Fracking is not used for all natural gas/oil operations. Yet much of the US public/media discussion conflates natural gas and fracking, or fossil fuels and fracking—someone says natural gas, and the writer (or reader) changes it to fracking. People have sent me to ecowatch, The Guardian, and others that should do better.
So, hoping to decrease confusion a bit, here is US information on fracking, and human-caused earthquakes, followed by international differences.
What is fracking?
Hydraulic fracturing is one method of obtaining natural gas and oil.
Water, sand, and chemicals are injected down a vertical well at high pressure to fracture the rock, increasing pore size. This allows gas or oil to flow more readily. Pressure is decreased, and the injected fluids, fluids from the ground, and gas or/and oil flow back up the well.
Wells are typically more than 1 mile (2 km) deep. This is where the gas/oil is, and well below the groundwater. The horizontal section is typically 1,000 – 6,000 feet (300 – 1800 meters). Wells require >1 million gallons/year.
Oil and gas in traditional wells flow without the fracking, although methods to improve flow are often used.
When was this method first use?
Fracking has been used in vertical wells for half a century; in California where I live, Kern County began using fracking in the 1970s. Its use in horizontal wells began in the late 1980s.
Update 7/4/2015: Naval Civil Engineering Laboratory did first tests on horizontal drilling in tests that began in 1985, and released their results in 1993.
How much of US/world gas and oil production comes from fracking?
About half of US gas and oil come from fracking.
Does fracking cause earthquakes?
The fracking process itself causes tiny ground motions which are monitored as part of the process. Sensitive equipment is needed; we can’t feel them. The Earth Story discusses these earthquakes, from – 2 to 1 on the Richter scale, on its facebook page.
There were three earthquakes as of 2012 attributed to fracking, all larger than magnitude 1, in Great Britain, Oklahoma (see Oklahoma link), and Canada. The National Research Council in Induced Seismicity Potential in Energy Technologies (2012) does not see an important risk from fracking earthquakes.
Over the last few years, it has become clear that injecting waste water from enhanced oil recovery, or natural gas or oil wells of any type, sometimes produces earthquakes. Guglielmi, et al discuss their study in the 12 June Science: they inject fluid into a particular fault, and seismicity depended on injection rate. Fracking wasn’t mentioned (although a number of articles and blogs link to this study in “fracking causes earthquakes” article.)
Weingarten, et al in the 19 June Science, use copious information from Oklahoma and Texas fossil fuel operations, then correlate earthquakes with reservoir depth, injection rate, etc. They found that before 2000, about 20% of seismicity in the central and eastern US was associated with injection wells; this rose to 87% between 2011 and 2014. Three quarters of this was associated with enhanced oil recovery. The only risk factor appears to be high injection rates (>300,000 barrels per month), so the oil and gas industry can cut earthquakes dramatically by reducing injection rates.
What’s in the water?
Injected water contains a number of chemicals to aid the process.
Mark Zoback, professor of geophysics at Stanford, served on a committee to look at hazards of fracking and how to address them; he isn’t worried about any of the chemicals used by industry. However, water coming out of the wells picks up considerable amounts of arsenic, selenium, and other constituents of the shale, and needs to be handled safely.
The committee recommendations to the Secretary of Energy on fracking can be found here.
Does fracking result in huge natural gas release?
Brandt, et al in 14 February, 2014 Science found that US natural gas leaks have been underestimated. The evidence that leaks are larger than thought does NOT appear in areas where there is fracking.
Geothermal power sometimes uses fracking
In order to expand the use of geothermal energy, enhanced geothermal systems, or EGS, are needed. One of these methods uses fracking to increase the flow of hot water.
Independent of that, extraction of water for geothermal electricity can result in earthquakes. Monitoring is important, and, I understand, earthquakes from geothermal are easy to prevent.
Do other types of energy cause earthquakes?
Sichuan earthquake link
The May 2008 earthquake in Sichuan, killing 80,000 people, is widely believed to have been caused by the reservoir built to supply hydroelectric power. This assertion was made within days of the earthquake, based on the weight of the reservoir when full, and because earthquakes are especially likely when this weight decreases; water levels fell before the earthquake. This has not been proved according to scientific standards, but the assertion has appeared unchallenged a number of times in Science.
The same article says,
Seismologists have been collecting examples of triggered seismicity for 40 years. “The surprising thing to me is that you need very little mechanical disturbance to trigger an earthquake,” says [seismologist Leonardo] Seeber [of the Lamont-Doherty Earth Observatory in Palisades, New York]. Removing fluid or rock from the crust, as in oil production or coal mining, could do it. So might injecting fluid to store wastes or sequester carbon dioxide, or adding the weight of 100 meters or so of water behind a dam.
National and international differences
US regulations vary by states; here is a partial list.
The European Union has a set of recommendations rather than requirements, due to UK opposition to the latter. I haven’t found an overview that tells me what assertions are actually valid.
United Kingdom regulations differ a bit from those in the US:
• tighter regulations on well linings to protect the aquifer.
• fewer chemicals in the injected water.
• the collected flowback cannot be stored in open pits, which can lead to surface water contamination, but must be stored safely.
More information on the chemicals and and flowback storage can be found at the UK Department of Energy and Climate Change.
Fracking in temporarily on hold in the UK, but industry is optimistic that it can begin fracking soon.
Update 7/4/2015: From The Guardian, nine county councillors rejected fracking. Cuadrilla will appeal, but prospects look poor.
It’s about climate change
I have talked to and read a number of people in climate change, and they give one of two answers when asked about fracking. Either
fracking is good because it allows us to produce natural gas cheaper than coal, and that allows a rapid decrease in greenhouse gas emissions from electricity. Or
fracking is bad because it opens a large new source of fossil fuels, and it replaces low greenhouse gas forms of energy like nuclear power.
Every expert I have talked to or read provides one or both of those answers when asked about fracking. No other concern comes close to their concerns about the effect of fracking on climate change. Not the arsenic in the water, earthquakes, nothing.