Summary
ISIS has consolidated control over several oil fields throughout Syria and Iraq, most notably the Al-Omar oil field in eastern Syria's Deir al-Zor, seized from its rival the Nusra Front earlier this month.
Meanwhile in Iraq, reports indicate that ISIS has begun selling oil extracted from several small fields at a considerable profit. Officials from the Iraqi oil industry have mentioned profits of $1 million a day for ISIS from the group's Iraq operations – outside of their control are much larger fields under the control of the central government in the south, and the Kurdish authorities in the north.
There are also questions over how sustainable the oil fields are.
In Iraq, the oil is often taken to Syria or smuggled into Turkey and Iran.
The Iraqi authorities, meanwhile, have now begun actively targeting the trucks used to transport ISIS' oil, which could put a serious dent in the group's revenue.
Northern Iraq's oil infrastructure was already in decay prior to the insurgent gains spearheaded by ISIS last month.
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