The most significant scholarly article (cited by 582 other scholars, according to Google Scholar) on hydraulic fracturing was published in 1972 in the American Association of Petroleum Geologists Journal by M.K. Hubbert and D.G. Willis. This was a technical article that theorized that the most efficient fractures should be made perpendicular to the axis of least stress, that this axis should be horizontal, and that therefore the fractures would be vertical. Such conclusions had a strong influence on the modern methods of hydraulic fracturing and horizontal drilling.
Today these processes are highly computerized and specified to the conditions in which the well is being drilled. Computer simulations that incorporate information about the thickness of shale, rock fracturing characteristics, and more are carried out before any drilling takes place. The enormous natural gas industry has developed these models in order to drill more economically and safely. Additionally, these elements are constantly being monitored, or are reported monitored, to ensure that everything goes smoothly and that any errors are immediately rectified.
Horizontal drilling is fairly easy to understand in contrast with vertical drilling. Both methods extend into the shale formation deep below the surface, but horizontal wells curve once they reach the shale. By continuing further into the shale at a horizontal angle, the well exponentially increases surface area and employs the principles laid down by Hubbert and Willis. While horizontal wells can cost $2.5 million or more (as opposed to $800,000 for vertical wells), they have far greater efficiency in producing the gas. Horizontal wells may be developed to extend 2,000 to 6,000ft into the rock formation, in contrast with vertical wells, which could as little as 50ft of exposure. This not only increases efficiency, but it also reduces the number of physical wells and "pads" (from which there may be several wells) on the surface. Such a process maximizes production while minimizing infrastructure associated with drilling (such as roads and pipelines) and the loss of aesthetic disruptions to the landscape. "The spacing for vertical well completions in the Marcellus are predicted to start on 40 acre spacing, while horizontal well are predicted to be spaced at intervals closer to 160 acres," according to J. Daniel Arthur, illustrating how preferable horizontal drilling may be to those concerned about aesthetics.
But what exactly is hydraulic fracturing? It is a process by which the shale formation is stimulated to fracture beyond the extent that it would simply by drilling into the rock, and to help the gas overcome barriers that might prevent it from being captured. This is done by pumping millions of gallons of fracturing fluids into the well, the majority of which end up remaining in the ground. Fracturing fluid is made up almost entirely by water and the other largest ingredient is sand. The remaining fraction of the liquid contains many chemicals that assist in breaking down layers of shale to release the maximum quantities of natural gas.
These chemicals are one of the main points of contention with the process. Until September 2010, natural gas companies were not required to disclose the content of these chemicals, because they claimed them to be intellectual property. As stated in my previous entry, the EPA recently ordered these companies to provide that information as the first step in the latest investigation into hydraulic fracturing. Some authors, such as Arthur, assert that significant quantities of rock separate the shale from drinking water reservoirs so as to negate the claim that hydrofracking pollutes drinking water. He states that "in some parts of the Marcellus Shale production area there is as much as 7,000ft of sedimentary rock strata ... between the Marcellus and the shallow groundwater system in parts of the Appalachian Basin." According to him, the chemicals, regardless of their toxicity, are unlikely to pollute underground drinking water systems.
As will be noted in the discussion of Gasland, however, there is considerable concern that the fracturing fluids that do return to the earth's surface will not be disposed of properly. Gasland attempts to depict an irresponsible industry that dumps the excess water into existing aqua systems. Not only that, but the personal testimonies and physical evidence of tap water makes a case that Arthur's conclusion may not be accurate.
The main problem with this issue is the lack of reliable information, which has been and will continue to be my goal to seek out. The 2004 EPA study was taken to task by Hannah J. Wiseman in 2008 with her 55 page article, which casts considerable doubt on the EPA's findings. In fact, the current efforts of the EPA to investigate further points to their own doubts as to the legitimacy of the findings. Industry publications, however, insist that the practice is safe, and the EPA's 2004 study was used to push through legislation that exempted the process from the Safe Drinking Water Act. There is even less information, therefore, about the chemicals employed, because the government is not regulating it as stringently as many believe it should. One such group is the Environment American Research and Policy Center, which released an article written by Michael Berkowitz detailing the numerous health hazards associated with many known fracking chemicals.
Further entries will investigate these allegations of health risks. The facts remain, however, that hydraulic fracturing and horizontal drilling greatly increase the efficiency of drilling for natural gas and that they are essential for the economically feasible production of natural gas. Understanding the actual process of hydraulic fracturing is helpful to unravel the causes for concern.
Bibliography:
Arthur, J Daniel, Bohm, Brian, Layne, Mark, et all. “Hydraulic Fracturing Considerations for Natural Gas Wells of the Marcellus Shale.” The Ground Water Protection Council 2008 Annual Forum. 21-24 September 2008. Presentation. Web. 12 October 2010.
Berkowitz, Michael. “Toxic Chemicals on Tap: How Natural Gas Drilling Threatens Drinking Water.” Environment America Research and Policy Center. November 2009. Web. 12 October 2010.
Hubbert, M.K. and Willis, D.G. "Mechanics of Hydraulic Fracturing." American Association of Petroleum Geologists Journal. 1 December 1972. pages 239-257.
Wiseman, Hannah J. “Untested Waters: The Rise of Hydraulic Fracturing in Oil and Gas Production and the Need to Revisit Regulation” (September 23, 2008). Fordham Environmental Law Review, Vol. 20, p. 115, 2009. Available at SSRN: http://ssrn.com/abstract=1595092
Zeller, Tom. “E.P.A. to Study Chemicals Used to Tap Natural Gas.” The New York Times. 9 September 2010. Web. 10 October 2010.
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