Oil 101 – What is Natural Gas?
The first 10 episodes of the Oil 101 podcast have covered the ‘Microbes to Markets’ journey of getting hydrocarbons out of the ground, converting them to useful products, and bringing them to consumers.
Now we turn to the ‘What is…?’ portion of Oil 101. We started with the most basic of oil and gas questions, What is Crude Oil?, now let’s do a quick discussion of ‘What is Natural Gas?’.
In this episode of the Oil 101 podcast series, we will discuss what exactly crude oil is and some of the key components of crude oil that affect it being refined into useful petroleum products.
In this 6-minute podcast, we will discuss:
- What is natural gas?
- Associated vs non-associated gas
- What makes natural gas ‘clean’
- Measuring natural gas – heating value and volume
- Uses of natural gas
Listen to ‘What is Crude Oil’ below:
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- Oil 101 – A Free Introduction to Oil and Gas
- American Gas Association – AGA
- Podcast: Introduction to Natural Gas
What is Natural Gas?
Natural gas, like crude oil and coal, is a mixture of hydrocarbon compounds which are multiple combinations of carbon and hydrogen atoms. As far as the oil and gas industry is concerned, natural gas occurs in two principal forms: associated gas and non-associated gas.
Associated gas occurs in conjunction with crude oil reservoirs — either dissolved in the oil or occurring separately in the same reservoir. Since it separates from the oil at the casing head of the production well, it is also known as casing head gas or oil well gas. There are huge quantities of associated gas produced with Middle East crude oil.
Associated gas often is re-injected into the producing well to raise the pressure to get more oil out of the well, or held in the reservoir until a distribution system can be developed to move the gas to market.
Non-associated gas occurs in gas-only reservoirs separate from crude oil. The majority of US natural gas production is non-associated gas.
The principal components of natural gas are methane and ethane with varying amounts of heavier hydrocarbons including propane, butane and pentane. Methane is a light hydrocarbon. It has a relatively low boiling point, so at room temperature it is a gas.
Natural gas is the cleanest of all the fossil fuels. The main products of the combustion of natural gas are carbon dioxide and water vapor, the same compounds we exhale when we breathe.
Unlike coal or oil, combustion of natural gas releases very small amounts of sulfur dioxide and nitrogen oxides, virtually no ash or particulate matter.
How Natural Gas is Measured
Like crude oil, natural gas has a variety of global and US measurements. We will focus on Heating Value and Volume measurements.
Heating Value – BTU
Natural gas, like other forms of energy, is measured in terms of heating value, or British thermal units, often called BTUs.
Natural gas is valued for its heating ability with end use heating values generally ranging between 950 and 1150 Btu per cubic foot.
One Btu is the heat required to raise the temperature of one pound of water one degree Fahrenheit. To put the Btu in perspective, ten burning matches release 10 Btu.
Volume – Cubic Foot
When measuring volume, natural gas is commonly measured in cubic feet. One cubic foot of natural gas releases approximately 1,031 Btu.
Natural gas reserves are measured in terms of volume as Millions , billions or even trillions of cubic feet (TCF). or billions of cubic meters (BCM or Bm3).
In natural gas production, prolific wells produce and deliver hundreds of thousands or even millions of cubic feet of gas per day (MMcfd).
Purchases and sales of natural gas are generally measured in millions of BTU’s (MMBTU’s).
Transportation capacity of natural gas, which is a function of pipeline size and compression capability, generally is measured as a consistent stream, expressed in volume per day – such as million or billion cubic feet per day.
Pipeline size is measured in terms of pipe diameter. Compression is measured in terms of pressure relative to atmospheric pressure at sea level, expressed as pound-force per square inch gauge (psig).
What is Natural Gas Used For?
Because of its clean burning characteristics and heating value, natural gas is used around the world as follows:
- Residential sector users are housing units. Natural gas uses include heating, cooking, and fueling appliances such as water heaters and clothes dryers.
- Commercial sector users consist of business and government facilities. Common uses of natural gas associated with this sector also include space and water heating, air conditioning, lighting, refrigeration and cooking – just on a scale larger than residential.
- Industrial sector users consist of all facilities and equipment used for producing, processing or assembling goods. Industrial uses parallel those of commercial users. As examples, natural gas is used to fuel industrial processes, such as heat treating steel or manufacturing glass. It is also a feedstock for other chemical products such as fertilizer.
- Power generators are utilities that produce, transfer and sell electricity. Power generators, the largest sector of industrial sector users, burn natural gas (and other fuels) to produce electric power. A gas-fired power plant has much lower emissions of carbon dioxide (CO2) and nitrous oxides (NOx) than coal or oil-fired plants.