What Is a Degasser?

B. Turner

A degasser is a piece of industrial equipment used during oil and gas drilling operations. It serves as part of a mud system, and is designed to remove gaseous contaminants from drilling fluid. Combined with a solids-removal device like a shale shaker, the degasser can help to clean the drilling mud and allow it to be reused continuously during drilling operations. By removing bubbles of gas from this fluid, the degasser also helps to reduce the risk of explosions and other dangers on the drilling site.

Degassers, when combined with shale shakers that remove the solids from the fluid, are key in effective drilling operations.
Degassers, when combined with shale shakers that remove the solids from the fluid, are key in effective drilling operations.

Drilling fluid, or mud, plays an important role in the drilling process. This blend of chemicals, oil and water gets pumped down into the bore hole to remove rock cuttings and stabilize the walls of the bore. It then rises back up to the surface, carrying rock and debris with it. In some types of wells, the drilling mud may also bring back pockets of natural gas, methane, or carbon dioxide. These gases not only pose a risk of to drilling operations, but also to workers and equipment nearby.

As the gas exits the bore hole, it can be drawn into one of two different types of degasser units. Vacuum degassers rely on vacuum pressure to separate the gas from the liquid. For more advanced applications, drilling companies often rely on a poor boy, or atmospheric degasser. These units use an internal impeller to spread drilling mud across a series of baffle plates, thus increasing the surface area of the mud. By spreading the mud out over a larger area, poor boy degassers release trapped air and purify the mud for reuse.

Before or after degassing, the drilling fluid must pass through a solids-removal system. This generally involves a screened device known as a shale shaker, which separates rock cuttings and debris from the liquid mud. After all solid and gaseous materials have been removed, the drilling fluid can be recirculated through the drilling mechanism.

On drilling operations where natural gas or other gaseous materials are present, the degasser plays a critical role in protecting workers. As these gases are brought to the surface, they could lead to fires or explosions, or simply impact air quality around the drilling site. Gas bubbles left in drilling fluid can built up in the drill lines or cutting bit, which could cause workers to have to halt operations. By removing these bubbles, companies can maximize equipment life and reduce maintenance and repairs.

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Discussion Comments


@allenJo - I never thought I’d hear anyone talk about “purifying” mud. But I guess if you’re in the oil industry, mud is not all that bad. I imagine that some of these technologies have other applications, like for water treatment or other chemical cleanup operations.

I can easily see how they could use vacuum degassing to purify ponds and lakes and swamps. Swamp gas in particular has been shown to be dangerous in sufficiently high quantities.

Perhaps they could use these degassers to completely drain out the gas from the swamps and make them completely useful for fresh water life.


You wouldn’t think mud could be dangerous, would you? But there have been cases of drilling rig explosions over the past few years, and I have no doubt that the gas in the mud has been implicated in the disasters.

Degassing is therefore an important process. I only hope it’s a very thorough process. Of the different methods of degassing listed here, I don’t know which of them would be the most effective.

It appears that the advanced degassers go the extra mile to purifying the mud. Perhaps these are the best methods of cleaning the mud and making it safe.

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