Horizontal drilling and hydraulic fracturing are safely unlocking extensive U.S reserves of natural gas and oil present in tight-rock formations and in shale (Hydraulic Fracturing, 2016).
Healy, 2012 found that hydraulic ‘fracking' or fracturing is a technique applied by drilling engineers to improve or stimulate fluid flow from the subsurface rocks.
The United States relies on natural gas and oil for most of its energy requirements and this is projected to continue over the next decades. During the previous decade, the United States has encountered revolution in energy industry with production of natural almost at 50 percent and domestic crude oil production estimated at over 80 percent.
Therefore, horizontal drilling and hydraulic fracturing are safely unlocking the United States vast natural gas and oil reserves found in tight-rock formations and in shale. The hydraulic fracturing has been in use in the natural gas and oil industry since 1940s and produced seven billion oil barrels and over 600 trillion natural gas cubic feet (Hydraulic Fracturing, 2016).
The hydraulic fracturing is considered as both an opportunity and energy for stronger and better lives and for a more-energy secure nation. According to Hydraulic Fracturing, 2016 this method is a source of manufacturing jobs and consumer savings. Hydraulic fracturing is largely responsible for changing the United States' energy industry from a limited option to almost limitless alternatives. It means overall economic growth and individual prosperity opportunities.
Briefly, Healy, 2012 ascertains that hydraulic fracturing comprises the processes of thrusting a water-rich liquid into a borehole until the rock fractures due to the fluid pressure in the depth.
This pumped fluid is made up of small particles called proppant (mostly quartz rich sand) that serves in prop-opening the fractures. After hydraulic fracking, the well pressure is released and water that contains the released natural gas streams back to the surface well head.
To ensure more efficient and better coverage of aimed shale gas reservoir, the boreholes are usually diverged away from the vertical orientations into sub horizontal alignments. The fracking fluid contains little amounts of chemical additives (normally<2 percent of the total volume) in addition. For example, acids which assists in scaling up inhibitors, initiate fractures and corrosions so as to protect the lining of the boreholes and gelling agents in altering the fluid viscosity.
According to Köster, 2013, shale refers to a compressed fine-grained kind of a sedimentary rock which is formed from organic matter, silt and clay. It is a type of natural gas that is trapped inside the small pore spaces during shale formations. Moreover, it is hydrocarbon mixture of gases which mainly consists of methane. The other hydrocarbons present are NGLs (Natural Gas Liquids) such as butane, propane and ethane. Shale also contains hydrogen sulfide, nitrogen and carbon dioxide.
The horizontal drilling permits vertical drilling of several thousands of meters (usually 6,000 meters) deep and 90 degrees turning and horizontal drilling (Köster, 2013). The process makes it possible to run multiple target zones from a single drilling pad. It increases productivity significantly and also enlarges the recoverable reserves. Hydraulic fracking or fracturing creates fractures during formation of shale that releases the gas. The fracturing fluid is then pumped under very high pressure (100 bar) into a drilling pipe to either create new fractures or widen the existing ones. Water is the main component of this fluid. It is normally mixed with quartz sand and about three to twelve chemicals amounting to 0.5 to 2 percent (Bukkis, 2013). The precise compositions remains as secret by the drilling firms.
According to Köster, 2013, an estimate of between 7 and 15 liters of water are used in each well. Sand is used in holding the cracks open so as to elevate the quantities of extracted natural gas. The chemicals can include butyldiglycol or gels (usually 0.2 L/t water) which increases the viscosity of fracturing liquid to better transport foaming agents such as N2 and CO2, sand, acids like acetic, hydrochloric acids, boric or formic acids which assists in disintegrating reserves of rock formations, anti-corrosion agents that protects the site on addition of acids and biocides which averts bacteria growth in the organic components. An approximate of between 20 and 70 percent of the liquid solution is recovered. The residual water remains on the ground. The recovered liquid is usually contaminated with salts and chemicals from the rock formation. It is ether directly disposed or transported to the treatment facilities. The process of extracting energy from tight-rock and shale formations using horizontal drilling or hydraulic fracturing takes an estimated duration of between one and two months from the site preparation to the actual production, after which the production continues over the next 20 to 40 years from the same well (Hydraulic Fracturing, 2016).
Foremost, the effects on water. Healy, 2012 ascertains that changes in water infiltration and hydrology resulting from the new infrastructure and unintentional surface releases of wastewater and fracturing chemicals can have an impact on the surface water resources and shallow groundwater. A risk to the potable groundwater is accounted to upward movement of saline waters and natural gas from leaking well casings and probably also from natural fractures that exists in the old abandoned wells, permeable faults and natural rock fractures. The top environmental concerns includes huge water quantities which are utilized and contaminated water from the earth layers is pumped in addition to the fracking chemicals (Healy, 2012).
Secondly, an environmental effect results from the greenhouse gases. The extracted natural gas from tight-rock formations and shale replaces oil. Specifically, this takes place in generation of electricity and can reduce the environmental effect of fossils fuel in addition to slowing the anthropogenic climate change. The extent to which the development of shale gas slows the climate change and decreases the GHG emissions is based on a number of factors such as the distribution systems, the replaced energy source (such as oil and coal vs. renewables and nuclear) and amounts of methane releases from wellhead gas leakage (Council of Canadian Academies, 2014).Thirdly, effects on land. The large-scale development of shale gas signifies the beginning of successive decades of drilling and production of the Canada's tens of thousands of boreholes. The development will lead to both dispersed and local land impacts. The evaluation of the surroundings' effects from the shale gas does not thus focus on one well pad or well but should also consider cumulative and regional impacts (Council of Canadian Academies, 2014).
The other is effect on Social Impacts and Human Heath. The social and health impacts have not been well investigated. Whereas the development of shale gas provides diverse economic benefits, it might also negatively affect community well-being and air and water quality due to rapid expansion of extraction industries in both semi-rural and rural regions (Healy, 2012). The prospective community effects includes safety and health issues linked to the sudden influx and truck traffic of a huge transient workforce. The psychological impacts on communities and impacts which have already been reported relates to physical stresses such as noise as well as perceived lack of trustworthiness of government and industry according to Council of Canadian Academies, 2014.
Lastly, impacts on the seismic events. Though hydraulic fracturing may result to minor earthquakes, the majority of the experienced earthquakes by the public have resulted from wastewater re-injection and not the hydraulic fracturing itself. According to most experts, the probability of a hydraulic fracture to cause an earthquake is too low (Council of Canadian Academies, 2014). Healy, 2012 confirms that the small earthquakes (commonly known as induced seismicity) may result from the alteration of balancing forces during the rock formation.
First, environmental regulation should be enacted. This entails holding the natural gas firms responsible for any harms to the surroundings by requiring them to reveal chemicals which are put inside the gas wells. Moreover, these companies should be obligated to disclose all additives in form of chemicals which are used in fracking. Also it should be a requirement that they apply best management practices for surface spills (Zoback, Kitasei & Copithorne, 2010).
Secondly, improved wastewater treatment should be observed. Treatment plants which involves chlorination emits unwanted byproducts known as trihalomethanes. If hydraulic fracturing wastewater is treated by such plants it results to environmental contaminations. Thus one method of mitigating this issue is by requiring treatment firms to reduce chloride content present surface water discharge (Gregory, Vidic & Dzombak, 2011).
Finally, water recycling should be applied. As explained above, the natural gas company pays for flow-back liquid be treated in a wastewater plant. Moreover, it is more costly for the company. In a bid to solve the problem, the back-liquid should be recycled on the site and re-utilized. It has a benefit of reducing disposal costs, obtaining the water required in fracking process and enhancing the firm's public image (Zoback, Kitasei & Copithorne, 2010).