The agreement struck between the five permanent members of the UN Security Council plus Germany (P5+1) and Iran on March 2 paved the way for a comprehensive deal to begin lifting sanctions in late June. Iran has been off limits to most foreign investors for nearly a decade. Unsurprisingly, it is regarded as El Dorado by many international corporations, particularly those in the energy sector.

Exxon is the world’s largest listed energy group, and like all big international oil companies it is facing structural challenges that make it difficult for it to grow. Stability while throwing off a lot of cash may be the best they can do.

Wintershall will continue investing in its core regions, with Russia remaining the most important area for the company.

OPEC oil ministers expressed optimism about their strategy of pumping more crude oil and fighting for market share, amid expectations they will stick to their production target when they meet at the end of the week.

China started construction last week of a pipeline to receive Russian gas, Russian state gas company Gazprom said on Tuesday.

Greece expected to sign a memorandum on Turkish Stream during the St. Petersburg International Economic Forum, which will be held June 18-20.

Russia's Gazprom plans to start building a pipeline to Turkey this month to get gas to Europe without going through Ukraine, company sources said, although it has no firm agreement with Ankara and faces opposition from the European Union.

Russian oil output remained unchanged in May at a post-Soviet high of 10.71 million barrels per day (bpd), Energy Ministry data showed on Tuesday, three days before OPEC meets to decide on output levels.

The top oil officials of Iraq and Venezuela said on Wednesday that $75 to $80 a barrel was now a "fair" price for oil, reflecting an emerging consensus on a possible equilibrium for volatile markets.

OAO Gazprom, the biggest natural gas producer, will probably see lower gains in Europe for at least four years as weaker oil prices and rising competition threaten to further cut its profits, a government forecast showed.