treated and disposed of. There have been cases in which wastewater has escaped impoundment and flowed into streams or contaminated surface drinking water wells.
Another issue raised by fracking opponents is that the dissolved salts in well wastewater contain traces of radioactive elements derived from the shale. The good news is that Pennsylvania's Department of Environmental Protection reports that tests downstream from wastewater plants that treat gas well water find that levels of radioactivity are below federal standards for safe drinking water.
In short, the use of water is the aspect of fracking that worries citizens and drives activism against the technique.
Luckily, there may be a technical fix that addresses these water worries and does an end run around drilling opponents: gas-fracking.
Developed by GasFrac Energy Services in Alberta, Canada, gas-fracking uses liquefied petroleum gas (LPG), which consists mostly of propane, instead of water to crack open shale formations to release oil and natural gas. Robert Lestz, GasFrac's chief technology officer, and his colleague Audis Byrd spent 10 years developing the technique.
Lestz explains that the company produces an LPG gel using phosphate esters, iron sulfate activator, and magnesium oxide. None are seriously toxic or are thought to be carcinogenic. The injected LPG gel combined with sand fractures the shale formations to release trapped oil and/or natural gas.
As a hydrocarbon, propane easily mixes with natural gas and returns to the surface where it can be recovered and reused or flared. Since essentially no water is used and the gelling chemicals are relatively benign, there is no possibility that well wastewater can contaminate wells or streams.
Gas-fracking is also more efficient than hydrofracking. In conventional fracking, injected water tends to block the pores and cracks through which natural gas would otherwise flow into the well. This does not happen with gas-fracking. As a consequence, Lestz claims that gas-fracked wells often produce 20 to 30 percent more natural gas than hydrofracked wells. Another difference: hydrofracked wells often need to be flared for a couple of weeks to purge the fluids. This wastes saleable product and emits extra greenhouse gases. Gas-fracked wells, which need far less flaring, save gas and can go into production sooner.
There are, however, additional safety concerns when dealing with large quantities of propane. Unlike water, LPG is flammable. In January 2008, a well site in Alberta suffered a blast as a result of a propane leak. Three workers suffered non-life-threatening burns, and GasFrac suspended its operations to devise techniques aimed at preventing future accidents. Lestz claims that insurers give the company the same risk rating as conventional hydrofrackers.
So far, the company has fractured 300 oil and gas wells in both Canada and the United States. And Lestz has spent time recently at various forums talking with concerned citizens in New York and Pennsylvania. "I have been real surprised," he said, "at how well accepted our process has been by communities up there."
In his March energy speech, President Obama declared, 'We've got to make sure that we're extracting natural gas safely, without polluting our water supply."
So far, the evidence suggests that the worst fears about hydrofracking appear to be considerably exaggerated by opponents of natural gas drilling. Nevertheless, a technology like gas-fracking may be just what the president is looking for.
Downtown Charlottesville resident Ronald Bailey is Reason Magazine's science correspondent and author of "Liberation Biology: A Moral and Scientific Defense of the Biotech Revolution."