Membrane technology in nitrogen generation
Oil production in the Middle East is big business. Last year, the Middle East produced around 31.6 million barrels of oil per day1! Nevertheless, the oil industry is confronted with numerous challenges throughout the different stages of the oil production process.
In the drilling stage the crude oil extracted from oil wells contains hydrogen sulfide (H2S), a highly corrosive and flammable gas. So the H2S needs to be removed before the crude oil can be transported to petroleum refineries or stored. For this process, oil companies rely on a nitrogen stripping system. In most cases liquid nitrogen is the go-to solution, but offshore drilling platforms throw a spanner in the works. Liquid nitrogen and maritime transport is not really the perfect combo. The answer? Membrane technology.
Oil production, how does it work?
Extraction of crude oil by drilling oil wells.
At this stage, the crude oil doesn’t yet comply with international standards (or Reid Vapor Pressure), because it is mixed with water, salts, gases and hydrogen sulfide.
Crude oil stripping
The H2S has to be removed from the crude oil to match the conditions specified for Reid Vapor Pressure. Since H2S is highly corrosive to storage tanks and pipelines, this stripping process has to be completed before exporting the crude oil to petroleum refineries. Also, hydrogen sulfide is a highly flammable and explosive gas.
The oil industry uses a nitrogen stripping system to remove the H2S. Why nitrogen? Nitrogen is an inert gas that prevents the flammable gases from igniting and thus eliminates the risk of explosion.
Once the H2S has been separated from the crude oil, it can be converted to a waste product that can safely be disposed of or it can be used in the manufacturing of sulphur.
After the stripping process, the crude oil can be safely transported to export pipelines or petroleum refineries.
Liquid nitrogen versus membrane technology
In general, liquid nitrogen (LIN) is often deployed to fuel the stripping system. But LIN poses many problems when it comes to offshore oil fields.
The biggest challenge is the transportation of liquid nitrogen. In order to reach the offshore processing plants, liquid nitrogen has to be transported from the shore to the offshore plant via ISO tanks. Unpredictable weather conditions make it hard to rely on sea transport. Due to these circumstances, one can never be completely sure if and when the nitrogen will reach the offshore plant.
In addition, liquid nitrogen is subject to evaporation losses. Nitrogen can only be kept in its liquid form at an extremely low temperature. However, when liquid nitrogen is transported from the shore to the offshore plant, nitrogen will start to evaporate due to an increase in temperature.
Membrane technology could offer a solution for this transportation hassle. How does it work? Compressed air is pushed through a set of polymer fibers or the membrane. As the compressed air moves through the membrane, the nitrogen molecules are separated from the other molecules. Compare it to a colander: the nitrogen molecules are too big to pass through the small holes.
Atlas Copco Rental designs new nitrogen solution
Excellent service support is an absolute must in the oil production industry. The oil production process – from drilling the well to stripping the crude oil and export – runs 24/7. A constant supply of nitrogen is therefore critical. Atlas Copco Rental designed a nitrogen generation package using the membrane technology, with a back-up plan functioning at all times.
In one specific customer case, the package comprised 2 nitrogen units working day and night; 9 high-pressure air compressors; 4 operators working in two shifts; one senior service engineer and accessories like manifolds and hoses. The first nitrogen spread is a 100% back-up of the second spread that functions at night. More specifically, the first nitrogen spread operates during the day, while the second nitrogen spread serves as its back-up. This eliminates the need to transport liquid nitrogen from the shore with all the associated risks.
Rudolf Menezes, Area Rental Supervisor at Atlas Copco Services Middle East explains: “This back-to-back spread ensures the continuous availability of nitrogen and brings down the risk of breakdown to 0%. And it is also completely in line with the main goal at Atlas Copco Rental: bringing maximum uptime to our clients”.