There is no doubt that offshore energy production is becoming popular. Large companies extract oil and natural gas from these subsea wells. In this process, they use FLNG and FPSOs to ensure oil and gas extraction is profitable and efficient. However, these two facilities differ, leading to the FLNG vs FPSO debate.
This debate is not about which ship or floating facility is better. Instead, people generally confuse them for their purpose and use case. Remember, FPSOs are all about the extraction, refining, and storage of oil. On the other hand, the FLNG process liquefies and stores the natural gas. In this article, I will discuss all the differences between FLNG and FPSO.
Overview of FLNG & FPSO
In the previous article, I compared FSO and FPSO. Both of these ships are related to crude oil and its processing. However, the FLNG is unique and has nothing to do with crude oil and its storage.
FLNG stands for “Floating Liquefied Natural Gas unit”. It is a floating facility, or ship, with gas-refining equipment. So, it takes natural gas (raw) from the seabed. After that, it processes, filters, and liquefies it at a very low temperature. This liquefied natural gas is stored in the ship’s storage container or tank.
The liquefied natural gas remains stored on the ship. Once the container is filled, the separate LNG carrier (a small boat) arrives and takes the liquefied gas from the FLNG. This offloading makes the container ready for incoming gas. In this way, the FLNG continues to operate and extract gas from the seabed.
Imagine raw natural gas undergoes purification and filtration to remove water and other impurities. All this happens on the FLNG, indicating how good these ships are! The FPSOs differ in that they are more concerned with oil extraction and processing.
FPSO represents “Floating Production, Storage, and Offloading unit”. These ships extract crude oil (mixed with water) from the seabed. After that, they filter and refine the crude oil to produce fully filtered, pure oil. They store this oil in storage tanks and then offload it to tankers or small ships.
Sometimes crude oil also contains water and gas. But the FPSO uses a separation process to filter and remove these gases. Interestingly, these gases are wanted and are not stored. In simple terms, the FPSO only processes, refines, and stores the oil. Like an FLNG ship, this ship also has equipment on board, but it is for processing crude oil.
What are the Differences Between FLNG and FPSO?
Got the basic idea of both FLNG and FPSO? Let’s discuss the significant differences between these two floating facilities or ships.
1- Working Process
FLNG and FPSO differ in their basic working principles. The FLNG remains above the gas field present at the subsea level. They extract the natural gas from those fields. This extracted natural gas is raw and has many contaminants. FLNG has advanced equipment that filters and purifies the natural gas. After this, the purified natural gas undergoes another liquefaction process.
During liquefaction, natural gas is converted into a liquid. How? This is done by reducing the temperature up to -160 degrees Celsius. Liquefied natural gas (LNG) is then stored in cryogenic tanks and offloaded using specialized LNG carriers. On the other hand, FPSOs extract crude oil from subsea wells. Since it is crude, this oil has many contaminants.
Those include mixed water, gases, and other chemicals. The FPSO has advanced equipment for processing and refining the oil. So, the mixture of water, gases, and other chemicals is filtered out. The pure oil is then stored in the FPSO’s storage tankers. Remember, an FPSO only processes and filters oil, while an FLNG processes natural gas and produces LNG.
2- Function & Purpose
Both FLNG and FPSO help produce energy without requiring the construction of large factories. Remember, setting up a large factory for refining crude oil or natural gas would be very costly. Both FLNG and FPSO are floating ships or units that process natural gas and crude oil, respectively. However, the FLNG only processes natural gas and produces LNG.
On the other hand, FPSO focuses only on oil. As I mentioned earlier, crude oil is transported from subsea wells to the FPSO via hoses and pipelines. Similarly, natural gas is also pumped to FLNG via pipelines. The FPSO filters, refines, stores, and offloads oil. On the other hand, FLNG refines natural gas, liquefies it, and stores it.
3- Energy Demand & Handling
I consider FLNG a more energy-consuming LNG production unit or floating facility. Why? The reason is that FLNG has to pass the natural gas through the liquefaction process. In this process, heavy-duty compressors and refrigeration systems are used to cool the gas. Remember, these compressors can achieve temperatures as low as -160°C.
So, these compressors consume more energy, which makes FLNG more expensive. On the other hand, FPSOs also consume energy during crude oil refining. The small refineries and filtration tools require energy for their operations. However, they don’t consume as much energy as the FLNG unit or ships do. Handling both of these ships is very challenging.
Both of them pose different challenges when it comes to handling. How? The FLNG produces LNG (which is a very cool liquid). On the other hand, FPSOs produce highly flammable oil. In case of mishandling, there will be serious consequences. So operators and crew members on both FLNG and FPSO must be alert.
4- Storage Type & Offloading Method
FPSOs are relatively easier to store, and their offloading is also less challenging. Why? The reason is that the FPSO refines flammable oil, which does not require any environmental conditions. It is kept under normal pressure and temperature.
So, it can be stored in regular storage containers or in FPSO tanks. Additionally, this refined oil can be offloaded to any ship with ease. However, he FLNG processes the natural gas, liquefies it, and cools it to very low temperatures. This LNG (Liquefied Natural Gas) requires very low temperatures during its storage. Due to this, this liquefied gas is stored in the cryogenic tanks.
These tanks have features that allow them to maintain very low temperatures (-160°C). As a result, the LNG remains in good condition. Also, the offloading of this LNG from cryogenic tanks requires specialized LNG carrier ships. These carriers can safely transport LNG to the next facility. They do it safely because of their ability to maintain very low temperatures.
5- Equipment & Safety
As I said earlier, FPSO and FLNG are floating ships or units that carry large equipment. This equipment helps them process crude oil or natural gas, respectively. Right? However, they differ in terms of the key equipment onboard. FPSOs carry equipment such as separators, storage tanks, oil processing and refining units.
On the other hand, FLNG also has equipment for processing and liquefaction of natural gas. Those include refrigeration systems, compressors, cryogenic tanks, and more. This equipment helps process natural gas and convert it into LNG. When it comes to safety, both FLNG and FPSO come with some safety tools.
The FPSO comes with a temperature control system to maintain a moderate temperature. It also has fire extinguishers and some other tools for emergency handling. On the other hand, FLNGs are also safer, thanks to their leak detection and pressure control systems. However, crew and employees must be careful and follow guidelines to ensure safety on both FLNG and FPSO.
6- Deployment & Lifespan
Deploying an FPSO is relatively easier than deploying an FLNG. It is done using multiple marine airbags and other equipment. Additionally, deploying FPSOs takes less time, enabling quicker operations. Once deployed, the FPSO can serve for almost 15 to 20 years. On the other hand, FLNGs are very complex and their deployment is challenging.
The reason is that these FLNGs consist of many heavy-duty pieces of equipment, such as compressors and cryogenic tanks. So, their deployment requires more control and care. In terms of lifespan, an FLNG can last 20 to 25 years. Why? The reason is that these marine ships are made from heavy-duty materials. So, they resist the aquatic conditions and perform better and longer.
7- Cost & Complexity
FPSOs are a cost-effective option compared to FLNGs. Why? The reason is that FPSOs are made with affordable materials. They don’t require high-end storage systems, such as cryogenic tanks. Additionally, they consist of only oil refining units, which are relatively easier to make. Additionally, its operation and handling are also less complex than in FLNG.
Why is FLNG more expensive? That’s mainly because of the materials and equipment onboard. They consist of heavy-duty compressors and refrigeration systems for liquefying natural gas. Additionally, they come with cryogenic tanks, which are very costly. These tanks are designed to maintain a low temperature of around -160°C.
All this equipment and components make the FLNG very costly. The launch, maintenance, and operation of FLNG are complex and challenging. In fact, the staff or crew of FLNGs are highly trained to operate them. In fact, launching an FLNG takes many hours, indicating its complexity.
Заключение
As I said, FLNG vs FPSO is not about which is better. Right? It is all about understanding their differences and getting to know them. Remember, both of these ships or floating units serve different needs and purposes. For example, FLNG extracts natural gas from subsea fields, liquefies it, stores it, and later offloads it.
On the other hand, an FPSO is concerned only with crude oil. If the crude oil contains mixed gases, the FPSO filters the gas, releases it, stores only the refined oil, and then offloads it. For gas extraction, FLNGs are the best option. On the flip side, FPSOs can get the job done when it comes to subsea crude oil.