At current consumption levels, oil reserves are expected to last about 40 years. Gas reserves are estimated at 65 years. But each additional percentage point in recovery postpones the deadline by two years.

According to the BP Statistical Review of World Energy, there are 1.39 trillion barrels of proven oil reserves¹. This compares with one trillion barrels consumed since the beginning of the oil era. Reserve estimates have risen constantly, thanks to the discovery of new deposits and, more recently, the extraction of frontier oils. Another opportunity exists to postpone Peak Oil: increasing the recovery rate at existing fields is as good as discov ering a new deposit.

Approximately 35% of the oil in the ground is recovered, meaning that an average of two barrels of oil is left in the ground for each barrel brought to the surface. Exploiting a field to the maximum requires advanced recovery techniques. The primary recovery rate from light crude deposits (the percentage of oil surging naturally to the well head) is often about 25%. Even in liquid form, oil contains dissolved gases that are released when the reservoir's pressure drops due to drilling, or when oil surges to the surface. Operators always try to regulate the pressure of the reservoirs and the output of the wells to extract the oil and the dissolved gases simultaneously and for as long as possible.

Significant progress has also been made in all methods of secondary recovery. Solutions to increase the recovery rate include the injection of gas or water into the reservoir. As Nathalie Alazard-Toux, Director of Economic Studies at the Institut français du pétrole, explains, “each additional percentage point in recovery for all known deposits increases global reserves by two years.” An additional 10% in the recovery rate – admittedly a very favorable scenario – would recover 600 billion additional barrels from global reserves.

Tertiary recovery begins when a deposit approaches the end of its operating life. The viscosity of the oil is lowered by injecting polymers, carbon dioxide or steam into the deposit. In situ burning is another method: some of the oil is burned in the deposit itself to heat the surrounding rock. The heaviest oil components are burned in the process (5 to 10% of the crude content). The temperature reaches 600-800 °C, pushing the oil towards the production wells.

1. Including bituminous sands.