On Aug. 23, Mexico's oil regulator, known as CNH, approved auction terms and contracts for a dozen onshore oil and gas fields to be bid out next year as part of a series of tenders following a landmark energy sector opening.

The second phase of the so-called Round Two tender will feature licenses, CNH said. Winners will be announced on April 7, 2017.

The fields are located in the gas-rich Burgos Basin in the southern state of Chiapas, as well as in the Southeast Basin, which is home to many of Mexico's best-producing shallow-water fields. Seven of the blocks are for exploration and extraction, while five are for exploration.

Hoping to reverse slumping crude output, Mexico ended the decades-long monopoly of national oil company Pemex in 2013, paving the way for private and foreign producers to operate on their own. A sharp fall in crude prices over the past couple years, however, has made that harder.

The 2017 auctions will follow three auctions that began last year covering both shallow-water and onshore blocks. The first highly-anticipated deepwater auction is scheduled to take place in December.