What exactly is natural gas, and how is it used?
Natural gas is the least carbon hydrocarbon, smells, looks, and isn’t harmful. For cooking and heating, it gives off heat, and it runs power plants that give electricity to homes and businesses. Many different things are made with it, from clothes to glass. It also powers many industrial processes that make all kinds of things, from paint to plastics.
These plants turn natural gas into cleaner-burning fuels and other products. Shell has a lot of these plants around the world. We also cool it down to -162oC (-260oF), making it into a liquid that is easy to ship to places that need a lot of electricity. We offer liquefied natural gas (LNG) cleaner fuel for ships, trucks, buses, and trains.
We are working to bring in more LNG to meet future needs. To show you how this works, we are building the world’s largest floating LNG production facility, called Prelude FLNG. It will let us get to gas fields off the coast of Australia that would otherwise be too expensive or difficult to get to. We can then turn natural gas into LNG that can be shipped to other countries.
There are a lot of organic materials that have been decomposed over the last 550 million years. Natural gas is made from these materials. This organic material is mixed with mud, silt, and sand on the seafloor. Over time, it became buried under the seafloor. The organic matter was sealed off from the rest of the world and heated and pressured until it was broken down into hydrocarbons by thermal decomposition.
People call natural gas all of the lightest hydrocarbons found in the air when things are normal. It is a colorless, odorless gas mostly made up of methane when natural gas is in its purest form. Unlike other hydrocarbons, methane is the simplest and lightest. It is a highly flammable compound with one carbon atom in the middle and four hydrogen atoms (chemical formula: CH4).
The fate of natural gas depends on the porosity and permeability of the rock around it. Porosity is the amount of space inside the grains of a rock. There is a lot of space in porous rocks like sandstones, which have up to 25% porosities. This means that they can store a lot of fluids like oil and water. Permeability measures how well the pore spaces in a rock are linked together. A very porous stone lets gas and liquids flow through it quickly. A less permeable rock doesn’t let fluids pass through.
After natural gas forms, it will rise to the surface through spaces in the rock because it is less dense than the remains of the stone. There are many natural gas deposits we find today that happened to be in places where the gas got into a very porous and permeable rock under an impermeable layer of gravel. This meant that the gas could not reach the surface and escape into the air.
There are two types of natural gas: conventional and unconventional. Traditional natural gas deposits are often found near oil reservoirs, with the gas either mixed with the oil or floating on top. Abnormal deposits come from shale gas, tight gas sandstone, and coalbed methane sources.
Resources and reserves of natural gas in the US
The United States has a lot of natural gas, and discoveries and better drilling methods have made it much more likely that we’ll be able to get more of it in the future. EIA estimates that the US has 2,203 trillion cubic feet of natural gas retrieved with current technology made in 2009.
Conventional resources make up 46 percent of the total resource base. The rest comprises unconventional natural gas resources, like tight gas, shale gas, and coalbed methane, which make up the rest of the resources. The total amount of gas in the United States is 273 trillion cubic feet. 273 trillion cubic feet of gas are called reserves, extracted under current economic and operational conditions.
As of 2012, the world’s largest known gas reserves are in Russia, five times as much gas as the United States. People in Iran and Qatar have four and three times as much gas as the United States. People in Saudi Arabia and Turkmenistan have a lot of gas too. The total amount of natural gas in the world is thought to be 6,707 trillion cubic feet.
Experimentation and production of natural gas resources from the ground up
Seismic testing can look for natural gas deposits like it is used to look for petroleum. Seismic trucks or more advanced three-dimensional tools are used in these tests. They set off a series of small changes near the Earth’s surface to make seismic waves that travel thousands of feet underground, where they can be used to find natural gas.
Geophysicists can build a picture of the subsurface structure by measuring how long waves travel through the Earth at acoustic receivers called geophones. They can also look for places where gas might be found. However, an exploratory well must be drilled to see if the rock formation is full of natural gas or other hydrocarbons that can be economically extracted.
As soon as a site is viable, vertical wells are drilled to penetrate the caprock and reach the reservoir. There, the gas rises to the surface because of its buoyancy. It can then be cleaned and sent to homes.