Well Injection, Quakes Linked
Legislative panel told fracking is not big concern
Morgantown Dominion Post
10 October 2012
By David Beard
CHARLESTON — There’s no evidence to date that fracking causes
earthquakes — but there is some correspondence between quakes and
deep-well injection of wastewater.
Michael Hohn, director of the West Virginia Geological and
Economic Survey, based in Morgantown, conveyed this to members of
a joint legislative Judiciary subcommittee Tuesday morning.
The U.S. Geological Survey reports: “Earthquakes induced by human
activity have been documented in a few locations in the United
States, Japan and Canada. The cause was injection of fluids into
deep wells for waste disposal and secondary recovery of oil, and
the filling of large reservoirs for water supplies. Most of these
earthquakes were minor.”
Several injection wells in the Youngstown, Ohio, area were closed
this year after a series of 11 quakes — the strongest magnitude
4.0 — in late 2011, according to reports.
Braxton County experienced what Hohn called a “swarm of
earthquakes” in 2010 — all of them mild, as high as 3.4, which can
Hohn pointed out that Braxton has one injection well.
Sen. Clark Barnes, R-Randolph, asked Hohn about the counties
immediately northeast — Lewis and Upshur. Hohn said those counties
have many more wells, and several months after the Braxton swarm,
they experienced two small quakes.
The risk factors for quakes from human activity include proximity
to fault lines, how the activity affects the pore pressure of the
rock formations where the activity takes place, and the degree the
formations are subject to stress and brittleness.
In the case of the West Virginia quakes, no one knew there was a
fault line there until the quakes occurred. Now they know one runs
southwest to northeast — paralleling the line of the mountains.
Fracking — hydraulic fracturing of the rock formation to allow gas
to follow — doesn’t pose much seismic risk, Hohn said. There are
35,000 shale wells and only three instances of seismic activity
associated with them — one in England and two in Oklahoma — and
the data on one of the Oklahoma quakes are inconclusive.
There are 30,000 injection wells in the nation. An area in central
Arkansas experienced about 100 quakes in 2011, before activity at
two injection wells was suspended, according to the Center for
Earthquake Research and Information. The highest was 4.7, enough
to cause some damage.
After the wells were closed, the number and severity of the quakes
decreased, leading scientists to believe the quakes were connected
to the wells — though not convinced enough to call it proof.
The National Academy of Sciences National Research Council said
this in a report this year: “Of all the energy-related injection
and extraction activities conducted in the United States, only a
very small fraction have induced seismicity at levels noticeable
to the public (that is, above magnitude 2.0). ... Hydraulic
fracturing to date has been confirmed as the cause for small, felt
seismic events at one location in the world. The process of
hydraulic fracturing a well as presently implemented for shale gas
recovery does not pose a high risk for inducing felt seismic
It continues: “Water injection for disposal has been suspected or
determined a likely cause for induced seismicity at approximately
8 sites in the past several decades. However, the long-term
effects of increasing the number of waste water disposal wells on
the potential for induced seismicity are unknown, and wells used
only for waste water disposal usually do not undergo detailed
geologic review prior to injection, in contrast to wells for
enhanced oil recovery and secondary recovery.”
Hohn said quakes can continue for months or years following
injection. It’s hard to evaluate the potential in advance, as
there’s no way to locate unmapped faults and measure the stress.
In response to a question from subcommittee co-chairman Delegate
Tim Manchin, D-Marion, Hohn said the quakes can become more severe
over time. The last Ohio quake was the strongest.
Hohn said that U.S. Geological Survey earthquake expert William
Leith told Congress in June there’s still not enough data, but
recommended states require seismic monitoring as part of the
Hohn told Manchin four monitors ranged as far as a well is deep —
about a mile — would cost about $100,000 total.
Manchin asked Hohn if the Braxton quakes have produced evidence of
water wells suffering damage or diminished water levels, or of
cracked gas well casings. Hohn said he’s had no word on any of
Hohn said the jury is still out on one potential wave of the
future: Carbon capture and sequestration — storing carbon dioxide
emissions underground so they don’t produce greenhouse effects.
The National Research Council said this in its report: “Carbon
capture and storage differs from other energy technologies because
it involves the continuous injection of very large volumes of
carbon dioxide under high pressure, and is intended for long term
storage with no fluid withdrawal. The large net volumes of carbon
dioxide that would help reduce global carbon dioxide emissions to
the atmosphere may have potential for inducing larger felt seismic
events due to increases in pore pressure over time; potential
effects of large-scale carbon capture storage projects require