Greece gearing up for offshore exploration revival as ExxonMobil joins Ionian Sea block

November 6, 2025, by Dragana Nikše

U.S.-headquartered energy giant ExxonMobil, UK-based oil and gas player Energean, and Greece’s Helleniq Energy Upstream have signed a farm-in agreement for ExxonMobil’s participation in a concession in the northwestern Ionian Sea.

Farm-in agreement signing; Source: Energean via LinkedIn

Under the deal, ExxonMobil will acquire 60% of the Block 2 concession, with Energean’s stake reducing from 75% to 30%, and Helleniq Energy’s from 25% to 10%. Energean will stay on as operator of the concession during the exploration stage. If a hydrocarbon discovery is made, ExxonMobil will assume operatorship during the development stage.

Dr. John Ardill, Vice President of Global Exploration, at ExxonMobil, stated: “We look forward to working with the Greek government and our partners to evaluate the exploration potential of Block 2 in a safe, effective and environmentally responsible manner. This significant exploration agreement paves the way for potential future exploratory drilling investments in the 2027 timeframe.”

Block 2 is described as the most mature concession in Greece in terms of readiness for exploratory drilling. It is located in the northwestern Ionian Sea, next to the Italian Exclusive Economic Zone (EEZ). Energean claims that this is the largest unexplored offshore structure in the Mediterranean, with potential prospects to substantially enhance the energy security of Greece and the broader region.

In 2022, 2,244 square kilometers of 3D seismic data were acquired for the area. Their processing and interpretation confirmed that the Asopos structure is the most mature target for exploratory drilling. Last October, ExxonMobil and Helleniq also completed the first phase of seismic research in the plot designated as Southwest of Crete.

Mathios Rigas, CEO of Energean, sees the agreement as an important step toward harnessing Greece’s natural resources and strengthening the country’s role on Europe’s energy map. According to him, this is an opportunity to prove that Greece can achieve energy independence, utilizing domestic energy resources responsibly.

“The success of this initiative could become a turning point for Greece’s energy security and for the future of the next generations,” said Rigas.

Provided all required approvals and permits are obtained, exploratory drilling at Block 2 is expected to take place in late 2026 or early 2027. Another condition for this to happen is the extension of the exploration phase to ensure sufficient time for project completion within the planned schedule.

According to Energean, this drilling operation will be the first exploratory offshore drilling in Greece since 1981, when the well that led to the discovery of the Katakolo hydrocarbon field was completed. Furthermore, the company added that the only offshore wells drilled in Greece over the past two decades have been its wells in Prinos.