Mexico’s oil regulator has announced that state-owned oil company PEMEX must take a minimum 45% stake in its first-ever proposed joint venture with would-be private partners to develop oil reserves in the Mexican portion of the deepwater Gulf.

As reported by Reuters, Mexico’s National Hydrocarbons Commission (Comisión Nacional de Hidrocarburos, or CNH) said that the Trion joint venture will be bid out in the form of a license contract, which is similar to a concession. It will include two operators, one of which must have between a 30 to 45% stake in the project.

Global oil majors are widely expected to bid in the December auction to help develop the Trion light oil field in the Perdido Fold Belt, just south of Mexico’s maritime border with the United States.

Interested bidders have until Sept. 15 to pre-qualify for the auction by meeting both financial and technical minimum requirements, while the final version of the contract and bid terms will be published on Sept. 30.

The license contract to partner with PEMEX On the project will be awarded on Dec. 5. Mexico will also auction 10 separate deepwater fields, including four that surround Trion, in December.

Under the terms of the energy reform, PEMEX can partner with companies in exploration and production projects, but rather than being allowed to pick its partners, they will instead be selected by an auction run by CNH.

The partnership will allow PEMEX to share the investment needed to successfully develop the Trion field, which will be the company’s first major deepwater oil project.

The Trion field holds some 480 MMbbls and will require about $11 billion worth of investment. The field covers about 483 sq mi (1,250 sq km) and is located under more than 8,202 ft (2,500 m) of water.