Even though natural gas has been extracted and used for many years, the US natural gas resource’s estimated size has been steadily growing since the 1990s. This is primarily due to a rise in the feasibility of extracting gas from unconventional deposits. Unconventional natural gas, which comprises shale gas, tight gas, coal bed methane, and methane hydrates, has been more difficult and expensive to get than conventional gas.
Such sources could close the growing gap between what the United States makes and its consumption. However, they have more environmental problems in the process of making them. The Energy Information Administration says that unconventional gas in the United States is 2,203 trillion cubic feet. Of that, 167 trillion cubic feet are known as proven reserves, which means they can be recovered in the current economic and operational environment.
Shale gas
On the other hand, conventional gas is found in very porous reservoirs and can be easily tapped by standard vertical wells. On the other hand, Shale gas is located in its source rock, the organic-rich shale formed from the sedimentary deposition of mud, clay, silt, and organic matter in shallow seas.
Fredonia, New York, was home to the first well in the United States drilled for natural gas. In 1821, it hit a shale gas deposit. Using vertical wells to extract these shales was not cost-effective because other warranties could be more easily accessed in a different place. Today, shale gas is the fastest-growing source of natural gas in the United States and worldwide because of several recent changes.
A single well can now go through more shale gas and produce more gas because of new horizontal drilling technology. Hydraulic fracturing technology, also called hydrofracturing, hydrofracking, or fracking, has made it easier to get to shale gas deposits. This process involves pumping a lot of water, sand, and fluid chemicals into the well at a very high pressure to break up the rock and make it easier for water and oil to flow through it.
This isn’t the only reason shale gas exploration has become more popular. High natural gas costs between 2001 and 2008 have also made it more appealing. However, the rise in shale gas and the recent economic downturn have led to a massive drop in gas prices since 2008.
If you want to get shale gas, you have to drill a well vertically until you reach the shale formation, at which point the wellbore turns and moves horizontally to follow the shale horizontally. To keep the well open and protect the wellbore, a piece of steel tubing called “casing” is inserted into the well. As the last step, cement is then pumped into the well and pushed up the outside of the steel casing.
This seals the well and keeps natural gas and other fracking fluids, chemicals, and produced water from getting into groundwater. After the well is drilled and the suitable casing is put in place, small explosive charges are set off in the horizontal part of the well to make holes in the case where hydraulic fracturing will take place. There are many types of hydraulic fracturing operations.
In one, the fracturing fluid is pumped into the well at the same pressure. This causes the rock to split several hundred feet from the well. Some of the fracturing fluid is mixed with sand, which helps keep these cracks open when the juices are pumped out of them. Immediately after fracturing, gas will flow into the excellent bore and up to the surface, stored.
As of 2011, about 39% of the US’s natural gas reserves were shale deposits or 132 trillion cubic feet. Most of them were found in Texas, Louisiana, Arkansas, and Pennsylvania. These deposits can be found all over the United States, in places where conventional gas resources are also found. When it comes to natural gas production, the Marcellus Shale in Pennsylvania and West Virginia has seen a significant rise in recent years. The Barnett Shale is a similar story in Texas.
Tight gas sandstone
A type of natural gas called “tight gas” is when the gas moves into an area where there is a lot of space but not much space for it to move through. These reservoirs aren’t usually found with oil, but horizontal drilling and hydraulic fracturing often increase healthy output to a cost-effective level.
Coalbed methane
Natural gas and petroleum are usually seen together, but they can also be found in coal deposits that have been buried. Methane has been a danger to coal miners underground for a long time because the highly flammable gas is released during mining.
Coal seams that aren’t easy to get to can also be used to get this gas, called coalbed methane, by using the same well-drilling and hydraulic fracturing methods used to get shale gas. At the end of 2010, about 6 percent of the US’s natural gas reserves were in coalbed methane deposits. Most of them were in Colorado, New Mexico, and Wyoming.
Coalbed methane deposits have also drawn attention because of their potential to store carbon dioxide. Putting carbon dioxide (CO2) into coal seams that are hard to mine would make the CO2 replace the methane inside the coal, making it easier to get the natural gas out of the coal while not causing global warming.
Methane hydrates
Methane hydrates, made up of methane molecules inside a cage of water molecules, can be found in sediments in the Arctic and on the deep ocean floor. If you light methane hydrates, they will boil and start to burn. They’re the most common source of unconventional natural gas, but they’re also the hardest to get. Methane hydrates are both. As a rough estimate, the amount of methane hydrates in the Earth’s crust is thought to be 4,000 times more than was used in the United States in 2010.
However, the technical difficulties of getting the resource economically are enormous, and only a tiny fraction of the real help is found in high enough concentrations to get. There is also a natural risk that the rising temperatures caused by global warming could break down methane hydrate deposits, releasing methane into the air and making the problem even worse.
Biogenic gas
Methanogens are a group of bacteria that can make methane, the main component of natural gas when they break down organic matter in an environment without any oxygen. Because this type of gas is made from organic material that was buried in the Earth’s crust at very elevated temperatures and pressures, it’s called “biogenic.” Biogenic methane has the same properties as thermogenic methane to be used in the same way.
Livestock manure, food waste, and sewage can all make biogas, a renewable energy type. One study says that the technical potential of livestock manure alone could provide 1 percent of the country’s energy needs and cut the country’s greenhouse gas emissions by 4 percent, just by using it for energy.
There are already a lot of US farmers who have invested in anaerobic digesters and generators that use livestock waste to make electricity and heat (and more money for their farms). Small-scale biogas production has been used for a long time in parts of the developing world, especially in Asia. Farmers collect animal manure in vats and capture the methane as it decays.
Another source of biogas that isn’t being used is landfilling. A landfill is a place where people put their garbage. Bacteria break down the organic material in the trash and make gasses like carbon dioxide and methane when they do this. Instead of letting these gasses go into the air, where they can cause global warming, landfill gas facilities can capture them, separate the methane, and burn it to make electricity, heat, or both.
