There are two new dimensions to international oil markets that are creating a dilemma for Opec and may be sowing the seeds of an oil price shock. The first is the fallout from the Arab uprising, which began in 2011. The second is the development and application of shale technology – horizontal drilling and hydraulic fracturing or “fracking” – to oil production.

A significant consequence of the upheaval in the Middle East and north Africa is that oil-producing governments need more revenue to pay for social policies that will assuage popular unrest. This requires higher prices. For example, in 2008 it was estimated that Saudi Arabia needed about $50 a barrel to balance the books. Last year estimates put the figure closer to $95.

Such high prices will produce market responses and this is where shale technology comes in. This relatively high-cost technology has led to a dramatic increase in oil production, most obviously in the US. The new Review of World Energy Statistics from BP shows that 2012 recorded the highest single-year increase in US oil production ever.