What will happen in 2015? I cannot predict the future, but oil demand is clearly linked to economic growth. The International Monetary Fund expects the global economy to grow this year. So, global oil demand is expected to grow as well.

But seeing today's prices, supply may even decline, as prices are close to cash costs, according to consultants such as Wood Mackenzie. As a result, energy companies could shut down some of their production.

If the brighter economic outlook becomes reality, the market could tighten, which would support higher prices. But two questions remain: How far and how long will prices fall? And how quickly can prices recover?