This is from the oil well fires from after the Gulf War, when Saddam’s retreating forces set alight Kuwait’s reserves. These guys are part of a company contracted after the war to clean up the disaster and this is one of the methods they used. It was in a documentary (can’t remember the name) and apparently they were a firefighting company so would light the oil well on fire, then detonate some explosives to remove oxygen away from it, thereby making the clean-up process much simpler (wouldn’t quote on me this though).

-/u/ftxs