How Natural Gas is formed: Natural gas, composed of one Carbon atom and four Hydrogen atoms, is a fossil fuel that formed from layer after layer of organic matter such as dead plants, animals, and trapped gases. This decaying organic matter was eventually covered by layers of rock and subjected to intense pressure and increased heat. After millions of years, fuels that we use every day are formed: natural gas, crude oil, and coal. Deposits of natural gas are usually found a few miles underground land or water, in deep shale, and in highly dense rock deposits.
How We Get to Natural Gas Deposits: Preparation and Analysis (around two weeks): The first step is to find the drilling site. Geologists first look at the geology to determine where a suitable drilling site might be, and then utilize many technologies, including seismic surveys, where energy, in the form of sound waves, travels through and bounces off varying types of rocks, which allows geologists and geophysicists to “see” underground. Three-dimensional imaging and analysis is a computer assisted process that can create a map of the composition of earth’s crust. This one technique has advanced the field of seismic imaging tremendously. It has been estimated that it has increased the likelihood of successful reservoir location by 50 percent. ("NaturalGas.org")
After the potential site has been located construction of a new road to access the site is built if necessary. The drilling pad, where the actual well will be located, is also built to accommodate the equipment and specific requirements for drilling. After the proper permits for drilling operations, as well as permits that allow the extraction and sale of the natural gas, are obtained, an exploratory well can be drilled.
Drilling (eight to twelve weeks): Geologists and geophysicists work together, and use many different factors, to determine where to dig an exploration well. If they find natural gas, they can continue on with the process and begin extracting the natural gas. If a ‘dry well’ is found, meaning natural gas is not found, the team moves on to attempt to find a different location where they might find natural gas.
There are several processes involved in drilling:
How We Get to Natural Gas Deposits: Preparation and Analysis (around two weeks): The first step is to find the drilling site. Geologists first look at the geology to determine where a suitable drilling site might be, and then utilize many technologies, including seismic surveys, where energy, in the form of sound waves, travels through and bounces off varying types of rocks, which allows geologists and geophysicists to “see” underground. Three-dimensional imaging and analysis is a computer assisted process that can create a map of the composition of earth’s crust. This one technique has advanced the field of seismic imaging tremendously. It has been estimated that it has increased the likelihood of successful reservoir location by 50 percent. ("NaturalGas.org")
After the potential site has been located construction of a new road to access the site is built if necessary. The drilling pad, where the actual well will be located, is also built to accommodate the equipment and specific requirements for drilling. After the proper permits for drilling operations, as well as permits that allow the extraction and sale of the natural gas, are obtained, an exploratory well can be drilled.
Drilling (eight to twelve weeks): Geologists and geophysicists work together, and use many different factors, to determine where to dig an exploration well. If they find natural gas, they can continue on with the process and begin extracting the natural gas. If a ‘dry well’ is found, meaning natural gas is not found, the team moves on to attempt to find a different location where they might find natural gas.
There are several processes involved in drilling:
- There is the traditional vertical drilling, where a hold is drilled straight down, creating a wellbore, using tools that are specially designed to cut through the thick and dense rocks of the earth’s crust. In order to allow for faster and safer drilling, a substance often called drilling mud, or drilling fluid, is used to keep the drill head from over-heating, push the rocks back up to the surface, and stabilize the hole.
- Once past underground water aquifers, the drill pipe is replaced with a steel pipe, which is called the surface casing ("How is gas extracted from the ground?"). This surface casing allows cement to be poured down to the bottom and back up, between the outside of the steel surface casing and wellbore, in order to protect groundwater and aquifers, sources of our freshwater, from pollution. Depending on the geology and depth of the well, additional casings may be required to prevent any contamination or pollution.
- Horizontal drilling allows us to reach and extract natural gas and other hydrocarbons trapped in shale formations, and is a continuation of vertical drilling processes. Once the well has reached a certain depth, the wellbore begins to turn, and eventually ends up horizontal to the surface. Once the specified distance has been reached, the drill pipe is removed, additional casing is placed down the well, and cement is poured to prevent the casing from movement.
- After the well has been completed, a highly specialized piece of equipment called a perforation gun is lowered down into the rock layers. This gun is then fired, about a mile underground, and creates holes, a few inches long, in both the surface casing as well as the cement casing that connects the rock formations containing natural gas and oil. The perforation gun is then removed, and the process of hydraulic fracturing, also known as fracking, can begin.
- In order for hydraulic fracturing to take place, a large amount of water, estimated to be between one and eight million gallons, is mixed with sand and certain chemicals to create a mixture called fracking fluid. This fluid is used to prevent bacteria growth, which prevents corrosion of the well casing, and improves the performance and efficiency of fracking.
- This fluid is then pumped at high pressures from storage tanks by equipment on the surface down the wellbore, and through the perforations created by the perforation gun which causes fractures in the shale containing natural gas and oil. The sand used in the fracking process keeps the fractures open, so that the fossil fuels flow when the pump pressure is relieved.
- After the fossil fuels have been extracted, the horizontal section that is dry is isolated with a plug, and the perforating guns create the next fractures further down the horizontal wellbore. The process is then repeated for the entire length of the well, sometimes to a distance of one to two miles.
Sources: "Chemical Use In Hydraulic Fracturing." Chemical Use In Hydraulic Fracturing. Ground Water Protection Council and Interstate Oil and Gas Compact Commission. Web. 10 May 2015. http://fracfocus.org/water-protection/drilling-usage.
"Delivery and Storage of Natural Gas." Energy Explained, Your Guide To Understanding Energy. United States Department of Energy, 6 June 2014. Web. 10 May 2015. http://www.eia.gov/energyexplained/index.cfm?page=natural_gas_delivery.
"DOE - Fossil Energy: How Fossil Fuels Were Formed." DOE - Fossil Energy: How Fossil Fuels Were Formed. Fossil Energy Office of Communications, 12 Jan. 2013. Web. 10 May 2015. http://www.fe.doe.gov/education/energylessons/coal/gen_howformed.html.
Estefani, Guillermo. "Natural Gas." Artinaid. 12 Apr. 2013. Web. 10 May 2015. http://www.artinaid.com/2013/04/natural-gas/.
"How Is Gas Extracted from the Ground?" How Is Gas Extracted from the Ground? United Kingdom Onshore Oil and Gas, 2013. Web. 10 May 2015. http://www.ukoog.org.uk/knowledge-base/drilling-process-kb/how-is-gas-extracted-from-the-ground.
"NaturalGas.org." NaturalGas.org. 20 Sept. 2013. Web. 10 May 2015. http://naturalgas.org/naturalgas/.
"Delivery and Storage of Natural Gas." Energy Explained, Your Guide To Understanding Energy. United States Department of Energy, 6 June 2014. Web. 10 May 2015. http://www.eia.gov/energyexplained/index.cfm?page=natural_gas_delivery.
"DOE - Fossil Energy: How Fossil Fuels Were Formed." DOE - Fossil Energy: How Fossil Fuels Were Formed. Fossil Energy Office of Communications, 12 Jan. 2013. Web. 10 May 2015. http://www.fe.doe.gov/education/energylessons/coal/gen_howformed.html.
Estefani, Guillermo. "Natural Gas." Artinaid. 12 Apr. 2013. Web. 10 May 2015. http://www.artinaid.com/2013/04/natural-gas/.
"How Is Gas Extracted from the Ground?" How Is Gas Extracted from the Ground? United Kingdom Onshore Oil and Gas, 2013. Web. 10 May 2015. http://www.ukoog.org.uk/knowledge-base/drilling-process-kb/how-is-gas-extracted-from-the-ground.
"NaturalGas.org." NaturalGas.org. 20 Sept. 2013. Web. 10 May 2015. http://naturalgas.org/naturalgas/.