Recovery – interrelation of petroleum product and entry raw material, expressed in mass percentages.
Recovery (production) of oil/petroleum and gas – extraction of oil/petroleum and natural gas (as well as gas condensate and associated water) from a reservoir through a well to the wellhead on the surface.
Recoverable reserves – the quantity of discovered mineral raw material (oil/petroleum and natural gas) whose extraction is technically possible.
Refinement/improvement – the technological process where harmful and non-useful admixtures are separated from useful mineral raw material; where production of petroleum and gas are concerned, refinement is: separation of natural gas from petroleum, gas condensate from natural gas, water from petroleum and natural gas, cleaning petroleum to eliminate solid particles, separation of harmful admixtures from natural gas (carbon-dioxide, hydrogen-sulphide, mercury, etc.), dividing natural gas into ingredients (methane, ethane, propane, butane, pentane), etc.
Reforming – transformation of hydrocarbons from one form into another (alkanes into cycloalkanes or into aromatics) using catalysts, temperature and pressure.