How to save the world using game theory ?

Why does it seem so hard for the Organisation of Petroleum Exporting Countries (OPEC) to reach an agreement on crude oil production ? Looking at the oil prices evolution since 2014 leads us to a statement : oil producers are facing a hard time in terms of profits. It would be to their entire benefit to agree on a lower amount of production, so that they could higher the oil prices.
Although the oil price is sometimes naively seen as a simple variable value, which only depends on the economic conditions, a thorough glance on the international oil market makes us consider that various microeconomic tools are taken into account.