A year ago, the ONE GUYANA floating production, storage and offloading (FPSO) vessel achieved first oil, bringing the Yellowtail development into production and adding another major source of crude to Guyana’s offshore output.
The development quickly moved from an initial 75,000 barrels per day (b/d) in its first month to its design capacity of 250,000 b/d within three months. That rapid ramp-up helped push Guyana’s total oil production to roughly 900,000 b/d by November 2025.
But reaching that production rate was the result of a process that began six years earlier.
From discovery to development
ExxonMobil announced the Yellowtail-1 discovery on April 18, 2019, its 13th discovery in the Stabroek Block. The well encountered about 292 feet of high-quality oil-bearing sandstone in approximately 6,046 feet of water.
Appraisal drilling followed later that year, with Yellowtail-2 encountering two additional hydrocarbon-bearing reservoirs. By 2020, ExxonMobil and its Stabroek Block partners were assessing Yellowtail as the block’s fourth development, later incorporating the Redtail discovery announced that September about 2.5 kilometers northwest of Yellowtail.
The project then moved through the regulatory and investment process. The Environmental Protection Agency granted environmental authorization in March 2022 based on the environmental impact assessment submitted by Exxon, while the Ministry of Natural Resources approved the field development plan and granted the production license in April 2022. ExxonMobil and its co-venturers made final investment decisions in April, approving the roughly US$10 billion development.
Building ONE GUYANA
SBM Offshore received the contract to construct, install, lease and operate ONE GUYANA, while Saipem was awarded the contract for the subsea umbilicals, risers and flowlines connecting the wells to the FPSO.
Construction took place in Singapore, where the FPSO moved from hull work and topside integration to final commissioning. The hull entered drydock in March 2023 for mooring and riser work before moving to the Seatrium yard for module integration. By early 2025, construction and commissioning were complete, and ONE GUYANA departed Singapore in April for Guyana after a voyage of more than 11,000 nautical miles.
Upon arrival, the vessel became Guyana’s fourth FPSO processing up to 450 million cubic feet of gas per day, injecting 300,000 b/d of water and storing about 2 million barrels of crude.
Yellowtail adds more than another FPSO
Yellowtail’s production ramp-up was rapid, but its importance extends beyond bringing another FPSO into operation. The development is designed to recover about 925 million barrels from the Yellowtail and Redtail fields through six drill centers and up to 67 development wells.
OilNOW’s tracking shows that Guyana produced more than 109 million barrels of crude during the first four months of 2026, averaging approximately 911,000 b/d. Yellowtail accounted for about 262,000 b/d of that output.
Yet, further production growth is expected before the end of the year. ExxonMobil is expected to undertake production optimization work at Yellowtail that could raise output to approximately 290,000 b/d, subject to government approval.
