TEL AVIV, Israel – Technical constraints again have forced Noble Energy to suspend well deepening operations on the deepwater Leviathan gas discovery offshore Israel.
Following halting of the original Leviathan 1 exploration well, Noble re-entered the well to resume drilling toward lower layers earlier this year, according to Delek Group, owner of partner Delek Drilling.
Last week, however, Noble advised the partners that the well deepening had been suspended before reaching the primary target middle Cretaceous and lower Cretaceous layers, at a final depth of 6,500 m (21,325 ft) below sea level - the deepest drilled to date in the Levant basin.
This was due to high pressure encountered in the lower Oligocene layers higher up, and the mechanical limits of the wellbore, which had originally been planned as an exploration well of the Leviathan natural gas reservoir.
At around 6,300 m (20,670 ft) below sea level, gas was detected, but this layer is not considered to be a natural gas reservoir owing to the characteristics of the rock. However, what was found comprised heavy natural gas, which suggests an active hydrocarbons system may be present in the deeper layers.
In addition, the high pressure registered at the lower depths indicates potential for an overlying seal which could mean a hydrocarbons reservoir exists below this layer.
Noble intends to analyze the well data over the next two months, including electric, radio-active, and seismic logs compiled while drilling. The company will investigate the feasibility of using a rig with equipment to penetrate the targeted deeper layers under their anticipated pressures.
Delek adds that the updated budget for the drilling program is around $270 million, including $100 million for the deepening operation.
The Leviathan partners have agreed to perform production testing on the Leviathan natural gas reservoir, using the semisubmersible Homer Ferrington. This three-week exercise should start shortly and will involve flowing gas from the layers of the reservoir at different rates (up to 40 MMcf/d or 1.1 MMcm/d), in order to measure the pressure within the reservoir and to analyze the gas composition.
The budget for the testing is around $30 million, which is in addition to the $27 million for the assigned for the equipment and keeping the rig on standby.