How Does an Offshore Oil and Gas Compressor Work?
The high demand for energy around the world has led to the migration of oil and gas fields from land to offshore. Yet in order to work, offshore oil and gas plants need compressors.
In these offshore oil and gas facilities, compressors such as centrifugal and reciprocating compressors are used in drilling gas and extracting resources from the sea.
However, since the equipment used for the offshore drilling of gas is not installed on land, but in water, it makes it needful for a compressor to be compact in design.
A compact design will ensure that the compressor is installed quickly, and it takes the least amount of installation space. Similarly, these compressors need to be easy to install, operate, and maintain on a timely basis.
It is also essential for these machines to be able to withstand the force of the sea since the ocean could potentially impact them. These and many more, are the requirements for compressors that are used in offshore drilling of oil and gas.
What is a Compressor?
A compressor is a mechanical device that is used to increase the pressure of a compressible fluid such as a gas or vapor. The compressor also reduces the volume of the gas as it passes through it.
The advantage of increasing a fluid’s pressure, but reducing its volume, helps to transport larger amounts of gas using a pipe of a specific size. The natural gas can also be sent from the production site to the consumer using a supply chain.
On the same note, there is the benefit of being able to transmit fluids over long distances while bypassing additional boosting stations that would’ve been a necessity.
Compressors are used in the oil and gas industry for the following:
- Gas lift
- Gas gathering
- Processing operations of gas
- Transmission and distribution systems
- Reinjection of gas in a bid to provide pressure maintenance
- Reduction of the gas volume for storage or shipment by tankers
Types of Compressors Used in the Offshore Oil and Gas Industry
Reciprocating and centrifugal compressors are the two main types of compressors in the oil and natural gas sector.
Here’s a brief outline of each type of compressors:
1. Reciprocating Compressors
In a reciprocating compressor, the compression of natural gas is made possible by means of a reciprocating motion carried out by the crankshaft.
But first, the gas passes through the suction manifold into the compression cylinder where its compression takes place.
2. Centrifugal Compressors
Centrifugal compressors rely on their impeller or rotating disk to increase the velocity of the gas. This rotation and increased velocity move the gas to the divergent duct section where the gas is then converted to pressure energy.
Centrifugal compressors are also used for continuous, stationary transportation of natural gas. They have also found a use case in the processing and transmission industry segments.
How Compressors are Used in Offshore Oil & Gas Production
The use of compressors in the extraction of crude oil and gas is believed to raise oil and gas recovery by 40% to 50%. This is double the recovery rate of conventional methods.
To that effect, some types of compressors employed in offshore oil and gas production include:
1. Flare Gas Recovery Compressors
Flare gas was once believed to be useless, but today, the reverse is the case. This is because compressors paired with a drive motor are now used to recover flare gas. This can then be used as a resource.
That being the case, flare gas is no longer burnt and left to waste, as was evident before. The use case of the flare gas recovery compressor is in an offshore oil and gas drilling facility in the United Arab Emirates.
As is a requirement for compressors used in offshore gas drilling facilities, this flare gas recovery compressor was also easy to install, operate, and maintain.
On the other hand, flare gas consists of highly corrosive constituents, which makes it needful for these compressors to be built with corrosion-resistant materials and coating technologies. Similarly, 3-point support systems are installed underneath the compressor’s common base plate to give it resistance.
These systems also offer support from the constant movement of the sea that would’ve affected the equipment’s operation or lifespan.
What’s more, a large reaction force is also generated from the piping in the offshore facility as a result of the facility’s restriction. For this reason, such a compressor is built to withstand this force.
2. Offshore Gas Drilling Facilities with Compressors
Several offshore gas drilling facilities take advantage of compressors for gas shipments. An instance of this is an offshore oil and gas field that uses compressors to extract gas from the Pacific Ocean.
Given that this facility is in the Ocean, its compressors have several stabilization technologies to give them endurance from the frequent movement of the sea. In the same vein, the compressor adopts a compact layout to make its installation a breeze in offshore plants where installation space is limited.
3. Wet Gas Compressor
Wet gas compressors are also used for drilling gas in offshore facilities. Substances contained in the gas, including polymer components cling to the compressor’s rotor and gas passageways.
As a result, there is a frequent increase in shaft vibration and a decrease in performance. Nonetheless, this vibration can be curbed to provide a stable long-term operation.
The latter is made possible by building compressors with technologies that reduce the adherence of these substances. On the same note, these compressors have structures that make it easy to disassemble the machine and clean them if an adherence occurs.
Compressors have widely been adopted in offshore drilling of oil and gas. It’s worth noting that various types of these machines can be employed. Despite their differences, it all boils down to using a compressor that is easy to install, operate, and maintain frequently.
Likewise, such a compressor must withstand the pressure of the sea. It must withstand other forces as well from the facility environments that may affect its stable operation. When these factors are put into consideration, then such a compressor would offer reliable performance and withstand unfavorable environmental conditions.
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