Understanding Energy: Examining how production ships use associated gas
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FLOATING production, storage and offloading (FPSO) vessels are used to safely produce oil and gas in some of the world’s deepest offshore production areas. FPSOs will be critical to developing Guyana’s oil and gas resources, all of which are located in deepwater. Already, Guyana has one FPSO in operation, the Liza Destiny, with two more under construction. Cutting-edge technologies have been developed for FPSOs to maximise production, and ultimately revenues, while limiting environment impacts.

As with most oil deposits, oil in Guyana is found alongside “associated gas”—natural gas that has been trapped underground and is produced as a biproduct of oil production. FPSOs can make use of this gas in a variety of ways, and disposal of excess amounts of gas is a critical decision for oil producers.

After a small amount of gas is used to provide clean and efficient power for the FPSO vessel, the operating company then reinjects the remaining gas into the ground, pipes it to shore or flares it off. Most commonly, FPSOs reinject the produced natural gas into the reservoir. This is often the most profitable option for small volumes of associated gas since it can help maintain reservoir pressure and maximise oil production. Reinjection is safe and avoids environmental challenges. This is how most of the associated gas produced by the Liza Destiny FPSO will ultimately be used.

Gas that can’t be reinjected or piped away must be dealt with for the safety of the crew. When Exxon was unable to reinject gas due to a faulty compressor, the only safe option was to flare the gas.

That led to several months during which the FPSO in Guyana flared larger amounts of gas. Though still small by global standards, it could not be reduced until the gas compressor issue was fixed. Now, the “pilot flare,” which accounts for less than 0.5 per cent of the natural gas produced on the FPSO, is all that is left.

Pilot flares are necessary safety measures on nearly all production platforms dealing with associated gas. It’s useful to think of the pilot flare as similar to the pilot light on an oven. When you turn on your oven, it ignites the gas automatically without needing to open the oven and stick a match inside. That’s because the oven has a small pilot flame that is always on at the back of the oven. This small flame continuously burns a tiny amount of gas to ensure that the oven is ready to use. The pilot flare on an FPSO functions in the same way but is more critical for safety.

Flaring must be available at a moment’s notice on an FPSO, which is why platforms flare a miniscule amount of gas on a continuous basis to keep the flaring option open in case of an emergency to avoid putting workers at risk. Flaring is normally the safest way to deal with over-pressure situations and other emergencies on board.

While flaring receives the most attention in the media, companies do not like to flare more than is absolutely necessary if they can safely avoid it because there are better, more profitable alternatives. FPSOs like the Liza Destiny are therefore designed to avoid routine flaring.

It’s also useful to look at how flaring is handled in a country with a reputation for strong environmental regulations like Canada. Platforms off the coast of Canada have permits to flare more natural gas than the Liza Destiny FPSO in Guyana because they are typically older designs that were not able to minimise environmental impacts to the same extent.

Longer term, Guyana will be looking to another option for some of its associated gas that Canada has long exploited: piping gas to shore to generate reliable and cheap electricity. While this option can be economically beneficial to the home country, extra infrastructure and investments are needed to ensure that a safe pipeline and power plant are available to transform the gas. Guyana is looking to take advantage of this option within a few years as soon as the infrastructure can be built.

While flaring continues to dominate discussions, it’s critical to realise that a small level of pilot flaring is both normal and an important safety feature for oil production. Guyana remains on a path to avoid larger and more damaging practices like routine flaring that are common in some jurisdictions around the world—a step that should help cement its place as a forward-thinking and environmentally responsible oil producer for the 21st century.

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