'The U.S. remains by far the most important': OPEC is predicting that competition with the U.S. will drop significantly in less than five years, allowing members of the world’s largest oil cartel to keep dominating the market. During a meeting in Algiers, Algeria, members of the Organization of the Petroleum Exporting Countries (OPEC) predicted Sunday that U.S. shale growth would “slow significantly” after 2023, triggering renewed demand for their own oil.