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In-depth | ENVIRONMENT

Flared gas recovery becomes commercial reality

Te environmental case for flare reduction has always been compelling. Now, with technology available that converts stranded flare gas into a range of desirable products for energy consumers, the commercial case has become equally convincing.

T

he World Bank has identified the recovery of the gas currently flared or vented by the oil industry as

one of the key ways to meet the world’s increasing demand for fossil fuel energy. Today, at least 150 billion m3 of natural gas is reckoned to be flared or vented annually. Not only does this equate to around 25% of the natural gas consumed by Europe alone, it adds about 400 million tonnes of CO2

to

worldwide emissions per year. Increasing environmental awareness

has proved a driver for regulation in the shipping and offshore industries in recent years. However, short of a global ‘polluter pays’ policy, it is the monetisation of ‘green’ initiatives that will first attract investors. A small band of engineering firms in

the gas business segment possess proven technology that can contribute to a significant reduction in flaring worldwide. However, only now has a supplier

emerged that can offer the market not only the prospect of reduced flaring, but also a full range of viable options to convert recovered gas into marketable liquefied natural gas (LNG), liquefied petroleum gas (LPG), or electric power. After its 2009 acquisition of the

Technology and Products business division related to flare gas ignition and recovery previously offered by Norwegian oil service company Aibel, fluid handling specialist Hamworthy establishes a unique position in the market.

Zero flaring

Te Zero Flaring concept became reality in the North Sea, following an initiative taken by Statoil (formerly known as Statoil Hydro) a decade ago, encouraged by Norwegian tax concessions for technologies shown to cut CO2

emissions. Using a combination of blower, ejector

18

Anti-flaring shown on a rig (Credit: Hamworthy plc).

and compression technology, ignition and an inert gas system to prevent air ingress in the flare line, the Technology and Products division developed an approach to flare gas recovery yielding a product that can be used either as a fuel source for plant onboard an offshore installation, reinjected into the well for pressure support, or directly mixed with the export gas in the pipeline. Te process sees flare gas initially fed through a gas treatment plant, where compressors and separators work in combination to separate out the heavy fractions. Kjell-Ove Lie, Hamworthy business unit

director – Gas Recovery, said that in the Norwegian North Sea case, gas that would have otherwise been flared was of the same quality as that distributed by the pipelines. Tis had provided an ideal launching pad for a technology that could be enhanced and adapted for more challenging circumstances, where flare gas exhibited different characteristics. He said that the operation

had shown that 100% of flared gas could be recovered under normal conditions. In practice, of course, some gas flaring

is inevitable for safety reasons, while the amount an investor is prepared to commit to a system’s complexity will determine how much gas is recovered. However, Lie added that shutting off unnecessary flaring had demonstrably recouped 60-70% of gas that would have otherwise been lost, while CO2 emissions generated by offshore installations in the North Sea had thus been cut by the same amount. He pointed out that earlier

environmentally driven projects, like the prohibition on releasing volatile organic compounds in the North Sea, had gone on to become self-supporting economic propositions. BP subsequently took up the Technology

and Products offering in the UK segment of the North Sea, although it is fair to say that the oil major’s scaling down of operations

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