Since Daesh captured the oil-rich province, it has been selling oil to the Assad regime, though it controls most of the oil fields in the region.
Despite all the Russian and Iranian support for the regime, which has been ongoing since the beginning of the Syrian Revolution, they still cannot cover all the oil needs to the regime, meaning that there are some channels upon which Assad relies to secure his needs of oil and energy. The fact that the regime and Daesh agree not to share the real number of the oil production in their controlled territory and not to reveal their oil trade confirms the strong cooperation between both.
The Assad regime is not only buying oil from Daesh, but it also helps the organization in the administration of some of the oil fields.
Daesh exploits the bad and tragic living conditions of civilians by using them to refine oil with very basic materials. The primitive tools used to extract and refine oil have led many of the civilians to suffer from inflammation and breathing issues. In addition, there are some women who have given birth to disfigured babies due to the pollution in the region that has been caused by the primitive means of refining and extracting oil.