ExxonMobil has made what its global exploration chief described as a “big discovery” in the Stabroek Block offshore Guyana, but the company has not publicly disclosed the details of the find.
The discovery was made between late August and early September, according to comments by ExxonMobil Vice President and Head of Global Exploration John Ardill.
Ardill discussed the find during the Energy Intelligence Forum in London on October 5 and 6, according to Energy Intelligence correspondent Marc Roussot, who reported that the discovery could potentially lead to a 10th development in the Stabroek Block.
ExxonMobil is conducting appraisal work and production testing to better understand the resource, with an application to the Guyana government for a development permit expected next year, according to the report.
However, the company has not disclosed a resource estimate or confirmed whether the discovery is commercially viable.
In comments shared publicly, Ardill said ExxonMobil was continuing exploration and appraisal activities around its Ranger discovery, made in 2018, in the central part of the Stabroek Block.
The company is drilling appraisal wells to collect additional subsurface data and assess whether the resources can support commercial development.
Ardill also identified Rockhead, a well drilled earlier in 2026, as one of the nearby exploration prospects being evaluated for a possible tie-back to a future Ranger development.
A tie-back allows a new discovery to be connected to existing or planned production infrastructure, potentially avoiding the cost of developing an entirely separate offshore production facility.
It remains unclear whether the recently reported “big discovery” is associated with Rockhead, another nearby prospect or a separate well.
The find adds to exploration activity in the Stabroek Block, where ExxonMobil operates alongside Chevron and CNOOC, holding interests of 45%, 30% and 25%, respectively.
The block has been the centre of Guyana’s offshore oil expansion since the Liza discovery in 2015. Production began in December 2019 and has since grown to more than 900,000 barrels per day.
ExxonMobil said that the Stabroek Block had an estimated resource base of just under 11 billion barrels of oil equivalent. The company has not said whether the newly reported discovery would materially change that estimate.
A new discovery does not automatically translate into additional production or government revenue. Further appraisal is needed to determine the size and quality of the resource, while a commercial development would require additional technical and regulatory steps.
The company has previously identified further exploration opportunities using artificial intelligence and advanced subsurface analysis. In July, ExxonMobil Chairman and Chief Executive Officer Darren Woods told shareholders that the company saw potential for additional discoveries in Guyana, while stressing that more work was needed to confirm those opportunities.
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