Troll Phase 3 Stage 2 project starts gas production ahead of schedule and under budget in the North Sea

On August 22, the Troll Phase 3 Stage 2 subsea project came on stream in the North Sea—ahead of schedule and under budget. Equinor operates it alongside partners Petoro, Shell, TotalEnergies, and ConocoPhillips. The project accelerates production of 1.94 trillion standard cubic feet of gas from the Troll West reservoir—roughly equivalent to nearly two years of France’s total gas demand.

New Troll subsea project begins production

Production from Troll Phase 3 Stage 2 officially kicked off on August 22, marking a significant milestone for Norway’s largest gas-producing field. The subsea project taps into the Troll West reservoir, unlocking 1.94 trillion standard cubic feet of additional gas—nearly two years’ worth of France’s entire gas demand. That’s a meaningful addition to European energy supply.

Equinor operates the project with partners Petoro, Shell, TotalEnergies, and ConocoPhillips. Petoro holds the largest stake at 55.93%, followed by Equinor at 30.55%, Shell at 8.19%, TotalEnergies at 3.69%, and ConocoPhillips at 1.64%. Investment was approved just over two years before the project came on stream.

She also highlighted the operation’s low-emissions profile: both Troll A and the Kollsnes plant run on electricity from shore rather than on-site gas turbines.

Project delivered ahead of schedule and below cost estimate

The original plan called for a start-up toward the end of 2025. Coming on stream in August means it arrived several months early—a notable outcome in an industry where large offshore projects routinely run over time and over budget.

Costs came in several hundred million Norwegian kroner below the original estimate of NOK 12.3 billion ($1.17 billion). Much of that saving came from the eight-well drilling campaign, which wrapped up in five and a half months, 25 percent faster than planned.

“We start production with excellent HSE results, ahead of schedule and several hundred million Norwegian kroner below the cost estimate,” said Trond Bokn, senior vice president for project development at Equinor. He credited efficient marine operations and a highly efficient drilling campaign as the main drivers of that performance.

Infrastructure and Norwegian supply chain involvement

The Deepsea Aberdeen rig, operated by Odfjell, handled the drilling, with services from SLB and Baker Hughes. Aker Solutions built templates and manifolds at its Egersund facility for main supplier OneSubsea. Ocean Installer took care of the subsea installation work on the field.

A 17.4-mile, 36-inch pipeline connects the new infrastructure to existing facilities. The Pioneering Spirit—the world’s largest pipelay vessel—installed that pipeline, with line pipe stored on Stord. Randaberg Industries supplied spools and pipeline end terminations, while OneSubsea’s Moss facility provided the umbilical. Aker Solutions also carried out modifications on the Troll A platform itself.

The project reused design and standardized solutions from the Troll Phase 3 development, which came on stream in 2021. That approach cut both execution time and costs, and Equinor now sees it as a model for future subsea developments.

Effect on European gas supply and Norwegian revenues

Troll is central to European gas supply—gas from the field alone meets around 10 percent of Europe’s total demand. The Troll A platform and the Kollsnes processing plant together form the backbone of Norwegian gas exports to the continent.

“This project accelerates production from the reservoir, helping maintain today’s high level of gas exports from Troll and Kollsnes for as long as possible,” said Lill Harriet Brusdal, vice president for Troll and Kvitebjørn at Equinor. She also highlighted the operation’s low-emissions profile: both Troll A and the Kollsnes plant run on electricity from shore rather than on-site gas turbines. More than 90 percent of profits from the Troll field flow to the Norwegian government through taxes and Petoro’s direct ownership stake.

Background: Troll field at 30 years and future development plans

Troll turns 30 in 2025 as Norway’s largest gas-producing field, a milestone that coincides with one of its most productive periods. The field holds around 40 percent of all gas reserves on the Norwegian continental shelf, and its annual energy production equals roughly three times Norway’s total annual hydropower output.

Development has unfolded across three phases. Phase 1 addressed the gas in Troll East, producing Troll A and the Kollsnes plant. Phase 2 focused on oil in Troll West, resulting in the Troll B and C platforms. Phase 3 targets the gas cap above the oil column in Troll West, with gas routed to Troll A and onward through existing infrastructure.

The partners aren’t stopping there. Earlier in 2025, they approved the next development step: the TWIN project, short for Troll West Increased Gas Recovery North. That decision signals continued confidence in the field’s long-term resource base and in the standardized, phased approach that made Troll Phase 3 Stage 2 work.

1.94 trillion standard cubic feet of gas

Troll Phase 3 Stage 2 began production on August 22—several months ahead of its planned late-2025 start and several hundred million NOK below its $1.17 billion (12.3 billion NOK) cost estimate. The project unlocks 1.94 trillion standard cubic feet of gas from the Troll West reservoir, supporting European supply and Norwegian state revenues. An eight-well drilling campaign finished 25 percent faster than scheduled, with the Norwegian supply chain playing a broad role across drilling, installation, and fabrication. With the TWIN project already approved, development of the Troll field—now in its fourth decade—keeps moving forward.

Kelly Lippke

Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.