Shale gas
Shale gas is a type of natural gas that is found deep within shale rock formations, which are fine-grained sedimentary rocks formed from organic materials over millions of years. While production of shale gas dates back to the 1800s, it gained significant traction in the late 20th and early 21st centuries due to advancements in extraction technologies. The United States is rich in shale gas, with major formations like the Barnett, Marcellus, and Haynesville Shales contributing to its energy independence and economic growth.
The extraction process primarily involves horizontal drilling and hydraulic fracturing (fracking). Horizontal drilling allows access to gas that is difficult to reach with traditional vertical methods, while fracking helps to fracture the rock and release gas more efficiently. Despite its benefits, including reduced greenhouse gas emissions compared to coal and oil, shale gas production raises environmental concerns. These include water usage, the management of wastewater, potential contamination of drinking water, and noise and air quality impacts on nearby communities.
In 2022, shale gas accounted for a significant portion of the nearly 36.35 trillion cubic feet of natural gas produced in the U.S., highlighting its crucial role in the nation’s energy landscape. As the industry continues to evolve, discussions around its economic benefits versus environmental drawbacks remain central to the debate surrounding shale gas.
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Shale gas
Shale gas is a type of natural gas found deep within the earth in shale rock formations. Shale gas production has been around since the 1800s, but it did not generate much interest until the end of the twentieth century and into the twenty-first century. Shale gas is found all over the world, and the United States has several shale-rich areas located throughout the country. Shale gas is an important energy source for the United States because the country does not have to fully rely on foreign gas imports. While the industry flourished in the early twenty-first century, extraction methods have been seen as controversial and possibly damaging to the environment.
Background
Shale gas is trapped in shale rock formations. These formations are a type of fine-grained sedimentary rock that is formed by the deposit of materials on the earth's surface or within bodies of water. Other types of sedimentary rock include sandstone and limestone.
Some shale rock formed more than four hundred million years ago during the Devonian period. Sediment accumulated at the bottom of bodies of water, and organic matter such as plants and animals decomposed and became part of these rock layers. The organic matter formed pockets of methane gas within the shale rocks. These pockets are called shale plays, and they are located in different areas throughout the world. Important plays in the United States include Barnett Shale in Texas, Marcellus Shale and Utica Shale in the eastern United States, and Haynesville Shale and Fayetteville Shale in Louisiana and Arkansas.
Shale gas is locked tightly in shale rock. Two ways are used to retrieve shale gas: horizontal drilling and hydraulic fracturing. Most wells are drilled vertically, meaning straight downward. Horizontal drilling, also called directional drilling, is drilling downward and then horizontally in either direction. It is used to gain access to gas that is trapped deep in the earth and under objects that make it difficult to attain. A vertical well is first drilled into the shale rock. When the well is drilled to the desired depth, the drill bit is turned perpendicular to continue drilling the well horizontally.
Horizontal drilling is used to reach gas that cannot be retrieved by vertical drilling. For example, a gas reserve under a park may make vertical drilling impossible without disrupting or ruining the area. Horizontal drilling allows for drilling in an area away from the park because the drilling can be steered under the ground. It allows multiple wells to be drilled from just one single drill pad, also called a platform or site. It also lets wells penetrate as many rock fractures (which release the gas) as possible. Horizontal drilling is not only used to extract shale gas, but also to install utility lines under the ground in areas where it is not feasible to run these lines above the ground. Horizontal drilling is expensive compared to vertical drilling, but it can greatly increase the output of a gas well; this, in turn, drives up production and potential profits.
Once the shale rock has been drilled horizontally, the method of hydraulic fracturing can be used to help make the rock more permeable and allows the gas to flow from it. Hydraulic fracturing, also known as fracking or hydrofracking, is used to fracture the shale and release gas from the rock. Pressurized water, chemicals, and sand (or other materials) are pumped into the well, and the liquids create cracks in the shale, helping to move the gas. The sand gets into the cracks and helps to keep them open. The network of interconnected cracks allows the gas to flow quickly and efficiently into a well, especially over long distances.
Topic Today
The shale gas industry became important to the United States in the twenty-first century. While drilling for shale gas had been explored for several centuries, it saw a renewed interest when newer technology made the industry more profitable. Hydraulic fracturing allowed once unproductive wells to produce a large quantity of gas and become productive.
The increased production of shale gas resulted in a gas boom for the United States. Larger supplies are available domestically, helping to lower prices and reduce the need for foreign gas imports. The industry created numerous jobs. As it expanded, it required workers to drill wells, construct pipelines, operate machinery, drive vehicles, and build and operate production facilities. In addition, it created royalty payout programs for landowners who allowed drilling on their properties for a fee. Shale gas has been found to be better for the environment because it helps reduce greenhouse gas emissions. Burning natural gas is cleaner than gas or oil and emits fewer pollutants, such as carbon dioxide (CO2), nitrogen oxide, and sulfur dioxide, into the air.
Despite these advantages, drilling for shale gas is controversial. Several environmental concerns surround the production of shale gas. Drilling and fracturing wells require significant amounts of water. This can affect an area's available water resources and disrupt aquatic habitats. In addition to the need for water, the wastewater produced by fracking also presents problems. This wastewater—called fracturing fluid—usually contains chemicals and must be treated before it is disposed of or recycled for reuse. Spills and leaks of this fluid can release potentially hazardous chemicals into the ground, pollute drinking water supplies and the environment, and affect surrounding habitats.
Drilling for shale gas and constructing drilling platforms and production facilities is noisy and disrupts people living in the surrounding area. While some people readily agree to wells being built and used on or near their property, this affects those living in the surrounding area who did not have this choice. Shale gas production requires the transportation of materials to and from drilling sites and takes a toll on roads and interstates. Diesel fumes from these vehicles can also affect surrounding air quality.
By 2022, the United States produced nearly all the natural gas that it utilized. This amounted to 36.35 trillion cubic feet of natural gas produced per year. Shale gas made up a significant portion of this natural gas production, with the United States producing 31.6 trillion cubic feet of shale gas in 2022.
Bibliography
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"What Is Directional Drilling?" Geology.com, geology.com/articles/horizontal-drilling. Accessed 25 Nov. 2024.
"What Is Fracking and Why Is It Controversial?" BBC, 26 Oct. 2022, www.bbc.com/news/uk-14432401. Accessed 25 Nov. 2024.
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