Energy companies have found new use for hydraulic fracturing to extract natural gas from shale rock
Fracking is a three-step process. Gas companies first drill a well, then frack it, then harvest the gas, says David Blackmon, who works for a gas company in Houston called El Paso Corp.
First, the company builds a drill pad of about 24,000 square meters (about 258,000 square feet) in size. In order to create a clean surface from which to work, “We have to level off the ground and pave it with white, chalky caliche [kuh-lee-chee] rock,” Blackmon explains.
Then the company brings in a large structure with equipment for drilling deep underground. Called a drilling rig, it is typically about 45 meters (150 feet) tall. Because many underground gas reservoirs are large, a company drills multiple wells to extract as much gas as possible. Drilling the first well takes a couple of months. But once the company understands the characteristics of the local rock, it can drill an additional well in a few weeks. Horizontal drilling allows companies to harvest more gas with fewer wells than in the past. At the Eagle Ford gas field that the El Paso Corp. is developing in Texas, workers drill down for 2.1 to 3.6 kilometers (7,000 to almost 12,000 feet), then drill horizontally for another 1.2 to 1.8 kilometers.
Their work zone resembles the construction site for a skyscraper: There are cranes, clanking pipes, throbbing engines. Workers wear steel-toe boots and hardhats for safety. While some people might find the big equipment exciting, many who live near such operations do not like it.
“Even though we’ve had oil and gas development in the United States for some time, it’s now moving into neighborhoods where maybe there wasn’t heavy industry before,” says Nadia Steinzor of Earthworks.
At a fracking site, companies clear trees and vegetation to make way for big equipment. In addition to drilling rigs used to make the well, “You start to have a lot of traffic trucking in water and chemicals for fracking,” she explains. Tanks are installed to separate fracking fluids from the gas as it is harvested. Noisy compressor stations run night and day to squish the gas and send it away through a pipeline. Besides loud noise, the equipment can bring new odors.
All of this activity can radically change the character of a small town’s environment.
Blackmon agrees that the work can be loud, particularly the fracking, which he says has “a noise level similar to what you’d hear on an airport runway.” Not surprisingly, workers wear earplugs.
The fracking process itself takes two or three days for each well. “We bring in tanks and big generating engines to power the pumps,” Blackmon explains. On a big frack site on the Eagle Ford gas field, he notes, “we are averaging 4.5 million gallons [or 17,000 cubic meters of water used] per frack.”
After the underground rock is fractured, the gas company installs equipment atop the shale deposit to keep the gas contained. This equipment, consisting of a series of valves and pipes, allows the company to harvest the gas at a manageable pace.
The final well-pad area — the developed, flat ground that contains the closed well — is about 4,000 square meters, Blackmon says. Green plants are allowed to revegetate the surrounding land.
C. Cooney. “Cool Jobs: People with a taste for chemistry.” Science News for Kids. May 30, 2012.
Learn more about natural gas at the U.S. Energy Information Administration’s website for kids.
Teacher’s questions: Questions you can use in your classroom related to this article.