US Patent 7770643 Hydrocarbon recovery using fluids

The recovery of hydrocarbons from hydrocarbon bearing rock, sands or other geological materials (collectively “rock”) uses a recovery fluid. In certain embodiments, the recovery fluid includes miscible compounds or an azeotrope-forming mixture (including an azeotrope), used alone or with other compositions. Two or more compounds in the recovery fluid yield a mixture with different and/or improved characteristics over those of one or more of the component compounds in both liquid and vapor states.