However, the majority of crude oils, and this applies to the heavier, more viscous petroleums, which are processed by distillation, are usually separated into the lighter fractions and the bottom or. as it is more generally called, the reduced crude.

• 但是，经过蒸馏处理的大多数原油，包括比重较大、粘度更大的原油，一般都分离为较轻组分和残渣，或者更多称作常压重油。