Middle East oil exporters are locked in an increasingly fierce battle for the world's fastest-growing markets in Asia, as producers worldwide ship more crude east to compensate for shrinking demand from the United States and Europe.
The fight for the trillion-dollar Asian oil market has ended decades of comfortable dominance for Middle East producers, who faced so little competition that refiners in Asia complained of being charged a premium of a dollar or so per barrel above what buyers in Europe or the Americas paid.
The picture has changed as rising US shale supply has sapped demand in the world's largest crude consumer for the imports it previously bought from Latin America and West Africa. In Europe, years of shaky economic performance and increasing fuel efficiency have shrunk Russia's traditional market.
With nowhere else to expand, producers are pushing for more sales in Asia. The competition will become even stronger if sanctions on Iran are lifted in coming months and the million barrels per day (bpd) in Iranian exports that have been choked off returns to the market.
Under sanctions, Iran fuelled the competition by offered discounts, easy credit and free shipping to keep oil flowing. If sanctions are lifted, it may have to be even more aggressive to regain market share.
Amid these shifting market pressures, the Organization of the Petroleum Exporting Countries meets on Wednesday to consider adjusting its output target of 30 million bpd.
With oil prices well above $100 a barrel, OPEC is likely to leave the target unchanged for now, say delegates who will attend the meetings in Vienna.
"These market dynamics - rising Iraqi output, increase in non-OPEC production, particularly in North America, and the potential return of Iran over the longer term - are going to put downward pressure on oil futures and OPEC producers will face an increasing challenge going forward," IHS oil consultant Victor Shum said.
Iran's shrinking supply has facilitated Iraq's expansion, providing Baghdad with ready made markets. Iraqi output is rising as international energy companies repair the damage wrought on its industry during years of sanctions and war.
Oil sales are paying for Iraq's reconstruction and, seeking to sell every barrel available, officials are playing hardball.
"We'll do our best to market the maximum amount of oil. We don't want to leave our available oil idle," a senior Iraqi official told Reuters, declining to be identified as he was not authorised to talk to the media. "So good luck