Photo by Cindeka Nealy/Genesis

Fracking: Fact or fiction?

Energy | Horizontal drilling is boosting domestic natural gas production, and dubious controversy over its safety

Issue: "Effective Compassion," June 16, 2012

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.

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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.


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