By Arathy Somasekhar

HOUSTON (Reuters) - Peru's niche Bretaña crude oil is gaining popularity in the United States, with the first cargo discharging in the U.S. Gulf Coast this month as U.S. refiners seek alternatives for declining Mexican heavy crude.

Bretaña, a rare heavy sweet crude with minimal metals, is produced in the Peruvian side of the Amazon rainforest. It is then barged along the Amazon river and loaded onto larger ships that depart from Brazil. 

The vessel Radiant Pride transported about 300,000 barrels of Bretaña from Manaus, on the banks of the Negro river in Brazil, and discharged on Jan. 2 in Houston, ship tracking data from Kpler and LSEG showed.  

The cargo was bought by oil major Shell, a source said. Shell declined to comment. 

"Given the drop in heavy sour crude from Mexico to the U.S. Gulf Coast over the last year, we are starting to see new heavy grades being pulled in to backfill this loss - this is a trend we only expect to continue," said Matt Smith, an analyst at Kpler.

U.S. imports from Mexico fell to their lowest on record in 2024 as the Latin American country's oil production fell and a larger portion of output remained at home to be refined.

Two cargoes of Peru's Bretaña, a relatively new entrant into the market since production began in 2018, discharged at the U.S. West Coast last year - one at Marathon Petroleum and another at PBF Energy terminals, the Kpler data showed.

Marathon Petroleum declined to comment. PBF Energy did not immediately reply to a request for comment. 

PetroTal Corp, the producer of Block 95 where the Bretaña oilfield is located, bought the assets from Canadian producer Gran Tierra Energy in 2017, and currently produces about 20,000 barrels of oil per day, according to Chief Executive Officer Manuel Zúñiga.

Challenges with transporting the crude via a pipeline operated by Peru's state oil firm Petroperu led to a brief halt in exports between 2022 and 2024, Zúñiga said. 

Petroperu has struggled in recent years to keep the line operational amid spills and social conflict interrupting its flow. 

Three cargoes of Bretaña headed to the U.S. West Coast and one to the U.S. East Coast between 2020 and 2022, Kpler data showed.

About 90% of the Bretaña crude produced by PetroTal is exported, and the remaining is transported by barges to Petroperu's refinery in Iquitos, Zúñiga said. 

PetroTal has a contract with Houston-based Novum Energy under which Novum buys the crude for export and arranges its transportation, Zúñiga added.

Novum did not immediately respond to a request for comment.

While PetroTal hopes to increase production, permitting delays as well as reliance on barges are a current limitation, Zúñiga said. 

"You need access to the pipeline," Zúñiga said, adding that the company is working to secure use of the infrastructure. 

Petroperu said last year that it would hold negotiations with producers in the Peruvian jungle so that they can use the pipeline with a fair rate to help cover operational costs.