Mexico's Pemex will present its first possible deepwater tie-up with oil firms in the Trion Field to its board this week, according to people familiar with the matter. This is another major step in the opening up of Mexico's oil and gas industry.

As part of the farm-out process, Pemex cannot choose which company would help it develop each project, but can suggest specific partners with which to work. The ultimate decision lies with oil regulator, the National Hydrocarbons Commission.

After its state monopoly was ended in late 2013, Pemex was awarded certain blocks in an oil tender known as "Round Zero" and it is now looking for partners to help it develop the so-called farm-outs, which have been plagued by delays.

The first proposed farm-out will be focused on the Trion Field in the Perdido area near the U.S. border, three people familiar with the matter told Reuters. Trion has proven, probable and possible reserves of 305 million barrels of oil equivalent.

Earlier on June 9, Marco Cota, director of exploration and extraction of hydrocarbons in the energy ministry, announced that Pemex would present its first tie-up proposal this week, without mentioning which field it would target.

"It'll be taken to the board, and one of the themes will be the migration of one allocation ... a deepwater allocation," he said.

Since 2014, Pemex has said it is looking for tie-ups in the Trion and Exploratus fields, which are both in the Perdido area.

Cota said that the goal was for this Perdido farm out to take place at the same time as a major deepwater tender later this year. Mexico's oil regulator has scheduled its first-ever deepwater auction in early December for 10 blocks in the Gulf of Mexico, after constitutional amendments in 2013 ended a nearly eight-decade monopoly by Pemex.

The government hopes the oil sector opening will revive oil output in Mexico, which has been falling since 2004.