In Iraq, Exxon Mobil Corp.’s prospects were finally beginning to look up. This week, they got a little cloudier. Oil production at the Exxon-led West Qurna-1 field in southern Iraq has doubled, now capable of delivering half a million barrels of crude a day. And the company recently obtained more generous terms in its contracts with the government, booking higher profit margins. But in mere days, Islamic militants have overrun two major cities and Kurdish forces have taken over a third, exposing security vulnerabilities that could jeopardize the billions of dollars western companies are spending to revitalize Iraq’s energy sector. The unrest has pushed up global oil prices , but it’s hardly welcome news for the likes of Exxon, BP PLC and Royal Dutch Shell PLC. Those companies have done much of the heavy […]