MIDLAND, Texas-Hydraulic fracturing. Fracking. It sounds like an epithet, and many environmentalists blame it for earthquakes and poisoned drinking water. But fracking has supporters-especially consumers who are spending less to heat their homes because the controversial technology has increased natural gas supplies and lowered prices. So what is fracking? Does it deserve the invective aimed its way? I set off for Midland, Texas, to find out.
Mark Merritt climbs out of his dusty F150 pickup, hands me a hard hat and safety glasses, and leads me on a tour of a gas well where a "frac" job is taking place. The lanky, soft-spoken Texan is the director of oil and gas operations at Fasken Oil and Ranch, an exploration and production company based in Midland. We're surrounded by equipment: tractor trailers filled with water, sand, miles of steel and composite tubing, hoses and wires snaking along the dusty ground. I can't hear above the steady, incessant thrumming of a dozen heavy diesel compressors pumping thousands of gallons of water and sand deep beneath the earth.
We get some relief from the noise only when we step inside the portable office trailer that serves as control room, operations center, and small kitchen. Technicians in fireproof coveralls monitor computer terminals that continuously spit out data: pressure, temperature, fluid mix, flow rate, and micro-seismic activity around the well bore. All this bustle and noise is temporary. In less than a week the frac job will end, and the crew will haul the equipment to the next job.
The equipment is more sophisticated today, but oil and gas operators in Texas have been "fracking" wells for the past 65 years to get at oil and gas contained in "tighter"-less permeable-oil shale formations. More than a million frac jobs later, fracking is a routine step in the oil and gas production process, but now petroleum engineers have added a new twist: They turned their well bores 90 degrees to drill horizontally through low-permeability shale formations. The result: Oil and gas operators boosted natural gas production so significantly that prices plummeted from almost $10 per thousand cubic feet (mcf) to around $2 per mcf today.
To understand why fracking works, you have to understand a little bit about geology.
Mark Merritt says "most people have an idea that it's just a big cavern down there that we just drill and tap into." But it's not like that. Oil and gas are trapped in rock formations deep in the earth. Conventional drilling aims at "reservoirs" that are almost like sand, saturated with hydrocarbons easy to extract. These reservoirs are highly porous, with lots of microscopic bubbles containing oil and natural gas distributed throughout the rock, making it something like a very hard sponge. Those pores are connected to each other by naturally occurring, microscopic fractures. Those fractures make the rock permeable. You don't need fracking to get oil out of reservoirs that are porous and permeable.
Often, though, shale is not particularly porous or permeable. Merritt holds out a small core sample of shale taken from two miles below the earth, between Midland and Odessa, Texas. "This may be a few percent porosity," he says as he fingers the hard, black piece of rock. Picture a cube of rock two feet on each side. The amount of oil and gas containing pore space would be about the volume of a major league baseball-but spread throughout the total volume of the rock.
The rock Merritt is holding is 10,000 times less permeable than that in a "conventional reservoir." It has fewer pores and fewer naturally occurring fractures, so operators use fracking to "stimulate" the rock to create additional tiny fractures, making the shale more permeable and releasing the oil and gas hidden in those microscopic pores to flow to the well bore.
During a short but intense frac job, operators inject a mixture of fresh water and sand into a well at very high volumes and pressures. Perforations at the end of the well bore allow this sand/water mixture to force its way into the rock formation, opening up tiny crevices, or fractures, in the rock. The sand is deposited in these crevices, propping them open and providing a pathway for the trapped hydrocarbons to make their way to the well bore. Operators extract the "frac fluid," minus the sand, and recycle it.
Petroleum engineer Randy King has been involved with hydro-fracking for 25 years. "We've refined this technology for decades," he says. "The only thing new is now we're taking those drill bits and instead of going vertical, we're going horizontal into the formation, and thus exposing more of the well bore to the formation-allowing us to do more fracs per well." That means a single horizontal gas well is as productive as at least four traditional vertical wells.
Here's where the story takes a political turn. Fracking has led to more productive gas wells and more optimistic projections about the amount of natural gas that companies can recover from shale rock. Those developments have driven down the price of natural gas-normally a good thing, especially when the United States is striving for energy independence.
But low natural gas prices have undermined efforts to make so-called "green" energy technologies-wind and solar-economically viable, putting the oil and gas industry squarely in the sights of environmental organizations. They blame hydraulic fracturing for everything from contaminating drinking water with methane and other chemicals to causing earthquakes.
Kate Sinding, a senior attorney with the Natural Resources Defense Council, told me her environmental advocacy group's concerns with fracking run the gamut from air pollution to waste water to a perceived lack of sufficient regulatory oversight of onshore oil and gas operations. She noted the theoretical possibility that fracking chemicals or naturally occurring underground contaminants might migrate to drinking water sources through existing natural faults or fractures that have intersected with fractures created through fracking.
"Even though it happens at significant depth, there is the potential for this kind of contamination pathway to be created," says Sinding: "It's not something that would show up right away." She acknowledges that this possibility has never been documented, but quickly reminds me that spills of fracking fluids and waste, or problems with gas leaks from well bores, have happened in the past.
In Texas, past history of oil and gas activity goes back over 100 years. Fasken Oil and Ranch operates on land its founder, Toronto attorney David Fasken, started buying in Texas in 1913. After they discovered oil on their ranch in the 1940s, the Faskens spread across the Southwest. The family still holds 300,000 acres in west Texas, and the company manages both cattle and oil and gas operations. It operates wells on the same land where cattle graze. Mark Merritt is amused that anyone would associate fracking and contaminated drinking water: "We own the surface-we want to use the fresh water for cattle and people for many years to come. ... We believe it's safe so we're fracking on our own land!"
We walk over to a flatbed trailer stacked with long, cylindrical steel tubes called casing. Merritt points out that this casing, nearly 10 inches in diameter and weighing nearly 100 pounds per linear foot, is part of the triple layer of steel and cement that Texas laws and regulations require as a well passes through the fresh water aquifer, where an oil or gas well is most likely to affect drinking water. It's a requirement common to all oil and gas wells and has nothing to do with hydraulic fracturing.
Again, a little knowledge of geology is important to understand why many experts dismiss worries about fracking and water contamination. Huge distances exist between freshwater aquifers and the rock formations where fracking takes place. Drinking water wells are fairly shallow-about 500 or 600 feet deep. An oil and gas well is fracked at depths between 5,000 and 10,000 feet. The miles of rock between the surface and the shale formation create tremendous overpressure that works against the fracture stimulation process. Pressures this deep can be almost 5,000 pounds per square inch (psi), so it takes a great deal of energy to create these man-made, microscopic fractures, which extend radially outward from the well bore no more than 500 to 700 feet (see well bore illustration).
"Think about it," says Randy King, "You're trying to bust up something 5,000 or 6,000 feet below the surface of the earth. It's got a lot of pressure in it, so you can only move a man-made or induced crevice so far. So if you've got a 500-foot crevice or fracture, you've still got 5,500 feet of rocks and sand and limestone and granite and who knows what between you and the surface."
Not everyone is convinced by that argument. About two years ago, the EPA bypassed the Railroad Commission of Texas, which regulates oil and gas activity in the state, and issued an emergency order against Range Resources, an independent oil and gas operator in Fort Worth. The EPA claimed that Range Resources' fracking activities posed an imminent danger to residential areas by causing contamination of private water wells in North Texas. The EPA's order required Range Resources to provide clean drinking water to several families in the area.
The Railroad Commission conducted a detailed investigation, held hearings, and determined the EPA's allegations were not supported by the science. Methane may have been in the drinking water of those North Texas families, but it did not get there as a result of fracking. The Railroad Commission said the methane in the drinking water was naturally occurring, biogenic methane, created by the decomposition of organic material through fermentation, not thermogenic methane associated with oil and gas activity. The EPA ignored that finding.
When a Texas judge concluded that residents and an environmental consultant had falsified a video showing how their methane-tainted water could be ignited, the EPA withdrew its order. John Tinterra, former executive director of the Railroad Commission, says the episode shows the tension between state regulators-who have broad power, local expertise, and inspectors in the field-and federal regulators, who don't have the broad regulatory framework or the depth of expertise to regulate all the oil and gas activities taking place throughout the country.
Texans are used to seeing oil pump jacks and gas wells in both urban and residential areas. They are tolerant of, if not totally comfortable with, an industry that has made Texas one of the wealthiest states in the nation. But much of the untapped gas shale reserve in the United States is buried deep beneath New York, Pennsylvania, and North Dakota, states without a comparable connection to oil and gas. Even with the potential for economic growth oil and gas development would bring to these states, it will be a challenge to overcome the "not in my backyard" resistance the industry will face.
As recently as five or six years ago, many experts thought the nation had only a seven or eight year rolling supply of natural gas. Hydraulic fracturing combined with horizontal drilling changed all that.
Randy King is convinced this wasn't accidental: "Now we think we have about 1,000 trillion cubic feet in recoverable reserves, so instead of an eight-year, we've got a 30- to 40-year supply. And honestly, God knew all that! We just didn't know it. Now it's become obvious that we're blessed with it, and all because those shales, which were never booked as crude reserves, are now productive because of horizontal drilling and fracturing, and the game has changed."
-Michael Cochrane is an industrial and systems engineer