Greece Seals 'Historic' Offshore Drilling Deal with ExxonMobil, Energean, and HelleniQ Energy in Ionian Sea

Landmark Agreement Signed in Athens

In a significant development for Greece's energy sector, a landmark agreement was signed on Thursday, November 6, 2025, involving ExxonMobil, Energean, and HelleniQ Energy for offshore natural gas exploration in the Ionian Sea. The deal, formalized during the sixth meeting of the Partnership for Transatlantic Energy Cooperation (P-TEC) in Athens, paves the way for the first exploratory drilling in Greek waters in over four decades.

The agreement focuses on Block 2, a concession located in the northwestern Ionian Sea, approximately 30 kilometers west of Corfu and adjacent to the Italian Exclusive Economic Zone (EEZ). This area is considered the most mature concession in Greece for exploratory drilling and is believed to hold significant untapped gas potential.

Consortium Structure and Exploration Details

Under the terms of the farm-in agreement, ExxonMobil will acquire a 60% stake in the Block 2 concession. The remaining stakes will be held by Energean, whose share will be reduced from 75% to 30%, and HelleniQ Energy (formerly HelleniQ Upstream West Corfu), with its stake decreasing from 25% to 10%. Energean will maintain its role as the operator during the exploration phase. However, should a commercially viable hydrocarbon discovery be made, ExxonMobil is slated to assume operatorship during the development stage.

The primary objective of this venture is to explore for natural gas. Block 2 is described as the largest unexplored offshore structure in the Mediterranean, with potential prospects estimated to contain up to 200 billion cubic meters (bcm) of natural gas. The planned exploratory well, named Asopos-1, will target a carbonate reservoir at a depth of 4,000 meters below the sea surface. Prior to this agreement, 2,244 square kilometers of 3D seismic data were acquired in 2022, confirming the 'Asopos' structure as the most promising target for drilling.

Timeline and Strategic Importance

Exploratory drilling is anticipated to commence in late 2026 or early 2027, contingent on obtaining all necessary governmental approvals and an extension of the exploration phase. This operation will mark a significant milestone, as it will be the first offshore exploratory drilling in Greece since 1981, when the Katakolo hydrocarbon field was discovered.

Greek Prime Minister Kyriakos Mitsotakis hailed the agreement as 'historic,' stating, 'Today we are writing a new chapter in Greece's energy history. This is not just another investment—it is the first exploratory drilling in our country in almost 40 years.' Minister of Environment and Energy Stavros Papastavrou echoed this sentiment, emphasizing the strategic value of the partnership in bringing advanced technology and capabilities to Greece's hydrocarbon sector.

The deal is expected to enhance Greece's energy security, reduce its reliance on imported fuels, and strengthen its position on Europe's energy map. The initial investment for this phase is estimated to be between $50 million and $100 million. The presence of high-ranking U.S. officials, including U.S. Energy Secretary Chris Wright and U.S. Interior Secretary Doug Burgum, at the signing ceremony underscored the broader geopolitical significance of the agreement for transatlantic energy cooperation and European energy independence.