Crude classification terminology: Which base type of crude oil is commonly referred to as an asphaltic crude in refinery practice?

Introduction / Context:
Refineries often classify crude oils based on the predominance of hydrocarbon families: paraffinic, naphthenic, or mixed. This classification guides expectations for product slates, residue properties, and asphalt yield during processing.

Given Data / Assumptions:

• Asphaltic residues arise when heavier polycyclic and polar components concentrate in the bottom fractions.
• Naphthenic crudes are typically richer in cycloparaffins and polycyclic materials.
• Terminology reflects observed residue characteristics.

Concept / Approach:
Naphthenic-base crudes yield residues with higher asphaltene content and are therefore commonly called asphaltic crudes. Paraffinic crudes tend to produce waxy residues and higher paraffin content in distillates. Mixed crudes sit between these extremes and “aromatic” is not a standard crude base label in this context.

Step-by-Step Solution:

Verification / Alternative check:
Refinery handbooks routinely equate naphthenic-base crudes with asphaltic character and paraffinic-base crudes with waxy character.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing high aromatic content in products with the “aromatic” label for crude base; the conventional pairings are paraffinic (waxy) vs naphthenic (asphaltic).

Final Answer:
Naphthenic