Floating liquefied natural gas (FLNG) projects could offer a cost-competitive alternative to offshore venting and flaring as operators increasingly take aim at their carbon footprints, industry experts said at the Offshore Technology Conference in Houston this week.

Around 30% of offshore associated gas is flared globally, said Technip Energies SE’s Jean-Philippe Dimbour, director of business development and offshore technology. That presents an opportunity for FLNG to monetize wasted gas, he said. In addition, liquids production could make floating projects even more economic.

“When the gas composition is rich, even more revenues can be generated from production on sales of higher-value byproduct liquids,” he said. Those liquids could include condensate, natural gas liquids (NGL) and liquefied petroleum gas (LPG).

Offshore oil producers have a number of options to dispose of their associated gas, including injection or piping it onshore. However, the options can be costly or difficult to build depending on where the field is located, Dimbour said.

He painted a picture of an alternative, central LNG hub that could be connected to floating production units in deepwater fields or shallow-water platforms. The scheme could benefit new offshore oil developments, “where the associated gas management can become a showstopper against the greenhouse gas emissions,” he said.

“The monetization of associated gas will become an enabler for such oil development.”

Technip Energies has led engineering efforts on several FLNG projects including Royal Dutch Shell plc’s Prelude unit offshore Australia and the Eni SpA-operated Coral South project under construction offshore Mozambique. 

The company recently developed a “Megamodule” concept for FLNG topsides to reduce project costs and schedules. “The key features are based on the design and construction of large, integrated modules with multiple functionalities instead of multiple modules,” Dimbour said. 

The concept could allow operators to produce more LNG with the same amount of space as traditional projects, he added. 

Dimbour presented a comparison between an LNG-only floating project versus a project that would include liquids production using the Megamodule concept. The project including liquids production would require a 6% increase in capital expenditures, but they may be offset by a 20% increase in returns, he said. The carbon footprint could also be reduced, he added.

Costs Rise

Folding in additional production on an FLNG project isn’t a new concept. Shell’s Prelude is already capturing liquids, said KBR Inc.’s Shane Tierling, senior technical leader. However, he told the audience that Prelude is also one of the highest-cost projects in the FLNG space on a per-metric ton basis at $2,000. By comparison, the Tango FLNG project, which is smaller and built on a barge, was built at a cost of $600/metric ton, according to Tierling.

However, Prelude represents the “gold standard” when it comes to FLNG, Tierling added. Prelude uses dual-mix refrigeration technology, and it is able to withstand Category 5 hurricanes, he said.

Other FLNG operators have been able to achieve cost savings by repurposing LNG tankers. Golar LNG Ltd. was the first reuse an LNG tanker with the Hilli FLNG unit off Cameroon, which came online in 2018.

“Call it saved by the bell because you’re taking an end-of-life life carrier and finding new use for it,” Tierling said of the Hillii project.

By reusing an old vessel, Golar was able to shave 39% off steel savings compared to a newbuild, Tierling said. It also resulted in a 33% reduction in greenhouse gas emissions related to facility construction, he added.

Golar is looking to ramp up production from Hilli next year by 200,000 tons with total utilization at 1.4 million tons. The recent agreement with its upstream partners included an option to grow capacity by another 400,000 tons from 2023 to 2026.