Earthquakes in the Oilpatch: the Regulatory and Legal Issues Arising Out of Oil and Gas Operation Induced Seismicity

JurisdictionUnited States,Federal
Publication year2017
CitationVol. 33 No. 3

Earthquakes in The Oilpatch: The Regulatory and Legal Issues Arising Out of Oil And Gas Operation Induced Seismicity

Monika U. Ehrman

University of Oklahoma College of Law

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Monika U. Ehrman*


There has been a tremendous increase in earthquake activity in traditionally non-seismically active states, such as Oklahoma, Texas, Kansas, and Ohio. In fact, Oklahoma has surpassed California to become the most seismically active state in the United States. Over the last five years, many researchers have pointed to a correlation between seismic activity and certain oil and gas operations, such as wastewater fluid injection and hydraulic fracturing. Oil and gas companies, state regulatory agencies, and local and state governments are unsure of how to proceed given that most of this activity is occurring in states with a strong and economically vested interest in petroleum production. "Frackquake" litigation is on the rise in these states causing courts and parties to puzzle over causation. This Article reviews the geologic mechanism, scientific studies, applicable federal environmental legislation, state regulatory framework, and corresponding litigation related to oil and gas induced seismicity. Finally, this Article provides the foundation for further induced seismicity literature, in addition to offering strategies for and identifying challenges faced by stakeholders.

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The small, North Texas town of Azle, Texas (pop. 10,947) straddles the hydrocarbon-rich counties of Parker and Tarrant.1 Before the area became synonymous with the Barnett shale and its ensuing oil and gas development, Azle was best known as the home of Western author James Reasoner.2 Like most of Texas, it was not renowned for seismic activity.3 But all that was to change.

Between 1970 and 2007, Azle residents experienced just two earthquakes;4 by the start of 2008, residents reported seventy-four minor earthquakes.5 Around that same time, natural gas development activity climbed sharply as oil and gas operators moved into the area to develop Barnett shale prospects using a combination of horizontal drilling and hydraulic fracturing.6 By 2009, scientific research led some to conclude that fluid injection may be responsible for the seismic activity.7 Five years later, the seismic activity continued.8 Azle residents, frustrated with a perceived lack of action by the state, boarded a bus and traveled to the seat of Texas government.9 They named their trip, "Shake the Ground in Austin."10 There, over 100 people attended a hearing of the state oil and gas regulatory agency—the Railroad Commission of Texas—which promised to study the seismic activity, but later denied any direct correlation with petroleum development.11 The next year, in 2015, a research team

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consisting of scientists at Southern Methodist University (SMU) in Dallas, the University of Texas at Austin, and the United States Geological Survey (USGS), the federal agency charged with, inter alia, studying and monitoring earthquake activity, concluded that oil and gas operations likely caused Azle's seismicity.12

Induced seismicity is not a recent phenomenon. In the 1800s, English coal mines reported seismic activity after removal of overburden in search of coal;13 hydroelectric dams and geothermal energy operations have also caused seismic activity;14 and in the 1960s, the United States Army discovered that injection of fluids into the subsurface could induce earthquakes.15 However, with respect to oil and gas operations, induced seismicity is still a most unexpected and troubling phenomenon.16 After a spate of earthquakes in areas that were not historically seismically active, scientists began investigating a possible relationship with shale gas development.17

Occurring in such states as Arkansas, Colorado, Kansas, Ohio, Oklahoma, and Texas,18 the earthquakes thus far have been small, with few injuries to persons or property.19 Public concern has led to scientific and academic studies focusing on wastewater reinjection and hydraulic fracturing as possible causes.20 Both processes are

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currently necessary to develop unconventional hydrocarbons, such as shale oil and gas and coal bed methane.21

Many of these first studies originally classified hydraulic fracturing as low-risk with respect to seismic causation and concluded that there was no direct evidence that hydraulic fracturing triggers earthquakes;22 but, traditionally seismically inactive states, like Oklahoma and Kansas, continued experiencing an increase in earthquakes.23 In fact, in 2014, Oklahoma experienced twice as many earthquakes as California, a state recognized for its seismic activity.24 One year later, Oklahoma received the dubious honor of surpassing California and Alaska to become the most seismically active state in the country.25 To investigate this increase, scientists turned their attention to wastewater disposal wells.26

In 2010, Congress requested that the National Academy of Science study the seismic events related to oil and gas operations.27 According to the resulting report, reinjection of wastewater posed a greater risk of man-made seismic events than hydraulic fracturing did.28 John Armbruster, of the Lamont-Doherty Earth Observatory at Columbia University, has been studying seismic events and hydraulic fracturing in Ohio and is "virtually certain" that wastewater reinjection caused a 4.0 magnitude tremor near Youngstown.29 Armbruster argues that "any disposal well that's been pumping stuff into the ground for months can cause earthquakes."30 In response to the tremors, Ohio state officials ordered four disposal wells in the

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area to close.31 In a March 6, 2015 press release, the USGS concluded that Oklahoma's heightened earthquake activity since 2009 was likely not caused by random fluctuations in natural seismicity rates, but rather by wastewater injected into deep geological formations.32

Academic and scientific communities report various positive correlations regarding the induction of seismic activity by wastewater injection; however, the studies are ongoing and various stakeholders often question or dispute the conclusions.33 Whatever the science, the judicial and regulatory processes continue, leaving courts and regulators to review and decide the issues associated with induced seismicity vis à vis oil and gas development.34 Certainly, this lack of scientific certainty has not preempted an influx of induced seismicity litigation.

This article reviews the scientific theories and studies regarding induced seismicity, in addition to examining the current regulatory framework and litigation arising out of these seismic events. Lastly, it provides strategies to aid stakeholders and identifies challenges likely to arise in the future. Part I of this Article provides a review of the geoscience theories regarding natural and induced seismicity.35 Part II reviews the current scientific literature regarding a possible relationship between certain oil and gas operations and induced seismicity.36 Part III reviews the existing regulatory structure addressing seismicity in affected states, including possible applicable

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environmental legislation.37 Part IV discusses the resulting litigation involving oil and gas seismicity.38 Part V sets forth possible strategies for stakeholders.39 Finally, Part VI offers the author's conclusions, including identifying future areas of concern.40

While this Article reviews and discusses various scientific studies regarding induced seismicity and the wastewater and hydraulic fracturing processes, it does not support or advocate any conclusion. It simply reports the findings issued by various scientific and engineering groups. Although the Article may address international examples, it focuses on the United States.

I. Review of the Current Science Regarding Natural and Induced Seismicity

Analyzing induced seismicity requires a basic understanding of how man-made events can generate earthquakes. This section provides a brief explanation of both naturally occurring and induced, sometimes referred to as "anthropogenic," seismicity.41 In the next section, this Article reviews the current literature regarding the possible relationship between seismic activity and two oil and gas operations—wastewater disposal and hydraulic fracturing.42

A. Explanation of Natural Seismicity

Seismology is the study of elastic waves, including compressive waves such as sound waves and shear waves, in the earth43 and includes the "study of earthquakes and the structure of the earth, by

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both naturally and artificially generated seismic waves."44 Seismicity refers to the "geographic and historical distribution of earthquakes."45

An earthquake generally occurs from the motions of the tectonic plates that make up the earth's lithosphere—"the solid, outer part of the [e]arth, including the brittle upper portion of the mantle and the crust."46 Originating in the 1950s and developing over two decades, the plate tectonics theory evolved out of Alfred Wegener's continental drift theory, first proposed in 1912.47 Plate tectonics theorizes that Earth's outer shell is divided into several tectonic plates—comprised of both continental and oceanic crust—that glide over the mantle—the rocky inner layer above the core.48 These plates "act like a hard and rigid shell compared to Earth's mantle."49 Although Wegener did not have an explanation for how continents could move around the planet, scientists now explain this movement using plate tectonics, which is considered geology's unifying theory.50

Unlike puzzle pieces, the plates do not neatly connect with each other.51 Instead, they are part of a dynamic geologic process whereby they push up, slide against, and move away from each other.52 These movements result in...

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