THE nuclear accord reached in Vienna on Tuesday could eventually reshape global oil markets. After almost two years of talks, the holder of the world’s fourth-biggest crude reserves will benefit from an easing of international sanctions on exports in return for curbs on its nuclear program.

How much more oil can Iran produce?

Iranian Oil Minister Bijan Namdar Zanganeh says the country can increase exports by 500,000 barrels a day as soon as sanctions are lifted, then an additional 500,000 a day in the following six months. Iran produced an average of 2.8 million barrels a day this year.

Goldman Sachs Group Inc. says adding 500,000 barrels a day will take about a year because Iran must first demonstrate its compliance with the terms of the nuclear accord and revive aging wells. Further expansion will need foreign investment, BNP Paribas SA says. The country also has 30 million barrels stored on tankers that it could ship more quickly, according to Bank of America Corp.

What’s the timetable for oil exports?

Sanctions will remain in place at least until United Nations monitors report on Iran’s compliance with the deal in December, diplomats involved in the talks said Tuesday. The International Atomic Energy Agency will issue a report by Dec. 15, Director General Yukiya Amano said. The European Union will lift sanctions once Iran has met its nuclear obligations, according to the diplomats.

Restrictions will “snap back” if the terms of the deal are violated, President Barack Obama said.

What is Iran’s potential?

Iran’s oil reserves are estimated at 157.8 billion barrels by BP Plc. That’s enough to supply China for more than 40 years. The first crude deposits found in the Middle East were discovered in Iran in 1908, and the country was pumping 6 million barrels a day seven decades later.

Capacity has since declined as Iran’s wells have been deprived of sufficient investment and advanced technology to offset falling reservoir pressure. Western oil companies have mostly been absent since the 1979 Islamic Revolution.

What does Iran’s return mean for OPEC?

Zanganeh presented his 11 OPEC counterparts with a letter at their meeting last month saying they should prepare for Iran’s return.

The 12-nation group has exceeded its self-imposed limit of 30 million barrels a day since June 2014. Saudi Arabia’s focus on defending market share by increasing production rather than price by curtailing output means all members are free to pump as much oil as they please.

More Iranian crude could amplify Saudi Arabia’s strategy of pressuring producers with the highest costs while also increasing competition among OPEC members for Asian customers.

Global markets are already contending with an oversupply that International Energy Agency data indicates will be about 800,000 barrels a day in the second half. Brent crude is currently forecast to rebound to an average of about $67 a barrel in the rest of 2015, according to analyst estimates compiled by Bloomberg, as U.S. supply growth slows.

Which markets will Iran target?

Iran’s priorities are Asia and then Europe, Zanganeh said in May. The 1 million barrels of daily sales lost following the 2012 sanctions were split between the two regions. Iran’s Asian trade was mostly taken by Saudi Arabia and Kuwait, whose crudes are chemically similar, according to the U.S. Energy Information Administration. In Europe, Iranian oil was displaced by Russia, Saudi Arabia and Iraq.

Crude exports of about 1.1 million barrels a day have continued to buyers granted exemptions by the U.S.: China, South Korea, Japan, India, Turkey and Taiwan.