Colombia last had an auction in 2014. The government held off recent bidding rounds because of low international crude prices, repeatedly postponing an auction that had been set to take place last year.

"With the 20 blocks that we are submitting for investment consideration, we hope to discover about 1 billion barrels of oil," Luis Miguel Morelli, president of the National Hydrocarbons Agency (ANH), told reporters.

The government expects investment of about $600 million to explore the 18 onshore blocks and two offshore blocks that will begin to be awarded in June, Morelli said.

Colombia has proven reserves of 1.7 billion barrels, equivalent to 5.7 years of consumption, with average production of 865,000 barrels per day. About 50 percent is destined for domestic consumption and the rest for export.

The government has said it wants to increase reserves to at least 10 years of consumption.