American Oil and Gas Reporter - March 2017 - 25

TECHCONNECTIONS
Government And
Industry Responding To
Induced Seismicity
Anyone working about anywhere in the Mid-Continent over
the last several years is pretty likely to have heard a lot about induced seismic events or earthquakes related to the oil and gas
industry in this area. Readers even may have experienced a
couple of these events themselves.
While there is some debate about exactly how many of these
events are tied directly to oil and gas production-specifically
injecting produced water into disposal wells-studies are showing
that there may be a relationship between oil and gas production
and increased seismic activity. But studies also show that
hydraulic fracturing is not, or at least rarely is the cause of these
seismic events, as some folks would have you believe.
A report from the U.S. Department of Energy indicates that
government agency believes much induced seismic activity may
be tied to injecting produced water into disposal wells in various
regions. Some of these events have reached magnitude ranges
between 3.0 and 6.0. Over the last several years, there has been
work going on to identify the risks associated with wastewater
injection, to begin to predict the probability and impact of these
events, and to develop strategies and technologies designed to
mitigate the risks.
Anyone working in the Mid-Continent also knows injecting
produced water into disposal wells is an established technology
that has been in use for many years. What seems to be occurring
has little to do with the injection itself, but rather the rate at
which companies are injecting.
According to DOE, tectonic forces are responsible for the
vast majority of earthquakes around the globe. However, in
certain cases, human activities can trigger a seismic event. In
Oklahoma, for example, as the number of seismic events larger
than 3.0 began to increase, researchers began to correlate these
events with wastewater injection deep into subsurface rock formations. According to the Oklahoma Geological Survey, the
events occurring near unconventional oil and gas plays were
unrelated to hydraulic fracturing, but rather to disposing the
water associated with oil and gas production.
Geologically, there are certain features that must be present
for an induced seismic event to occur. These features include an
existing fault, some sort of subsurface stress that brings the
fault close to failure, and a change in that stress caused by either
injecting or withdrawing fluids. Additionally, there seems to be
a relationship between the distance between a fault and a well,
reservoir permeability of the rocks around the fault, and the rate
of injection.
These events seem to occur in areas with older metamorphic
rocks that underlie disposal reservoirs. According to the DOE,
injection wells that are in these areas may be more prone to
induce a seismic event, but can be managed simply by reducing
the amount of water injected as well as the period of injection.
According to an article in the Wall Street Journal, data from
the U.S. Geological Survey show that most of the seismic
activity felt by large groups of folks is centered near Oklahoma
City and Dallas-Fort Worth, and that high-risk states include

"Operators are working with state and federal
governments to develop the best course of action

moving forward.

Oklahoma, Kansas, Texas, Colorado, New Mexico and Arkansas.
In Kansas, as well as other states, operators are addressing
the issue. A document from the Kansas Independent Oil & Gas
Association illustrates Kansas' history of earthquakes, which
stretches for millennia-especially along the Nemaha Ridge,
which spreads north and south across much of Kansas and
Oklahoma. This area is also home to many of Kansas' and Oklahoma's significant and historical oil fields.
The document also states that because oil and gas are
produced in almost every county in Kansas, the likelihood of an
event being located near a disposal well is almost certain, and
that ongoing analysis is required to differentiate between a
seismic event that is related to human activity and one that is
not.
While scientists tend to agree that under certain conditions,
day-to-day oil and gas production can cause a seismic event,
the risk appears to be extremely low, with fewer than 0.5
percent of all wells in Kansas being linked to a seismic event.
That said, operators are working actively with state and federal
governments and regulatory agencies to research these events
and develop the best course of action moving forward.
As industry begins to develop business plans around the
risks associated with induced seismicity, education is a key to
addressing the issue head-on. In May, the Petroleum Technology
Transfer Council will be hosting a single-day workshop in
Tulsa designed to provide updated information about what we
have learned so far, as well as the technology, monitoring, legal
issues, and regulations that may impact operators moving
forward. Visit pttc.org for more information.
❒

JEREMY VISCOMI is the Mid-

Continent regional lead for
the Petroleum Technology
Transfer Council. He has more
than a decade of experience
in developing and organizing
technical conferences and special events, primarily in the
oil and gas industry.
MARCH 2017 25

http://www.pttc.org

American Oil and Gas Reporter - March 2017

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