An oil exploration campaign led by Exxon Mobil Corp. at the Tanager-1 well in the Kaieteur Block offshore Guyana discovered hydrocarbons but it does not appear to be financially viable on its own, a spokesman for the company said Nov. 17.

As part of a consortium with Hess Corp. and China’s CNOOC Ltd., Exxon has made 18 discoveries totaling some 9 billion barrels of recoverable oil and gas in Guyana’s massive Stabroek Block, southwest of Kaieteur. Production of light, sweet crude from Stabroek’s Liza-1 well began last year.

Exxon is also the operator of Kaieteur and holds a 35% stake in the block, where Cataleya Energy Ltd. and Ratio Guyana Ltd. each hold 25% stakes. Hess holds the remaining 15%.

“We remain committed to evaluating the exploration potential in the Kaieteur Block,” the spokesman said.

Exxon’s oil discoveries have the potential to transform the economy of Guyana, a poor South American country of some 750,000 people that has until now depended on agriculture and mining. But other oil explorers' discoveries have not been as promising as Exxon's finds in the Stabroek Block.

Westmount Energy Ltd., which holds shares in Cataleya and Ratio, told the London Stock Exchange on Nov. 17 that preliminary evaluation of the Tanager discovery indicated it contained less-valuable heavy crude. Westmount said it expected the well to be plugged and abandoned in the coming days.