The truth about underground fissure / Chris Mooney

Creating cracks in an oil shale layer once to release natural gas may not endanger drinking water sources, but repeated cracking can be problematic

If the underground cracking of oil shale using water, known as fracking, is contaminating the drinking water in the United States? The debate is heating up and the scientists have begun to express their opinion.

Anthony Ingrafi, a professor of engineering at Cornell University and an expert on the controversial natural gas drilling method, attended a March 2011 conference hosted by the US Environmental Protection Agency (EPA) in Arlington, Virginia. After the conference he had a lot to say on the subject. There he met scientists from the leading gas and drilling companies: Devon Energy, Chesapeake and Halliburton. The scientists gathered to help the agency decide the question: Does the method really cause toxic chemicals and gas to flow into drinking water sources in several US states, as its opponents accuse? The answer is at the center of an escalating dispute in New York state, Pennsylvania, Texas and Colorado, as well as in Australia, France and Canada.

The basic method, whose full name is hydraulic fracturing, has been used in conventional wells since the late 40s. When a vertical well shaft penetrates a layer of oil shale, chemically treated water and sand are injected into it at high pressure to crack and crack the rocks and release the natural gas trapped in them. However, recently, this method was combined with a newer technique known as directional drilling, or horizontal drilling. With this method, it is possible to rotate the leveling drilling head down to 20 degrees and then continue drilling along the layer, parallel to the ground, for a distance of hundreds, even thousands of additional meters. As a result, a "gas panic" occurs. Remote layers of methane-rich shale suddenly became accessible. According to the estimate, there are about 90 trillion cubic meters of such "unconventional" gas shale available in the US, which is enough for consumption for decades. However, fuel industry email correspondence published in June 23 in the New York Times suggests that this resource may be more expensive and more difficult to exploit than the companies claim.

The main drawback stems from the fact that horizontal fracturing requires huge volumes of water and chemicals that are not needed in vertical wells. Huge ponds and tanks are also needed to store the chemical-rich water that comes back and forth from the wells after fracking.

Ingrafi sat in the conference room and watched industry scientists casually dismiss the ideas that fracking was causing drinking water wells to be contaminated and kitchen faucets to catch fire. After all, according to their logic, the shale layers may be buried a mile or two deep, completely separated by hundreds of meters of rock from the drinking water aquifers that are closer to the surface. And that is precisely why it has been so difficult to exploit them until now. The crack explosion may have a lot of power, but not that much. In their opinion, the method is not capable of cracking such a thick layer of rock and creating, through the cracks that will be created, a connection between the horizontal drilling tunnels and the groundwater close to the ground.

"I've seen beautiful PowerPoint slides describing what they think is really going on," says Ingrafi, who used to work with the global gas supply company Schlumberger but later rose to prominence as one of the leading scientific critics of the gas rush. "In each of the lectures, the lecturer concluded with the conclusion that this is largely improbable," however, Ingraffi explains, these analyzes took into account only one "crack": only one water explosion, in one horizontal tunnel, only once. But in order to maximize access to gas, the companies may drill more than ten horizontal tunnels close to each other at one site, and they may crack the tunnel in different sections in each well and perhaps even many times.

One must take into account "the three dimensions of space and time," says Ingrafi. He doubts that a single horizontal crack could connect the shale layers to the surface. But "if you look at the problem as I just described it, I think the chances are increasing. How much? I don't know."

Guilty by definition

The scientists and standard setters who are now trying to answer this complicated question have delayed the deadline a bit. We should have conducted such studies לפני that the crack has become so controversial. The method is now the cause of political conflict after the New York State Department of Environmental Protection recently revealed its plan to grant drilling companies access to 85% of the Marcellus and Utica acreage, two shale formations located in this state. Fracking will be prohibited in the watershed of the cities of New York and Syracuse because the water supply to these cities is not filtered from the source to the civilian consumer.

The department based its approval after examining several studies and claims it plans to regulate all drilling work with strict regulations. These actions effectively cancel a previous regulation that banned fracking throughout the country, and this despite the fact that the US Environmental Protection Agency (EPA) is still in the middle of a safety study, the writing of the first draft of which should be completed at the end of 2012. The department in New York, which does not want to wait for the scientific report of the EPA published its final regulations in October 2011 and opened them for public comment in early December.

The pressure to drill in New York before the EPA test results are released is forcing experts to decide which claims against the method have weight and which require new studies. The answers to this very confusing topic ultimately depend on the different definitions of the concept of crack.

If we refer to the entire process of unconventional gas drilling from beginning to end, he is already guilty of several serious crimes. This huge industrial operation requires an incredible amount of water, between 7 and 15 million liters per horizontal tunnel, plus about 60,000 to 240,000 liters of chemicals, and all this times the number of wells in one drilling site. Moving these liquids requires entire fleets of tankers and large storage tanks.

Then you have to treat the water returning from the drilling. Up to 75% of the water that is pumped in under pressure returns and goes out. This water is loaded not only with a cocktail of chemicals used to facilitate the flow of fracturing fluid, protect the pipeline, kill bacteria and many other purposes, but also with radioactive materials and salts that come out of the underground layers themselves. The toxic water should be stored in the field and then transferred to treatment facilities or for reuse. Most companies store the water in open pits that they dig. Many states in the US require companies to cover the bottom of the pit with plastic sheets to prevent leaks. Some of them even require that the pits be far enough from surface water sources. The problem is that even if the proper preventive measures are taken, the lining of the pits may tear and the pits may overflow after heavy rain. According to bills in the state of New York, it will be allowed to store reclaimed water only in sealed containers and take appropriate measures to prevent seepage.

All these processes can cause accidents. "This is not a risk-free industry," explains Terry Engelder, an expert on hydraulic fracturing at Pennsylvania State University, who generally supports the process, but has sometimes criticized the companies involved in it. Indeed, a series of investigations by the New York Times documented possible contamination of the drainage basins of major rivers in Pennsylvania, such as the Susquehanna River and the Delaware River, due to inadequate treatment of water returned from wells. Domestic faucets in the country smelled bad or caught fire, and companies were prosecuted and fined. In the most recent case, the Pennsylvania Department of Environmental Protection fined the Chesapeake Company $16 million for contaminating XNUMX family water wells with methane gas as a result of improper drilling practices.

All these failures can only be blamed if the term cracking includes the entire industrial process. But this cannot be done if it only includes the underground blasting with water designed to crack the rock after drilling. Even the people immersed in the subject may differ in their opinions regarding this essential subject. "There is a vulnerability in the use of the large quantities of chemicals, but it is actually a normal industrial threat and not a threat from the cracking process itself," asserts Val Washington, who previously served in the New York State Department of Environmental Protection. But Ingrafi from Cornell University sees things differently: "I would like the industry to stop playing the 'crack doesn't cause pollution.' You have to drill to crack. They hide behind semantics and definitions.”

But to prove that the crack, as theIndustry Defines it, is the problem, we need to examine the most well-known claim, but the most difficult to prove: the idea that the mentioned threat stems from the fact that the intense explosions of water underground directly cause the contamination of the drinking water. According to this claim, the explosions open unexpected paths through which gas or liquid can move and flow from the deep shale layers to the groundwater close to the ground.

The concrete culprit

To see just how complicated the issue is, let's look at the enforcement actions taken by the EPA against the gas company Range Resources of Fort Worth, Texas, a company that drills in the famous Burnett shale. The EPA claimed that two drinking water wells located near two of the company's gas wells were contaminated with methane from a deep "thermogenic" source. Such gas is created in the shale layers, unlike "biogenic" methane created by bacteria in underground pockets close to the ground, at depths that also characterize drinking water aquifers. The EPA also claimed that one of the water wells also contained chemicals sometimes used in fracking, such as benzene, and that the water produced from it was flammable.

The EPA ordered the company to provide clean water to affected parties, determine whether other nearby wells are also contaminated and take several other steps. The gas company reacted strongly. She absolved in court of any responsibility by relying on the "large horizontal and vertical distances" between the sites. In mid-September 2011, the matter was discussed in the US Court of Appeals. But it is crucial that even if the EPA is right, and Range Resources is to blame for the fault, that does not prove that a crack deep in the ground caused it. The Environmental Protection Agency demanded that the company determine which "gas flow paths" were involved in the incident, and there are many possible paths. The gas could have migrated all the way from the fractured shale along some unknown path. But it is possible that this was caused by poor sealing up the vertical well, much closer to the surface.

In such contaminations, the drilling companies point the main suspicion, usually, to defects in the sealing cement layer. According to the industry definition it is not part of the cracking process. On the way down, any drilling passes through layers close to the ground that contain groundwater, and it may also pass through unknown pockets of gas. The drillers fill the space between the gas pipe and the walls of the well with concrete so that light gas cannot rise on the outside of the pipe and possibly seep into the groundwater. A failure in the sealing may also allow the chemical-laden water that returns at high pressure after the crack to leak out.

Sealing with concrete is the clearest and simplest "weak link," says Anthony Gorody, a hydrologist and consultant to gas companies, who supports fracking. Other scientists strongly agree. "If you do a poor job of sealing the well, you open up a possible way for the materials to leak out," explains ecologist and water resources expert Robert B. Jackson of the Nicholas School of the Environment at Duke University. Despite the regulations that oversee the sealing of wells with concrete, and despite the industry's efforts to improve work practices, it may not be possible to fully solve the problem. "A significant proportion of concrete sealants will fail in their mission," says Ingrafi. "It will always be like this. It's simply part of the rules of the game in this field."

Contamination from poor sealing is a longstanding problem in traditional vertical wells, where fracking was also sometimes used. According to Val Washington, who worked for the New York State Department of Environmental Conservation, "We have a lot of wells in the western part of the state that have produced oil and gas for decades. Fracking has always been a method of extracting gas from these very hard shale layers. This method was accepted for maybe 20 years." But the difference is that now in the horizontal drillings "because of the depths where the gas is found, and because of the combination of fracturing with horizontal drilling, today millions of liters are used in each fracturing instead of 300,000 liters as in the past," apart from the increase in the amount of chemicals accompanying it.

Dangerous at any depth?

Poor sealing has caused several cases of groundwater contamination due to gas drilling with the new methods, including the contamination for which Chesapeake was fined a million dollars. "Methane migration is indeed a problem in some areas. This is a completely true fact," says Engelder. The question is, if there are other reasons. If the problem of groundwater contamination really boils down to sealing, one could argue that the definition of fracturing used by the industry is acceptable, and stricter regulations are needed to monitor the companies when drilling - exactly the measures New York State is now proposing.

Jackson and his colleagues recently published in the Proceedings of the National Academy of Sciences of the USA the most intriguing study on possible gas migration. It has some findings in favor of environmentalists but also in favor of industrialists. Jackson says that the reactions he received when this hotly controversial article was published ranged from phrases such as "You saved my life" to "Get a hold of yourself and start doing something useful!"

Jackson's team analyzed samples from more than 60 private water wells that lie above the Marcellus Shale Formation in northeastern Pennsylvania and the Utica Formation in upstate New York. He found methane in 51 of them, and found that the wells closer to drilling sites contained much higher amounts of the gas. Chemical analysis determined that a significant portion of this methane is of the deep thermogenic type and not of the biogenic type that bacteria produce closer to the surface.

However, none of the samples contained fracturing fluids or salts characteristic of deep shale layers. Jackson therefore believes that most of the contamination is due to poor sealing and closing of the wells. He raises another possibility: some of the cracks created by the cracking of a deep layer may extend upward and connect to fissures or openings that were there before. Such cracks will allow the gas to move upwards and reach far. Northeastern Pennsylvania and northern New York are "strewn with old, abandoned wells," says Jackson. "And decades ago, the wells were not sealed, and they were not plugged when they finished drilling. Imagine this Swiss cheese, full of holes and extending hundreds of meters deep - we don't know where they are."

But if methane does enter drinking water due to unconventional gas drilling methods, why aren't chemicals used in the fracking process also entering them? The answer to that can only be guessed by Jackson and Englander. When methane begins to be released from the rock, the initial pressure is enough to push water and chemicals up the shaft. But this current soon subsides. After that, only the gas is light enough to bubble and rise vertically upwards. The water cannot do this.

Still, if water-induced cracks are able to connect to existing fissures or old wells, the chemicals could endanger groundwater. Cracks may form "outside the range". Kevin Fisher, an engineer at Pinnacle Technologies, a Halliburton subsidiary, examined thousands of cracks in horizontal wells in the Barnett and Marcellus shale formations, and determined their length using microseismic monitoring equipment. He found that the most extreme cracks in the Marcellus Formation reached a vertical distance of nearly 600 meters. This still provides a margin "and a very good physical separation between the hydraulic fracture tips and the water-bearing aquifers," Fischer claims.

Other engineers interpret similar evidence differently. In British Columbia, Canada, the authorities recorded 19 different cases of "communication between cracks", cases where new wells connected with other wells in unexpected ways. In one case, a connection was made between wells at a distance of about 600 meters from each other. The British Columbia Oil and Gas Board warned drillers with these words: "It is proving difficult to predict how large-scale hydraulic fracturing operations will cause cracks to progress." The council added that cracks may extend far beyond expected due to the weakness of the overlying rock layers.

But all this does not prove that fracturing of a horizontal oil shale layer did cause direct contamination of an aquifer. The CEO of the US Environmental Protection Agency (EPA), Lisa Jackson, said not long ago that no such case has been recorded, but added that "investigations" are underway. However, the absence of evidence of contamination is not evidence of the absence of contamination because each site is an individual case. The New York Times and the "Environmental Working Group" [a non-profit whose purpose is to disseminate environmental information - the editors] recently revealed a case of alleged contamination from 1984 in which a cracked well in West Virginia may have connected with an old, abandoned well nearby and caused drinking water contamination. The industry disputes the veracity of the claims.

More science late?

In order to convict or acquit the crack, no matter how it is defined, additional data is needed. This is the location of the study conducted by the EPA. The agency is examining a variety of ways in which the drilling could contaminate the water sources, from unsealed or leaking reservoirs, to poor sealing of wells to a possible connection between deep cracks and the surface. The agency will review five alleged drinking water contamination cases, including two in Pennsylvania, to rule on each one. The agency will also monitor future drilling activities from start to finish at two additional sites. It will also use computer models to simulate what is happening in the depths of the earth, in places that no one can reach.

Ingrafi recommends developing a powerful model that can repeat over and over again a scenario where many wells are operating, that will perform repeated fracturing and where gas and liquid can move in a volume of 2.5 million cubic meters of rock, all over the course of several weeks of drilling. "You need really big supercomputers," he says, to determine if there is a possibility of contamination. "If you show me such a model I can tell you what I think. Is this a slim chance or something that could happen every day." The minimum, in Ingrafi's opinion, would be models that would be able to say what are "the more likely circumstances in which gas can migrate compared to other situations."

Hard to find a computer model like this. The model that is usually used to simulate underground reservoirs in academic studies, and which the EPA also plans to use, is the model called Tough 2. But Ingrafi claims that it is not at a "commercial level". Large corporations use their own models, and in his opinion "the best options in terms of personnel, software, equipment and data are in the hands of the operating companies and the drilling services." He fears that the Tough 2 model "will struggle to handle all the defects, connections and crack progressions" at the level of detail needed to determine whether a new passageway for unwanted flow has suddenly broken through.

Meanwhile, Gorody and Jackson agree that the EPA should monitor the chemistry in drinking water wells at new sites before and after drilling begins. Discovering new chemicals only after drilling has begun would greatly weaken the industry's common claim that the water was naturally contaminated even before the rigs arrived and that residents in the area simply didn't notice.

Jeffrey Thain, a petroleum geologist from the Institute for Enhanced Petroleum Recovery at the University of Wyoming, has another suggestion for solving the fracking puzzle: order companies to add an easy-to-identify chemical marker to each company's special fracking mix. If they find the marker where it shouldn't be, it will serve as incriminating evidence. Thein says that the introduction of such a marker is "relatively easy", although he claims that "the industry generally does not look favorably on his proposal." The EPA says they are "considering" the use of markers. The agency also adds that most of the information it received from the industry about the chemicals used for cracking is "confidential business information" according to the companies involved in the matter, and therefore the EPA did not release it to the public. Legislation can change this situation.

A study by the EPA may illuminate and clarify the complicated and contradictory claims. But the new insight may come too late. "The fracking has never been rigorously studied," says Amy Malle, a senior policy analyst at the US National Natural Resources Defense Council. "This is a big experiment with no solid scientific parameters to guide it." But New York State seems convinced that strict regulations are enough to protect its citizens.

Residents of New York, Pennsylvania and other states who are opposed to fracking place signs in their yards that look like "no parking" signs - a red circle crossed by a diagonal line with the word FRACK written behind it. However, ironically it is very possible that the gas companies are indeed guilty of negligence in the way they drill and divert waste, while the fracking technology itself may be innocent. The yard signs may be wrong, but the fears may be correct.

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About the author

Chris Mooney hosts the podcast "Point of Inquiry" (www.pointofinquiry.org) and is the author of three books, including "The Republican War on Science".

And more on the subject

Methane Contamination of Drinking Water Accompanying Gas-Well Drilling and Hydraulic Fracturing. Stephen G. Osborne et al. in Proceedings of the National Academy of Sciences USA, Vol. 108, no. 20, pages 8172–8176; May 17, 2010. www.nicholas.duke.edu/cgc/pnas2011.pdf

Environmental Protection Agency Draft Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources. EPA, February 2011. Available at www.epa.gov/research

Revised Draft Supplemental Generic Environmental Impact Statement on the Oil, Gas and Solution Mining Regulatory Program. New York State Department of Environmental Conservation, September 2011. www.dec.ny.gov/energy/75370.html

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