(Adds details on Pemex targeting Trion field)
By Gabriela Lopez and Ana Isabel Martinez
MONTERREY/MEXICO CITY, June 9 (Reuters) - Mexican state oil firm Pemex will present to its board this week its first possible deep-water tie-up with oil firms in the Trion field, according to people familiar with the matter, another major step in the opening up of its oil and gas industry.
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 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, located in the Perdido area near the U.S. border, three people familiar with the matter told Reuters.
The field has proven, probable and possible (3P) reserves of 305 million barrels of oil equivalent (boe).
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.
Earlier on Thursday, 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 deep-water 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 aim was for this Perdido "farm out" to take place at the same time as a major deep-water tender later this year.
Mexico's oil regulator has scheduled its first-ever deep water 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. (Additional reporting by Dave Graham; Writing by Gabriel Stargardter; Editing by Marguerita Choy and Alistair Bell)