Related Clues:

• Barrel-producing gp.
• Angola joined it in 2007
• Oil acronym
• Qatar joined it in 1961
• Barrel org.
• Petroleum cartel
• Oil group
• Oil alliance
• Gas group
• Big NYSE influence
• Barrel-making gp.?
• 30-Across cartel
• Petroleum-regulating gp.
• It has us over a barrel
• Cartel since '60