The ever-increasing demands for energy coupled with political instability in many oil-producing regions overseas have pushed industrialized nations to develop the means to access fossil fuels located in domestic reserves. Shale is known to potentially trap large amounts of natural gas, and large reserves of shale are located throughout the United States. Among the methods utilized to release these stores of natural gas is hydraulic fracturing with high-pressure water and chemicals applied to layers of rock – a process better known as "fracking."
Fracking a layer of shale – once – is unlikely to cause major ecological and other problems. However, repeated fracking in a single location, as is the general practice, introduces a risk of methane migration, groundwater contamination, backflow of contaminated water into household water system located near fracking sites and even earthquakes. Backlash has begun to occur through documentaries like ´´Gasland´´. A major challenge for the 21st century is to find an economically – feasible yet environmentally – sound means of tapping vast fossil fuel reserves located in this country.
The United States was able to generate all the crude oil it needed from domestic oil supplies and relatively inexpensive land-based oil rigs until 1970, when the first imports began from the Middle East. Since then, oil imports have continued to increase, so that now the United States now imports more than half the crude oil it uses. (Ironically, America exported more gasoline than it imported in 2011.)
By contrast, as late as 2009, 98 percent of all the natural gas used in the United States was produced in North America. Nonetheless, the country's natural gas production had faced a steady decline for decades. However, recent discoveries of vast reserves of natural gas, coupled with 21st century technologies, mean that the there is enough natural gas located in North America to satisfy current rates of consumption for 100 years or longer, according to industry-backed studies.
The technology behind fracking has existed for decades. Originally a mixture of water and sand, plus a small proportion of chemicals, was forced down a well to cause fractures in the casing that allowed natural gas to flow freely. Among the first large scale attempts at fracking natural gas occurred in Texas during the 1980s. A Texas oilman named George Mitchell pumped millions of gallons of water at high volume into his well located on the Barnett Shale to break apart the rock and allow the natural gas to rise to the surface.
Devon Energy bought Mitchell out in 2002, and modified his fracking technique to include a larger proportion of chemicals, along with drilling directly into the shale formations, then turning operations sideways so that the drilling operation remains within the shale formation. Operations in the Barnett Shale began yielding more than four billion cubic feet of natural gas per day, making it the largest natural gas field in the country.
A major appeal of natural gas is its clean burning qualities. It is cleaner than oil or gasoline and certainly cleaner than coal. The problem arises when the attempts to access natural gas supplies and bring them to the surface.
Present – day fracking utilizes chemicals to reduce the friction of the water hitting the rock without reducing its force. Formerly, diesel fuel was a commonly added chemical, but the Environmental Protection Agency and major gas producing companies reached the mutual ´´memorandum agreement´´ in 2003 that put the end to the practice. Since then, substitute chemicals have included proprietary cocktails that are considered to be trade secrets, including the substance called LGC – 35 CBM, which is considered a potential carcinogen for humans.
A key to maximizing safety of oil and gas wells is guarding against cement failures. Cement failures occur in one of every 10 wells, including the Deepwater Horizon well that exploded in the Gulf of Mexico, according to an adviser for the Environmental Protection Agency.
Controls of the fracking process at the federal level are sparse since the US Congress exempted fracking from the Federal Safe Drinking Water Act of 2005. This is despite the occurrence of a series of incidents that have been linked to fracking, including several instances of ground water pollution in Colorado and Pennsylvania. A series of earthquakes in Ohio, a region not traditionally associated with tremors, has also been linked to disposal of fracking waste.
States like Ohio have responded by requiring rigorous standards for fracking wells to reduce the probability of fracking chemicals or even natural gas seeping into groundwater or making it way into residential tap water. Mandates include multi – layered pipelined comprised of cement, steel casing materials and drilling mud designed to seal off the fracking chemicals and natural gas from the surrounding natural sediment both vertically and horizontally.
The disposal of hydraulic fracturing fluid presents another major environmental challenge. Ohio and other states now require waste fluid produced by fracking to be disposed through Class II injection wells, considered environmentally conscious and safe for residents in the surrounding region. Other safeguards to protect groundwater and surrounding residential water systems include rigorous testing of well blowout prevention devices and strict monitoring of the fluid produced by fracking at every stage of the process.
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Source:Engineering Degree - Engineering Better Fracking Practices
