(Kaieteur News) – Guyana’s oil reserves have dropped below the 11 billion barrel estimate, ExxonMobil Guyana Limited (EMGL) reported this week.
The company in a productiodn report highlighted the unprecedented development in Guyana, moving from a “world-class” discovery just over a decade ago, to first oil only five years later which has evolved into one of the fastest deepwater development timelines in the industry.
Exxon is currently producing oil at four Floating Production Storage and Offloading vessels (FPSOs) in the Stabroek Block. Since 2019, Exxon has already produced one billion barrels of oil. To this end, thej company indicated that the country’s oil reserves have decreased to less than 11 billion barrels.
The company said, “With an estimated resource base of just under 11 billion oil-equivalent barrels and plans for up to eight offshore developments by 2030, the Stabroek Block is helping to meet demands across the Americas, Europe and Asia, contributing to global energy security and market stability.”
The issue of the oil reserves here has been a matter of public discussion. Guyana’s oil reserves have been stagnated around 11 billion barrels since 2022, despite major new discoveries and according to president of ExxonMobil Guyana Limited (EMGL), Alistair Routledge, this is so because “proved reserves” only increase when a project is financed.
In its 2025 Annual Report, Exxon reported that, “Additions to prove reserves include 2.1 GOEB (billion oil-equivalent barrels) from extensions and discoveries primary in the United States and Guyana and 0.1 GOEB related to United States acquisitions.”
Back in March, Routledge was asked by Kaieteur News how much of the 2.1-billion increase in reserves were from Guyana. While he did not offer a direct response, Routledge sought to clarify the terms “resources” and “reserves.” He said, “So this is probably the space where we get into the difference between resource versus reserves. So, every time we fund a project, we move resource to an approved category. So, resource is estimated, as ultimately recoverable, when we drill a well and we penetrate a reservoir, and we say, we think there’s this amount of resource that we could recover from that reservoir. But it is founded on a number of assumptions. It doesn’t move to prove until you fund a project that can develop that resource.”
Meanwhile, when asked whether there was an increase in proved reserves in Guyana, as highlighted in the report, Routledge said that Exxon added to its proved reserves after the Hammerhead project was approved. Be that as it may, the country’s estimated ultimate recoverable reserve still stands around 11 billion barrels according to him.
He said, “Well, in the reserves, when we approved the Hammerhead project, we added, I mean, I think our share of, you know, roughly 40 per cent of the resource that we said was proved, as we develop the Hammerhead project would then be added into that proved category for us.”
Consequently, the country manager noted, “On the estimated ultimate recovery, it’s still, you know, close to 11, is somewhere in that vicinity. But there’s a lot of, as we continue to do, appraisal work, and we produce reservoirs and we gather data. There’s, you know, puts and takes as we go through that assessment.”
In an invited comment, former Executive Director of the Environmental Protection Agency (EPA), Dr. Vincent Adams had said that the company was once again attempting to confuse the country using technical terms. The petroleum engineer argued, “Investors have nothing to do with reserves. That’s what this guy is good at-bringing up things to confuse people.”
He reminded that in the early discovery days, Exxon offered prompt reserve updates and did not wait for an investment decision. On resources versus reserves, Dr. Adams explained, “Oil resources is (determined based on) a technical calculation…the reserves add the economic component to it. It says you may tell me there is so much oil and I can technically recover so much of it, however because of the price of oil…right now because of the price of oil this reserve should automatically go up because it varies with oil prices.”
Meanwhile, ExxonMobil has already received regulatory approvals from the Government of Guyana (GoG) for seven projects. With four projects already producing, the company is progressing development activities to commence production at the Uaru, Whiptail and Hammerhead projects before 2030. In fact, Exxon is looking to secure at least one other project before the end of the decade.
It said, “Looking ahead, Uaru is expected to start up by the end of 2026. Construction is also underway on the sixth and seventh approved projects, Whiptail and Hammerhead, with Whiptail targeted for startup in 2027 and Hammerhead expected to begin production in 2029.”
The reserve update from Exxon, highlighting the decrease in oil reserves come amid heavy spending by ExxonMobil to explore and appraise wells in the prolific Stabroek Block. In 2025, the company reported an exploration expense of approximately US$128M compared with US$109M in 2024. Despite the heavy expenditure on oil exploration, the company has not announced a new discovery since March 2024.
The company has not published its expenditure for appraisal activities in the block. Appraisal is conducted after hydrocarbons are discovered. This is a critical phase that allows companies to better under the quality and quantity of resources within the reservoir. This rigorous process involves drilling of wells and testing of fluid properties. The process reduces uncertainty in resource volumes, helping companies to make informed investment decisions.
Notably, although Exxon completed appraising the discoveries, it offered no update to the public on these results. In 2025, Exxon appraised two major oil discoveries in the Stabroek Block, Lukanani and Ranger.
This was revealed by CNOOC, a 25% shareholder in the block. The company in its 2025 Annual Report highlighted “fruitful achievements in exploration” with new discoveries and appraisal activities conducted in China and overseas. As part of its overseas basin, the Chinese owned oil company reported, “The Lukanani oilfield and Ranger oilfield were successfully appraised in Guyana.”
Although the company completed appraising the discoveries, the country’s reserves remain stagnant and have in fact declined since the initial estimate of approximately 11B barrels. The Ranger One discovery was made by ExxonMobil since January 2018. At the time, the oil giant described the discovery- its sixth- as the company’s largest on record in Guyana. It explained that it began drilling the Ranger-1 well on November 5, 2017 and encountered approximately 230 feet (70 meters) of high-quality, oil-bearing carbonate reservoir. The well was safely drilled to 21,161 feet (6,450 meters) depth in 8,973 feet (2,735 meters) of water.
Meanwhile, Exxon announced the Lukanani- 1 discovery in April 2022. The Lukanani-1 well encountered 115 feet (35 meters) of hydrocarbon-bearing sandstone and was drilled in a water depth of 4,068 feet (1,240 meters).
To date, ExxonMobil has made 46 discoveries in the Stabroek Block, since the first discovery in 2015. Notably, oil-producing states around the world, including neighbouring Suriname have blocked oil companies from recovering costs spent to hunt for oil. Guyana on the other hand not only allows Exxon to recover costs for wells successfully drilled, but even dry holes encountered in the process.
The sweetheart deal signed by ExxonMobil in 2016 allows the company to recover costs related to its exploration activities, even if those efforts do not produce oil.
Leave a Reply