More than six years after Guyana began producing oil offshore, output from the Stabroek Block has reached a level where roughly 900,000 barrels of crude can be produced in a single day.
But getting that oil from the producing fields to buyers depends on a cycle that runs continuously offshore: oil is produced, stored temporarily on floating production, storage and offloading (FPSO) vessels, and transferred to export tankers when they arrive.
The key is timing. Production does not stop when a tanker is not at the FPSO. Instead, crude continues flowing into the vessel’s cargo tanks until an export tanker arrives and takes on a cargo. The vessel’s storage capacity allows those two operations to run at different times without interrupting production.
Production determines how quickly cargo builds
The amount of oil an FPSO produces determines how quickly its cargo tanks fill, while the vessel’s storage capacity determines how much crude can be held before the next tanker arrives.
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Guyana’s four producing FPSOs have different storage capacities. Liza Destiny can hold 1.6 million barrels, while Liza Unity, Prosperity and ONE GUYANA can each store about 2 million barrels.
At April 2026 production rates, the time needed to produce a typical million-barrel cargo varied significantly across the four developments. Liza 1 averaged 122,000 barrels per day (b/d), equivalent to about one million barrels every eight days. Liza 2 averaged 259,000 b/d, while Payara and Yellowtail averaged 261,000 b/d and 262,000 b/d, respectively. At those rates, each of the three newer developments produced roughly one million barrels every four days.
The tanker schedule provides the outlet
The frequency of tanker arrivals varies by development and reflects differences in production rates. Project documents indicate that Liza Destiny was designed to offload up to one million barrels approximately every five to 10 days, while the higher-producing Liza Unity and Prosperity FPSOs were designed around million-barrel offloads approximately every four to six days.
This schedule works with the rate at which crude is accumulating. A tanker arriving after several days of production can take on a large cargo, removing crude from the FPSO and creating additional space in its cargo tanks for continued production.
The timing is not fixed. Production rates, weather and ocean conditions can affect when a tanker approaches and how frequently cargoes are transferred.
What happens when the tanker arrives
An export tanker can arrive one day to several hours before its scheduled loading time, depending on weather and ocean conditions. It can wait several kilometers from the FPSO until conditions are suitable for the approach.
A mooring master then boards the tanker about 2 kilometers from the FPSO to guide it into position.
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The FPSOs use tandem offloading, with the tanker positioned behind the FPSO and connected through a hawser and floating offloading hose.
From storage tank to export tanker
Once connected, crude accumulated in the FPSO’s cargo tanks is transferred to the tanker.
Exxon’s EIA for the Stabroek Block developments identifies a typical export cargo of about 1 million barrels of crude. Loading can take about 24 hours for very large crude carriers and Suezmax vessels.
The complete operation, from the tanker’s approach and connection through loading, disconnection and departure, takes about 32 to 36 hours.
Once the tanker leaves, production continues, and the cycle starts again.
