How to Make the Oil Flow

WATER OR GAS INJECTIONPumping large volumes of water or natural gas into a field keeps pressure up and pushes more crude petroleum from the rocks. Fields under water injection typically have recovery rates up to 35%

THERMALOne of the new "enhanced recovery" techniques, this uses steam, electricity, or underground combustion to soften heavy oil and make it easier to pump out. The recovery rate using thermal techniques can go as high as 55%.

CHEMICALThis new method uses polymers to boost the power of water pressure and loosen trapped oil. Other chemicals, such as surfactants, make it easier to break oil free from rocks. This is in early development. Recovery rate: about 55%.

CARBON DIOXIDEUtility plants and oil fields both emit CO2. Oil companies want to pump the CO2 into wells to create enough pressure to force out oil. A kind of Holy Grail of enhanced recovery, this technique is only being used at a few sites.

Data: Royal Dutch Shell

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