Natural gas extraction from the Marcellus Shale led environmental group American Rivers last week to declare the Upper Delaware River the most endangered river in the country. However, stimulating wells using hydraulic fracturing (hydrofracing), which is now done on about 90% of the wells in the country, likely can't impact surface water, according to shale expert Terry Engelder.
Engelder, a geosciences professor at Pennsylvania State University, is considered one of the foremost experts on the Marcellus Shale. Last year he said as much as 498 Tcf of technically recoverable gas resources may be in the vast play, and his expertise has made him a go-to source for the industry and for state regulators (see NGI, Aug. 3, 2009). He spoke at the Ninth Annual Insight Information's Gas Shales Summit in Houston on Wednesday --
Wednesday coincidentally was the same day environmental group American Rivers named the Upper Delaware the most endangered in the United States in its annual America's Most Endangered River (MER) report.
According to the MER report, the Upper Delaware, which provides drinking water for 17 million people across New York, New Jersey and Pennsylvania, "is at risk from shale fracing for natural gas, a process that poisons groundwater and creates toxic pollution." The river and its watershed top the Marcellus Shale.
The Upper Delaware and its watershed are under threat, the MER report stated, because "multinational energy corporations have acquired drilling rights to large tracts of land in the watershed and requested permits to take clean water from the river to mix with chemicals (some toxic, undisclosed and proprietary), to make hydraulic fracturing fluid for injection into wells to release the gas.
"Each well requires between three and nine million gallons of water for fracturing. Thousands of truck trips per well are required to transport this water, contributing to greenhouse gas emissions. Extracting gas from shale may result in surface and groundwater pollution, air pollution, soil contamination, habitat fragmentation and erosion. The U.S. Department of Energy notes that 'produced wastewater' from gas drilling must be handled as toxic industrial waste."
American Rivers called on the Delaware River Basin Commission, which governs the watershed, to ban shale hydrofracing in the Upper Delaware watershed "until a thorough study of cumulative impacts is completed and the pollution potential of shale fracing is fully documented and assessed."
There's no doubt that some producers have not been good stewards of their drilling operations in the Marcellus Shale, Engelder said at the conference. But he doesn't think a few mistakes should condemn the industry.
"I like to point out to reporters a letter in 2009 from the Pennsylvania Department of Environmental Protection [DEP] that found that in an investigation over a 15-year period, in its review of more than 32,000 wells in Pennsylvania, they could find that only one-quarter of 1% may have impacted groundwater.
"More importantly, zero of the wells were negatively impacted by deep hydraulic fracturing."
Engelder said, "every person thinks they are an expert on hydraulic fracturing because of the noise from the drilling rigs, the traffic on the roads...But one of the things that is extremely difficult to do is to separate that stuff from hydraulic fracturing as it goes on inside the earth. That won't affect your water table."
There are "four reasons" why hydrofracing won't affect surface water, he said. "What [happens] on the surface is not the same thing as at depth."
Hydrofracing "causes acoustic events that can be mapped," Engelder noted. "Fracing contained within Marcellus cover rock is at 7,000 feet, and at that level, there is a very low permeability of water...
"Water within the earth is stratified by buoyancy. Fresh water is the least dense; it stays on the surface. Salt water is denser, and gas pressure has been contained in the denser water for millions of years. It's less likely to leak," and combined with frac fluids, almost impossible to reach the surface.
To visualize what takes place during a frac operation, Engelder asked the audience to look at the tiny cracks that exist on the wooden canvas used by Leonardo da Vinci when he painted the Mona Lisa masterpiece. The painting's cracks are similar to the joints, or fractures, within the earth. A series of joints comes off the gas shale, which is "a lot of undisturbed rock that's been undisturbed for a long period of time."
And heavy frac fluid is subject to viscosity. "Viscous honey flows slower than water. Gas has been contained in gas shales for millions of years and frac fluid allows the natural gas to move more easily. If it makes it out of the Marcellus, and admittedly, small amounts of methane are constantly emitted to the air and to water, but in small concentrations...If natural gas doesn't make it up, the frac fluid won't make it up.
"This type of physics ensures Pennsylvania protection from frac fluid," said Engelder.
Another point has been missed in the hydrofrac/water debate, he said. Pennsylvania didn't enact safe drinking water regulations until about 30 years ago, and "40% of all water wells in Pennsylvania do not meet recommended safe drinking water levels due to a lack of laws, requirements or regulations."
Engelder showed the audience a fact sheet titled "Methane Gas and Your Water Well," which was issued by the Pennsylvania DEP in 2004, long before intensive drilling got under way in the Marcellus Shale. But homeowners now are testing their water wells and finding that the water is contaminated -- by trace amounts of methane.
"Measuring the quality of water after drilling has started five miles away, 'well,' the homeowner says, 'obviously, the drilling affected my water well,' but that's not accurate." To stem problems associated with lawsuits over contaminated water wells, "Industry now has learned to...do its own testing on area water wells before they start drilling."
Engelder blamed the media for "taking an awful lot out of context" regarding so-called water issues in the Marcellus Shale. "I warn you right now," he told the audience, "the reporter gets the story and then the editor sensationalizes things..."
There "always will be accidents," he admitted. "I don't mean to imply that [well] casing protects the water table," referring to issues related to some incidents in Pennsylvania. "Some shallow Devonian gas pockets of Upper Devonian gas can be drilled through, causing leaks outside the intermediate casing because of a poor cement job." If centralizers aren't used when a well is cased, cement can be "squeezed" around the casing, which can allow gas to leach into the groundwater.
In light of the Macondo well disaster in the deepwater Gulf of Mexico, which has been thought to be the result of a poor cement job on the well casing, "My guess is that there now are a lot of opportunities to spend a lot of time with engineers to make proper cementing procedures," Engelder said.
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