Related Clues:

• Petroleum gp.
• Grp. with crude intentions?
• Group that includes the U.A.E.
• Iran, Iraq and nine others
• Crude letters
• Org. based in Vienna
• Energy acronym
• Arab oil org.
• Oil-cartel acronym
• 51 Across grp.
• Petroleum org.
• 'Well' financed grp.
• Powerful cartel
• Angola joined it in '07
• Crude cartel: Abbr.