The companies cited the best estimate for unrisked gross prospective gas resources provided by Texas-based consultants Netherland, Sewell & Associates.
They said they have not yet made a decision as to whether they will develop the reservoirs in the Tamar Southwest prospect.
Texas-based Noble Energy owns 36 percent of Tamar, while Delek Drilling and Avner Oil Exploration , both subsidiaries of Delek Group, hold 15.625 percent each.
Isramco Negev holds 28.75 percent and Dor 4 percent.
Two of the world’s largest offshore fields from the past decade were found in Israeli waters. The first of the fields – Tamar, with an estimated 10 tcf of gas – came online in late March.