The Science of Fracking
April 24, 2012
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BY BILLY LIGGETT
Central North Carolina is sitting on a treasure trove of potential natural gas reservoirs made up of organic shale deposited in the earth more than 200 million years ago.
To reach that gas - and potentially provide enough energy to power North Carolina for 40-50 years, according to some scientists - it will take a controversial method of drilling known as hydrofracturing, or “fracking.” While the economic impact of natural gas drilling could be considerable to the state and the Sandhills region, opponents say fracking comes with considerable environmental risks.
Campbell University, which sits less than a half-hour from the eastern portion of the targeted Deep River Basin, focused on fracking - specifically the science behind the method - during a forum as part of the 109th annual North Carolina Academy of Science meeting, held for the first time in Buies Creek in late March. Meeting organizer Dr. Karen Guzman, associate professor in Campbell’s Department of Biological Sciences, invited geologists, biologists and drilling professionals to discuss natural gas drilling and its potential benefits and risks for North Carolinians and their environment.
“This is new science,” said Rob Jackson, a professor in the Department of Biology and the Nicholas School of the Environment at Duke University. “We published our first paper in North Carolina just two years ago looking at the interactions of water quality in private wells and their proximity to natural gas wells. … We don’t have to rush this. We have time to get it right.”
Environmental science was the focus on the three-day Academy meeting, which also showcased work by students in addition to a keynote address by Duke University’s Dr. Stuart Pimm, who spoke on conservation biology and biodiversity.
The fracking forum’s moderator, N.C. State emeritus professor of zoology Dr. Charles Lytle, said the point of the discussion wasn’t to come out on one side of the debate, but to present the facts from all angles.
“You have extremists on both sides,” Lytle said, “but the truth is always someplace in between. We wanted to do this in a scientific setting where we present the pros and the cons.”
Jackson presented cases in Pennsylvania and Wyoming where high levels of methane in those areas were attributed to natural gas drilling. Despite those findings, Jackson said he was not opposed to the idea of fracking, if done properly and with strict environmental protections in place.
“If done right, I think natural gas is a better source for energy than coal,” he said.
Speaker Martin “Matt” Matthews, a former manager of geology and geochemistry at Gulf Oil, said no form of energy production is without its risks. After presenting a slide on the steps that go into fracking, Matthews admitted the potential for triggering earthquakes, but added that it’s not always a bad result.
“Fracking may add lubricant to a fault line, making it move sooner than it normally would,” he said. “But by happening sooner, you may have a 5.2 (Richter scale) quake as opposed to a 9.2 … so maybe it happening early is a good thing. Politically, that would never be a good thing, because people think it’s an earthquake we never would have had. But you’ll have it eventually if you live long enough.”
Duke professor and Chairman of the State Water Infrastructure Commission Bill Holman said the biggest environmental concern is water safety, since so much water - mixed with sand and hazardous chemicals - is needed in the fracking process.
“Forty-eight states regulate large water withdrawals,” he said, “and two do not. Those are North Carolina and Alabama. Our water regulatory system is certainly a weakness in this state.”
The “Why North Carolina?” portion of the forum was led by Ken Taylor, assistant state geologist and chief of the North Carolina Geological Survey. After presenting maps detailing the organic shale deposits - the Deep River Basin covers Durham, Chatham, Lee and Moore counties - Taylor said science (not politics) should be and should remain the heart of the fracking debate.
“Never look at a boss and say you know the answer when you don't,” he said. “When you don't know something, you say, ‘How can I work with somebody else to get that information?’ That's what science is about. There are lots of people on one side, and lots of people on the other side.
“I'm merely the scientist giving the facts.”
HOW TO ‘FRACK’
- Stake location, bid construction work, prepare location and padsite and bring in drilling rig and equipment.
- Drill vertical portion thousands of feet deep using conventional methods.
- Drill kick-off (curved) section, with the use of a downhole motor mounted directly above the bit in order to make the turn from vertical to horizontal. Downhole instruments called MWD (measurement while drilling) packages transmit sensor readings upward, allowing operators at the surface to build the angle.
- Drill horizontal wellbore, still using MWD to hold the angle and direction.
- Case off the horizontal lateral with steel casing to allow for completion and fracture stimulation, preparing the well for production.
- Pumping of water, sand and chemicals creates cracks (fractures) in rock; sand keeps the fissures open so natural gas can flow into the well.
WHAT IS FRACKING?
Hydraulic fracturing is a process that results in the creation of fractures in rocks. The fracturing is done from a wellbore drilled into reservoir rock formations to increase the rate and ultimate recovery of oil and natural gas.
Man-made fluid-driven fractures are formed at depth in a borehole and extend into targeted formations.
The fracture width is typically maintained after the injection by introducing a proppant into the injected fluid. Proppant is a material, such as grains of sand, ceramic or other particulates, that prevent the fractures from closing when the injection is stopped.
SOURCE: Environmental Protection Alliance
WHY NORTH CAROLINA?
Rock units in the Deep River Basin are potential candidates for the drilling methods used in other states. The potential natural gas reservoirs in these basins are gray and black organic shales that are thought to represent ancient lake sediments, deposited more than 200 million years ago. The Cumnock Formation contains organic-rich shales that might yield commercial quantities of natural gas … enough, some scientists say, to power the state for 40-50 years.