Geology Reference
In-Depth Information
In an effort to make hydrofracking more environmentally friendly, the EPA insti-
tuted new “green completion” (or “reduced emission completion”) rules in 2012,
designed to cut down on air pollution. In essence, the nearly 600-page set of rules
requires hydrofrackers to capture natural gas at the wellhead rather than flaring it
off or releasing it into the atmosphere.
Green completions are used in the week or so between the initial drilling of a
well and the time the well goes into production, a period when pollutants—and
valuable methane—billow out of the borehole into the atmosphere, “like popping
the top on a soda can,” as the Natural Resources Defense Council (NRDC) puts
it. That escaping gas represents half a trillion cubic feet of wasted gas annually,
NRDC estimates.
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Every well is different, and there is no one-size-fits-all green completion pro-
cess. When a well is drilled, it produces a mix of water, sand, hydrocarbon liquids,
and gas. The elements are separated in a cylindrical vessel that allows the pressure
from the well to drop: the liquids and solids drop while the gas rises. When hydro-
fracking dry gas, like that from the Marcellus Shale in New York, a green comple-
tion involves a two-step process to separate gas from flowback. In the case of wet
gas, like that found in the Marcellus Shale in northern West Virginia, a three-phase
separation separates gas from hydrocarbon liquids from flowback.
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Another target of green completion is the dramatic “flaring” of excess gas or oil.
Typically used in a well's early production, this venting clears impurities from the
well before production begins. But it also releases methane into the atmosphere. In
composing the new rules, the EPA acted on its Clean Air Act mandate to reduce
emissions of VOCs (volatile organic compounds) and potential carcinogens, such
as benzene. The agency estimates that green completions would eliminate 95 per-
cent of smog-forming VOCs emitted from over 13,000 new gas wells annually.
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During a green completion, wastewater is routed through a series of filters. A
sand trap collects the solid materials, which are sent to a landfill. The remaining
wastewater is cleaned, treated, and stored for reuse in the next drilling operation.
The natural gas is then channeled into a pipeline, captured, and sold. Indeed, a “co-
benefit” of the new rules is that, with the help of portable equipment to process gas
and condensate (a low-density combination of hydrocarbon liquids that are present
as gaseous compounds in natural gas), some 1 million to 1.7 million tons of meth-
