Shale Gas Development
Shale gas is naturally found in compact rocks that are less permeable and lies beneath the surface. It is trapped in extensive layers on rocks in every continent. According to Thomas et al. (2), Obama government believes that its extraction will help to reduce climate change. It caused the natural gas production to increase by 20% in 2010, and the government predicted a 46% percent production by 2035. Engineers have found two different technologies to extract the natural oil while considering the environmental effect of their processes. Shale gas is extracted through Hydraulic fracturing and horizontal drilling. Hydraulic fracturing technology involves the injection of chemicals into the inner layers of the soil. Because it is a natural gas, shale gas extraction has increased across the globe. Shale gas extraction using hydraulic fracturing is safer than extraction of minerals such as coal, which poses a threat to workers in the coal mines; however, it also has negative environmental impacts. What is in the fracturing fluid?
In order to create pressure in the shale rock, fracturing fluid is injected into the rock to create pressure and release hydrocarbon. In hydraulic fracturing, the source rock is made more permeable to cause the gas to flow to the well. Hydraulic fracturing opens the source rock to a distance of around one hundred meters. The micro-fractures created by the hydraulic fracturing results from pressure from water, chemical additives, and sand. The three substances form part of the fracturing fluid. A very high-pressure mixture of the fracturing fluid is injected into the well through appropriate casing. The pressure water then creates path for the gas through the cracks. Sand holds the cracks up while the chemicals protect the reservoir from bacterial contamination from the surface. Other substances used include the viscosifiers, which ensure the sand is suspended in water while the cracks are open.
Is it safe?Shale gas extraction using hydraulic fracturing poses little challenges to the workers at the wells since its effects cannot be felt immediately on the site. The fracturing liquid is injected using pipes and water tanks with large trucks are driven to the site. However, the environmental impacts of hydraulic fracturing make it an unsafe practice. The impacts include climate change, air emissions, water contamination, high water consumption, human health effects, noise pollution, risk of earthquakes and land use. These potential problems results to several legislative measures created in countries, which use hydraulic fracturing. Drinking Water Contamination
Water is an essential element of human growth and development in all living things, which is why its contamination threatens the life of both animals and plants. One of the problems faced by the oil drilling companies that use hydraulic fracturing is the contamination of water during the extraction process. Contamination of the surface water happens through spillage and cases of improperly built waste pits. Other reasons for contamination may include mistakes done during the drilling process or just poor maintenance mechanism. The waste pits are in some cases not well-maintained causing contamination of the surface water. Fluids are not supposed to escape the fractured formation, although this happens in most cases. When the fluid escapes the fractured formation, especially in abandoned wells, ground water becomes contaminated. Hydraulic fracturing also requires the use of a large amount of water. The waste cannot be used for drinking while a lot of water is also used and cannot be recycled for drinking. This excessive use of water poses a danger of climate change and human health effects in the society today. While international bodies join to protect water sources and conserve water, oil company focus on drilling and extraction of shale gas using a large amount of water. Earth Quakes
Micro-earthquakes, also known as induced seismicity can also result from hydraulic fracturing. Micro-seismic activities help to mark the vertical and horizontal extent of the fracturing. Although the magnitude of the micro-seismic activities is too small and does not reach the surface, tremors resulting from fluid injection have been felt by people on several occasions. One of the causes of magnitude 3 earthquake in the US is the water pushed towards the fault tends. The water causes earthquakes through a fault or slippage. Smaller earthquakes were detected between January 2011 and February 2012. The small earthquakes were over 109 and most of them resulted from fluid injection creating pressure at the preexisting sub-surface faults next to the wellbore.
Shale contains a great level of radium. The chemical element is resourceful in cancer treatment and industrial x-ray diagnostics. It is less required in oil fields. The fraction process displaces radium-tinged water that flows through the well up to the soil surface. Radiation levels can pile up at the of pipeline scale, bottom of the tanks and substance that is exposed to wastewater. The radium is displaced to the surface when water cracks the formation and hydrocarbons are released. Even the spent filters that are used in straining radium –laden create disposal problems since they contain elevated levels of radiation. There are regulations put in place to control illegal disposal especially in the states that experience intense freaking processes.
According to Hubbert and Willis (240), leakages are common in wells used to extract shale gas causing methane to migrate under the earth. Extraction of shale gas impacts on the environment through leaking both waste and extraction chemicals into the water suppliers. During extraction, greenhouse gases also leak causing pollution and improper processing of the shale gas. The challenge of reducing the leakages is that the natural gas extraction varies between different wells even in the same project. A strategy used to reduce the leakage in one well may not be enough in other wells within the same project (Ohio State University 2). Despite the release of methane through leakages, hydraulic fracturing of shale results to fewer emissions of greenhouse gas as compared to fossil fuels. Methane however has a global warming effect despite its infinite presence. The cement used in the wells normally becomes weak and the casing either fades away or becomes obsolete. There are poor maintenance and safety practices in the wells, which also leads to leakages. Air emissions are effects that take place during the extraction. It is primarily the escape of methane from the well and the different equipment used during the extraction process. According to Hubbert and Willis (243), drilling for the shale gas using hydraulic fracturing results to smaller leaks of greenhouse methane gas than the federal government had estimated. The total amount of leaked methane gas is more than one million tons in the US annually.
Hubbert, M. King, and David G. Willis. “Mechanics of hydraulic fracturing.” (1972): 239-257.
Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. Warner and Robert J.
Poreda. Noble Gases Identify the Mechanisms of Fugitive Gas Contamination in Drinking Water Wells Overlying the Marcellus and Barnett Shales. Proceedings of the National Academy of Sciences, 2014 DOI: 10.1073/pnas.1322107111
Ohio State University. “Fracking: Gas leaks from faulty wells linked to contamination in some
groundwater.” ScienceDaily, 15 Sept. 2014. Web. 4 Dec. 2014 <www.sciencedaily.com/releases/2014/09/140915095851.htm>.