The great state of Oklahoma has recently found fame as the world’s No. 1 earthquake hotspot, and a new report from the U.S. Geological Survey puts the blame squarely on the practice of disposing wastewater from oil and gas operations by injecting it underground. According to the agency, “induced seismicity” from these injection wells is so extreme in north-central Oklahoma that the region is now in league with parts of California that are historically notorious for a heightened risk of damage from natural earthquakes.
Aside from counting this as yet another environmental strike against petroleum, the new USGS report undermines the efforts of the natural gas industry to promote its product as a “cleaner” alternative to both petroleum and coal.
Earthquakes and fracking
The increased earthquake activity in Oklahoma and elsewhere in the U.S. has been linked to the emergence of fracking. Short for hydraulic fracturing, fracking is an oil and gas drilling method that involves shooting massive volumes of a chemical brine underground. It was practiced for decades in relative obscurity until the Bush administration engineered an exemption from federal water-safety regulations, enabling it to increase exponentially and intrude into new areas.
To be clear, so far researchers have tied very few earthquake episodes to the drilling action itself. The main linkage has come about as drillers have pursued underground injection as the most economical and convenient way to dispose of the vast quantities of wastewater that result from fracking.
Conventional oil and gas drilling can also bring up large quantities of wastewater, which also contributes to underground injection sites.
In other words, while there is a fracking connection to induced seismicity in the U.S., the problem is more accurately thought of as a broad lifecycle issue for the oil and natural gas industry.
Assessing earthquakes, induced or natural
The assessment of earthquake hazards is difficult even under ordinary circumstances, and induced seismicity plasters a whole new layer of complexity onto the effort, because it is a human action that can vary considerably depending on changes in public policy, industry economics, technology and other variables that have nothing to do with geological history as previously charted by researchers.
Without federal oversight, regulation of injection wells (and fracking itself) has been left to a patchwork of state regulations. Oklahoma in particular seems to have left the barn door open when it comes to regulating wastewater injection. State policy was quite liberal until last year, when the alarming increase in seismic activity finally compelled state officials to implement a cascading series of controls on injection wells.
That may have been too little, too late. Despite new restrictions, seismic activity in Oklahoma has continued to increase this year and it has spread to new areas.
The new USGS seismic hazard model
In the aftermath of the U.S. oil and gas drilling boom, USGS has struggled to come up with a rational way to assess the totality of future earthquake hazards. Even as late as 2014, the agency was forced to eliminate induced seismicity from its national forecasts.
In the new earthquake report, titled 2016 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes, USGS lays out a path forward that takes induced seismicity into account for the first time ever. Rather than focusing on long-term projections, the new report focuses on the coming year.
USGS notes that the evidence trail is not yet fully defined from a technological point of view, but since 2010 the circumstantial episodes have added up to a pattern that can no longer be ignored, given a corresponding increase in oil and gas operations.
That could change almost overnight depending on the evolution of new regulations or shifts in focus by the industry, which accounts for the relatively short, one-year term of the study.
Earthquakes and other stakeholders
Earlier this week, the Associated Press previewed the new USGS report and noted that the Federal Emergency Management Agency drafted several studies for the potential impacts of major earthquakes on Dallas, Texas.
According to AP, the probability of a major quake of 4.6 or higher is extremely low in the Dallas area but still “plausible” according to a USGS researcher, an observation that is sure to catch the attention of local stakeholders.
In more bad news for the Texas fracking industry, the U.S. Army Corps of Engineers has raised concerns over the impact of gas fracking operations on the integrity of the Joe Pool Lake dam in North Texas. The lake — a collaborative effort involving USACE and local agencies — is a relatively young piece of major water infrastructure, having been completed in 1989. It is a popular recreation destination for the Dallas area, and it serves as a water supply reservoir for the city of Midlothian.
In March, USACE announced that fracking would be banned within 4,000 feet of the dam and wastewater injection would be limited within five miles.
In its announcement, USACE noted that the Joe Pool lake sits over the Barnett Shale formation, a major locus of oil and gas activity in the U.S. In recognition of potential hazards posed by that activity, an initial protective zone of 3,000 feet was established when the dam was first completed.
The new rules are based on a study commissioned from the top Ohio-based engineering firm DLZ National, which indicated the need for much stronger protection:
“The study results were then used to inform a risk assessment of the dam, which identified potential failure modes associated with mineral extraction and the consequences of those failure modes on project performance and, most importantly, on life safety.”
“USACE has concluded the 3,000-foot exclusion zone at Joe Pool Dam does not sufficiently meet our minimal tolerable risk guidelines and therefore, poses a risk to the dam, the lake, and the public.
“As a result of this finding, USACE has adopted a 4,000-foot exclusion zone at Joe Pool Dam. Within that zone no drilling will be allowed, regardless of depth. USACE is also working to protect the project from the effects of induced seismicity by limiting injection wells within five miles of Joe Pool Dam.”
The Texas Railroad Commission, which functions as the state’s oil and gas regulator, has challenged USACE’s authority to make unilateral decisions of that sort. However, given the popularity of Joe Pool Lake with stakeholders outside of the oil and gas industry, it’s likely that the commission will have a tough time getting USACE to relax the new restrictions.
Image (screenshot): via U.S. Geological Survey, page 6.