US oil explorer Kosmos Energy’s first well in the Western Sahara has failed to find hydrocarbons in sufficient quantities to make the discovery viable for commercial development.

Kosmos says its KOS CB-1 exploration well encountered gas and condensate.

“While it has not delivered a commercial discovery, it confirmed the exploration potential of the Cap Boujdour block and demonstrates the presence of a working petroleum system,” said Kosmos spokesperson to Thomas Golembesk.

“We remain optimistic about exploration offshore Western Sahara and will be using the information gathered from CB-1 to refine our exploration plan in the region, including deciding on the location and timing of a potential second well.”

The well was located approximately 170 kilometres offshore in 2,135m of water. It was drilled on plan to a total depth of 5,700 meters at a net cost to Kosmos of approximately $85m.

Kosmos has held rights to conduct exploration activities in the Cap Boujdour permit area since 2006 under a petroleum agreement with the government of Morocco’s Office National des Hydrocarbures et des Mines (ONHYM).

Kosmos operates the Cap Boujdour license with 55 per cent equity. Its partners are ONHYM, which holds a 25 per cent stake and Capricorn Exploration and Development Company Limited, which is a wholly owned subsidiary of Cairn Energy PLC and holds a 20 per cent stake.

The Western Sahara is claimed by both the government of Morocco and the Algeria-backed indigenous Saharawi group, the Polisario Front. While most of the region is controlled by Morocco, neither entity’s sovereignty is recognised by the UN.

Due to the disputed nature of the territory, oil companies have been wary of drilling in its waters, which hold the last unexplored cretaceous basin in the Atlantic Ocean.

Kosmos Energy has previously said it believes the basin could hold as much as a billion barrels of oil.