[LONDON] Oil prices fell on Wednesday as investors digested the likely impact of increasing Iranian fuel exports at a time of heavy oversupply.
A milestone nuclear deal reached on Tuesday between six world powers and Iran will mean sanctions that have limited sales of Iranian oil for several years are likely to be lifted in early 2016.
An official at the National Iranian Oil Company said on Wednesday that Iran's oil production can increase by 500,000-600,000 barrels per day (bpd), confirming the prospect of a ramp-up in supply from a nation that holds some of the world's largest oil reserves.
Iran can reach its pre-sanctions level of 4 million bpd within six to twelve months if there is enough demand, he said.
Most analysts agree that first Iranian oil exports could enter the global market in early 2016, but their estimated additional volumes vary between 300,000 and 700,000 bpd.
Analysts at Goldman Sachs estimate Iran could supply and extra 200,000-400,000 bpd in 2016 on top of a release of 20-40 million barrels from floating storage.
"We view the 2016 prospects for higher Opec production, including from Iran, as a growing downside risk to our oil price forecast," Goldman Sachs analysts said in a note to clients.
Goldman's current forecast is for Brent to average US$58 a barrel in 2015 and for US$62 next year, while it expects US crude to average US$52 and US$57 respectively this year and next year.
By 1104 on Wednesday Brent crude was down 50 cents at US$58.01 a barrel. US futures fell 35 cents to US$52.69.
Iran, a member of the Organization of the Petroleum Exporting Countries, exported almost 3 million bpd of crude at its peak before Western sanctions reduced shipments to about a million bpd over the past two and a half years.
Traders are also keeping an eye on China for clues to the health of the economy. A savage correction shaved about 30 per cent off the country's stock market in the past month before Beijing support measures helped to stem the tide.
China, one of the world's top energy consumers, reported stable economic growth on Wednesday at an annual rate of 7 per cent.
French bank Natixis said there was a risk of oil prices falling further if China's economy slows while global oil production stays close to record highs.