* Exports of medium-sweet Buzios may start in Oct -sources
* Petrobras hires trader in Singapore to market oil to China
* Chart of Brazil oil flows to China: tmsnrt.rs/2JPyQXp
By Florence Tan and Alexandra Alper
SINGAPORE/RIO DE JANEIRO, July 27 (Reuters) - Brazil's state-controlled energy company Petrobras plans to push more crude oil to top importer China by marketing a new medium-sweet grade that could be shipped from October, two sources with knowledge of the matter said.
Petrobras expects to start pumping pre-salt oil from new platforms in the fourth quarter that would add to output from Latin America's biggest producer and lift its exports.
The new supply could enlarge Brazil's market share in China as buyers there cut oil imports from the United States following Beijing's announcement it would impose tariffs on U.S. crude in retaliation against similar moves by Washington.
"Petrobras' oil export curve is increasing and China is currently the company's main market," a Petrobras spokesman said in an e-mail.
"With (Chinese) refineries' growing interest in buying oil directly from producers ... Petrobras will grow its presence with these refiners."
Petrobras started production in April at its wholly-owned Buzios pre-salt field in the Santos basin from platform P-74, located about 200 km off the Rio de Janeiro coast in water depths of 2,000 metres, according to the company's website.
Two more platforms, P-75 and P-76, are to come online in the fourth quarter. Total Buzios output is expected to grow to 750,000 bpd by 2021, once an additional four platforms come online, the company said.
Buzios crude has API gravity of 28.4 degrees and contains about 0.31 percent sulphur, similar in quality to Brazil's Lula crude, one of the most popular oils in China, the company said.
The new supply could help lift Petrobras' crude oil exports, which dropped 53.8 percent in June from a year ago to 696,000 barrels per day (2.86 million tonnes) as the company hiked its refinery output.
Petrobras' overall production in June stood at 2.03 million bpd, down 1.5 percent from May.
Brazil's oil liquids output, including biofuels, is expected to rise by 200,000 bpd to 3.5 million bpd in 2019, after holding steady in 2018, according to consultancy Energy Aspects.
China's demand for low-sulphur crude, such as oil from Angola and Brazil, jumped over the past two years after its independent refiners, also known as teapots, were allowed to import crude.
That has moved Brazil up two notches since 2017 to fifth on China's supplier list, with 657,000 bpd in the first quarter this year, according to data from China customs.
The teapots' oil imports from Brazil more than doubled in the first half of 2018 to 350,000 bpd compared with the same period a year ago, according to Beijing consultancy SIA Energy.
More than half of Brazil's shipments to China went through ports in Shandong province, home to most of China's independent refiners, according to Thomson Reuters Eikon data.
Petrobras also supplied the first crude cargo to Chinese chemical producer Hengli Group for the start-up of its new refinery in northeast China in the fourth quarter of this year. New Brazilian crude Mero was also delivered to Shandong in June.
Petrobras has expanded its trading team in Singapore to step up marketing efforts in China, the two sources familiar with the matter said. The company has appointed a business development person from within the company and hired a crude trader from a Chinese refiner who will join in September, the sources said.
"In order to improve market share in China, and considering the entry of the teapots in the international market, Petrobras considers that it is necessary to have a professional fluent in Mandarin for the specific development of this market," the company said, without confirming the new hire.
Asia's largest refiner Sinopec bought a third of China's Brazilian oil imports in the first half of 2018, up 13 percent from a year ago, SIA Energy analyst Seng Yick Tee said.
"Sinopec and independents have the appetite for additional crude imports from Brazil, and the potential tariffs on U.S. crude is one of the reasons," Tee said.
Trade flow data on Eikon, however, shows Brazilian exports to Shandong look set to drop in the third quarter - before the additional Buzios platforms start up - as poor margins and tighter credit have forced teapots to cut runs.
The tough environment is expected to push independents to seek more competitive oil supplies, Tee said.
Other sellers of Brazilian crude include Royal Dutch Shell and Equinor. State-owned China National Petroleum Corp (CNPC) and CNOOC Ltd also have equity stakes in Brazilian oilfields.
Reporting by Florence Tan in SINGAPORE and Alexandra Alper in RIO DE JANEIRO; Editing by Tom Hogue