How Hydraulic Fracking Works

To understand why fracking was developed, imagine a traditional drilling operation. A well works great if we're tapping into a big pool of gas or water underground, allowing us to pump up the resource from the reservoir. But when the resource we're trying to capture is trapped tightly in the pores of shale, how do we release it and bring it to the surface?

It starts off pretty similarly: A deep well is drilled. Chesapeake Energy estimates that the average depth of its wells is 7,700 feet/2,347 meters (roughly six Empire State Buildings stacked end to end [source: Chesapeake Energy]). The Colorado Oil and Gas Association gives the diameter of the hole at 12.25 inches (31 centimeters). When the well reaches the right depth, it takes a right or left turn (referred to as the kick off point) and becomes horizontal. That horizontal section may span 1,000 to 6,000 feet, or 305 to 1,829 meters [source: EPA].

Steel casing fits in the wellbore, aka the hole drilled. The steel is intended to protect groundwater and the surrounding area from any potential leakage during hydraulic fracturing. Down at the horizontal section of the well, the steel is perforated through with a tool that can penetrate the steel and cement of the well to create small holes for water or tiny particles to escape through -- much like your kitchen colander. At that point, a water solution (that we'll explore more later) is pumped in at an extremely high pressure.

When the solution reaches the perforated points, the liquid is too much for the rock to absorb, and the rock cracks. It takes three to 10 days for fracturing to be complete [source: Halliburton]. Additives and sand found in the water mixture hold open these fissures, allowing the gas (or whatever resource) to escape and be brought up to the surface in the water that's pumped back up, and separated. Those resources may flow from the cracks for years or potentially decades [source: Energy in Depth]. The wastewater is stored and treated, pumped into injection wells or recycled; it's also stored in open-air pits or used on roads [source: NRDC].

The equipment that is used in fracking is (predictably) heavy duty. Keep in mind that an estimated 200 tankers are needed to bring 1 million gallons (3.8 million liters) of water to a well, and that deeper shale beds might require 2 to 10 million gallons (7.6 to 37.9 million liters) of water [sources: EarthWorks, ProPublica]. Dozens of "pump trucks" alone are required to shoot the pressurized solution down the wellbore [source: Energy in Depth].

Before we get to some of the issues associated with hydraulic fracturing, let's take a look at some reasons why people are so fracking excited.

As you can imagine, there are some pretty serious critics of fracking. But before we get into the pitfalls of the operation, let's address some of the advantages that proponents describe.

For starters, many point out that fracking provides people with loads of accessible resources that are normally trapped in the pores of rock.

There are environmental arguments, too: Instead of drilling many wells, the process involves drilling one well that shoots off horizontally, which has advantages on the surface landscape. Estimates say that 90 percent of natural gas wells today must be accessed through fracking [source: Bateman]. In addition, it's also argued that natural gas is a more environmentally friendly fuel than oil or coal, and that's true: It does burn more cleanly, with drastically reduced carbon dioxide, nitrogen oxide and sulfur oxide emissions [source: EPA]. (We'll see in the next section some arguments against the "clean" nature of fracking.)

Companies like Chesapeake Energy and Halliburton are also quick to point out that any time the U.S. is reducing its dependence on foreign oil, it's advantageous to American companies and consumers. And there's no doubt that hydraulic fracking has been successful at getting domestic U.S. natural gas: From 1.1 million fracking operations over the past 60 years, Americans have received roughly 600 trillion cubic feet (nearly 17 trillion cubic meters) of natural gas [source: Halliburton].

And we can't forget job creation and its friend, revenue. The New York State Department of Environmental Conservation estimated that if the state reopened its doors to fracking (it instituted a ban on fracking in 2008), 17,6000 jobs would be created and $125 million in tax revenue would be accumulated [source: Schaefer]. Fracking -- and the oil and mining industry in general -- is no mom-and-pop operation. There are big bucks in it, and that's motivation enough for some. That big payout doesn't happen though for operators who accidentally tap into water supplies or destroy properties with accidents. For this reason, it could be argued that the payout is actually going to compel the operators to follow safe and ethical practices [source: Groundwater Protection Council].

So far, we've only discussed the logistics and the benefits of hydraulic fracturing. But fracking isn't exactly a slam-dunk when it comes to safety. In fact, for pretty much every argument we put forth in the last section for fracking, there's a pretty virulent counter.

For one, fracking is still a hard-core mining operation. Meaning that drilling -- and the trucks, pumps, transports and storage containers -- are all still going to be present at the site, along with the necessary related infrastructure. Although gas companies are eager to make it sound like finding natural gas on farmland would be a godsend to cash-strapped farmers, there are also the issues of pipelines causing damage to crops and equipment tearing up roads [source: Schaefer].

One of the biggest complaints about fracking is not the act itself, but the fluid that's pumped into the well to cause fractures. Chemical additives make up 0.5-2.0 percent of the sand and water mixture [source: EarthWorks]. The additives include acids to help dissolve minerals, chemicals found in detergents, disinfectants and household cleaners [source: McGraw]. Do keep in mind that millions of gallons of the stuff is used; 4 million gallons (15 million liters) of fracking fluid would then equal 300 tons of chemical additives [source: EarthWorks]. A huge concern is that these fluids are staying in the ground and leaching into soil and groundwater. (Not to mention the potential of surface spills.)

After the fracturing occurs, there are more concerns. The tiny fissures can travel far, which implies they could technically end up cracking into a water supply. (While this hasn't yet been documented, potential cases are being studied [source: McGraw]). That means that the oil or natural gas could get into the drinking water.

There's also the problem of the enormous amounts of wastewater generated. Billions of gallons of wastewater needs to be disposed of yearly. Often, that means treating it at local wastewater plants -- with subsequent release into the surface water [source: NRDC]. Some also evaporate off the more volatile chemicals in the compound, which means that for all the talk of "clean burning natural gas," there are air pollution concerns when it comes to mining the gas (not to mention the tankers, trucks and equipment that are on the road, which doesn't help pollution) [source: EarthWorks].

And one of the problems we'll explore in the next chapter is that nobody is quite sure about how harmful all this is.

Although a simplified use of fracking has been around since the mid-1800s, it was really only in the last two decades that fracking technology developed such that an economical, commercial scale could be achieved. Let's keep in mind that more than 90 percent of the U.S.'s natural gas comes from domestic sources; although the U.S. doesn't have the same kind of reserves that oil-rich Middle Eastern countries possess, it does have enough energy to power every natural-gas powered device for the next 20 years [source: McGraw].

Because fracking for shale gas is such a new enterprise, critics bemoan the lack of research and heavy scientific study that (by all accounts) should accompany such heady stuff. But research is being done, which give both sides of the issue more nuance. One claim that has recently come up is that fracking causes such volatility underground that earthquakes arise from the enormous pressure of the water being pumped in. The National Research Council couldn't find any evidence to support the claim, but don't get out your drill yet: The group did find that the water being shot out of the wells into storage tanks was linked to small earthquakes [source: Associated Press]. So earthquakes were happening, but their cause was different than predicted.

It's hard to deny -- for good or bad -- that fracking has nothing short of revolutionized the mining industry. Due to fracking, the U.S. has seen its oil production soar. By 2013, the U.S. is set to produce 11.4 million barrels of oil per day -- rivaling Saudi Arabia's leading 11.6 million barrels [source: Associated Press]. Exxon Mobil Corp. and Chesapeake Energy expect to drill tens of thousands more wells by 2020, and the national implications have caused the U.S. Department of Energy to become more involved in investigation of practices and safety [source: Kirkland and ClimateWire].

Also hard to disagree with? Making sure the chemical compounds and practices used in fracking are safe for those working and living around the affected areas. Executives at Halliburton made headlines in 2011 when one of them drank fracking fluid to prove its safety. And while it sounds silly, you can give the company credit for making the point that it had actually changed the composition of the fracking fluid so the materials in it were sourced from the food industry [source: Tsai]. Its new CleanStim fracking fluid promises a reduced risk of chemical exposure and -- along with new water treatment and bacterial mitigation resources -- make up the new CleanSuite technology that Halliburton is hoping will alleviate health and environmental concerns about fracking [source: Halliburton].

Sounds well and good, but it's undeniable that it'll take a lot more study to convince everyone that fracking is safe.