Shares rose 4.5 percent to $1.44.

A well drilled in the Tempranillo area in the Huila province in South-eastern Colombia was found to yield between 1,600 barrels a day and 2,400 barrels of crude a day.

The company produces about 400,000 barrels of oil equivalent a day, so the discovery is not really significant for the company, said Rupert Stebbings, a Medellin-based analyst with Interbolsa.

"The stock is starting to trade on checks it cannot cash - great potential but a long way to go," he said.

The gain this week was the largest gain for the company in months. The company plans to more than double daily crude-oil output to 1 million barrels by 2015 as Colombia, Latin America's No. 5 oil exporter, seeks to maintain its self-sufficiency in petroleum. The country's oil output has fallen 40 percent in the past seven years.