Leviathan Gas Field, Levantine Basin, Mediterranean Sea, Israel
Leviathan Natural Gas Field, located in the eastern Mediterranean Sea area, off the coast of Israel, was discovered in December 2010. The discovery is situated in 1,645m of water in the Levantine Basin, located approximately 130km west of Haifa, Israel.
At the time of discovery, the Leviathan gas field was the most prominent field ever found in the sub-explored area of the Levantine Basin, which covers about 83,000 square kilometres of the eastern Mediterranean region.
The Leviathan field falls within the precinct of the Rachel and Amit licenses. Production is expected to commence in 2017.
Partners of Noble Energy with interest in Israel's Mediterranean field
Houston-based oil and natural gas exploration and production company Noble Energy is the operator of the Leviathan gas field. Its share in the project is 39.66%. The Leviathan field is the largest discovery ever for Noble Energy.
Delek Group subsidiaries, Delek Drilling and Avner Oil Exploration, have a working interest of 22.67% each in the Leviathan project. Ratio Oil Exploration is the other stakeholder, with 15%.
Geology of the Levantine Basin and recoverable oil and gas reserves
The Levantine geological basin was formed in several main tectonic stages, and early Mesozoic rifting led to the shaping of a large graben and horst system, stretching across the onshore and offshore Levant Basin. The basin is infilled by post-rift tertiary sedimentation.
Reservoirs within the basin mainly contain Mesozoic and Paleogene sandstones, near shore marine and submarine sandstones and Jurassic and Cretaceous shelf-margin carbonates.
The Oligo-Miocene reservoir rocks at Leviathan field are deep-water slope and fan sandstones sealed by sedimentary rocks of the mid to late Miocene age and Messinian age salt. Natural gas at the Leviathan field was found in several sub-salt Miocene intervals.
As per the US Geological Survey (USGS) estimates, the entire Leviathan Basin holds a mean approximation of 1.7 billion barrels of recoverable oil and a mean of 122 trillion cubic feet of recoverable gas.
The Leviathan gas field's natural gas reserves are estimated to be about 17 trillion cubic feet (tcf). Besides natural gas, the field is said to contain 600 million barrels of oil beneath the gas layer.
Exploration and drilling by Noble Energy at the Leviathan field and wells
Noble Energy commenced drilling on the Leviathan-1 well in October 2010 using the Sedco Express deep-water semi-submersible rig, which is owned by Transocean. In the first stage of drilling, the well was drilled to a depth of 5,170m. It encountered a minimum of 67m of natural gas pay. The gas was discovered in several sub-salt Miocene intervals.
In the second stage of drilling, the well is intended to touch an additional depth of 2,030m, where the estimated natural gas reserve is expected to reach 25tcf.
In May 2012, drilling operations at the Leviathan-1 well were suspended after reaching a depth of 6,522m, approximately 678m short of the target depth. The suspension took place due to high well pressure and mechanical restrictions of the well-bore design. The work is not expected to restart until the end of 2013.
Drilling of Leviathan-2 well was started in March 2011 by the Pride North America rig. The drilling operations, however, had to be stopped after detecting a flow of water in the well hole.
Drilling of the Leviathan-3 well commenced in June and was successfully completed in December 2011. The third well, located approximately five kilometres east of the original Leviathan discovery, was drilled to a total depth of 5,226m and encountered a minimum of 88m of natural gas pay.
Maritime border issues between Lebanon and Israel over the gas field
Lebanon considered the Leviathan and Tamar gas fields to extend into Lebanese territory and claimed Israel was ignoring this fact. Israel retaliated by threatening to use force to protect its gas discoveries.
The rights dispute was resolved in August 2010 when the Lebanese Government presented its official view to the United Nations, where it stated that the two disputed gas fields, Tamar and Leviathan, do not fall within its territory.