tag:theconversation.com,2011:/ca/topics/fracking-fluids-21478/articlesFracking fluids – The Conversation2023-04-03T12:27:43Ztag:theconversation.com,2011:article/1939152023-04-03T12:27:43Z2023-04-03T12:27:43ZCompanies that frack for oil and gas can keep a lot of information secret – but what they disclose shows widespread use of hazardous chemicals<figure><img src="https://images.theconversation.com/files/518576/original/file-20230330-20-te72z5.jpg?ixlib=rb-1.1.0&rect=23%2C15%2C5168%2C3440&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A deep injection well used for disposal of fracking wastewater in Kern County, Calif.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/deep-injection-well-used-for-disposal-of-wastewater-kern-news-photo/566446781">Citizens of the Planet/Education Images/Universal Images Group via Getty Images</a></span></figcaption></figure><p>From rural Pennsylvania to Los Angeles, more than 17 million Americans live within a mile of <a href="https://doi.org/10.1289/EHP1535">at least one oil or gas well</a>. Since 2014, most new oil and gas wells <a href="https://www.eia.gov/todayinenergy/detail.php?id=34732">have been fracked</a>. </p>
<p><a href="https://www.nrdc.org/stories/fracking-101">Fracking</a>, short for hydraulic fracturing, is a process in which workers inject fluids underground under high pressure. The fluids fracture coal beds and shale rock, allowing the gas and oil trapped within the rock to rise to the surface. Advances in fracking launched a huge <a href="https://www.simonandschuster.com/books/The-Boom/Russell-Gold/9781451692297">expansion of U.S. oil and gas production</a> starting in the early 2000s but also triggered intense debate over its health and environmental impacts. </p>
<p>Fracking fluids are up to 97% water, but they also contain a host of chemicals that perform functions such as dissolving minerals and killing bacteria. The U.S. Environmental Protection Agency classifies a number of these chemicals as <a href="https://cfpub.epa.gov/ncea/hfstudy/recordisplay.cfm?deid=332990">toxic or potentially toxic</a>. </p>
<p>The Safe Drinking Water Act, enacted in 1974, <a href="https://www.epa.gov/uic/underground-injection-control-regulations-and-safe-drinking-water-act-provisions">regulates underground injection of chemicals</a> that can threaten drinking water supplies. However, Congress has <a href="https://digitalcommons.law.buffalo.edu/belj/vol19/iss1/1/">exempted fracking from most federal regulation</a> under the law. As a result, fracking is regulated at the state level, and requirements <a href="https://www.jstor.org/stable/44134029">vary from state to state</a>.</p>
<p>We study the oil and gas industry in <a href="https://scholar.google.com/citations?hl=en&user=0ljDCPkAAAAJ">California</a> and <a href="https://scholar.google.com/citations?user=aBGLAAYAAAAJ&hl=en">Texas</a> and are members of the <a href="https://sarawylie.com/wedj-lab/">Wylie Environmental Data Justice Lab</a>, which studies fracking chemicals in aggregate. In a recent study, we worked with colleagues to provide the first systematic analysis of chemicals found in fracking fluids that <a href="https://doi.org/10.1016/j.envpol.2022.120552">would be regulated under the Safe Drinking Water Act</a> if they were injected underground for other purposes. Our findings show that excluding fracking from federal regulation under the Safe Drinking Water Act is exposing the public to an array of chemicals that are widely recognized as threats to public health.</p>
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<a href="https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of a fracking operation." src="https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=529&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=529&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=529&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=665&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=665&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518584/original/file-20230330-19-6wvvu3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=665&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A schematic of a hydraulic fracking operation, with wastewater temporarily stored in a surface waste pit.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/fracking-royalty-free-illustration/501046435">wetcake via Getty Images</a></span>
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<h2>Averting federal regulation</h2>
<p>Fracking technologies were originally developed in the 1940s but only entered widespread use for fossil fuel extraction in the U.S. in the early 2000s. Since the process involves injecting chemicals underground and then disposing of contaminated water that flows back to the surface, it faced potential regulation under multiple U.S. environmental laws. </p>
<p>In 1997, the 11th Circuit Court of Appeals ruled that fracking should be <a href="https://www.leagle.com/decision/19971585118f3d146711376">regulated under the Safe Drinking Water Act</a>. This would have required oil and gas producers to develop underground injection control plans, disclose the contents of their fracking fluids and monitor local water sources for contamination. </p>
<p>In response, the oil and gas industry lobbied Congress to exempt fracking from regulation under the Safe Drinking Water Act. Congress did so as part of the <a href="https://www.epa.gov/uog#:%7E:text=The%20Energy%20Policy%20Act%20of,regulation%20under%20the%20UIC%20program.">Energy Policy Act of 2005</a>. </p>
<p>This provision is widely known as the <a href="https://doi.org/10.3390/w4040983">Halliburton Loophole</a> because it was championed by former U.S. Vice President Dick Cheney, who previously served as CEO of <a href="https://www.halliburton.com/">oil services company Halliburton</a>. The company patented fracking technologies in the 1940s and remains one of the world’s largest suppliers of fracking fluid. </p>
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<h2>Fracking fluids and health</h2>
<p>Over the past two decades, studies have linked exposure to chemicals in fracking fluid with a wide range of health risks. These risks include <a href="https://doi.org/10.1515/reveh-2014-0057">giving birth prematurely and having babies with low birth weights</a> or <a href="https://doi.org/10.1289/ehp.1306722">congenital heart defects</a>, as well as <a href="https://doi.org/10.1016/j.jacc.2020.10.023">heart failure</a>, <a href="http://dx.doi.org/10.1001/jamainternmed.2016.2436">asthma and other respiratory illnesses</a> among patients of all ages. </p>
<p>Though researchers have produced numerous studies on the <a href="https://doi.org/10.1093/acrefore/9780190632366.013.44">health effects of these chemicals</a>, federal exemptions and sparse data still make it hard to monitor the impacts of their use. Further, much existing research focuses on individual compounds, not on the cumulative effects of exposure to combinations of them.</p>
<h2>Chemical use in fracking</h2>
<p>For our review we consulted the <a href="https://www.fracfocus.org/">FracFocus Chemical Disclosure Registry</a>, which is managed by the <a href="https://www.gwpc.org/">Ground Water Protection Council</a>, an organization of state government officials. Currently, <a href="https://www.fracfocus.org/learn/about-fracfocus">23 states</a> – including major producers like Pennsylvania and Texas – require oil and gas companies to report to FracFocus information such as well locations, operators and the masses of each chemical used in fracking fluids. </p>
<p>We used a tool called <a href="https://qbobioyuz1dh57rst8exeg.on.drv.tw/open_FF_catalog/Open-FF_Catalog.html">Open-FracFocus</a>, which uses <a href="https://codeocean.com/capsule/9423121/tree/v14">open-source coding</a> to make FracFocus data more transparent, easily accessible and ready to analyze. </p>
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<figcaption><span class="caption">This 2020 news report examines possible leakage of fracking wastewater from an underground injection well in west Texas.</span></figcaption>
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<p>We found that from 2014 through 2021, 62% to 73% of reported fracks each year used at least one chemical that the Safe Drinking Water Act recognizes as detrimental to human health and the environment. If not for the Halliburton Loophole, these projects would have been subject to permitting and monitoring requirements, providing information for local communities about potential risks.</p>
<p>In total, fracking companies reported using 282 million pounds of chemicals that would otherwise regulated under the Safe Drinking Water Act from 2014 through 2021. This likely is an underestimate, since this information is self-reported, covers only 23 states and doesn’t always include sufficient information to calculate mass. </p>
<p>Chemicals used in large quantities included <a href="https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=85&toxid=21">ethylene glycol</a>, an industrial compound found in substances such as antifreeze and hydraulic brake fluid; <a href="https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=1162&toxid=236">acrylamide</a>, a widely used industrial chemical that is also present in some foods, food packaging and cigarette smoke; <a href="https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=239&toxid=43">naphthalene</a>, a pesticide made from crude oil or tar; and <a href="https://wwwn.cdc.gov/TSP/ToxFAQs/ToxFAQsDetails.aspx?faqid=219&toxid=39">formaldehyde</a>, a common industrial chemical used in glues, coatings and wood products and also present in tobacco smoke. Naphthalene and acrylamide are possible human carcinogens, and formaldehyde is a known human carcinogen.</p>
<p>The data also show a large spike in the use of <a href="https://www.atsdr.cdc.gov/toxfaqs/tfacts3.pdf">benzene</a> in Texas in 2019. Benzene is such a potent human carcinogen that the Safe Drinking Water Act limits exposure to 0.001 milligrams per liter – equivalent to half a teaspoon of liquid in an Olympic-size swimming pool. </p>
<p>Many states – including states that require disclosure – allow oil and gas producers to withhold information about chemicals they use in fracking that the companies declare to be proprietary information or trade secrets. This loophole greatly reduces transparency about what chemicals are in fracking fluids. </p>
<p>We found that the share of fracking events reporting at least one proprietary chemical increased from 77% in 2015 to 88% in 2021. Companies reported using about 7.2 billion pounds of proprietary chemicals – more than 25 times the total mass of chemicals listed under the Safe Drinking Water Act that they reported.</p>
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<h2>Closing the Halliburton loophole</h2>
<p>Overall, our review found that fracking companies have reported using 28 chemicals that would otherwise be regulated under the Safe Drinking Water Act. Ethylene glycol was used in the largest quantities, but acrylamide, formaldehyde and naphthalene were also common. </p>
<p>Given that each of these chemicals has serious health effects, and that hundreds of spills <a href="http://dx.doi.org/10.1021/acs.est.6b05749">are reported annually at fracking wells</a>, we believe action is needed to protect public and environmental health, and to enable scientists to rigorously monitor and research fracking chemical use. </p>
<p>Based on our findings, we believe Congress should pass a law requiring full disclosure of all chemicals used in fracking, including proprietary chemicals. We also recommend disclosing fracking data in a centralized and federally mandated database, managed by an agency such as the EPA or the National Institute of Environmental Health Sciences. Finally, we recommend that Congress repeal the Halliburton Loophole and once again regulate fracking under the Safe Drinking Water Act. </p>
<p>As the U.S. <a href="https://www.reuters.com/business/energy/us-poised-regain-crown-worlds-top-lng-exporter-2023-01-04/">ramps up liquefied natural gas exports</a> in response to the war in Ukraine, fracking could continue for the foreseeable future. In our view, it’s urgent to ensure that it is carried out as safely as possible.</p><img src="https://counter.theconversation.com/content/193915/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vivian R. Underhill receives funding from the National Institute for Environmental Health Sciences. </span></em></p><p class="fine-print"><em><span>Lourdes Vera serves on the coordinating committee of the Environmental Data and Governance Initiative, which develops practices and tools to generate, analyze, steward, and improve environmental data and information. </span></em></p>Fracking for oil and gas uses millions of pounds of chemicals, some of which are toxic or carcinogenic. Two researchers summarize what companies have disclosed and call for more transparency.Vivian R. Underhill, Postdoctoral Researcher in social Science and Environmental Health, Northeastern UniversityLourdes Vera, Assistant Professor of Sociology and Environment and Sustainability, University at BuffaloLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1020082018-08-30T18:09:03Z2018-08-30T18:09:03ZInjecting wastewater underground can cause earthquakes up to 10 kilometers away<figure><img src="https://images.theconversation.com/files/234105/original/file-20180829-195301-rouwvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Storage site for wastewater from hydraulic fracturing operations just outside Reno, Texas.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Drilling-Quakes/d63475291d3b44c3b27b22ce8190a049/4/0">AP Photo/LM Otero</a></span></figcaption></figure><p>Earthquakes in the central and eastern United States have increased dramatically in the last decade <a href="https://earthquake.usgs.gov/research/induced/overview.php">as a result of human activities</a>. Enhanced oil recovery techniques, including <a href="https://www.petropedia.com/definition/1132/dewatering">dewatering</a> and <a href="https://www.petropedia.com/definition/55/hydraulic-fracturing">hydraulic fracturing</a>, or fracking, have made accessible large quantities of oil and gas previously trapped underground, but often result in a glut of contaminated wastewater as a byproduct. </p>
<p>Energy companies frequently inject wastewater deep underground to avoid polluting drinking water sources. This process is responsible for a surge of earthquakes <a href="https://earthquakes.ok.gov/">in Oklahoma</a> and other regions.</p>
<p>The timing of these earthquakes makes it clear that they are <a href="https://earthquake.usgs.gov/research/induced/overview.php">linked with deep wastewater injection</a>. But <a href="https://websites.pmc.ucsc.edu/%7Eseisweb/emily_brodsky/">earthquake scientists like me</a> want to anticipate how far from injection sites these quakes may occur. </p>
<p>In collaboration with a researcher in my group, <a href="https://websites.pmc.ucsc.edu/%7Etgoebel/index.html">Thomas Goebel</a>, I examined injection wells around the world to determine how the number of earthquakes changed with the distance from injection. We found that in some cases wells could trigger earthquakes <a href="http://science.sciencemag.org/content/361/6405/899">up to 10 kilometers (6 miles) away</a>. We also found that, contradictory to conventional wisdom, injecting fluids into sedimentary rock rather than the harder underlying rock often generates larger and more distant earthquakes.</p>
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<a href="https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=370&fit=crop&dpr=1 600w, https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=370&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=370&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=465&fit=crop&dpr=1 754w, https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=465&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/234094/original/file-20180829-195301-lqcpz5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=465&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Cumulative number of earthquakes with a magnitude of 3.0 or larger in the central and eastern United States, 1973-2015.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/news/6-facts-about-human-caused-earthquakes">USGS</a></span>
</figcaption>
</figure>
<h2>Transmitting pressure through rock</h2>
<p>Assessing how far from a well earthquakes might occur has practical consequences for regulation and management. At first glance, one might expect that the most likely place for wastewater disposal to trigger an earthquake is at the site of the injection well, but this is not necessarily true. </p>
<p>Since the 1970s, scientists and engineers have understood that injecting water directly into faults can jack the faults open, making it easier for them to slide in an earthquake. More recently it has become clear that water injection can also cause earthquakes in other ways. </p>
<p>For example, water injected underground can create pressure that deforms the surrounding rock and pushes faults toward slipping in earthquakes. This effect is called <a href="https://www.comsol.com/multiphysics/poroelasticity">poroelasticity</a>. Because water does not need to be injected directly into the fault to generate earthquakes via poroelasticity, it can trigger them far away from the injection well.</p>
<p>Deep disposal wells are typically less than a foot in diameter, so the chance of any individual well intersecting a fault that is ready to have an earthquake is quite small. But at greater distances from the well, the number of faults that are affected rises, increasing the chance of encountering a fault that can be triggered. </p>
<p>Of course, the pressure that a well exerts also decreases with distance. There is a trade-off between decreasing effects from the well and increasing chances of triggering a fault. As a result, it is not obvious how far earthquakes may occur from injection wells.</p>
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<figcaption><span class="caption">Surveillance video from a grocery store in Crescent, Oklahoma captures impacts of a magnitude 4.2 quake, July 27, 2015.</span></figcaption>
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<h2>Where to inject?</h2>
<p>To assess this question, we examined sites around around the world that were well-isolated from other injection sites, so that earthquakes could clearly be associated with a specific well and project. We focused on around 20 sites that had publicly accessible, high-quality data, including accurate earthquake locations. </p>
<p>We found that these sites fell into two categories, depending on the injection strategy used. For context, oil and gas deposits <a href="https://energy.usgs.gov/GeochemistryGeophysics/GeochemistryResearch/OrganicOriginsofPetroleum.aspx">form in basins</a>. As layers of sediments gradually accumulate, any organic materials trapped in these layers are compressed, heated and eventually converted into fossil fuels. Energy companies may inject wastewater either into the sedimentary rocks that fill oil and gas basins, or into older, harder underlying basement rock.</p>
<p>At sites we examined, injecting water into sedimentary rocks generated a gradually decaying cloud of seismicity out to great distances. In contrast, injecting water into basement rock generated a compact swarm of earthquakes within a kilometer of the disposal site. The larger earthquakes produced in these cases were smaller than those produced in sedimentary rock.</p>
<p>This was a huge surprise. The conventional wisdom is that injecting fluids into basement rock is more dangerous than injecting into sedimentary rock because the largest faults, which potentially can make the most damaging earthquakes, are in the basement. Mitigation strategies around the world are premised on this idea, but our data showed the opposite.</p>
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<figcaption>
<span class="caption">How wastewater injection can make earthquakes: In basement rocks (left), injection activates faults in the small region directly connected to the added water, shown in blue. In sedimentary injection (right), an additional halo of squeezed rock, shown in red, surrounds the pressurized fluid and can activate more distant faults.</span>
<span class="attribution"><span class="source">Thomas Goebel</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Why would injecting fluids into sedimentary rock cause larger quakes? We believe a key factor is that at sedimentary injection sites, rocks are softer and easier to pressurize through water injection. Because this effect can extend a great distance from the wells, the chances of hitting a large fault are greater. Poroelasticity appears to be generating earthquakes in the basement even when water is injected into overlying sedimentary rocks. </p>
<p>In fact, most of the earthquakes that we studied occurred in the basement, even at sedimentary injection sites. Both sedimentary and basement injection activate the deep, more dangerous faults – and sedimentary sequences activate more of them.</p>
<p>Although it is theoretically possible that water could be transported to the basement through fractures, this would have to happen very fast to explain the rapid observed rise in earthquake rates at the observed distances from injection wells. Poroelasticity appears to be a more likely process. </p>
<h2>Avoiding human-induced quakes</h2>
<p>Our findings suggest that injection into sedimentary rocks is more dangerous than injecting water into basement rock, but this conclusion needs to be taken with a rather large grain of salt. If a well is placed at random on Earth’s surface, the fact that sedimentary injection can affect large areas will increase the likelihood of a big earthquake. </p>
<p>However, wells are seldom placed at random. In order to efficiently dispose of wastewater, wells must be in permeable rock where the water can flow away from the well. Basement rocks are generally low permeability and therefore are not very efficient areas in which to dispose of wastewater. </p>
<p>One of the few ways that basement rocks can have high permeability is when there are faults that fracture the rock. But, of course, if these high permeability faults are used for injection, the chances of having an earthquake skyrocket. Ideally, injection into basement rock should be planned to avoid known larger faults. </p>
<p>If a well does inject directly into a basement fault, an anomalously large earthquake can occur. The <a href="http://dx.doi.org/10.1126/science.aat2010">magnitude 5.4 Pohang earthquake</a> in South Korea in 2017 occurred near a geothermal energy site where hydraulic injection had recently been carried out. </p>
<p>The important insight of this study is that injection into sedimentary rocks activates more of these basement rocks than even direct injection. Sedimentary rock injection is not a safer alternative to basement injection.</p><img src="https://counter.theconversation.com/content/102008/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Brodsky receives funding from the Department of Energy Basic Energy Sciences program. </span></em></p>New research shows that injecting wastewater deep underground can cause earthquakes far from the injection site. It also raises questions about which rock layers are the safest injection targets.Emily Brodsky, Professor of Earth and Planetary Sciences, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/910442018-02-01T19:08:00Z2018-02-01T19:08:00ZEarthquakes from the oil and gas industry are plaguing Oklahoma – here’s a way to reduce them<figure><img src="https://images.theconversation.com/files/204419/original/file-20180201-123826-2f16dq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cracked-broken-asphalt-road-earthquake-302898791?src=dmHZm0uGER0c4O4MA3hrnw-1-36">Shutterstock</a></span></figcaption></figure><p>“There are better ways we can be doing things,” <a href="https://www.youtube.com/watch?v=cege0s_N-M0">says Erin Brockovich</a>, the environmental activist portrayed in the Oscar-winning 2000 film, who has become one of <a href="http://www.stwnewspress.com/news/local_news/erin-brockovich-to-talk-earthquakes-in-oklahoma/article_537612fa-6348-5188-bede-31a0d0008abd.html">the latest people</a> to draw attention to the frequent man-made earthquakes plaguing the US state of Oklahoma.</p>
<p>In 2008, the state recorded only one earthquake of magnitude 3 or greater (big enough to be felt by people locally). In 2015, the number of earthquakes of equivalent magnitude peaked at <a href="https://earthquakes.ok.gov/">a staggering 903</a>. Oklahoma has been transformed from a seismic dead zone <a href="http://www.nature.com/news/race-to-unravel-oklahoma-s-artificial-quakes-1.17368">to a hotspot</a> in less than a decade. </p>
<p>Scientists attribute this <a href="https://earthquakes.ok.gov/wp-content/uploads/2015/04/OGS_Summary_Statement_2015_04_20.pdf">unprecedented increase in seismicity</a> to the oil and gas industry injecting its wastewater (known as “saltwater”) deep underground. In a study published in the <a href="http://science.sciencemag.org/lookup/doi/10.1126/science.aap7911">journal Science</a>, my colleagues and I have now shown that the size of these man-made earthquakes is strongly linked to the depth at which the saltwater is injected. As a result, reducing the depth of injections could significantly reduce the likelihood of larger, damaging earthquakes.</p>
<p>There are now more than <a href="http://www.occeweb.com/og/ogdatafiles2.htm">10,000 injection wells</a> dotted across Oklahoma. This includes both oil recovery wells and wells used to dispose of the saltwater that is an unwanted byproduct of the oil and gas extraction process. The water is injected deep underground, typically at depths of 1km to 2km. This deliberately is well below the level of fresh ground water supplies in order to avoid contamination. Since 2011, well operators have injected on average <a href="http://www.occeweb.com/og/ogdatafiles2.htm">2.3 billion barrels of fluid</a> a year into layers of sedimentary rock deep underground.</p>
<figure>
<iframe src="https://player.vimeo.com/video/186029718" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
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<p>The link between Oklahoma’s earthquakes and wastewater disposal was firmly established by <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/41/6/699/131273/potentially-induced-earthquakes-in-oklahoma-usa?redirectedFrom=fulltext">a 2013 study</a> that showed a strong association between the injection zone and earthquakes, including the 2011 magnitude 5.7 Prague event. </p>
<p>Since 2015, some <a href="http://www.occeweb.com/News/2016/03-07-16ADVISORY-AOI,%20VOLUME%20REDUCTION.pdf">new regulations</a> have led to an overall decline in the number of earthquakes. But the total seismic energy (the “moment”) <a href="http://science.sciencemag.org/content/early/2018/01/31/science.aap7911">has not dropped as significantly</a> as expected. In fact, a number of powerful earthquakes including Pawnee (magnitude 5.8) – the largest in state history – struck in 2016, after the new regulations came into effect. There is also some concern that there have only been fewer earthquakes because a <a href="http://newsok.com/oklahomas-earthquake-count-improved-in-2017-data-shows/article/5576892">lower oil price has led to less oil production</a> and saltwater disposal, and that seismicity would increase if the oil price rises again. </p>
<h2>Modelling the earthquakes</h2>
<p><a href="http://science.sciencemag.org/lookup/doi/10.1126/science.aap7911">Our new study</a> sheds light on the complexity of Oklahoma’s induced seismicity. We created a computer model of the relationship between seismic activity, geology and injection operations using six years’ worth of fluid disposal data from across the state. It shows that the more saltwater is injected and the greater the depth it goes to, the larger the resulting earthquake.</p>
<p>The injection is even more likely to cause earthquakes at depths where layered sedimentary rocks meet the crystalline “basement” rocks below them, at depths of between 1km and 6km. This shouldn’t be surprising because we know that when fluid gets into the spaces within rocks it can considerably weaken them. Pressurised fluids can effectively <a href="https://earthquake.usgs.gov/research/parkfield/fluids.php">lubricate ancient fault zones</a> that may have locked-in stresses built up over time, making them more prone to failure.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1885&fit=crop&dpr=1 754w, https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1885&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/204421/original/file-20180201-123846-1i4r9qz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1885&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gernon infographic.</span>
<span class="attribution"><span class="source">Thomas Gernon</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Raising injection well depths further above the basement rocks in key areas could significantly reduce the annual energy released by earthquakes, in turn making larger earthquakes less likely. Current regulations can require operators to either reduce injection or raise the depth at which wells inject relative to the crystalline basement, but often the amount is not given or not based on scientific evidence.</p>
<p>We hope our approach could help regulators test the effects of new regulations and the potential impact of new injection wells. Another major benefit is that our model can easily be updated as more data becomes available. This is important as different areas have become seismically active over time. This type of model could be used to identify when certain locations become more vulnerable to earthquakes, and help manage seismicity in Oklahoma and other areas where saltwater injection takes place.</p>
<p>Most people involved, including Erin Brockovich, admit “<a href="https://www.youtube.com/watch?v=cege0s_N-M0">effective, immediate and realistic steps</a>” are required to tackle Oklahoma’s earthquake problem. The science of saltwater disposal can provide some practicable solutions, and our study is just the first step. We need the support of researchers, operators and regulators, to ensure this approach has a lasting impact on reducing man-made earthquakes.</p><img src="https://counter.theconversation.com/content/91044/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Gernon does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research shows the size of man-made earthquakes is linked to how deep industry wastewater is injected into the ground.Thomas Gernon, Associate Professor in Earth Science, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/805132017-07-13T14:26:29Z2017-07-13T14:26:29ZExplainer: unpacking the issues around fracking in South Africa<figure><img src="https://images.theconversation.com/files/177688/original/file-20170711-28771-ltrtnm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">South Africa's Karoo has shale gas and could be the location for fracking exploration.</span> <span class="attribution"><span class="source">Reuters/Mike Hutchings</span></span></figcaption></figure><p><em>South Africa has been considering shale gas development in the Karoo – an arid part of the country that spans more than 400 000 square kilometres – to add to its energy mix. The possibility of “fracking” in the region has provoked heated debate. The Conversation Africa’s Ozayr Patel asked Robert Scholes and Greg Schreiner to unpack the issues.</em></p>
<p><strong>What’s happening in terms of shale gas development in South Africa?</strong></p>
<p>The Scientific Assessment for Shale Gas Development in the Central Karoo <a href="http://seasgd.csir.co.za/">was published</a> in October 2016. So far no decisions on the current exploration right applications have been made, <a href="http://ewn.co.za/2017/03/31/fracking-will-go-ahead-in-the-karoo">despite reports to the contrary</a>. If rights are granted, exploration activities could start within the next 3-5 years, conditional on the results of site-specific environmental impact assessments. </p>
<p>If it’s found that gas from deep shale layers can be liberated at commercially viable flow rates, the Karoo could be the location of a domestic gas industry within the next 20 years, lasting for several decades. </p>
<p>The public and the regulators have had lots of questions about the potential development of shale gas in the Karoo. The scientific assessment assembled a team of over 140 experts to evaluate these questions, clustered under 17 broad issues raised by the stakeholders. It is perhaps the most comprehensive study of its kind undertaken in South Africa. </p>
<p><strong>Is there gas under the Karoo?</strong></p>
<p>Definitely. The deep boreholes drilled in the 1970s revealed traces of gas, especially in the shales of the Whitehill Formation at the bottom of the Karoo geological sequence, several kilometres below the surface. At the time it was deemed non-recoverable because it is “tight” gas, reluctantly yielded by the rock. Technical advances, especially horizontal drilling and hydraulic fracturing (fracking), now make it possible <a href="https://www.propublica.org/special/hydraulic-fracturing-national">to extract tight shale gas</a>. </p>
<p>This does not mean that it’s economically viable to do so in the Karoo. Large volumes of gas have been claimed to be present based on sparse data, but the economically recoverable resource is much, much smaller. Best current estimates put it in the range 5 to 20 trillion cubic feet (tcf). By global standards, even the top end would be relatively small. For example, the proven reserves of conventional gas in the Mozambique Channel are 75 tcf. But by local standards, even the low end would be helpful; the offshore Mossgas field, now almost depleted, was <a href="http://www.offshore-technology.com/projects/mossel/">less than 1 tcf.</a></p>
<p><strong>What are the benefits of shale gas development?</strong></p>
<p>Why use gas at all when there is abundant cheap solar and wind energy? Because adding quick-to-respond gas turbines into the South African energy mix increases the ability of the power generation system to use intermittent renewable energy sources in a way which slow-to-respond power sources like coal and nuclear cannot. </p>
<p>This technical policy decision has already been taken, as reflected in the country’s <a href="http://www.energy.gov.za/IRP/irp-2016.html">integrated resources plan</a>; the only question is where to source the gas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=530&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=530&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178036/original/file-20170713-32666-nh6kbj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=530&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cartoon demonstrating the difference between ‘conventional’ and ‘unconventional’ gas reserves.</span>
<span class="attribution"><span class="source">adapted from
http://worldinfo.org/2012/01/point-of-view-unconventional-natural-gas-drilling</span></span>
</figcaption>
</figure>
<p>Relative to the use of imported gas, a viable Karoo shale gas find would save foreign exchange, accrue tax and employment benefits and improve national energy security. The number of jobs provided is quite small, especially for the low-skilled unemployed (a few hundred). The size of a shale gas industry in financial turnover terms is of the same order of magnitude as the existing Karoo farming and tourism industries. So it would make little sense to promote shale gas if it were to the significant detriment of existing, longer-term sectors.</p>
<p><strong>What are the main concerns?</strong></p>
<p>Fracking has been shown to increase the frequency of small earth tremors. But the Karoo is exceptionally seismically stable, and the increased risk of dangerously large earthquakes was judged by the scientific assessment <a href="http://seasgd.csir.co.za/">to be small.</a></p>
<p>The risk to water resources is the biggest concern to all those involved. Each production well needs about 15 million litres of fluid to frack. The fluid is mostly water (it doesn’t have to be fresh), sand and a small quantity of potentially harmful chemicals. After fracking, the fluid is pumped back to the surface and stored for fracking the next well. Eventually the contaminated water must be purified, the hazardous material sent to a licensed disposal facility (currently there are none in the Karoo), and the clean water returned to the environment. </p>
<p>The greatest risk is that the fracking fluid leaks into the surface water and shallow aquifers used by people, livestock and the ecosystem, due to inadequate sealing of the upper parts of the borehole, or following a spill on the surface. These risks can be reduced, but not eliminated, <a href="http://seasgd.csir.co.za/">by good engineering.</a></p>
<p>Current potable water resources in the Karoo are already fully allocated. The additional water requirements for shale gas development would either need to use water from local non-potable sources, such as deep saline groundwater, or water imported from outside the region.</p>
<p>The impact of shale gas development on the unique Karoo fauna and flora would mainly come from the accompanying habitat fragmentation and disturbance, rather than physical destruction. Each well-pad occupies just over a hectare, and the number per well-field is about 50. A small gas find may be one well-field, a big find may be five. So the area directly affected is a tiny fraction of the Karoo land area, even once the connecting roads and pipelines are considered. The exact location of the well-pads is quite flexible, which reduces the potential impact on both the rich Karoo cultural heritage resources and particular plant or animal populations.</p>
<p>The biggest and least tractable impact is likely to be social: the introduction of noise, traffic, lights, workers, work-seekers and their dependants into a formerly quiet environment, already struggling to service the resident population.</p>
<p><strong>What questions remain?</strong></p>
<p>Fracking in the Karoo has been presented as a “yes-no” decision that will be taken by government. In reality, the choices are more nuanced, far in the future, and not solely governmental. The scientific assessment asked “under what circumstances and under what regulations would it be sensible?’” It found no reason to completely eliminate shale gas as an option – if best practice is followed. The question that will determine if development proceeds is whether the resource is sufficiently attractive for the private sector to invest the billions of rand needed. Only exploration can answer that.</p><img src="https://counter.theconversation.com/content/80513/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Scholes received funding from the CSIR to lead the Scientific Assessment of Shale Gas. He is a Trustee of WWF-SA. </span></em></p><p class="fine-print"><em><span>Greg Schreiner does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>South Africa has been considering shale gas development in the Karoo region. The gas, will be expensive to explore and extract, will be used as part of the country’s energy mix.Robert (Bob) Scholes, Professor Bob Scholes is a Systems Ecologist at the Global Change Institute (GCI), University of the WitwatersrandGreg Schreiner, Sustainability scientist, Council for Scientific and Industrial ResearchLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/673172016-11-10T15:34:38Z2016-11-10T15:34:38ZConsidering the technical readiness of South Africa to support the shale gas industry<figure><img src="https://images.theconversation.com/files/145066/original/image-20161108-16685-5ff7il.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">South Africa's Karoo region, in the south west of the country, is thought to have significant reserves of shale gas.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The discovery and exploitation of very large shale gas reserves in countries like the United States have transformed <a href="http://onlinelibrary.wiley.com/doi/10.1002/ente.201402177/abstract">the energy market</a>. South Africa may also possess potentially large resources of shale gas. This could have a significant positive impact on the country’s energy balance should it be decided to exploit these resources.</p>
<p>The exploitation of these key energy resources might also have a significant social, economic or environmental impact while also presenting considerable technical challenges.</p>
<p>Given the recent challenges the country is facing in terms of <a href="http://www.gov.za/issues/energy-challenge">energy supply</a>, the possibility of exploiting shale gas deposits for power generation is of current significance. Shale gas also presents other downstream opportunities. Some include providing a key resource for the production of liquid fuels and chemicals, or enabling the development of a domestic market for gas as a cleaner <a href="http://www.mckinsey.com/global-themes/middle-east-and-africa/south-africas-bold-priorities-for-inclusive-growth">energy resource</a>.</p>
<h2>Uncertainties</h2>
<p>South Africa’s Karoo region, in the south west of the country, is thought to have significant reserves of shale gas. Recently there has been considerable interest from the government and various companies like Shell, Falcon and Bundu to develop a shale gas industry there. <a href="http://research.assaf.org.za/handle/20.500.11911/14">Considerable uncertainties</a> exist regarding the extent of these reserves and the geology at depths where they are typically found. These and other uncertainties and constraints include the following.</p>
<ul>
<li><p>The quantum of shale gas in the Karoo is still unclear: estimates range between <a href="http://www.eia.gov/todayinenergy/detail.php?id=11611">20 and 400 trillion cubic feet</a>. None of these reserves has yet been proven.</p></li>
<li><p>There are also constraints relating to geographical regions. For example, no fracking may take place in the vicinity of the <a href="https://www.ska.ac.za/">Square Kilometre Array station project</a>. The project consists of the largest network of radio telescopes ever built.</p></li>
<li><p>Ensuring that no hydraulic fracturing takes place at depths less than 1500m to protect groundwater resources will also reduce the geographical area of interest.</p></li>
<li><p>Shale gas exploitation requires the use of relatively large quantities of water. Given that potable groundwater should preferably not be used for any such exploitation, greater clarity is needed on the availability of deep-level saline water. This is considered to be acceptable for use in hydraulic fracturing.</p></li>
<li><p>Baseline studies need to be carried out to ascertain with greater certainty the environment at depths greater than 3 km underground. Such baseline studies should also ensure that there is a clear understanding of the status of the human and natural environments before any fracking commences.</p></li>
<li><p>South Africa has a serious shortage of the high-level skills that would be required to implement such an industry. Strategies need to be set in place to develop skills to ensure sustainable development of the shale gas industry.</p></li>
<li><p><a href="http://research.assaf.org.za/handle/20.500.11911/14">International experience</a> has highlighted the critical need to have all the necessary legislative and regulatory structures in place. But also, a sufficient number of regulators with the required skills before a shale gas industry is launched.</p></li>
<li><p>The implementation of a shale gas industry in an area like the Karoo may have a significant socio-economic impact on the local population. Similar concerns have been expressed in studies especially from <a href="http://www.scienceadvice.ca/uploads/eng/assessments%20and%20publications%20and%20news%20releases/shale%20gas/shalegas_fullreporten.pdf">Canada</a> and <a href="http://www.acola.org.au/index.php/projects/securing-australia-s-future/project-6">Australia</a>. So it is important to ensure that there is a full understanding of the potential impact. Plans must be developed to manage them.</p></li>
</ul>
<p>Resolution of these uncertainties requires extensive and ongoing consultation with all relevant parties. As such government has an important role to play as an honest broker of key information.</p>
<h2>Risk and challenges</h2>
<p>These uncertainties point to specific risks and challenges associated with the establishment of a shale gas industry in South Africa. This will require government to create an enabling environment to encourage investment in the industry while also ensuring that the state and local communities benefit. It is also critical that there is clarity regarding the pricing structures that may prevail. This is crucial when the industry begins to exploit the shale gas reserves, and obviously requires a clearer understanding of the potential quantum of the known reserves.</p>
<p>Establishing a shale gas industry presents complex technical and economic challenges, and implementation will require a whole-of-government <a href="http://research.assaf.org.za/handle/20.500.11911/14">approach</a>.</p>
<p>A structure at government level to facilitate and coordinate all the activities relating to the industry is recommended. This could coordinate the awarding of licences by various government departments and would have oversight of the activities of the regulators.</p>
<p>Awarding a production licence should proceed after satisfactory completion of terms associated with an exploration licence. This would require operators to demonstrate compliance of processes with legislation.</p>
<p>It is evident that before a shale gas industry in South Africa is implemented, important baseline studies need to be done. This will determine both the exact status quo prior to the commencement of a shale gas industry and the technical, social and economic consequences of such a development.</p><img src="https://counter.theconversation.com/content/67317/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cyril O'Connor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Shale gas holds considerable advantages. But there are still a number of uncertainties around whether South Africa is ready for such a bold step.Cyril O'Connor, Emeritus Professor Department of Chemical Engineering Faculty of Engineering and the Built Environment, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/488732015-10-12T20:52:17Z2015-10-12T20:52:17ZHydraulic fracturing components in Marcellus groundwater likely from surface operations, not wells<figure><img src="https://images.theconversation.com/files/98136/original/image-20151012-17843-mmioai.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fracking well injects large volumes of water, chemicals and sand to fracture rock. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/128012869@N08/15137840369/in/photolist-p4FoxK-pmbHr8-pb2D6K-pm9SeQ-pb1LHJ-8Qt9W3-ptYyHn-duPq4B-duPiQv-oo4EZF-q5h6jQ-bg6vWP-cTFWRm-ofjtM7-pj9woy-jbjgHt-pseDWM-duUXWm-duPpDX-duUZHy-duUZ7S-duUYDm-duUZpG-duUYxG-duUXTs-duPo42-duPoBe-duUZhj-duPnVv-duUZxd-duUVqy-duPmn4-duPoJZ-dL46uE-duV13A-duURU1-a1fVT3-pXegcN-fQuaVd-jboCF3-q3Le2D-qk9dAb-q3MLPc-qhVyxN-q3MMhM-podjgd-qk9c79-q3Ld2H-q3D6To-qmDJdT">128012869@N08/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>US natural gas production <a href="http://www.eia.gov/dnav/ng/hist/n9070us2A.htm">increased by 42%</a> between 2005 and 2014, largely due to recent advances in horizontal drilling and high volume hydraulic fracturing. One of the largest natural gas reservoirs in the US, the Marcellus Shale, underlies much of the state of Pennsylvania, and there is concern that chemicals used in association with gas extraction will end up in local drinking water supplies.</p>
<p>Our <a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1511474112">study</a> showed that organic chemicals detected in groundwater wells were derived from surface releases (i.e., spills at the ground surface) from hydraulic fracturing operations, rather than transport from deep shale formations. This analysis provides more clarity on potential issues related to hydraulic fracturing and can help communities and industry better address potential water contamination events. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98099/original/image-20151012-17811-1pm8juj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=293&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The number of Pennsylvania shale gas wells (dots on the map) increased significantly in seven years, and much of that growth was due to unconventional well drilling in the northeastern corner of the state.</span>
<span class="attribution"><span class="source">Brian Drollette</span></span>
</figcaption>
</figure>
<h2>The bigger picture</h2>
<p>To get natural gas from underground shale formations, drillers inject large volumes of water, sand, and some chemicals into wells, which fractures the rock and releases the trapped gas.</p>
<p>Earlier this year, the US Environmental Protection Agency (US EPA) issued a long-awaited <a href="http://cfpub.epa.gov/ncea/hfstudy/recordisplay.cfm?deid=244651">assessment</a> of hydraulic fracturing and directly noted “there is insufficient pre- and post-hydraulic fracturing data on the quality of drinking water resources.” </p>
<p>Our study helps to address this issue by collecting complimentary geochemical data over a wide geographic area. Nearly 1,000 organic chemicals are disclosed as additives in hydraulic fracturing, but it is unclear if they enter drinking water supplies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=490&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=490&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=490&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=615&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=615&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98139/original/image-20151012-17807-1frtli3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=615&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wastewater from hydraulic fractured wells is collected and disposed of in containment pools or, for permanent disposal, in injection wells.</span>
<span class="attribution"><a class="source" href="http://www2.epa.gov/hfstudy/hydraulic-fracturing-water-cycle">EPA</a></span>
</figcaption>
</figure>
<p>There are a number of potential migration pathways to groundwater aquifers, including: faulty gas well casings, leaking waste containment ponds, underground fuel storage tanks, migration from deep shale (formations approximately 1 mile deep), and surface releases associated with hydraulic fracturing activities. We determined that the likely exposure pathway was from surface operations at gas well sites and not from deep subsurface transport. </p>
<p>These findings are encouraging, because disclosed spills of chemicals at the surface can be targeted for rapid clean up, and homes in the area can employ point-of-use water treatment technologies when needed. In other words, surface releases are much easier to treat and control than subsurface processes. Also, the types of organic chemicals detected in this study are readily treated by in-home water filtration systems that employ charcoal or activated carbon.</p>
<p>Since domestic fossil fuel production often necessitates the colocation of industrial operations with residential areas, there is an inherent environmental and public health risk associated with accidents, just as with any engineering practice. </p>
<p>Shale gas exploration has increased the area in the US subjected to this type of risk, and efforts to minimize human and machine error will minimize the impacts on local residences. Further, better accident reporting and environmental monitoring can help local municipalities ensure the safety of their drinking water in cooperation with gas extraction experts. </p>
<h2>Evidence of fluids</h2>
<p>In this study, we focused on over 50 compounds organic compounds associated with hydraulic fracturing to address a gap in research on this topic. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98137/original/image-20151012-17811-j0w2eg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Containment ponds from hydraulic fracturing wastes that come up from natural gas wells.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/marcellusprotest/4955490403/in/photolist-8xUbDH-8P7Zxd-8P4TpD-8P7ZtQ-cXw4vy-8NQF4r-cXvRWh-cXvJam-8xXez5-8z948p-8xUaUi-8xXfk9-8xXekL-8xUbTz-8xXeQm-8xUd4T-8xUc76-8xUbqp-8xUbak-8zcc5b-depRR1-depRNo-depRzh-depSVZ-depSZc-depRSN-depTa2-depT9k-depSRg-cXvVfh-cXvTuy-cXvYJs-cXvQDW-depRLY-depST6-depSWD-depSU4-depTax-depRHE-8yFtpi-8yJytW-8yFtqF-8yFtcT-8yFtsH-8yJyvb-8yJyAE-8yJymE-8zcbuA-8zcbiC-8zcbdJ">marcellusprotest/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Levels of diesel range organic compounds (hydrophobic chemicals with boiling points similar to diesel fuel) in the groundwater samples were dilute (less than 200 parts per billion). However, they were statistically correlated with distance to the nearest active shale gas well in the region and were significantly higher within a one kilometer radius of a gas well. </p>
<p>These results are similar to studies of hydrocarbon gases (e.g., methane, ethane, and propane) in the same region. In particular, active shale gas wells that have had a documented environmental health and safety violation were spatially correlated with groundwater that contained higher levels of diesel range organic compounds. Furthermore, a known hydraulic fracturing fluid additive, bis(2-ethylhexyl) phthalate, was detected in a subset of samples. This chemical is used in many industrial materials and practices, but it was not detected in a wide range of samples or representative natural water (i.e., a natural spring in the study area).</p>
<h2>Upward migration?</h2>
<p>A common question regarding the environmental and public health consequences of natural gas extraction via hydraulic fracturing is whether or not fluids can travel from shale horizons to drinking water aquifers through geologic faults and fissures. That is, can hydraulic fracturing fluids migrate upward through cracks to contaminate sources of drinking water?</p>
<p>Proposed upward migration scenarios could introduce the nearly 1000 disclosed organic industrial chemicals used during the fracturing process to shallow groundwater. To date, this remains unproven and undocumented. </p>
<p>The detected organic compounds in the sampled groundwater in our study were not the result of migration of fracturing fluids from the shale horizon to drinking water aquifers. This was demonstrated using a series of complimentary analyses.</p>
<p>For example, fluids migrating from deep shale horizons should contain high amounts of unique noble gases and salts, but the groundwater samples that contained higher diesel range organic compounds did not contain these other chemical markers. In contrast, the chemical character of the groundwater showed the water was in relatively recent contact with the surface of the Earth and was not related to the salt content.</p>
<h2>Outstanding questions</h2>
<p>Our study focused solely on a region of developed Marcellus Shale in northeastern Pennsylvania, and it is important to note that the results of this study may not translate across all shale formations within the US. Spatial and temporal separations of hydraulically fractured shale horizons can vary widely due to local geology. </p>
<p>Similarly, vertical distances between aquifers and shale formations, as well as the historical oil and gas development in the region, can affect the transport times of deep subsurface fluids to shallow groundwaters. Therefore, continuous monitoring will provide a better understanding of potential risks that may arise over time and space.</p>
<p>Considering that domestic fuel production is growing, it would be helpful to compare the rates of spills associated with natural gas production with spills from other chemical or fuel industries. In ocean transport of oil, only <a href="http://www.eia.gov/beta/international/regions-topics.cfm?RegionTopicID=WOTC">0.00007%</a> of the volume is released on average (including large spill years). Since gas extraction violation reports do not include volumes, it is not currently possible to answer the question: are surface releases associated with hydraulic fracturing any worse than other fuel technologies on which we rely? Having the volume information will help improve the industrial practices and safety of the growing natural gas industry.</p><img src="https://counter.theconversation.com/content/48873/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brian D. Drollette receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Desiree L. Plata receives funding from the National Science Foundation. </span></em></p>Fracking fluids in Marcellus shale have contaminated groundwater but new study finds that the source is likely from surface spills, not leaks from underground wells.Brian D. Drollette, PhD Student, Chemical & Environmental Engineering, Yale UniversityDesiree L. Plata, Assistant Professor of Chemical & Environmental Engineering, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.