KUNM

Shaky Ground: Fracking And Earthquakes

Mar 18, 2015

Credit Wikimedia Commons / U.S. Environmental Protection Agency

Inevitably, when talking about oil and gas development, the word fracking comes up in conversation.

In the coming weeks, KUNM will be airing more feature stories on oil development in northwestern New Mexico. And I'll be posting here about some of the more technical issues I explore, such as fracking, or hydraulic fracturing. 

Although the energy industry has used hydraulic fracturing as a way to draw more fossil fuels from wells since the mid-twentieth century, the word fracking has really only entered the public lexicon within the last decade—and become popular within the past couple of years. 

It's probably safe to say that the public owes a measure of thanks to former Vice President Dick Cheney for raising the profile of hydraulic fracturing.

Cheney is a former CEO of Halliburton, the company that pioneered fracking in the 1940s. Fourteen years ago, he encouraged Congress to exempt the practice from regulation under the Clean Water Act and pressured the U.S. Environmental Protection Agency to alter studies of its impacts on public health.  

More recently, as the practice has spread to states like New York and Pennsylvania, interest in fracking has burgeoned even more.

(As an aside, it's useful to remember that New Mexico is way ahead of the curve on hydraulic fracturing. Companies have been fracking wells in New Mexico for decades and almost all of the tens of thousands of natural gas and oil wells in the state have been—or are being​—fracked.)

One of the federal agencies with scientists studying hydraulic fracturing is the United States Geological Survey. And within the past year, USGS scientists have released two papers particularly relevant to New Mexico. 

In October 2014, the Bulletin of the Seismological Society of America published a paper about USGS investigations into seismic activity in New Mexico's Raton Basin. Between 1972 and July 2001, the basin had experienced only one earthquake with a magnitude of four or higher. Between August 2001 and 2013, there were 12.  That's a 40-fold increase.

Companies have been fracking wells in New Mexico for decades and almost all of the tens of thousands of natural gas and oil wells in the state have been—or are being​—fracked.

Those recent quakes were concentrated in an industrial area, wrote scientists, and the change in the rate of earthquakes wasn't random. Rather, they were related to the deep injection of wastewater from coalbed methane development. 

(Fracking is the process during which drillers inject water, chemicals and sand into fissures, the better to free up the natural gas or oil that's below the earth. Reinjection is when companies dispose of that wastewater by injecting it back below the ground's surface.)

In that 2014 paper, scientists noted that energy companies began reinjecting wastewater in New Mexico in 1999—and since 2004, median injection rates in the Raton Basin have been about 1.2 million barrels of wastewater per month. 

According to the paper, the "vast majority" of the seismic activity took place within 5 kilometers of wastewater injection wells. 

And if you're really a glutton for technical writing, you can parse this important paragraph, too: 

In addition to stresses coming directly from the well-head, there are other, more broadscale stress changes that come from fluid injection. With the injection of fluids, there will be significant fluid movement to accommodate the increases in fluid volume. The fluid redistribution will change the stress field. Poroelastic effects are also important, as pore spaces will get filled and additional pores may be opened or closed due to the increased fluid pressure.

In other words: Water, under pressure, runs to wherever it will fit. And as the pressure increases and more water is pumped underground, it stresses the surrounding rocks.  

Last month, the USGS's Earthquake Science Center put out another paper—this one focused on how to cope with the quakes being caused by fluid injection.  

According to the paper, large areas of the U.S. that had been considered "geologically stable" have recently become seismically active. "The increase in earthquake activity began in the mid-continent starting in  2001 and has continued to rise," scientists wrote. "In 2014, the rate of occurrence of earthquakes with magnitudes of 3 and greater in Oklahoma exceeded that of California." 

To a large extent, they wrote, the increase is due to "fluid-injection activities used in modern energy production." 

Addressing the problems will require a number of steps, the scientists advised. One of those is developing a model for industrial seismic hazards, the same way models are developed for natural earthquakes so people can design buildings that will withstand seismic activity and establish building codes to ensure structures are safe.

Those models would need to be updated frequently, they wrote, since injection rates change as natural gas and oil production increases or decreases and changes across regions. And of course, developing models requires conducting monitoring. 

State and federal agencies, as well as industry, emergency responders and the public will all need to work together, since there are so many research needs, regulatory overlaps and potential hazards. 

And, wrote the scientists, transparency is important, too.

Even if the data is owned by industry, they wrote, "regulators must ensure that seismic data are not withheld from the public." Injection data—including daily injection rates, wellhead pressures, depth of the injection interval, and properties of the target formation—should all be accessible to the public. 

Open sharing of data, they write, can benefit all stakeholders by enabling the research necessary to reduce hazards. 

To read more from USGS on hydraulic fracturing, check out the agency's FAQ's page. Click that link and follow the links with each question to see videos and read additional resources.