The potential for a natural gas prospect at the Leviathan site was identified by geologist Eitan Aizenberg, co-founder of the small Israeli
oil exploration company Ratio. To assist with exploring the prospect Ratio enlisted the cooperation of another Israeli firm,
Delek, who then brought in Texas-based
Noble Energy to the venture – with whom it had previously developed the small Mari-B offshore gas field in southern Israel under the Yam Tethys partnership. The initial exploration well, Leviathan 1, was drilled to a depth of and the discovery was announced on December 30, 2010. The cost of drilling the exploration well was $92.5 million. The well was drilled by the
Homer Ferrington rig. The second stage of drilling of the Leviathan 1 well was intended to reach a depth of , which would include an additional natural gas reserve and potentially 600 million barrels of oil. While the gas discovery at -5170m was made in the
Tamar sands layer which was already known to contain gas, the additional oil and gas potential exists in layers that have not been explored in the Levant basin. Noble has twice failed to reach the deeper layers due to technical challenges with drilling to the extreme depths involved. However, during drilling towards the intended target some gas was detected and as of 2012 Noble still had plans to explore those layers. The Leviathan gas field was the second largest gas field in the
Mediterranean Sea after the August 2015 discovery of the
Zohr field off the coast of Egypt, only 6 km from Cyprus's Block 11.
Chevron Corporation, which acquired Noble Energy in October 2020, operates Leviathan with a 39.66% working interest;
Delek holds 22.67%; Avner Oil Exploration holds 22.67%; and Ratio Oil Exploration holds the remaining 15%. It was announced on 21 May 2014 that Woodside Energy pulled out of an agreement to take a stake worth up to $2.7 billion in Israel's flagship Leviathan gas project, as the group developing the field shifted focus to regional markets. In the summer of 2014, Netherland, Sewell & Associates (NSAI) made an upward revision on the amount of gas reserves, giving a 2P value of 621 BCM. The expected year of production was stated to be 2017. In April, 2015, the Israel Ministry of Energy reported that it was working with NSAI and the Leviathan partners to understand the discrepancy between the NSAI revised estimate and the estimate provided by other analyses provided to the ministry, indicated a best estimate of only 16.5 tcf (470 BCM). On 19 October 2015, Russian President
Vladimir Putin and Israeli Prime Minister
Benjamin Netanyahu agreed to allow major concessions for
Gazprom to develop the Leviathan reserves. On 19 February 2018, The partners in Israel's Tamar and Leviathan natural gas fields signed $15 billion in deals to export natural gas to Egypt over 10 years. One accord calls for the sale of 3.5 BCM of natural gas annually from the Leviathan field, for a total of 32 BCM, estimating the sale from the Leviathan field to reach $7.5 billion. Regarding the deal, the Egyptian president,
Abdel Fatah al-Sissi, declared about the project : "Has a lot of advantages for us (Egyptians). And I want people to be reassured".
Yossi Abu, chief executive of
Delek Drilling, said: "I think that the main thing is that Egypt is becoming the real gas hub of the region". In September 2020, the owners of the field agreed to sell $190 million worth of natural gas to a power plant in
Ramat Hovav. In late February 2023, partners involved in Leviathan announced spending of $51 million to prepare a new floating LNG floating terminal, and an additional $45 million in expanding production. The floating LNG terminal, expected to come online in the mid-to-late 2020s, is expected to expand capacity to 6.5 bcm. According to CEO of Ratio Energies, Yigal Landau, "The development plan will enable a significant increase in Leviathan's production to 21 bcm (billion cubic meters) a year." On August 7, 2025, Leviathan signed the largest export agreement in Israel's history worth approximately US$35 billion to supply gas to Egypt.
Inovo BV and Ratio Oil Inovo BV, the
Dutch corporation owned by
Kamil Ekim Alptekin, claims to be the sole Turkish representative in Ratio Oil Exploration. Ratio has denied that it has any affiliation with Alptekin or Inovo BV, though
BuzzFeed News has produced evidence documenting a relationship dating back to at least early 2016. ==Technical description==