Venezuela's share of Latin America's proven oil reserves has risen from 67% to 87% over the past decade, according to data compiled by BNamericas.

The Caribbean nation's crude volumes climbed almost fourfold over the period to 298Bb, boosted by discoveries in the Orinoco heavy oil belt.

Brazil is the region's next most prolific explorer, lifting reserves to 15.6Bb from 11.2Bb after a succession of oil finds in the Atlantic's pre-salt region.

Ecuador and Colombia have each expanded their oil portfolios by 60% since 2004. Ecuador's proven reserves rose from 5.1Bb to 8.2Bb while Colombia's tally hit 2.4Bb from 1.5Bb.

Bucking the trend were Mexico and Argentina, which both reported declines. Mexico's proven reserves fell to 11.1Bb from 14.8Bb while Argentina's available deposits dipped to 2.4Bb from 2.7Bb.

According to Rio de Janeiro-based oil consultancy A&P, proven reserves do not guarantee production gains, particularly in the case of Brazil's state-run oil company Petrobras.

"There have been some significant discoveries in Brazil and they deserve attention," A&P director Arthur Pimentel told BNamericas.

"But the challenge now is to develop and commercialize these fields, some of which lie at unprecedented depths for oil production."