Bitumen 60/70 transported from the producer to refineries

Bitumen  (bitumen 60/70)  is a mixture of  aromatics, resins, saturates and asphaltenes. The saturates are nonpolar material including branched, cyclic saturated hydrocarbons and linear hydrocarbons. The asphaltenes and resins have polar substituents.
Asphaltenes are insoluble in an excess of pentane (or heptanes) whereas the resins are miscible with pentane (or heptanes).
amount of asphaltenes, aromatics, saturates and resins in bitumen (bitumen 60/70) may be measured whit a SARA (Saturate, Aromatic, Resin and Asphaltene) analysis method. amounts of asphaltenes, resins, saturates, and aromatics in bitumen (bitumen 60/70) is dependent on the geographical location of the bitumen (bitumen 60/70) and the test method used.
heavy petroleum liquids have an API (American Petroleum Institute gravity) gravity of less than 20°. Extra heavy petroleum liquids is defined as a dense petroleum liquids with an API (American Petroleum Institute gravity)  gravity of less than 10°. Bitumen (bitumen 60/70) has an API gravity of less than 10° and an extremely high viscosity. Bitumen (bitumen 60/70)  is distinguished from extra heavy petroleum liquid by the degree in which it has been degraded from the original crude oil. Often bitumen (bitumen 60/70)  is present as a solid and does not flow at 25 Degrees Celsius temperature.
After extraction of bitumen (bitumen 60/70)  it must be transported from the producer to refineries for processing. The transportation of bitumen (bitumen 60/70) by pipeline requires that the viscosity of bitumen (bitumen 60/70) be low enough so that the pumping requirements and the size of the pipeline are economically optimal. There are several methods which bitumen (bitumen 60/70)  may be transported by pipeline. These methods include; core annular flow; dilution; oil/water emulsion formation; heating; and partial field upgrading.
Dilution is a conventional method that producers have used to transport bitumen (bitumen 60/70) . Dilution requires large quantities of diluent to reduce the viscosity and make the bitumen (bitumen 60/70) easier to pump through the pipeline. At the refinery, the diluent is typically separated from the bitumen (bitumen 60/70) and pumped back to the production site via separate pipelines for reuse.
Typically, in order for pipeline transportation of bitumen (bitumen 60/70)  to be possible, diluent is added to the bitumen (bitumen 60/70)  to prepare a mixture of bitumen (bitumen 60/70)  and diluent. Diluents are mixtures of hydrocarbon solvents or hydrocarbon solvents which are added to the bitumen to improve the movement of the bitumen through a conduit.