The Sedco Express rig is already in position at the Leviathan well, and will remain there for 120 days, according to a notice sent to shipping companies.The Leviathan 3 well will verify the natural gas reservoir found by the 3D seismic survey of the structure, and Leviathan 1 well in December 2010. The best estimate is 16 trillion cubic feet of natural gas and the high estimate is 21 trillion cubic feet.Drilling at the Leviathan 3 well was suspended at depth of 2,600 meters on September 5, due to a technical breakdown in the blowout preventer in the Pride North America rig.This breakdown resulted in Leviathan’s partners – Delek Group, Noble Energy Inc. and Ratio Oil Exploration – losing confidence in the rig’s owner, Pride International Inc., which was acquired by Britain’s Enesco plc in 2005.After repairs, the Pride North America rig is due to begin drilling the Dolphin 1 well at the Hanna license, also owned by Delek, Noble Energy, and Ratio, which has an estimated 550 billion cubic feet of gas with a geological probability of success of 73 percent.The Sedco Express rig, owned by Transocean Ltd.arrived at Leviathan after completing the development well at Tamar, owned by Delek, Noble Energy, Isramco Ltd., and Alon Natural Gas Exploration Ltd., two weeks ahead of schedule.It is not known when drilling of the Leviathan 1 well will resume, or which rig will carry it out. The well is due to drill to the deeper oil-bearing strata found in the 3D seismic survey of the structure. The two candidates to drill the well are Sedco Express rig and the Homer Ferrington rig, owned by Noble Corporation, which is currently drilling an exploratory well at Noble Energy’s Block 12 concession in Cypriot waters near Leviathan.Noble owns 39.66% of Leviathan licenses Rachel and Amit, Delek Group units Avner Oil and Gas LP and Delek Drilling each own 22.67% and Ratio owns 15%. The companies own the same stakes in the Hanna license.