The Leviathan, a gas field offshore Israel, is undisputedly one of the largest gas discoveries in the Mediterranean Sea, and until the recent Zohr discovery in Egypt, it was THE largest discovery in the area.

Named after a Biblical sea monster, the Leviathan field was discovered in 2010, and operated by the U.S. oil and gas company Noble Energy, in partnership with Israeli Delek Group.

The field development plan, which entails a fixed platform off the coast of Israel, was given by the Israeli energy ministry’s approval last week, a step forward to first gas expected to be produced late in 2019, although no official start-up date has been given.

However, within the ministry’s approval, there was something else that raised eyebrows around the industry – the Leviathan size estimate.

In its statement last Thursday, the Ministry of National Infrastructures, Energy and Water Resources revealed around 20% lower than previous thought Leviathan gas reserves estimate.

The ministry said Leviathan held 17.6 trillion cubic feet of gas (or around 500 billion cubic meters), down from Noble Energy’s estimate of around 22 TCF (or around 620 billion cubic meters).

Furthermore, the energy ministry said that the gas amount estimate could be changed, as it was awaiting additional data, including the drilling results from the “Leviathan 5” well.

Responding to these reports however, on Sunday, June 5, in a filing to Tel Aviv stock exchange, the Israeli partners developing the field said the field reserves estimates remained unchanged.

Offshore Energy Today has reached out to Noble Energy, the operator of the project, seeking clarification and more info.

In an e-mail to Offshore Energy Today, a Noble Energy spokesperson said: “Noble Energy engages world-class engineering firms to perform independent assessments of resources and reserves on our assets. We are confident in these reserve estimates, which are developed in accordance with the Society of Petroleum Engineering and U.S. SEC reporting standards.”

According to Noble Energy, Netherland, Sewell & Associates estimates Leviathan’s recoverable resources at 21.9 Tcf.

“We have drilled four wells and performed a flow test on the reservoir, and we have been producing a similar reservoir at the Tamar field for three years. The compilation of our drilling information, flow test data and production data from a similar field along with the independent assessment by Netherland Sewell gives us confidence in the recoverable resource estimate of 21.9 Tcf,” the Noble Energy spokesperson said.

Leviathan essential for energy security

While the ministry provided a differing opinion on the size of Leviathan, compared to the operator’s one, it still highlighted the importance of the field development for Israel.

Giving his approval last week, energy minister Yuval Steinitz said the Leviathan was essential for the country’s energy security and that gas from it would spur growth for the local economy. While the gas will supply the local needs, Steinitz also highlighted the fact that “after years of delays, the vision of Israel as a supplier of natural gas is on the way.”

Noble Energy operates Leviathan with a 39.66 percent working interest. Other interest owners are Delek Drilling with 22.67 percent, Avner Oil Exploration with 22.67 percent, and Ratio Oil Exploration (1992) Limited Partnership with the remaining 15 percent.